Brief Summary of Minutes of Annual Meeting

Voted on next destination for meeting: San Juan to be held in cooperation with Puerto Rico Extension.

Washington

Cut Flowers: Botrytis diseases are among the most damaging diseases on ornamental bulb and cut flower crops. To improve the management of these diseases, Washington State University has demonstrated that a preharvest application of isolfentamid (Astun) to flower buds were as effective as a 5-second postharvest dip of peony flower buds in fungicides in providing provided effective control of Botrytis development during the display of peony flowers.

Sudden Oak Death: As a result of shipping Phytophthora ramorum infected plants from a 450 acre nursery in Washington to a number of states throughout the U.S., Washington State University provided technical support to WSDA and APHIS regulators to delineate the extent of the infestation at the nursery, determined that all of the isolates obtained at the nursery were the NA2 lineage, and collaborated with WSDA and APHIS to carryout mitigation efforts (removal and destruction of plants and soil steaming) at the nursery.

CoFirGE Project: In 2010 the Collaborative Fir Germplasm Evaluation (CoFirGE) Project was organized as a collaboration of university research and extension faculty and Christmas tree grower associations in five production regions of the United States (CT, MI, NC, PA and the Pacific Northwest) and Denmark. The goal of this project is to identify regionally adapted sources of Turkish and Trojan firs that produce superior Christmas trees across production regions in the United States and Denmark. Washington State University has confirmed previous assessments showing that the top performing species and sources of trees in the Nisqually, WA CoFirGE plot include a mix of traditional PNW-grown species, such as grand and noble, as well as less commonly grown species such as Turkish and Trojan firs. A number of Turkish and Trojan fir families continue to exhibit Christmas tree characteristics. 

Twig weevil biology: Scientist at Washington State University initiated a project to understand why the Douglas-fir twig weevil (Cylindrocopturus furnissi) has become a more prominent pest of Pacific Northwest-grown Christmas trees, including in true fir tree species previously unknown to be suitable for the insect’s feeding and development. Surveys have been conducted and specimens have been collected from over 20 sites in Oregon and Washington for use in population/phylogenetics. DNA sequencing of individuals varying by host association and by geographic origin is ongoing. Four long-term monitoring plots in Oregon and Washington have been established to determine the number of degree-days required for adult emergence. Choice feeding trials have also been conducted to determine the preferences of the beetles.

Nebraska

tate disease status: 2019 was the year that a shipment of infested Rhododendron plants from a nursery in Oklahoma introduced Phytophthora ramorum the causal agent of Sudden Oak Death into Nebraska. Of approximately 40 infested Rhododendrons that reached retail dealers about 30 were retrieved by the Nebraska State Department of Agriculture, and destroyed. It is believed that approximately 10 plants had been sold to the public and planted into the urban and suburban landscapes. All information on this incidence was censured so the forest pathologists and nursery and landscape pathologists were not informed until the nation was alerted, some 6-months after the incident.  This fall season commercial nurseries with Rhododendron from the major California nursery were found severely diseased with branch dieback and root rot caused by Phytophthora species. Phytophthora-positive ELISA tests, DNA sequencing of barcoding genes, and selective isolation from Rhododendron were accomplished by graduate students during lab exercises in a diagnosis course. 

A potentially destructive root and butt rot pathogen of hardwood trees, Pseudoinonotus dryadeus, has extended its reported range and entered Nebraska. It was first spotted on two separate oak trees in the Lincoln suburban housing district having boulevards lined with 100+ year old Quercus palustris, Pin Oak.  Oak wilt, Ceratocystis (Bretziella) fagacearum, has not been confirmed as present in Nebraska during the last few decades. Dutch elm disease is currently causing mortality in urban elms in Lincoln, NE.

2019 was an uncommonly wet growing season and this increased incidence of anthracnose and other foliage diseases. For a second report year in the decade, Callery pear suffered extensive defoliation from severe Cedar apple rusts. While Gymnosporangium clavipes the causal agent of Cedar quince rust is present, the defoliation was caused by the Cedar hawthorn rust. Gymnosporangium libocedri cause of Pacific Coast pear rust, and Gymnosporangium sebinae cause of European pear (trellis) rust have not been found.

Research: The research project involving the etiology of bud blight of spruce caused by Gemmamyces piceae, a pathogen considered as native to mountains in north western China. In Czech Republic, an extensive epidemic with mortality and severe damage has been reported in 2016 as occurring throughout much of Central Europe on Colorado blue spruce, Picea pungens. In 2017, widespread bud blight occurred on four species of Sitka, White, Lund, black and Colorado blue spruce, throughout north western, interior, and south eastern Alaska including national forests, parks, and urban landscapes.

We began whole genome sequencing of G. piceae from Czech Republic in 1917 and have this year expanded whole genome sequencing (WGS) to include Alaska Gemmamyces sp. WGS has been initiated in order to identify and select genetic markers (SNPs & SSRs) for a population genetics study. The study should reveal native, native invasive, and exotic invasive origins and predicted transportation pathways of introduction of the pathogen. 24 SSR markers have designed and utilized in identifying polymorphic alleles in a collection of strains. Differences recognized between European and American populations are shaping our concepts of the Gemmamyces species.

Five genes are being sequenced in order to properly identify and classify the fungi causing Aspen running canker, Western hemlock branch dieback and mortality, and Gemmamyces bud blights. Sequences of ITS- rDNA, LSU-rDNA, beta-tubulin, RPB2 (DNA directed RNA polymerase II subunit), and Elongation factor 1-alpha are being completed and used in phylogenetic analyses to clarify species in the relevant genera based on new (2016) phylogenetic studies from the Westerdijk Fungal Biodiversity Institute (formerly CBS). Formal morphological characterization of the pathogens is also being completed for publications.

Ohio

• Conifer trees, including Norway spruce, are threatened by fungi of the Heterobasidion annosum species complex, which severely affect timber quality and cause economic losses to forest owners. The timely detection of infected trees is complicated, as the pathogen resides within the heartwood and sapwood of infected trees. The presence of the disease and the extent of the wood decay often becomes evident only after tree felling. Fourier-transform infrared (FT-IR) spectroscopy is a potential method for non-destructive sample analysis that may be useful for identifying infected trees in this pathosystem. We performed FT-IR analysis of 18 phloem, 18 xylem, and 18 needle samples from asymptomatic and symptomatic Norway spruce trees. FT-IR spectra from 1066 – 912 cm^-1 could be used to distinguish phloem, xylem, and needle tissue extracts. FT-IR spectra collected from xylem and needle extracts could also be used to discriminate between asymptomatic and symptomatic trees using spectral bands from 1657 – 994 cm^-1 and 1104 – 994 cm^-1, respectively. A partial least squares regression model predicted the concentration of condensed tannins, a defense-related compound, in phloem of asymptomatic and symptomatic trees. This work is the first to show that FT-IR spectroscopy can be used for the identification of Norway spruce trees naturally infected with Heterobasidion
• Austrian pine (Pinus nigra) is a valuable component of the urban landscape in the Midwestern USA. In this area, it is impacted by the fungal pathogen Diplodia sapinea, which causes a tip blight and canker on infected trees. While the disease can be managed through the application of fungicides and/or by preventing environmental conditions that are favorable for the pathogen, these practices only temporarily alleviate the problem. A more sustainable solution is to use resistant trees. The objective of this study was to evaluate whether Fourier-transform infrared (FT-IR) spectroscopy combined with chemometric analysis can distinguish between trees that vary in susceptibility to sapinea. Trees were phenotyped for resistance to D. sapinea by artificially inoculating shoots and measuring ensuing lesions, seven days following inoculation. Then, three different chemometric approaches, including a type of machine learning called support vector machine (SVM), were used to evaluate whether or not trees that varied in susceptibility could be distinguished.  Trees that varied in susceptibility could be discriminated based on FT-IR spectra collected prior to pathogen infection using the three chemometric approaches: soft independent modeling of class analogy, partial least squares regression, and SVM.  While further validation of the predictive models is needed, the results suggest that the approach may be useful as a tool for screening and breeding Austrian pine for resistance to D. sapinea. Furthermore, this approach may have wide applicability in other tree/plant pathosystems of concern and economic value to the nursery and ornamental industries.
• Beech leaf disease (BLD) is a currently undiagnosed and seemingly lethal disease that is affecting American beech trees (Fagus grandifolia) in forests in the northeastern United States. The initial disease symptom is a dark interveinal banding pattern on the foliage, and the progressive symptoms are dark, crinkled leaves that dramatically reduce the canopy cover. Eventually, no new leaves are produced leading to tree mortality. The objective of this study was to discover the causal agent of BLD using a comparative metabarcoding approach to profile the microbial communities present in symptomatic and asymptomatic American beech leaves. This research will assist forest managers in protecting the American beech tree, a foundational tree species in the eastern United States’ beech-maple forest ecosystem and lead to further research focusing on screening for BLD resistance in the forest. In our study, we used molecular techniques based on gene regions of total beech leaf DNA and RNA to screen the leaves’ microbiomes for the main plant pathogen types (i.e. fungi, bacteria, phytoplasmas, viruses, and nematodes). Our results suggest that a nematode previously only detected in Japan, Litylenchus crenatae, is present on both asymptomatic and symptomatic leaves while two species of fungi and three species of bacteria are only present on symptomatic material. Based on the exotic nature of crenatae, this suggests that there may be an association between the microbes and the alien nematode which contributes to the manifestation of symptoms of BLD.

Indiana

State Diagnostic Records-Ornamentals

Report to date 2019: Number of diagnoses to date

Joint Research Extension Activity.

Continued work to update the Tree Doctor App and create the Purdue Shrub Doctor App. Janna is the rate limiting step. Data for the project to date includes:

Delaware

Delaware has cooperated with University of Maryland Cooperative extension (Stanton Gill) with research targeting difficult pests in nursery and greenhouse systems.  Some pests have included root feeding mealybugs or aphids, whiteflies, or mealybugs.  These projects have examined efficacy of biological control or non-neonicotinoid insecticides as alternatives to neonicotinoids for those in the green industry looking for such options. 

During 2019, the Plant Diagnostic Clinic processed approximately 560 non-survey routine clinic samples. Ornamentals, landscape annuals and perennials along with trees, shrubs, and turf made up 55% of total samples. There were no regulatory USDA CAPS survey samples, but nursery surveys for Delaware Department of Agriculture resulted in a few samples of boxwood. No boxwood blight was detected in retail or nursery sites, but other boxwood diseases and environmental stress are problematic. Fusarium wilt was detected in chrysanthemum nursery and retail sites.  

New reports included Pseudocercospora sp. on crape myrtle, Cryptocline sp. on birch, Cyperus strigosus (false nutsedge) on potted lily turf in a nursery, Phacidium (tar spot) on American holly, and Taxodiomyia (gall midge) on bald cypress. Spotted lanternfly (Lycorma delicatula) was detected in multiple sites across the state of Delaware.  Delaware cooperative extension worked closely with the Delaware’s Department of Agriculture in outreach and education efforts regarding spotted lanternfly and emerald ash borers – two recent invasive pests found in Delaware.

Florida

South Florida plant nursery industry is diverse and grown year-round. Some pests affecting Miami-Dade County on 2019 in south Florida

During dry season (November to April) of 2018-2019, mites were affecting crops such Crotons and Hibiscus. State specialists will be keeping an eye on this pest. No specific species identified yet.

On December of 2019, 8 years after Giant African Land Snail (GALS) eradication program started, the Florida Department of Agriculture and Consumer Services (FDACS) and the U.S. Department of Agriculture (USDA) reported over 168,500 snails being collected in 32 core areas of Miami-Dade County, and in one area of Broward County.

Clemson

Objective 1: New and emerging pests: Investigate detection methods, biology, and management of new and emerging pests

Crape myrtle bark scale was detected in South Carolina for the first time in 2019. Currently infestation is restricted to areas around Columbia, SC. Infestation was detected by a homeowner, who alerted Clemson University Extension Services, and the scale species was subsequently confirmed by USDA-APHIS.

A research project to develop degree-day model for redheaded flea beetle and strawberry rootworm in eastern Georgia and western South Carolina, with funding leveraged from the Center of Applied Nursery Research, has been completed in 2019. Degree-day units, with based temperature of 50°F and start date of January 1, were 478 DDG for the first detection of redheaded flea beetle adult, 572 DDG for peak activity, 874 DDG for 50 percentage of the population, 3291 DDG for 90% of the population, and 5656 DDG for the last detection of the beetles. Degree-day model could not be developed for strawberry rootworm because this species overwinter as adults, which become active whenever temperature was high enough to allow movement and feeding.

A collaborative multi-state research team formed under this working group continues to document the diversity and seasonal activity of elm bark beetles throughout the country. In South Carolina, only Scolytus multistriatus occurs in the costal plains (trapping site at Florence, SC), whereas both S. multistriatus (94%) and S. quadrispinosus (6%) occur in the Upstate (trapping site at Clemson, SC). No banded elm bark beetle was detected in 2018 and 2019.

Objective 2: Pesticide technology development: Evaluate effectiveness of reduced–risk pesticides, biopesticides, new and novel chemistries, and application technologies for control of key disease and arthropod pests of landscapes, nurseries, and Christmas trees

Research team at Clemson University had conducted 20 trials in 2018-2019 to evaluate the efficacy of novel and reduced-risk insecticides and miticides (afidopyropen, alpha-cypermethrin, BCS-507, chlorantraniliprole, cyantraniliprole, cyclaniliprole, flonicamid, fluopyram, flupyradifurone, indoxacarb, ISM-555) and biopesticides (Beauveria bassiana) against ambrosia beetle, sweetpotato whitefly, western flower thrips, potato aphid, melon aphid, green peach aphid, longtailed mealybug, citrus mealybug, Rhodesgrass mealybug, European pepper moth, redheaded flea beetle, twospotted spider mite, bermudagrass mite, billbug, southern chinch bug and mole cricket.

Objective 3: Pesticide alternatives: develop management strategies for key pests based on classical biological control, host plant resistance and cultural control

A MS student project has been initiated to investigate the compatibility between chordotonal organ TRPV channel modulator insecticides (IRAC Group 9) and the minute pirate bug, Orius insidiosus. The project will investigate the mortality and sublethal effects (fecundity and predation efficacy) of Orius when the predators are exposed to insecticides or their residue directly (through immersion and forced hydration bioassays) and indirectly (through residual toxicity bioassays). Results and implications of this project will become available in 2020.

Objective 4: Technology transfer: Develop and deliver science-based educational materials focused on management of key pests through outlets such as mass media, publications and fact sheets, eXtension.org and social media

Team at Clemson University had provided 31 extension presentations and 2 webinars to audience in SC and throughout the country. In addition, 34 e-newsletters “PestTalks” (with about 22,000 subscriptions) and other extension bulletins had been published. The team conducted 17 site visits and provided 199 species identification and management recommendations.