NC-226 Meeting Minutes
Development of Pest Management Strategies for Forage Alfalfa Persistence
Hilton Suites
Lexington, Kentucky
February 26-27, 2002

Tuesday, February 26

The meeting was called to order by Bill Witt, NC-226 Chair, at 1:10 pm on Tuesday, February 27, and he welcomed the group to Lexington. At Chairman Witt's invitation, we went around the table with introductions. He arranged a group dinner for Tuesday evening.

At 1:15 Chairman Witt introduced Dr. Nancy Cox, Associate Dean for Research, University of Kentucky, who addressed the committee. She described agriculture in Kentucky, and in particular emphasized the increasing importance of beef forages both in the state and in the College.

At 1:25 Chairman Witt asked Phil Larsen, NC-226 Administrative Advisor, for comments. NC-226 officially began on October 1, 1999, and the project is scheduled to have its midterm critical review this year. There was discussion on how multistate committees are reviewed and approved in general. He believes NC-226 has good interaction among the members, but thought more interaction is needed. Overall, he views NC-226 as positive.

At 1:35 Chairman Witt asked Preston Jones, CSREES, for comments. He described current reorganization efforts within CSREES, and specifically listed new leaders within the various departments. He described the current status of the budget, mentioning that support for IPM and related programs was unchanged from last year. Biosecurity was discussed, although APHIS and not CSREES is especially impacted. IFAFS was not supported for funding this year.

At 2:00 Chairman Witt reconvened the group and asked for a report from Objective 1 (Elucidate mechanisms by which biotic agents interact with abiotic factors to limit strand persistence of forage alfalfa), which has been coordinated by Jeff Volenec. Because of weather, Jeff was absent, so individuals reported on key findings from this objective.

Paul Vincelli, University of Kentucky, described Sclerotinia crown and stem rot studies. He has focused on developing evaluation techniques for screening varieties.

Fred Gray, University of Wyoming, discussed his research on brown root rot, Phoma sclerotioides, in Wyoming. He believes the pathogen is native, but introduced to alfalfa fields. The pathogen causes plant mortality after about three years, and also results in reduced yields. He uses RAPD markers for identification, and has been performing selection testing to increase host plant resistance.

Jennifer Cox, Ohio State University, discussed her research on the interaction between potato leafhopper and Fusarium. In a factorial design, her treatments consisted of all possible combinations of three cultivars, with and without leafhopper injury, and with and without Fusarium present. Combined stresses resulted in fewer plants, reduced yields, and lower crown and root rot weight. However, the interaction term in the ANOVA was not significant for any cultivar.

General discussion of crown rots continued. Fusarium is common in Ohio, occurring over several years. Fred Gray mentioned that grazing caused increases in crown rots in Wyoming. Bruce Anderson said that varieties used for grazing are less susceptible to crown rots.

Bill Lamp, University of Maryland, described the results of field and greenhouse studies with glandular-haired alfalfa cultivars and the occurrence of tolerance to leafhopper injury. Photosynthesis rates generally decrease shortly after the initiation of leafhopper feeding, but the reduction is less with the new glandular-haired cultivars.

Mark Sulc, Ohio State University, described a five-state study of historical trends within alfalfa since 1940. In the first two years of the study in Ohio, there was no significant relationship between year of release and annual forage yield, suggesting little or no genetic improvement in yield potential. In the third year of the stand (2001), Ohio data showed an increase in yield versus the year of variety release, suggesting genetic improvement over time in yield persistence. Stand density was not significantly related to year of release at the beginning of the third year, but significant stand loss was observed during 2001, and a stronger relationship may emerge between year of release and stand density ratings in early 2002. This study is being continued.

Mark also described the history of leafhopper resistance, stating that the differential between insecticide-treated and untreated plots of glandular-haired cultivars has diminished with greatly in the most recent resistant cultivar releases. A current cultivar, Pioneer 54H91 is over 70% resistant to leafhopper, and has shown reduced densities of adults and nymphs in 40x40 ft plots. , In older studies with the earlier releases, the susceptible cultivar appears to have better persistence than the resistant ones. Persistence data is not yet available on the newest releases.

Rod Youngman, Virginia Tech University, described a study by Teresa Dellinger, which was seeded in two locations. Alfalfa weevil was present at the Piedmont location, and less so at the Blacksburg location. She compared a leafhopper-resistant cultivar to a susceptible one. At the Piedmont location, alfalfa weevil caused severe injury to both cultivars. She found no significant difference in potato leafhopper densities at either location.

In a general discussion, Mark stated that the newest cultivars appear to have less yield drag. The timing of growth differs among cultivars, so this has resulted in differences in susceptibility to alfalfa weevil. As a result, weevil can cause more damage to glandular-haired cultivars that traditional ones. He believes the level of resistance to leafhopper is leveling off. The glandular-haired cultivars were oversold early on, and now it is hard to convince growers to try the new glandular-haired cultivars even though the price of seed is now similar.

Chairman Witt then initiated a discussion of objective 3. Rod Youngman discussed his studies of the interactive effects of natural enemies of alfalfa weevil. First, Bathyplectes curculionus was especially common in Virginia; now, 80-90% of the larval parasitism is caused by Bathyplectes anurus. No differences have been found in rates of parasitism among the varieties tested. He tested for insecticide impacts on natural enemies and concluded that the prevention of a leafhopper insecticide application with resistant varieties can result in the increase in activity and survival of alfalfa weevil natural enemies.

At 5:05 pm, Chairman Witt noted the many accomplishments of Bobby Pass to the alfalfa regional committees over the years, as well as to him personally. He was present at the first “Forage Legume Persistence” meeting in Pere Marquette State Park, continuing his support for alfalfa IPM. He passed away last December. Bill Lamp added that Dr. Pass was critical in the development in the current NC-226 project.

Chairman Witt concluded the discussion for the day with a reminder of when to meet for dinner.

Wednesday, February 27

At 8:15 am, Chairman Witt brought the meeting to order. Tim Dietz, Michigan State University, reported on research on behalf of Rich Leep. Their research has emphasized site specific management in alfalfa. They selected areas of low fertility to focus on management, and measured plant density changes from 25/ft2 in fall, 200, to 20 in spring, 2001, and to 12 in fall, 2001. There was no difference between the whole field versus site specific locations. Although there was no effect of boron applications at the Kellogg location, at Osceola boron resulted in less reduction in plant density. Generally, he concluded that there was no real economic advantage for site specific management.

Al Barta, Ohio State University, described a field study on alfalfa persistence based on observations of what happens to plants. Within a 40x100 ft area at 3 sites, he constructed 32 subplots in each of 4 blocks. Within subplots, he thinned plants to have 25 plants spaced about 2 cm apart within a row. Using laminate to mark locations of each plant, he could follow the history of individual plants. At each harvest, he destructively sampled a subplot, measuring yield components, pest injury, and distance to nearest neighbor. Losses varied across sites, with up to 8% loss. Losses were greater for spring planting than fall. Fusarium levels differed across sites, but levels did not differ between large and small plants. In addition, he screened for Micoleptodiscus crown and root rot, and found it present at two of the sites. There was no relationship between nearest neighbor distance and mortality. He found it was hard to define the cause of mortality; experimental manipulations may be necessary to study specific factors.

Bill Lamp, University of Maryland, provided an outline for an article to synthesize what is known about alfalfa persistence and what information is needed. Details of the outline will be sent to members late spring. The outline includes sections for the physiological cycles of alfalfa, demography and growth of alfalfa under optimum conditions, constraints caused by pests, constraints caused by management, constraints caused by abiotic factors, and interactions. The focus for each section is on yield components. The synthesis concludes with a strategy for persistence based on management and breeding. In general, the group thought the article was a good idea, and that it provided guidance for continuation of the project. Various outlets for publishing the synthesis were discussed, but no specific location was the consensus. Individuals were suggested to help with writing for various sections. These individuals will be contacted by Lamp later this spring.

Rod Madsen, University of Nebraska, described his research with Leon Higley on the effect of defoliation simulation on alfalfa growth and physiology. His simulation removed leaves from bottom to top of the plant, similar to spring blackstem and clover leaf weevil. This is in contrast to alfalfa weevil, which defoliates from top to bottom. His research is continuing this spring.

During the business meeting, Bruce Anderson agreed to become Chair and host the meeting in Lincoln, Nebraska in 2004. For 2003, Rich Leep will become Chair and host the meeting in East Lansing, Michigan starting at 1:00 on Tuesday, February 25, and ending at noon on Wednesday, February 26, 2003. Bill Lamp will continue to serve as Secretary. Objective coordinators will continue for 2003. Phil Larsen informed the group that if the voting member within a state changes, the Experiment Station Director should send a letter to Phil. Problems have been noted with the listserve; the current list held by Bill Lamp should be sent to Rod Madsen for updating [The list was faxed to Rod on 15 March].

Bill Lamp, University of Maryland, described a model website that he and others have developed for potato leafhopper, combining both basic biology and management information with up-to-date syntheses of specific topics under current research. Specific sections of the site include: scientific classification, taxonomy and identification, distribution, host plants, life cycle, life stages, feeding behavior and injury, population ecology, and management including host plant resistance, insecticides, and sampling for decision-making. A list of references is included, as well as links to other web sites. Contributors to date include: Elaine Backus, Ron Hammond, Bill Lamp, Elson Shields, Mark Sulc, and Paul Taylor. Other contributors are planned. Lamp plans to put the web site on the persist.umd.edu site during the summer.

Several items of the website were discussed. As a model for other pests, it was suggested that Craig Grau could develop a similar site for Aphanomyces in alfalfa. A suggested way to cite the website should be included, and the site should be peer-reviewed to enhance its value. Paul Vincelli suggested using the DOI number (digital object identifier), which allows citation even when the URLs changes. No specific university logo should occur on the home page, but a logo could be placed by the name of the person who actually set up the website.

Next year will follow the same reporting schedule. The Objective Summaries and State Reports should be circulated by email before each meeting, and that individuals should print copies for themselves to bring to the meeting. To keep the size of the reports to a workable size, it is suggested (but not required) that each research study report is limited to one page of text, tables, and figures. Subsequent to the meeting, the 3-page official report will be prepared. The following report components will then be placed on the web site (persist.umd.edu):

1. Meeting agenda
   
2. Meeting participants
   
3. Meeting minutes
   
4. Official 3-page report
   
5. List of membership
   
6. Objective summaries and state reports
   
7. List of publications
   

        The meeting concluded at 11:30 am.

Submitted by:

Bill Witt and Bill Lamp, May 1, 2002.