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Applied Research On Field Crop Disease Control 2004

ID

450-564

Authors as Published

P.M. Phipps, Plant Pathologist, Tidewater Agricultural Research & Extension Center, Suffolk; Virginia Tech

ACKNOWLEDGMENTS

The author wishes to thank the Virginia Agricultural Experiment Station and the many cooperators and contributors who provided the resources needed for conducting this applied research program. Special recognition is extended to Barron Keeling and Steve Byrum for technical skills needed to manage the Peanut/Cotton InfoNet, maintain nine weather stations, manage 30 field trials, collect critical data, maintain accurate records, process data, and prepare this report. The contributions of Dr. Benjy Cline at Virginia Tech in updating programs for the Peanut/Cotton InfoNet were greatly appreciated. Ed Hobbs, Carolyn Daughtrey, and Brenda McMurtrey are recognized for assistance in plant growth measurements and maintaining field plots. Dr. John Eisenback and Diane Reaver of the Department of Plant Pathology, Physiology & Weed Science contributed to this research by processing and identifying nematode populations in soil samples from cotton and peanut peanut trials.

LIST OF COOPERATORS AND CONTRIBUTORS

Virginia Polytechnic Institute and State University, and Virginia Agricultural Experiment Station
Mr. R. D. Ashburn, Farm Manager, Tidewater Agricultural Research & Extension Center
Dr. Benjy Cline, Department of Entomology
Dr. Dennis L. Coker, Tidewater Agricultural Research & Extension Center
Dr. Jon D. Eisenback, Dept. of Plant Pathology, Physiology, and Weed Science
Dr. Joel Faircloth, Tidewater Agricultural Research & Extension Center
Dr. D. Ames Herbert, Jr., Tidewater Agricultural Research & Extension Center
Mr. R. W. Mozingo, Tidewater Agricultural Research & Extension Center

Faculty at other Universities
Dr. Bill Branch, Peanut Breeder, Univ. Georgia
Dr. Dan Gorbet, Peanut Breeder, Univ. Florida
Dr. Tom Islieb, Peanut Breeder, NC State Univ.

County Extension Agents
Wes Alexander, Southampton, County, VA
Rex Cotten, City of Suffolk, VA
Paul Davis, Charles City County, VA
Glenn Rountree, Isle of Wight County, VA

Growers and/or land owners
Son Bailey, Waverly, VA ......................................................Weather Station
D. M. Barnes, Dinwiddie, VA ...............................................Weather Station
Cecil Byrum, Windsor, VA ...................................................Weather Station
Sammy Cox, Elberon, VA .....................................................Weather Station
Jay Darden, Newsoms, VA ...................................................Weather Station
Kenny Edwards, Branchville, VA .........................................Weather Station
M. L. Everett, Joyner, VA......................................................Weather Station
Glenn H. Hawkins, Skippers, VA..........................................Weather Station
Phillip Edwards, Smithfield, VA ...........................................Test Plot
Kenny Edwards, Branchville, VA .........................................Test Plot
Tom Hall, Charles City County, VA .....................................Test Plot
Rick Morgan, Corapeake, NC................................................Test Plot
Tommy Darden, Isle of Wight, VA .......................................Test Plot

Commodity Groups and Organizations
Cotton Incorporated
Cotton Foundation, Seedling Disease and Nematode Control Committee
National Cottonseed Treatment Program
Virginia Cotton Board
Virginia Peanut Board
National Peanut Board
Virginia Agricultural Council
Virginia IPM Program

Private Companies
AgraQuest, Inc., Davis, CA
Amvac Chemical Corp, Newport Beach, CA
BASF Corp., Raleigh, NC
Bayer CropScience, Kansas City, MO
Birdsong Peanuts, Franklin, VA
Cerexagri, Inc., King of Prussia, PA
Coastal Chemical Corp., Greenville, NC
Gustafson LLC, Plano, TX
Nichino America, Inc., Wilmington, DE
Sipcam Agro, Inc., Roswell, GA
Syngenta Crop Protection, Wilmington, DE
Taminco, Inc., Smyrna, GA
Tessenderlo Kerley, Inc., Eufaula, AL
Valent U.S.A. Corp., Cary, NC

POLICY FOR ACCEPTANCE OF PESTICIDES FOR TESTING

Research on synthesis and exploration of agricultural chemicals and biotechnology for use in pest control continues to provide new materials for field evaluation. Compounds are being made available by private companies and universities for local research in a variety of ways; ranging from a sample with a code number to a thoroughly tested material, with secure patents, technical data sheets, and comprehensive resumes of results of laboratory and field trials. Unfortunately, it is not possible for a scientist to include all materials and use patterns in a field research demonstration program. Therefore, materials are selected according to (i) overall need for a product in a particular crop or problem area, and (ii) overall promise of the material to improve crop management at the local level.

Before a material can be accepted for testing, the following descriptive information is required: (i) a list of the spectrum of biological activity, (ii) data on phytotoxicity and suggested rates of application, (iii) methods of application, (iv) formulations available, (v) mammalian toxicity (LD50), (vi) possible health hazards, and (vii) possible hazards to the environment. Additional information that would be desirable includes: (i) identity of the active ingredient(s) and inert materials, (ii) physical properties (solubility, MP, VP, stability, etc.), (iii) residue information, (iv) residual soil life, (v) EPA residue tolerance (if any) and registration status, (vi) patent status, and (vii) unit cost in commercial markets.

Upon completion of field applications, it is the responsibility of the sponsor to dispose of all unused test materials. Because of limited space in controlled pesticide storage facilities and expenses associated with shipping and disposal, all sponsors are encouraged to ship not more than 1.5 times the anticipated quantity needed to complete a test.

INTRODUCTION

According to records maintained over the last 72 yrs at the Tidewater AREC, rainfall in May, June, July, August, September, and October was 0.95, 0.83, 6.62, 5.23, 0.67, and 1.09 in. above normal, respectively. Rainfall during the period totaled 43.07 in., which was 15.39 in. above normal (Table 1). Maximum and minimum air temperatures each month averaged within 2 F of normal, except the maximum and minimum averaged 6 F and 7 F above normal in May and the minimum was 3 F above normal in September and October (see appendix). Most crops were planted in a timely manner and showed good emergence in the Tidewater area. In the case of peanut and cotton, many fields were flowering as much as 7 to 14 days earlier than expected as a result of good soil moisture and warm temperatures in May. As the harvest season approached, many fields exhibited early maturity and high yield potential. Some delays in harvest occurred as a result of heavy rainfall in mid-September and early to mid-October, but most fields were harvested without difficulty. No frost damage was observed in peanuts, since the first killing frost did not occur until November 9 and 10 when peanut harvest was complete in the region.

Peanut yields in 2004 are projected to average 3200 lb/A (Table 2). Excesses of moisture were favorable for cylindrocladium black rot, which was the most destructive disease of peanut in 2004 (Table 3). Early leaf spot and web blotch reduced yields of highly susceptible cultivars (VA 98R, NC-V 11) in some fields as a result of extended periods of high relative humidity during periods of frequent rainfall. However, many growers obtained good to excellent disease control where fungicide sprays were applied according to the Virginia leaf spot advisory program. The incidence of tomato spotted wilt virus (TSWV) and crop damage by tobacco thrips was about the same as 2003 and much less than 2002, which was a dry year with heavy losses to TSWV and thrips damage. Southern stem rot was observed at low levels, which is typical for southeastern Virginia. Most growers obtained good to excellent control of sclerotinia blight through timely application of fungicides according to the Virginia sclerotinia blight advisory program.

Cotton yields in 2004 are projected to average 880 lb or 1.8 bales/A. Only a few diseases caused significant damage in cotton production. Rhizoctonia damping-off of seedlings was common in the region, but the overall impact was minimal since stands were generally uniform and showed exceptional vigor as a result of highly favorable growing conditions in May and June. Poor stands were often associated with soil compaction by heavy rainfall immediately after planting. Crop damage by southern root-knot nematode, Meloidogyne incognita, accounted for the heaviest loss of yield in fields planted continuously to cotton for 5 years or longer. No significant losses to reniform nematode, Rotylenchulus reniformis, were detected in 2004. Instances of yield losses to stubby root and sting nematode were found, but overall were less than previous years due to the season-long favorable weather for crop growth. As in previous years, the Columbia lance nematode was not detected in field surveys across the region in 2004. Hardlock in cotton was found to occur in about 10% of locules in harvestable bolls. Biopsy assays indicated that Fusarium spp. were consistently associated with hardlock.

Powdery mildew, stagonospora leaf blotch, and tan spot were the most common diseases of wheat in southeastern Virginia. Leaf blotch and tan spot accounted for the greatest reductions of yield in the region. Occurrences of scab on heads were minimal in 2004 and had little or no impact on yield.

Corn yields are forecast to be 147 bu/A or 1 bushel above the record set in 2000. Total production is estimated at nearly 50 million bushels, up 32% from last year. The widespread occurrence of stubby root nematode and isolated patches of sting nematode were thought to account for most of the yield losses to disease in corn. Stalk rots and foliar diseases caused minor damage in the Tidewater area in 2004.

The November forecast for soybean yield in 2004 was 37 bu/A with an expected harvest of 520,000 acres in Virginia. Frogeye leaf spot, anthracnose, and nematodes were among the most common diseases of soybean in 2004 (Table 4). Frogeye leaf spot was the most aggressive and widespread foliar disease of soybean. Soybean cyst, root-knot and stubby root nematodes probably accounted for the greatest loss of yield.

The research described in this book was designed to evaluate strategies for improving disease control and the overall efficiency of crop production in Virginia. Commercial products are named for informational purposes only. Virginia Cooperative Extension, Virginia Polytechnic Institute and State University, and Virginia State University do not advocate or warrant those products named nor do they intend or imply discrimination against those not named.

The primary purpose of this book is to provide a summary of research for cooperators and contributors in various projects. Selected chapters have been submitted for publication by the American Phytopathological Society in Fungicide & Nematicide Tests, and Biological & Cultural Tests in 2005. Reprints of these publications are available upon request.

(All files below are available in PDF format and require the Adobe Acrobat Reader to open. If you do not already have the Reader installed on your computer, you can download a free copy from Adobe.)

Table of Contents

Rights

Virginia Cooperative Extension materials are available for public use, re-print, or citation without further permission, provided the use includes credit to the author and to Virginia Cooperative Extension, Virginia Tech, and Virginia State University.

Publisher

Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Rick D. Rudd, Interim Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; Wondi Mersie, Interim Administrator, 1890 Extension Program, Virginia State, Petersburg.

Date

May 1, 2009


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