Duration: 10/01/2016 to 10/01/2021

Administrative Advisor(s):

NIFA Reps:

Non-Technical Summary

Statement of Issues and Justification

The pecan industry now has a highly effective and sophisticated insect and mite pest management system in place that conserves the foliage and nut crop. This was achieved through research by the USDA/NIFA regional research projects in collaboration with extension specialists, private industry and cooperating pecan growers. Pecan foliage can be protected from aphid and mite feeding injury with “bottom-up” control methods where fertilizers, pesticides and ground cover plants are applied to the soil or with “top-down” control methods where the foliage is treated directly (usually with an airblast sprayer) with: insecticides; miticides; repellents; biological control agents, such as, insectary-reared insects and mites or cultured-microbes or their byproducts; natural products, primarily plant extracts; or soaps and surfactants that modify the leaf surface. Pecan nuts are currently protected by “top-down” controls with insecticide sprays timed to be applied when the pest populations occur in the orchard in sufficient abundance to cause economic injury to the crop. The key to effective nut pest control is to have an effective insect monitoring program ongoing in the orchard from budbreak to harvest. Pecan growers, throughout the U.S., have many control options including both federally registered insecticides and miticides and proven biological controls. Scouting techniques are also effective, well-known and used by a growing portion of growers. The system is not static and changes from season to season because of four main factors. First, INNOVATION leads to the development of new and more effective control methods each year. Second, REGULATION of insecticides and miticides can result in the gain/loss of their registration for use on pecan. Third, SELECTION within pest populations can develop a tolerance or resistance to certain chemical controls. Fourth, STATUS of the orchard changes with each season with respect to: climate; types and abundances of pests; value and size of the nut crop locally and across the region; and costs of production. The regional research approach has been an effective forum for finding alternative insect and mite controls and monitoring methods for pecan growers in the southern region of the U.S. since 1976. The current project S-1049, terminates on September 30, 2015 and the following narrative outlines our research plans for 2015 to 2020 seasons. Cooperating States Agricultural Experiment Stations and Agencies are: (Arkansas, Florida, Georgia, Kansas, Louisiana, New Mexico, Oklahoma, Texas, USDA). 

The need for research as indicated by stakeholders - Pecan growers universally demand improvements in insect and mite pest management.  No pecan growing region is without some type of arthropod pest problem and multiple problems are the norm.  Differences occur between the pecan growing regions in the portion of the insect or mite pest complex that is abundant at a sufficient level to cause economically significant injury to the trees, foliage or the nut crop.  California, Arizona, New Mexico and West Texas pecans typically have aphid and mites on the foliage and pecan nut casebearer and hickory shuckworm as nut pests. In East Texas and north to Oklahoma to southeastern Kansas then east through to the east Atlantic Coast of Georgia the major pecan insect and mite pests are: aphids, pecan weevil, pecan nut casebearer, hickory shuckworm and kernel feeding hemipterans. The widespread use of Bt cotton contributed to significant and concomitant reductions in insecticide use. Virtual elimination of broad spectrum insecticides provided an ideal environment for stink bugs and plant bugs to flourish. Stink bugs became the most important pests of soybean following expansion of its production in southern United States in the 1960s (McPherson and McPherson 2000). In most Bt cotton and soybean growing areas, control measures for emerging stink bug problems rely on pyrethroids. Alternative insect pest management strategies would be highly desirable. The big increase in wheat acreage in the upper Southeast is likely to cause problems with stink bugs. Wheat, Van Duyn says, is an ideal reproductive host for stink bugs. These stink bugs disperse from wheat, cotton, corn and soybeans into adjacent pecan groves and cause economic damage to the nut crop from water stage through harvest (Cowell et al. 2015). Pecan leaf scorch mite and Prionus root borers are key pests east of the Mississippi River in the southeastern U.S.  Outdated, online crop profiles for pecan production in Georgia (Guillebeau 2001) and Texas (Smith et al. 2002), Kansas (Kadir et al. 2001), North Carolina (Parker et al. 1999), and Arkansas (Johnson et al. 2003) indicated that the pecan weevil and kernel feeding hemipterans were the major late season kernel pests facing the U.S. pecan industry.  Annually, these pests continue to be of grower concern as noted by recent state-by-state surveys that assess pecan grower or industry needs for research/extension/marketing. These survey summaries have been used as stakeholder input and support for multistate, multidisciplinary pecan project proposals we have recently submitted or will submit for USDA funding. Insecticides are the main controls used for reducing damage by these two pest problems. The research committee of the Georgia Agricultural Commodity Commission for Pecan ranks black pecan aphid as the most serious foliage feeding insect pest. Stakeholders also want better resources placed on the internet to aid their in-season decision making on key pests.        

The importance of the research work, and consequences if it is not done - Since 1976, regional research in the southern states on pecan entomology has produced effective methods for detecting, predicting and managing insect and mite outbreaks in pecan orchards.  Pecan orchards that are not managed for insect and mite control each season will typically stop producing a significant nut crop within two seasons.  The damage potential of the nut feeding insects is sufficient to injure or destroy the entire nut crop each year and foliage insects can defoliate the trees early in the season throwing the trees in to a non-productive period that can last for several seasons (Dutcher et al 1984). 

The technical feasibility of the research – The primary problem in accomplishing pecan research goals is the establishment of a research site for field experiments to test new control methods.  Prior to 1976, most of the field experiments were run on the farms of cooperating growers often without untreated controls and only limited (or no) local controls, randomization and replication of treatments.  Since 1976, several experimental sites have been planted and are available for controlled field experiments under more uniform conditions at state agricultural experimental stations (SAES) and the USDA field stations.  The work at these locations has produced control methods that are thoroughly tested, interpreted, analyzed, refined and retested in statistically valid experiments. The trials determine the efficacy as well as the probability of achieving the efficacy.  Methods developed at these sites are readily transferred to commercial orchards.  Also, efficacy trials at the SAES sites have found methods that are ineffective or cause ancillary problems, such as, resurgence of secondary pests, or insecticide resistance and pest replacement problems. Biological control methods are relatively new to pecan growers. Advantageous interactions between cultural methods and pest populations are recently measured and just now being understood and manipulated by growers. Considerable extension and educational efforts will have to be initiated to ensure that growers understand how to use these new ideas in the field.  As examples: identification of beneficial insects and mites will become important and is not a skill that most growers have at this time; more frequent application of reduced rates of fertilizer coupled with aphid and mite scouting information is not currently practiced by growers; the use of clover as an intercrop is widespread but the movement of predators from the cover crop to the tree with food sprays and sicklebar mowing is not a common practice; identification of the fungi that attack aphids and coupling reduced frequency of fungicide sprays to encourage these fungi is not commonly used by growers.  The implementation of these known positive interactions is typically not associated with increased input costs and has been shown to be effective in research trials and limited grower demonstrations. Additionally, new developments in Information Technology provide a novel opportunity to develop deliverables with complex underpinnings using the computer and posting results on the internet. A major advancement in this regard has been established at http://pecan.ipmpipe.org/. Many if not most pecan growers now have cell phones. This will stimulate development of APPs to help pecan growers access information on best pecan management practices in order for them to make better and more timely management decisions. The advantages for doing the research work as a multistate effort – The advantages of  working as a team of entomologists and other complementary disciplines, especially horticulture and plant pathology, across the pecan growing regions are: 1. Methods can be innovated at one meeting location and then tested under a broad range of conditions and then altered to fit the conditions at each region; 2. Information of recent work can be presented and discussed each year by all participants so that scientists can access the results before the material is published since the publication process can take a year or more;  3.  Regional experiments can be conducted during the same season to measure the influence of environmental factors on the efficacy of the control methods and seasonal occurrence of the pests;  4.  Extension specialists and growers and publicists can be invited to the annual meetings to make presentations on important issues giving the technical committee members a better perspective on conditions in the pecan industry.

See attachment for Table 1 and 2

What the likely impacts will be from successfully completing the research work – Compare the % mortality required to prevent annual increases in the insect and mite populations (Table 1) with the relative efficacies of the current control methods (Table 2) and it is obvious that improved control methods are needed against all the key insect and mite pests listed.

The impact of the research is nothing short of saving the U.S. pecan crop each season from devastating insect and mite injury.  The reproductive potentials of the insect pests translate into   significant damage potentials when the insects and/or mites occur at levels of abundance that cause economic injury to the tree, foliage and nuts. The new control and delivery methods will however require more extension and educational efforts to be effectively applied by pecan growers.   Training is needed in the identification of beneficial organisms and to note how certain insecticide groups are deleterious to these beneficial organisms which result in pest outbreaks.

Related, Current and Previous Work

The insect complex associated with pecan in native and improved systems includes 180+ species of phytophagous insects (Payne and Johnson 1979, Harris 1983) and each is associated with a diverse array of natural enemies (Tedders 1985).  Insect management strategies range from total reliance on natural enemies to intensive integration of chemical and biological controls (Dutcher et al. 2003b).  The fruit and foliage in pecan orchards are susceptible to insect injury that can result in economic losses continuously for seven months each season.  Preventive insecticide applications are not practical over this long period of time.  For example, the first defense against aphid injury is the enhancement of insects that prey on aphids so-called aphidophaga. The second defensive method is to adjust the fertilizer application rates and times to prevent a flush of nitrogen in the leaf that causes an increase in the reproductive rate and survival of the pecan aphids. The third defense is the find pesticides for control of nut feeding pests that do not disrupt natural control of the pecan aphids by aphidophagous insects and entomophagous fungi. The final defense is to apply an aphidicide.

Monitoring Methods. - Monitoring methods to determine the presence and relative abundance of pecan insects and mites are important to find pest infestations and assess the abundance of beneficial insects that are exerting natural control on the pest populations. Previous research on monitoring methods has produced a sophisticated scouting program for the major pecan insect and mite pests (Dutcher, et al. 2003a,b).  Currently, a better sampling method is needed for insects and mites in the tree canopy above 20 ft.  Four sampling methods have been recommended for monitoring stink bug densities in pecans including: baited yellow pyramid traps (Mizell et al. 1997); black-light traps (Parker et al. 2005); visual surveys; and canopy knockdown sprays (Hudson 2014). There has been no correlation between stink bug catch by any of these sampling method and subsequent pecan damage by stink bugs. However, pecan damage occurs whenever there are one or more stink bugs captured in yellow traps during water through dough stage of nut maturation. It is hypothesized that yellow traps, baited with aggregation pheromones of both the brown and green stink bugs, will be the best way to detect presence of stink bugs. Cowell et al. (2015) noted that yellow pyramid traps may be the most acceptable method for growers to monitor for stink bugs in pecan groves. Further study is needed for using baited yellow pyramid traps to monitor for stink bugs in the lower canopy of pecan trees where the most nut damage occurs. There is no economic threshold for stink bugs, so preventative insecticide application(s) is recommended during the stink bug susceptible water through dough stages. Hickory shuckworm pheromone traps only capture moths in the spring and fall and miss the summer population as the traps do not function in high temperatures of the summer.  Prionus root borer pheromone-baited traps are highly effective and have been used by pecan growers to trap out the male beetles and time the application of soil sprays to control the female beetles before they lay eggs in the roots (Cervantes et al. 2006). Research is needed to improve prionus traps by adding solar-powered lights.

Organically Certified Production. -  This area is an ongoing multidisciplinary project supported by funding through 2017 from the USDA-NIFA Organic Transition Program to a group of researchers including the regional project participants in Georgia and Florida. Pecan, a highly nutritious commodity, constitutes the most valuable North American native nut crop.  As a result production of the crop under organic certification would provide a product that was even more attractive in the market place.  Advances in organic IPM strategies combined with appropriate whole-farm management systems offer the potential to develop viable organic production in the Southeast. The primary barriers facing organic production will be addressed: i.e., for insect pests, control of pecan weevil and pecan aphids, and for disease control, pecan scab.  Methods for insect pest and disease management will include biological control, organic insecticides and fungicides, and resistant cultivars.  Orchard floor management impacts tree nutrition and productivity as well as pest and natural enemy population dynamics.  Hence IPM approaches will be investigated along with optimization of orchard floor management. Treatment impacts on biodiversity will also be assessed and compared.  An advanced systems-based on-farm research approach will be implemented at five locations including three commercial farms.  Simultaneously, in-depth optimization of key components will be investigated (e.g., optimization of microbial biological control applications and cultivar resistance).   Socio-economic analysis will determine the profitability of selected strategies and measure project outcomes.  A multi-faceted outreach and extension program (ipmPIPE, eOrganic) will be implemented to disseminate organic related findings and recommendations facilitating adoption. In conjunction with this effort comparisons of the arthropod biodiversity between organic and conventional production is the subject of research by Mizell (FL) and Dutcher (GA). Methods used will enable assessment of arthropod species diversity in the tree canopy (blacklight and Malaise traps, foliage sampling) as well as on the ground (pitfall traps). Biodiversity relates directly to a number of ecosystem services such as biological control that are of great benefit in pecan production. The knowledge developed from this funding will serve as a basis to continue the effort to develop organic arthropod suppression measures in this regional project.

Safer Insecticides. - Chemical control strategies for pest outbreaks in pecan orchards have shifted in recent years from a reliance on broad-spectrum insecticides to the use of more pest targeted, reduced risk insecticides and biorational insecticides that are safer for the applicators and the environment as well as beneficial insects and mites.  Initially, insect growth regulators were evaluated for insect control against pecan weevil and lepidopterans (Payne and Dutcher 1985, Tedders 1977).  Efficacy was much lower than the broad-spectrum insecticides and registration was not pursued.  Broad-spectrum insecticides became the main control measures for preventing pest damage and are currently the only effective controls for pecan weevil, hickory shuckworm, kernel-feeding hemipterans and black pecan aphid.  Recently, newer insect growth regulator insecticides have gained acceptance among growers for control of lepidopteran pests (Dutcher et al 2003a).  However, the effective use of insect growth regulators in pecan orchards relies on an effective monitoring and prediction of oviposition and date of first significant injury for pecan nut casebearer and long residual activity for effective control of hickory shuckworm.  Growers in Georgia, however, have found that pheromone trap catch is not related to the amount of damage by pecan nut casebearer. For these growers, a spray of chlorpyrifos at the time when the first nut injury is found in the orchard has better efficacy than the insect growth regulator sprays at the time of nut injury predicted from scouting (R. Grebel, personal communication). Applications of plant growth regulators (e.g., gibberellins) have been discovered as a novel control mechanism for black pecan aphids (Cottrell et al., 2010). The use of plant bio-regulators disrupts the aphid’s ability to cause chlorotic zones that are necessary for feeding (Chen et al. 2009, Cottrell et al. 2009).  

Insect-Orchard Interactions. - Scientific literature on pecan IPM has many records of relations between insect outbreaks and orchard conditions.  Various management techniques that affect insect and mite densities include: tree phenology, cultivars, pruning off lower limbs to minimize stink bug in canopy, mowing orchard floor, adjacent landscapes of stink bug host plants and weather events.  As examples, pecan cultivars and trees of different ages (sizes) differ considerably in susceptibility to injury by pecan weevil, kernel-feeding hemipterans and black pecan aphids (Dutcher et al. 2001, Kaakeh and Dutcher 1994, Worley and Mullinix 1997) and most growers have detailed maps of the orchard noting cultivars and tree age.  Yet entire orchards are sprayed at the same time with the same chemical control when considerable savings could be accrued if the only more susceptible trees were treated. Certain pecan cultivars have a narrow window of susceptibility to pecan weevil oviposition with either a short kernel development time, or an early or late onset of kernel development (Harris 1985). Weevil can be controlled in these cultivars with 2-3 applications of carbaryl compared to 4-5 applications for standard cultivars.  Significant risk of hemipteran kernel damage is associated with pecan cultivar and with legume plantings (and other alternate host plants) adjacent to the pecan orchard.  Once in the orchard, stink bug damage is significantly greater in the lower third of the pecan canopy (Cowell, personal communication). Spot treatments of insecticide sprays to the trees in the first two border rows adjacent to the alternate host plants are effective in reducing stink bug damage (kernel spot) throughout the orchard. A similar approach is being used against the brown marmorated stink bug in tree fruit since most of the damage done in apples and sweet corn occurs in outer rows (Leskey et al. 2012). Legume trap crops between the trees and the alternate host plants are effective and have been used by pecan growers for reducing kernel spot.  Black aphid populations on susceptible cultivars cause significant leaf damage and defoliation at population levels of a few aphids per leaf (Wood and Reilly 1998).  However, on less susceptible cultivars the onset of the outbreak is often several weeks later than on susceptible cultivars. 

Optimism for the effectiveness of precision applications of carbaryl to tree trunks and spot treatments in highly infested portions of the orchard stems from recent reported research results that indicate that nut damage in a pecan tree is significantly correlated to the density of pecan weevils emerging from the soil directly beneath the tree (Dutcher et al 2003a).  In early replicated field trials, trunk sprays effectively killed adult weevils on the trunk for up 13 days after application of carbaryl (Cottrell and Wood 2003). It has been estimated that 70 – 80 % of the adult weevils fly to the trunk first (Raney and Eikenbary 1968) and could thus be targeted for insecticide application to manage pecan weevils.  This could reduce entire canopy sprays, which are known to be detrimental to natural enemies and flare aphid and mite populations (Dutcher and Payne 1983). The trees in native groves have a unique nut phenology in each tree adding to the variability in pecan weevil distribution (Reid and Mulder 2003).  Spot treatments of only the weevil infested portions of the pecan orchard has not been tested as a pecan weevil control method.  Pecan weevil distribution in the orchard can be estimated from tree-to-tree measurements of  % nut damage, crop load, and known population parameters of the weevil (Harris 1985) and then validated by extensive trapping of emerging adults with cone emergence traps from a known area of the soil surface (Raney et al.1970).  Accurate weevil distribution maps would allow the precision application of soil applied biocontrol agents and foliage and trunk sprays of carbaryl, thus reducing costs.  Research is needed to determine if spot spraying infested areas in orchards with localized infestations of weevils will effectively prevent nut damage in the entire orchard.

Intercrops. - Previous studies have shown increased diversity and abundance of native aphid-feeding insects (aphidophaga) by planting intercrops in pecan orchards.  Crapemyrtle aphid, commonly infests crape myrtle in the southeastern US and is a natural prey of multicolored Asian lady beetle in Southeast Asia.  Crape myrtle interplanted in pecan orchards may be important in increasing multicolored Asian lady beetle populations (Mizell  and Schiffhauer 1987). Significantly higher populations of lady beetles were found in various cool (Bugg et al 1990) and warm-season (Bugg and Dutcher 1989) covers.  Rice et al. (1998) found clover plus vetch to harbor significantly larger populations of lady beetles than mowed grass cover.  Unfortunately in both cases biological control of pecan aphids did not increase significantly.  Even though Rice et al. (1998) did not find a significant increase in biological control overall in groundcover-enhanced orchards, they did observe an increase in one isolated orchard where multicolored Asian lady beetle had recently become established.  Red imported fire ants can impede biological control by attacking other natural enemies of pecan aphids.  Dutcher (2004) observed greater biological control of pecan aphids when red imported fire ants were kept out of trees with an insecticide applied to tree trunks.  Combinations of red and white clovers or clover plus vetch also provide adequate nitrogen for pecan tree nutrition (Diver and Ames, 2000). 

Ant Control. - Insects are a major source of nutrition for red imported fire ants, Solenopsis invicta Buren (Hymenoptera: Formicidae).  These ants are important predators of pests including southern green stink bug (Krispyn and Todd 1982), cowpea curculio (Russell 1981) and pecan weevil (Dutcher and Sheppard 1983).  Pecan weevil larval populations are consistently reduced by 33% after the larvae drop to the soil surface from the pecans and before they burrow into the ground (Dutcher and Sheppard 1981).  Red imported fire ants also interact with aphids and aphidophaga in the pecan trees (Tedders et al 1990). Ant foraging can be partitioned with insecticide barriers sprayed on the tree trunks so that red imported fire ants will remain on the soil surface to prey on weevils and not interfere with aphidophagous insects in the trees. The effect of these trunk sprays has been effective in reducing aphid populations in the ‘Desirable’ trees in Georgia (Dutcher et al 1999) and ineffective in reducing aphid populations in ‘Cheyenne’ trees in Texas (Harris et al 2003).  Red imported fire ants can tunnel under the insecticide barrier without becoming intoxicated and produce a trail to the tree crown, esp. on older trees with heavy bark. Farnesol, an ant repellent that forms an impassable odor plume around the trunk successfully prevents Argentine ants from foraging in citrus trees (Shorey et al 1996). Current research has found that farnesol was not an effective repellent of ants on pecan trees but certain plant extracts (neem extract, sesbania extract), natural compounds (methyl anthranilate, methyl myristate) and an industrial repellent (methyl carbitol) are effective ant repellents that prevent foraging in pecan trees (Dutcher, manuscript in press).

Impact of Invasives on Commercial Production: The tawny crazy ant, Nylaneria fulva, that was first discovered Pasadena, TX (Houston area – Harris County) in 2002 has now spread to 27 Texas counties. Where this invasive is now established it has become the dominant arthropod in the eco-system, even running off and displacing the red imported fire ant. In 2013 TCA was discovered in a small commercial improved orchard in Brazoria County and initial management trials were initiated. Current work with TCA is focusing on determining the impact of this ant on commercial practices. Questions to be answered are impacts on natural enemies, impact on labor, impacts on production costs and harvest operations. The current thought is that this ant will in some form or fashion increase the cost of production.

Brown Marmorated Stink Bug: This invasive stink bug, first detected in PA in the mid 1990’s has now spread to 40 states in the continental US. In most pecan producing states east of line from Kansas to Texas, there have been several interceptions of adult brown marmorated stink bugs, but there is only one confirmed site with feral collected specimens which is Corpus Christi. Pecan has been listed a host plant but this species of Carya is not a dominant or common host plant in areas of the mid-Atlantic states so true impact on pecan is unknown. A grant funded project is underway in Texas that is focusing on training first detectors. Early detection of new infestations is important in monitoring, movement, determining new host plants and number of possible generations that may occur per season.

Trap Crops. - Two conditions of pecan known as black pit and kernel spot are caused by several species of true bugs belonging to the families, Pentatomidae and Coreidae. Initially, black pit and kernel spot were thought to be caused by diseases and treated as such until it was proven (Adair 1927) that these conditions were caused by several species of kernel feeding hemipterans. The primary kernel feeding hemipteran pests of pecan include the southern green stink bug, Nezara viridula; green stink bug, Acrosternum hilare;  brown stink bug, Euschistus servus ;  Dusky stink bug, Euschistus tristigmus  and the leaffooted bugs Leptoglossus phyllopus and L. oppositus. All of these insects are phytophagus and feed on a wide range of plants (McPherson and McPherson 2002). Stink bugs find crops such as cowpeas and soybeans more appealing than pecan trees when plots of these crops are planted near pecan orchards, gravitating toward the trap crop and away from the trees.  The primary challenges pecan producers face in managing these pest include the lack of economic thresholds to make management decisions, the long period of susceptibility to damage (nut set to harvest), the difficulty in scouting for damaging populations and the limitations on insecticide use near harvest.  Leguminous trap crops, sown adjacent to seedling and improved pecan orchards, effectively and consistently reduce the incidence of kernel spot by 50% in improved pecan orchards (Smith 1996, 1999). The trap crops are sprayed as the pods mature with an insecticide to kill the hemipterans before they enter the orchard (Coolman 2003).  Growing trap crops is beneficial for owners of small pecan orchards, as well as people who want to grow their pecan crops organically.  Growing a trap crop around the orchard controls stink bugs without spraying the trees (Smith 1999).  Sunflower, sorghum and millet are also attractive to kernel-feeding hemipterans and produce seed that is attractive to hemipterans in the early fall at the same time as the pecans are susceptible to kernel spot.  Mizell et al. (2008) have recently developed a generic trap cropping system that attracts the primary stink bug pests- the brown, dusky, green, southern green and leaffooted bugs as well as many of the minor stink bug species.  This scheme is neutral relative to farm scale and farmer philosophy and can be used in large containers for small acreage, organic or homeowners. Stink bug damage phenology varies across the pecan belt often occurring throughout most of the growing season in the central states (Smith 1996, 1999), but occurring mostly in fall in the eastern states (Dutcher and Todd 1983). The trap crop is customizable for the entire growing season and relies on fall plantings of hairy vetch, crimson clover and triticale for early spring, followed by buckwheat, sunflower, sorghum and millet for the rest of the season. Millet and sorghum can be ratooned to extend the life of plantings reducing establishment costs and buckwheat can be used as relay crop for quick maturity because it matures attractive seed within 5 weeks of planting.  All of these trap crop species provide the additional ecological service of enhancing biological control agents and pollinating species as well as providing food for wildlife (Mizell et al. 2008). In addition, yellow traps and stink bug pheromones (Mizell and Tedders 1995, Mizell et al. 1996) are available to increase the efficacy of trap crops by increasing the attraction of stink bugs to the plots away from the orchard. Trap crops must be strategically placed to intercept stink bugs as they move into the orchard and more research is needed at the landscape level to determine and exploit these ecological relationships. Toward that end, facilitation of stink bug control has recently been enhanced through additional knowledge of farmscape movement and improved monitoring based on optimized trap capture and pheromone use (Cottrell and Horton 2010, Cottrell et al. 2014, Tillman et al. 2010, 2014, Cowell et al. 2015).

In native pecan groves, trap crops or broad scale application of pesticides to control stink bugs populations are not practical since livestock and poultry are part of the system.  The mid-summer weeds in the groves are attractive to kernel-feeding hemipterans and the weeds provide a place for stink bug populations to develop within the grove itself and mowing of these weeds is an alternative control technique.  Trap crops also provide excellent food for quail.  Many pecan growers already plant small grains near the orchard border in the fall to feed wildlife and improve hunting, esp. for quail.

Predatory Mite Release. – Native phytoseiid mites (predators of pecan leaf scorch mite) in U.S. pecan orchards are a diverse group yet in improved orchards pecan leaf scorch mite outbreaks are very common.  Introduction of western predatory mite, Galendromus occidentalis, has been successful in young trees (20 years) and early indications are that they can also become established in older pecan trees.  The level of pecan leaf scorch mite control varies, however, from very good to none.  Western predatory mite will feed on pecan leaf scorch mite and the predators will disperse from one tree to the next.  Populations of the predators also increase by the end of the season and in young trees populations will carry over to the next season.   

These new insect and mite control methods can be used by pecan growers to reduce insect pest populations to manageable levels.  The overall goal of the regional research efforts is to maintain effective pest control for the pecan industry in the U.S. This will be accomplished by research in the development of:  more effective monitoring and forecasting methods to measure and predict the activity of insects and mites in the orchards; improved control methods for key insect and mite pests that are effective and maintain or improve nut production; and, web-based integration techniques that enable pecan growers to access to pertinent information for making decision in pest management that will be compatible with their pecan production methods. 

Microbial Control. - Biocontrol options such as microbial pesticides (entomopathogenic nematodes, entomopathogenic fungi and bacteria such as Chromobacterium subtsugae) have shown significant progress for control of pecan (Lacey and Shapiro-Ilan, Shapiro and Gardner, 2012; Shapiro-Ilan et al. 2003, 2007, 2008, 2009a,b, 2011, 2012, 2013 a,b).  Additional research is needed to expand and optimize these approaches.

Organic Approaches. – There has been a rise in interest and production of organic pecans and with that new methods for organic insect control methods must be adopted. Research toward this end (from our group) has been bolstered by a NIFA-Organic Transitions Grant. Novel methods including integration of microbial control for pecan weevil, organic pesticides for aphids, and natural enemy conservation are being implemented.

Objective 1:    Improved Monitoring and Forecasting Methods for Field Populations of Pecan Arthropods

1.1 Georgia and Florida – Identify, synthesize and evaluate the attractiveness of pecan plant volatiles and pheromones to pecan weevil and hickory shuckworm .

1.2 Georgia - Evaluate if trap placement and the addition of a solar-powered LED light to a pheromone baited trap will improve attractiveness to prionus root borers.

1.3 Georgia – Evaluate fan traps for detection of aphids and aphidophagous insects from the tree canopy. 

1.4 All states – Determine where hickory shuckworm damage occurs and how its life cycle varies across climatic zones within the pecan growing regions.

1.5 All states – Develop a real-time model adapted across climatic zones and adjacent landscapes to time protective insecticide treatments against stink bugs.

1.6 Florida and Georgia (USDA) – Hickory shuckworm is a direct pest of pecan nuts feeding on the shucks in late season. Currently it is mostly a “blackbox” in terms of impact because it is often suppressed by insecticides applied for other primary pests such as weevil or aphids. However, a pheromone was identified many years ago but it does not work well in the field. Given the new chemical identification and insect behavior technology available, we plan to take a new look at shuckworm pheromone production with the objective of improving a monitoring device. This will enable better assessment of the phenology and true impact of shuckworm in pecan.   

1.7 Regional Research (All states and USDA) – The collection, storage and retrieval of information on pest bionomics will be coordinated through the ipmPIPE system.

Objective 2.    Improved Control Systems for Pecan Arthropod Pests

2.1 Georgia - Release of predatory mites will be developed as a biological control of pecan leaf scorch mite. Further research is needed to determine if the control can be sustained in the orchard for more than one season from a single release and to measure their dispersal abilities within the orchard between trees and the optimum release time with respect to the relative abundance of pecan leaf scorch mites.

2.2 Georgia –  Red imported fire ant and argentine ant repellent and controls will be tested in conjunction with varying ground covers.

2.3 Louisiana - Alternative methods will be evaluated for applying insecticide applications for control of pecan phylloxera.

2.4 Regional Research (All states and USDA) –Chemicals with new modes of action and microbials to controls pecan insects and mites will be evaluated for efficacy, provide data to support the registration of products and acquire baseline toxicological data for pesticide resistance management.

Objective 3.    Integrate Pecan Arthropod Pest Control Methods with Pecan Production Methods

3.1 Georgia, USDA – Integration of chemical/ biological/ microbial agents with other IPM and orchard practices will be explored.

3.2: Florida and Georgia. – Compare biodiversity between organic and conventional production using pitfall and Malaise traps. 

Objective 4.    Develop real-time Decision Aids for Delivery on the Internet.

4.1 Regional Research (All states and USDA) – We will identify funding sources to sustain and update the online interactive communication system called Pecan ipmPIPE Platform at: http://pecan.ipmpipe.org/. Funds will be allocated in the budget of present and future grant proposals to support a web master to supervise updates and data input to Pecan ipmPIPE.

 

Methods   

Research Sites. 

Over 300 acres of pecan orchards are available for the field trials Georgia, Louisiana, Arkansas, Texas, Florida and U.S.D.A. for research and demonstration plots. The high acreage is needed for the proposed research because trees are the sample units for many experiments and tree density ranges from 10-27 trees per acre.  As examples, areas for research include:  Cultivar evaluations can be conducted at University of Georgia at Tifton in a provenance collection where numerous bearing pecan trees of old and new cultivars are planted and cultured for research. The University of Georgia’s Coastal Plain Experiment Station in Tift Co., Ga. with 50A of 20 year-old pecan trees at Ponder Farm, 33A in at the Southeastern Branch Station near Midville and 35A of leased pecans near Plains.  USDA-ARS Research Station, Byron, GA contains approximately 400 A of pecan for research purposes, the pecan blocks are interspersed with peach and forested land (the total area of the research farm is approximately 1200 A). 

Biological sources. 

Pecan insect and mites for various proposed bioassays will be produced naturally at highly infested and nontreated orchards.  Pecan weevil adults will be collected by mass trapping with emergence traps; larvae will be collected as they emerge from early harvested, infested nuts at the Plains, Carter, Cook and Midville Farms. Kernel-feeding hemipterans will be collected from insecticide-free plots of legumes, sorghum and millet planted at the Coastal Plain Experiment Station.  Blackmargined and black pecan aphids are ubiquitous and easily collected in large numbers from infested pecan trees.

Microbial control agents will be produced on-site or purchased from commercial suppliers.  Laboratory colonies of black pecan aphid, yellow pecan aphid and blackmargined aphid will be maintained on greenhouse-grown pecan seedlings.  Brown stink bugs are polyphagous and easily collected in pheromone traps throughout the summer and early fall. 

Statistical Analysis of Data. 

Standard software used for analysis will be SAS v. 9.2 (SAS 2008) though alternatives such as Microsoft Excel (Microsoft 2007) enhanced with Poptools (Hood 2009) will also be used for data storage and analysis. Each variable measured in controlled replicated trials will be analyzed for distribution and normal variables or variables transformed to approximate the normal distribution will be analyzed by univariate analysis of variance.  Significant differences (P< 0.05 level) between treatment means will be determined by the appropriate mean separation procedure, e.g. LSD-test for simple experiments with 2 or 3 treatments, Scheffe’ test for trials more than 3 treatments and with unbalance design,  Tukey’s test for large experiments with balanced design.  Relative variance will be estimated by calculating the coefficient of variance for each random variable and those with CV > 50% will be interpreted with caution (Steel and Torrie 1980). 

Objective 1. Improved Monitoring and Forecasting Methods for Field Populations of Pecan Arthropods

 

1.1 Georgia and Florida - Identify semiochemicals (host-plant volatiles and pheromones) for attracting weevils to traps, and repelling weevils from pecan nuts.  Surface extracts of the pecan shuck have many volatile compounds that may attract pecan weevil adults.  These compounds (91 compounds from hexane extraction and 214 compounds from solid phase microextraction) have been identified by GC-MS (Harrison and Mizell, unpublished work in progress). Field comparisons will be made of the attractiveness to pecan weevils of non-baited traps to traps baited with either a complete mixture host-plant volatiles and pheromone or a series of baits with sequentially more compounds or pheromone removed. A similar approach along with looking at pheromone production will be taken with hickory shuckworm.

 

1.2 Georgia – Improvements in pheromone trap placement and design will be field evaluated for monitoring for Prionus root borers. In 2009, pitfall traps with the sides sprayed with RainX and a pheromone dispenser placed over the opening successfully caught Prionus laticollis and P. umbricornus adult males. Trap catch of Prionus beetles will be compared in traps placed either along the border of the orchard or in the center of the orchard. Traps for female Prionus spp. beetles will be developed as pitfall traps amended with solar-powered LED lights and/or vanes radiated over the ground out from the center of the trap so that beetles will follow the vanes into the trap once the encounter the distal end. The pheromone tested in 2009 was derived from P. californicus. Female beetles in Georgia are needed to determine the pheromones for these species.

1.3 Georgia – Modifications will be made to improve a solar powered fan-light traps. Traps need to be waterproofed and made more portable. Test trap designs will be field compared for effectiveness in collecting samples of aphids and aphidophagous insects from the tree canopy.

1.4 All states – We need to delineate the distribution, compare life-cycles and optimize decision-making pest management protocols for hickory shuckworm. From mid-May through August, light traps will be run and pecans sampled for oviposition injury and nut drop in various climatic zones across the pecan producing regions of the US.

1.5 All states – A on-line, real-time degree day based model will be developed and validated across climatic zones where pecans are grown as a decision-making pest management protocol against stink bugs. In unique pecan growing climatic zones, three pecan orchards each will be selected that have adjacent landscape of soybeans or tree lines. These landscapes have resulted in higher numbers of stink bugs in pecan orchards from water stage on to harvest. At each site, daily cumulative growing degree-days will be recorded to delimit the nut development period from water through dough stages when nuts are most susceptible to economic stink bug damage. Four baited yellow sticky traps will be used to monitor presence of stink bugs in pecan trees, just before and during the nut susceptible period for early/mid/late season maturing pecan cultivars. At harvest, nuts will be assessed stink bug damage.

1.6 Regional Research (All states and U.S.D.A.) - Integration of weather and trapping information with biorational insecticides for control of pecan nut casebearer.  Trapping of adult moths, egg laying and first nut damage will be measured in similar experiments across the pecan belt.  The time of and duration of occurrence of these insect activities will be correlated with climatic variables at the trapping sites to further define existing degree-day driven models.  The emergence of the adults is later in the north than in the south and apparently the differences can be described by the accumulation of degree-days at each location.  The research basis for the degree-day model, however, lacks any direct measure of the effects of temperature on insect growth, development of metabolic rate. The current prediction model uses degree-days calculated from a base temperature interpolated from the correlation of field catch at different locations to the accumulated degree-days at each site. 

 

Objective 2. Improved Control Systems for Pecan Arthropod Pests

2.1 Georgia - Mite pest management will be developed by integrating biological and chemical control methods.  Phytoseiulis persimilis and Galendromus occidentalis have been shown to be effective as biocontrols of pecan leaf scorch mite. The predatory mites will be purchased and released in six commercial pecan orchards in Georgia (three orchards will receive P. persimilis, three orchards will receive G. occidentalis) as an inoculative release (release mites in one tree per acre) during the Fall of the first season of the project.  Each month from July to Oct the abundance of pecan leaf scorch mites and phytoseiid mites will be monitored in each release tree, adjacent trees (to note dispersal from release tree) and trees at least three tree spaces from the release tree (control).  These orchards will be managed without any changes from the grower’s standard methods.  The demonstrations will continue for three seasons.   Techniques for the transfer of predatory mites from donor orchards – orchards where predatory mites have been released in the previous season and have successfully overwintered and become established – to recipient orchards that lack predatory mites yet have pecan leaf scorch mite will be developed for pecan by testing methods that have been successful in fruit crops.  Overwinter predatory mites will be collected by pruning limbs in the donor orchard and affixing them to limbs in the recipient orchard during the early spring before budbreak.  Budbreak in pecan occurs later in the spring when ambient temperatures are already over the thermal threshold for mite activity. The transfer of overwintering mites will be tested at three dates in mid-January, mid-February and mid-March.  The second technique is to transfer leaves with predatory mites from the donor site to the recipient site during the summer and fall.  This technique will be tested on three dates.  Successful transfer techniques will create a sustained system and eliminate the purchase insectaries after the initial purchase.   

 

2.2 Georgia - Ant repellents (methyl anthranillate, methyl myristate and methyl carbitol) and insecticide treated baits will be evaluated in replicated field trials to enhance natural enemies in the intercrops by removing ants from the plants. The intercrops crops – crimson clover, hairy vetch and joint vetch - will be sown in the fall to provide alternate prey aphids for the predators in the spring.  Predator species will also be monitored.

2.3 Regional Research (Georgia, U.S.D.A., Louisiana) – New chemical microbial controls for pecan insects and mites will be evaluated for efficacy in controlled field experiments with a nontreated control and standard pesticide treatment.  Insects and mites will be monitored by standard methods in the plots and treatments will be applied when the pest population reaches a level of abundance greater than the prescribed action or economic threshold level.  Plots will be monitored for the injury caused by the pests and for the abundance of secondary aphid, leafminer and mite pests to determine if the new treatments cause secondary pest resurgence.  Baseline toxicological data will be collected by using laboratory bioassays of the mortality caused by a series of concentrations of the new insecticides or miticides to a sample of the pest population collected from the field.  Typically, a slide dip bioassay is effective for aphids, bollweevil test is effective for pecan weevil and treated leaf disc bioassay is effective for pecan leaf scorch mite.  Bioassays for pecan nut casebearer and hickory shuckworm have not been developed due to the lack of an effective rearing method.  Gregarious caterpillars – fall webworm and walnut caterpillar – can be tested by treating whole leaves and excising the leaflets and feeding them directly to the caterpillars.

Large plot applications will assess the ability of promising microbial control agents including nematodes (particularly Steinernema carpocapsae), fungi (Beauveria bassiana and Metarhizium brunneum) and the bacterium C. subtsugae, to control pecan weevil in organic settings. Microbial agents will also be compared with standard chemical insecticides in conventionally managed orchards. Small plot studies will be used to optimize application rates and timing and treatment combinations. Methods for microbial applications will be as described in Shapiro-Ilan et al. (2007). A variety of application and formulation approaches will be tested as well including the new persistent form of M. brunneum, microsclerotia, applied in a novel hydro-mulch (Goble et al. 2015). Economic analysis of organic approaches will be conducted (by University of Georgia Economist, Greg Colson).  

Certain plant growth regulators have been shown to prevent leaf chlorosis elicited by black pecan aphid feeding (Cottrell et al. 2010) and incorporation of this technology into commercial management systems has been initiated.  These bio- regulators will be tested further for increased efficacy in controlled field experiments (with various rates and timing of application) to ascertain their practical application in pecan production systems compared with standard chemical insecticides.

New chemical controls for stink bugs will be evaluated against existing controls to provide efficacy as well as residual activity data.  Stink bug efficacy tests will be conducted against brown and green stink bugs.  Pecan nuts on trees will be sprayed with insecticides and brought to the laboratory 1, 4, and 7 days after insecticide application.  For each day after application that stink bugs are tested, one stink bug will be placed into a cup with one nut and mortality assessed at 24 and 48 hr.  

Objective 3. Integrate Pecan Arthropod Pest Control Methods with Pecan Production Methods

3.1 Georgia, U.S.D.A. - Integration of banker plants including crape myrtle and leguminous intercrops to increase soil fertility and enhancement of biological control of pecan aphids by ladybeetles will be investigated in controlled field experiments to determine methods for attracting ladybeetles from the legume intercrops to the tree canopy and the planting density of cool and warm season intercrop plants that will increase the abundance of ladybeetles on the orchard floor. Application of lower amounts of commercial formulations of complete fertilizers will be investigated by improving the placement and timing of applications. Standard broadcast application of fertilizer will be compared to fertilizer: placed near the areas wetted by the irrigation system and fertilizer; placed in the herbicided strips; and, added to the planting clover in the cool season as a cover crop followed by the application of manures in the spring. The timing of the fertilizer application will be investigated to prevent rapid increases in leaf nitrogen levels that precede aphid outbreaks. A single spring application at the full rate will be compared to three monthly applications in the spring and early summer.

The frequency of fungicide sprays for pecan scab can lead to increases in pecan aphid populations be suppressing aphidophagous fungi leading to an aphid outbreak.  Eleven hours of leaf wetness triggers a pecan scab outbreak. Leaf wetness will be monitored in the experimental orchard and fungicides will be applied when the leaf wetness period exceeds 11 hours to reduce the frequency of fungicides and reduce control costs and enhance biological control of pecan aphids by endemic entomopathogenic fungi.

Integrated approaches using both chemical insecticides and fungicides and microbial agents will be explored.  Additionally integration of microbials with other orchard management practices such as cover cropping will be tested as well.

3.2: Florida and Georgia. - Biodiversity comparisons between organic and conventional production will be continued using pitfall and Malaise traps.  Arthropods will be sampled at several locations of conventional and organic production within the canopy and on the ground over the course of the year on a monthly basis.  As the data is developed and indicator species are determined for each production type, further treatment comparisons will be made to identify how these species are impacted directly by selected management inputs.    

Objective 4. Develop real-time Decision Aids for Delivery on the Internet.

Regional Research (All states and USDA) - Entomologists and their associates in the current S-1017, in concert with pecan producers, developed Pecan ipmPIPE launched in April 2009. S-1017 and the newly formed Pecan ipmPIPE Producer Advisory Board are currently exploring and prioritizing what tools fit best on this platform and how to provision the platform to deliver them. All states and USDA will cooperate with the Pecan ipmPIPE Producer Advisory Board and producers to: update the Pecan IPM toolbox; plan and develop or upgrade real-time decision aids; and improve adoption and use of IPM by stakeholders. This will include continuing to recruit and train producers cooperating in the current program as well as involvement in new efforts as they evolve. A number of orchards from different latitudes across the pecan growing areas of the southeastern U.S. will be monitored with pecan nut casebearer traps and record nutlet damage counts to determine which regions can benefit from monitoring and online real-time pecan nut casebearer model to time insecticide sprays. Results will be compared to an available degree day model for model validation.

Objectives

1. Improved Monitoring and Forecasting Methods for Field Populations of Pecan Arthropods
   
2. Improved Control Systems for Pecan Arthropod Pests
   
3. Integrate Pecan Arthropod Pest Control Methods with Pecan Production Methods
   
4. Develop real-time Decision Aids for Delivery on the Internet
   

Methods

Research Sites. Over 300 acres of pecan orchards are available for the field trials Georgia, Louisiana, Arkansas, Texas, Florida and U.S.D.A. for research and demonstration plots. The high acreage is needed for the proposed research because trees are the sample units for many experiments and tree density ranges from 10-27 trees per acre. As examples, areas for research include: Cultivar evaluations can be conducted at University of Georgia at Tifton in a provenance collection where numerous bearing pecan trees of old and new cultivars are planted and cultured for research. The University of Georgia’s Coastal Plain Experiment Station in Tift Co., Ga. with 50A of 20 year-old pecan trees at Ponder Farm, 33A in at the Southeastern Branch Station near Midville and 35A of leased pecans near Plains. USDA-ARS Research Station, Byron, GA contains approximately 400 A of pecan for research purposes, the pecan blocks are interspersed with peach and forested land (the total area of the research farm is approximately 1200 A). Biological sources. Pecan insect and mites for various proposed bioassays will be produced naturally at highly infested and nontreated orchards. Pecan weevil adults will be collected by mass trapping with emergence traps; larvae will be collected as they emerge from early harvested, infested nuts at the Plains, Carter, Cook and Midville Farms. Kernel-feeding hemipterans will be collected from insecticide-free plots of legumes, sorghum and millet planted at the Coastal Plain Experiment Station. Blackmargined and black pecan aphids are ubiquitous and easily collected in large numbers from infested pecan trees. Microbial control agents will be produced on-site or purchased from commercial suppliers. Laboratory colonies of black pecan aphid, yellow pecan aphid and blackmargined aphid will be maintained on greenhouse-grown pecan seedlings. Brown stink bugs are polyphagous and easily collected in pheromone traps throughout the summer and early fall. Statistical Analysis of Data. Standard software used for analysis will be SAS v. 9.2 (SAS 2008) though alternatives such as Microsoft Excel (Microsoft 2007) enhanced with Poptools (Hood 2009) will also be used for data storage and analysis. Each variable measured in controlled replicated trials will be analyzed for distribution and normal variables or variables transformed to approximate the normal distribution will be analyzed by univariate analysis of variance. Significant differences (P< 0.05 level) between treatment means will be determined by the appropriate mean separation procedure, e.g. LSD-test for simple experiments with 2 or 3 treatments, Scheffe’ test for trials more than 3 treatments and with unbalance design, Tukey’s test for large experiments with balanced design. Relative variance will be estimated by calculating the coefficient of variance for each random variable and those with CV > 50% will be interpreted with caution (Steel and Torrie 1980). Objective 1. Monitoring and Forecasting Methods 1.1 Georgia and Florida - Identify semiochemicals (host-plant volatiles and pheromones) for attracting weevils to traps, and repelling weevils from pecan nuts. Surface extracts of the pecan shuck have many volatile compounds that may attract pecan weevil adults. These compounds (91 compounds from hexane extraction and 214 compounds from solid phase microextraction) have been identified by GC-MS (Harrison and Mizell, unpublished work in progress). Compounds will be tested for attractiveness in the field each season. Baited traps will be compared to non-baited traps and compounds that attract more adult pecan weevils will be combined in mixtures and tested for attraction in the field. A similar approach along with looking at pheromone production will be taken with hickory shuckworm. 1.2 Georgia - Pheromone baited traps will be tested as a monitoring device for Prionus root borers. The protocol places the pheromone over the opening to a pail-shaped (~1 l cap.) pitfall trap with the sides sprayed with RainX to prevent the beetles from crawling out. In 2009, these traps successfully caught Prionus laticollis and P. umbricornus adult males. The pheromone is anticipated to be commercially available in 2010. During the course of the proposed research project, experiments will be conducted to compare trap catch in traps place along the border of the orchard to trap catch in traps placed in the center of the orchard. Traps for female Prionus spp. beetles will be developed as pitfall traps amended with vanes radiated over the ground out from the center of the trap so that beetles will follow the vanes into the trap once the encounter the distal end. The pheromone tested in 2009 was derived from P. californicus. Female beetles are needed to determine the pheromones for species that are found in Georgia 1.3 Georgia – Fan traps for aphids will be tested and reconstructed for use in pecan orchards over the next five seasons to improve the ease of the collection of samples and waterproofing and portability. Small solar powered fan-light traps will be tested in the tree canopy for their effectiveness in collecting aphids and aphidophagous insects. 1.4 Georgia - Hickory shuckworm light traps will be run and pecans will be sampled for oviposition injury and nut drop at the same 4 locations from May 15 to Aug. 15 each week and daily at Tift Co. to determine the flight activity and occurrence times for injury and nut drop of the summer population over five seasons. 1.5 Arkansas – Arthropod pest populations and pecan nut load vary each season, yet few studies have compared the risks associated with pest control decisions in off (low yield) vs. on (high yield) seasons. Season long insect sampling with standard trapping methods coupled with nut production loss assessments will be conducted in commercial orchards during each season of the proposed project to find correlations between infestation level and production. The plant diversity of surrounding landscapes is a third factor that is important to the risk associated with injury to pecan nuts by stinkbugs – a major pest complex of pecan. Attempts will be made to develop risk of infestation models based on information collected over several orchards and seasons. 1.6 Regional Research (All states and U.S.D.A.) - Integration of weather and trapping information with biorational insecticides for control of pecan nut casebearer. Trapping of adult moths, egg laying and first nut damage will be measured in similar experiments across the pecan belt. The time of and duration of occurrence of these insect activities will be correlated with climatic variables at the trapping sites to further define existing degree-day driven models. The emergence of the adults is later in the north than in the south and apparently the differences can be described by the accumulation of degree-days at each location. The research basis for the degree-day model, however, lacks any direct measure of the effects of temperature on insect growth, development of metabolic rate. The current prediction model uses degree-days calculated from a base temperature interpolated from the correlation of field catch at different locations to the accumulated degree-days at each site. Objective 2. Control Methods 2.1 Georgia - Mite pest management will be developed by integrating biological and chemical control methods. Phytoseiulis persimilis and Galendromus occidentalis have been shown to be effective as biocontrols of pecan leaf scorch mite. The predatory mites will be purchased and released in six commercial pecan orchards in Georgia (three orchards will receive P. persimilis, three orchards will receive G. occidentalis) as an inoculative release (release mites in one tree per acre) during the Fall of the first season of the project. Each month from July to Oct the abundance of pecan leaf scorch mites and phytoseiid mites will be monitored in the release tree and trees adjacent to the release tree and trees two tree spaces from the release tree. These orchards will be managed without any changes from the grower’s standard methods. The demonstrations will continue for three seasons. Techniques for the transfer of predatory mites from donor orchards – orchards where predatory mites have been released in the previous season and have successfully overwintered and become established – to recipient orchards that lack predatory mites yet have pecan leaf scorch mite will be developed for pecan by testing methods that have been successful in fruit crops. Overwinter predatory mites will be collected by pruning limbs in the donor orchard and affixing them to limbs in the recipient orchard during the early spring before budbreak. Budbreak in pecan occurs later in the spring when ambient temperatures are already over the thermal threshold for mite activity. The transfer of overwintering mites will be tested at three dates in mid-January, mid-February and mid-March. The second technique is to transfer leaves with predatory mites from the donor site to the recipient site during the summer and fall. This technique will be tested on three dates. Successful transfer techniques will create a sustained system and eliminate the purchase insectaries after the initial purchase. 2.2 Georgia - Ant repellents (methyl anthranillate, methyl myristate and methyl carbitol) and insecticide treated baits will be evaluated in replicated field trials to enhance natural enemies in the intercrops by removing ants from the plants. The intercrops crops – crimson clover, hairy vetch and joint vetch - will be sown in the fall to provide alternate prey aphids for the predators in the spring. Predator species will also be monitored. 2.3 Regional Research (All states and U.S.D.A) – New chemical microbial controls for pecan insects and mites will be evaluated for efficacy in controlled field experiments with a nontreated control and standard pesticide treatment. Insects and mites will be monitored by standard methods in the plots and treatments will be applied when the a pest population reaches a level of abundancde greater than the prescribed action or economic threshold level. Plots will be monitored for the injury caused by the pests and for the abundance of secondary aphid, leafminer and mite pests to determine if the new treatments cause secondary pest resurgence. Baseline toxicological data will be collected by using laboratory bioassays of the mortality caused by a series of concentrations of the new insecticides or miticides to a sample of the pest population collected from the field. Typically, a slide dip bioassay is effective for aphids, bollweevil test is effective for pecan weevil and treated leaf disc bioassay is effective for pecan leaf scorch mite. Bioassays for pecan nut casebearer and hickory shuckworm have not been developed due to the lack of an effective rearing method. Gregarious caterpillars – fall webworm and walnut caterpillar – can be tested by treating whole leaves and excising the leaflets and feeding them directly to the caterpillars. Large plot applications will assess the ability of promising microbal control agents including nematodes (particularly Steinernema carpocapsae), fungi (Beauveria bassiana and Metarhizium brunneum) and the bacterium C. subtsugae, to control pecan weevil in organic settings. Microbial agents will also be compared with standard chemical insecticides in conventionally managed orchards. Small plot studies will be used to optimize application rates and timing and treatment combinations. Methods for microbial applications will be as described in Shapiro-Ilan et al. (2007). A variety of application and formulation approaches will be tested as well including the new persistent form of M. brunneum, microsclerotia, applied in a novel hydro-mulch (Goble et al. 2015). Economic analysis of organic approaches will be conducted (by University of Georgia Economist, Greg Colson). Certain plant growth regulators have been shown to prevent leaf chlorosis elicited by black pecan aphid feeding (Cottrell et al. 2010) and incorporation of this technology into commercial management systems has been initiated. These bio- regulators will be tested further for increased efficacy in controlled field experiments (with various rates and timing of application) to ascertain their practical application in pecan production systems compared with standard chemical insecticides. New chemical controls for stink bugs will be evaluated against existing controls to provide efficacy as well as residual activity data. Stink bug efficacy tests will be conducted against brown and green stink bugs. Pecan nuts on trees will be sprayed with insecticides and brought to the laboratory 1, 4, and 7 days after insecticide application. For each day after application that stink bugs are tested, one stink bug will be placed into a cup with one nut and mortality assessed at 24 and 48 hr. Objective 3. Integration of techniques at points of known positive interactions between factors. 3.1 Georgia, U.S.D.A. - Integration of banker plants including crape myrtle and leguminous intercrops to increase soil fertility and enhancement of biological control of pecan aphids by ladybeetles will be investigated in controlled field experiments to determine methods for attracting ladybeetles from the legume intercrops to the tree canopy and the planting density of cool and warm season intercrop plants that will increase the abundance of ladybeetles on the orchard floor. Application of lower amounts of commercial formulations of complete fertilizers will be investigated by improving the placement and timing of applications. Standard broadcast application of fertilizer will be compared to fertilizer: placed near the areas wetted by the irrigation system and fertilizer; placed in the herbicided strips; and, added to the planting clover in the cool season as a cover crop followed by the application of manures in the spring. The timing of the fertilizer application will be investigated to prevent rapid increases in leaf nitrogen levels that precede aphid outbreaks. A single spring application at the full rate will be compared to three monthly applications in the spring and early summer. The frequency of fungicide sprays for pecan scab can lead to increases in pecan aphid populations be suppressing aphidopagous fungi leading to an aphid outbreak. Eleven hours of leaf wetness triggers a pecan scab outbreak. Leaf wetness will be monitored in the experimental orchard and fungicides will be applied when the leaf wetness period exceeds 11 hours to reduce the frequency of fungicides and reduce control costs and enhance biological control of pecan aphids by entomopathogenic fungi. Integrated approaches using both chemical insecticides and fungicides and microbial agents will be explored. Additionally integration of microbials with other orchard management practices such as cover cropping will be tested as well. 3.2: Florida and Georgia. -Biodiversity comparisons between organic and conventional production will be continued using pitfall and Malaise traps. Arthropods will be sampled at several locations of conventional and organic production within the canopy and on the ground over the course of the year on a monthly basis. As the data is developed and indicator species are determined for each production type, further treatment comparisons will be made to identify how these species are impacted directly by selected management inputs. Objective 4. Develop real-time Decision Aids for Delivery on the Internet. 4.1 Regional Research (All states and USDA) - All states and USDA will participate in cooperation with the Pecan ipmPIPE Producer Advisory Board and producers in the planning, development and delivery, in association with extension, of decision aids to improve adoption and use of IPM by stakeholders. This will include continuing to recruit and train producers cooperating in the current program as well as involvement in new efforts as they evolve. A number of orchards to represent different latitudes across pecan growing areas of the southeastern U.S. will be monitored with pecan nut casebearer traps and supplemented with nutlet counts to determine the need for and timing of insecticide sprays. Results will be compared to an available degree day model for model validation.

Measurement of Progress and Results

Outputs

• The project will generate new data on insect monitoring methods, chemical and biological pest controls and the interactions that occur in the field between soil fertility maintenance and pest control methods. New information will be generated on the seasonal occurrence of various arthropod pest populations and their associated beneficial insects and mites. Concurrent collection of climatic information will be analyzed for possible correlations between population dynamics and climate. New data on the efficacies of new control methods, the impact of the new control methods on the other insects and mites in the orchard, the interactions between the new methods and cultural methods, particularly, the maintenance of soil fertility with cover crops and commercial fertilizers will be generated by work of the new regional project. Decision aids and IPM education materials will be delivered on the Pecan ipmPIPE Platform. Producer usage will be tracked.

Outcomes or Projected Impacts

• Pest control and fertilizer costs are increasing rapidly in comparison to other pecan production costs. The greatest impact of the proposed research work will be the development of lower costs pest control and soil fertility maintenance costs for pecan growers. The new methods outlined in the proposed work will be compared with standard methods for efficacy against the pests and residual control after the application. New chemical controls that are more effective and have a longer residual control period than the standard method should be readily used by pecan growers. The released biological control agents may offer sustained control the pests for several seasons and have additional value to the pecan grower. Reduced fertilizer rates or the application of split applications of fertilizer several times during the season may reduce sudden flushes in leaf nitrogen and prevent aphid and mite outbreaks. Cover crops and inter crops add nitrogen to the soil and enhance biological control of aphids. Tracking information extracted from the Pecan ipmPIPE Platform will be analyzed to identify who was accessing what information, when and how much they growers were accessing, and then interpreted to determine probable effects on adoption of IPM; these results will be additionally informed by on-line surveys on the platform and independent surveys conducted in the various states. Overall, we expect producers to be better informed, increase adoption of IPM including biocontrol, apply fewer and better timed treatments and thereby reduce operating costs, risk of resistance and harm to the environment.

Milestones

Projected Participation

View Appendix E: Participation

Outreach Plan

The research work of the regional project will be reported in refereed publications of the Entomological Society of America, Georgia Entomological Society and other scientific journals. The pecan industry is fortunate to have a well-established network of state and regional grower associations that produce highly read and distributed, editor-refereed publications including: The Pecan Grower, Pecan South, Proc. Southeastern Pecan Growers Association, Northern Nut Growers Journal and Proc. of the Western Pecan Growers Assoc.  These associations also host annual meetings and field days that include educational sessions and equipment shows where the new control methods can be presented and demonstrated to the growers by the researchers or their extension counterparts. The information generated by the regional research project is also taken directly to the growers by extension specialist in all pecan producing areas of the U.S

Organization/Governance

The technical committee will have three officers - secretary, vice-chairman, and Chairman: A new secretary will be elected from the members of the technical committee each year to serve a three year term, the first year as Secretary, the second year as Vice Chairman and the third year as Chairman. The technical committee will meet one time per year to discuss research and plan new activities.

Literature Cited

Bugg, R.L., J.D. Dutcher and P.J. McNeill.  1990.  Cool season cover crops in the pecan understory: effects on Coccinellidae (Coleoptera) and pecan aphids (Homoptera:Aphididae).  Biol. Control 1: 8-15.

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