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Field and Forage Crops |
Predictions regarding cotton insects for the coming growing season -- even up to and beyond the time of planting -- are difficult to make. Overwintering pest levels and beneficial insect survival, the amount and quality of nearby crop and weed hosts, cotton crop development, and, most importantly, weather just prior to and during the growing season all affect insect levels. We also deal with insect pests that undergo several generations on other hosts before playing their hand on cotton. This makes early predictions even more difficult. Some observations for 2003, however, may be order.
Thrips have been tough for cotton producers for the past three years. Perhaps due to our cooler seedling grow-off conditions and the high amount of surrounding thrips host vegetation compared with our average field size, thrips levels are almost always higher and more damaging in the Carolinas and Virginia than elsewhere in the Cotton Belt. The odds appear to favor thrips becoming a significant pest in 2003.
The odds are that stink bugs will probably enjoy a banner year on Bollgard cotton in some regions of the state in 2003. Stink bug damage to bolls was high in both 2000 and 2001, although stink bugs gave most of our producers a break in 2002. This is another pest I'll be covering in greater detail in the North Carolina Pest News as the 2003 growing season progresses.
Bollworm moth levels have seesawed up and down for the past 7 years here. If this "trend" continues, we may be in for a lighter bollworm year than in the past four even years (1996, 1998, 2000 and 2002). One effective way to get an early indication of the timing and intensity of upcoming moth flights is to check out light trap counts online at the Cotton Insect Corner web site beginning in early July.
Over the coming crop year, weather conditions will essentially determine the timing and level of our potential insect problems, not to mention the impact on lint yield and quality. I, let alone meteorologists, have difficulty in predicting weather patterns (and their impact) more than about a week in advance. Fortunately, sound insect and plant monitoring and rapid responses to thresholds should play a major role in making the best of what nature has in store for cotton producers.
Upcoming cotton insect scouting schools in North Carolina will be posted beginning mid to late May in the North Carolina Pest News and on the Cotton Insect Corner web site.
The Cotton Insect Hotline Teletip tapes will be available next week. The tapes can be accessed at by telephone at 1-800-663-7301, then by pressing 4 for cotton insect updates. These taped messages will be updated on Wednesdays until the beginning of the mid-July major bollworm moth flights, then updated twice weekly until late August. Briefer MP3 sound tracks can now be found at the Cotton Insect Corner web site under What's New @ the Corner.
Soybean seed quality is exceptionally low for the 2003 growing season. Seed supplies of many soybean varieties will likely be limited. Poor conditions for harvest throughout most of the Southeast in 2002 are responsible for the poor seed quality. Several factors came into play to create this situation. Most of the southeast received excessive rainfall from September through November resulting in delays in harvest. The late soybean harvest resulted in additional weathering of soybean seed that impacts seed quality. Perhaps more serious than the fungal diseases on soybean seed is the mechanical damage much seed received either from continued shrink swell as soybean seed dried down and then swelled with increasing moisture, or from being harvested at relatively high moisture content. Another aspect is the increased contamination and infection of soybean seed by fungal diseases such as pod and stem blight (caused by the Phomopsis/Diaporthe complex) and purple seed stain (caused by the fungus Cercospora kikuchii). Other fungal diseases such as anthracnose, frogeye leaf spot, and brown leaf spot have also contributed to poor seed quality.
Mechanical Damage to Seed
The mechanical damage cannot be cured by remedial treatments, but some steps taken by growers can lessen the impact of this factor. Check labels on seed bags to determine the germination rate (expressed as a percent), or if you use saved seed have seed germination tested. Low germination rates can be compensated for to some extent by increasing the seeding rate. Typically we assume germination will be 85 to 95 percent, which is not likely true with most seed this year. The North Carolina Department of Agriculture & Consumer Services (NCDA&CS) has lowered the permissible germination rate to 75 percent for the 2003 season. Avoid additional handling of the seed if possible. Repeated transfer or movement of seed by mechanical means will probably increase the amount of physical damage to seed and lower germination rates even further.
Seed Treatment Active Ingredients and Their Efficacy
All seed treatments and all fungicides are not equal! Modern fungicides often have a narrow spectrum of activity against a few fungi. The most common seed problem associated with fungi is seed rot caused by pod and stem blight (Phomopsis/Diaporthe complex). The standard for treatment of this fungus is Vitavax (Carboxin), although Fludioxonil (one of the active ingredients in ApronMaxx) is also effective. Perhaps the most obvious problem on much seed this year is purple seed stain (caused by the fungus Cercospora Kikuchii). Purple seed stain usually has minimal effects on the quality of planting seed and is not controlled by Vitavax. A seed treatment with Thiabendazole must be used to control this fungus. Though it is not generally necessary to control this fungus, Thiabendazole will also likely control the fungus that causes frogeye leafspot (Cercospora sojina). This fungus is seed borne and was present in many susceptible varieties in the delta in 2002. Other fungicides that may provide control of certain diseases that are often added to various seed treatments include PCNB (Terrachlor), Captan, Azoxystrobin, and Mefenoxam (Metalaxl-Apron). The strengths for PCNB and Azoxystrobin are principally protection against soilborne diseases such as Rhizoctonia (Sore Shin) and others. Mefenoxam /Metalaxl (Ridomil Gold, Ridomil, or Apron) is only effective against specific fungi (Phytophthora and Pythium) that are more often soilborne and cause damping off. Protection against soilborne pathogens may improve stands but usually will not improve germination.
Seed Treatments
Should seed treatments be used? When soybean seed is infected with fungal pathogens, the proper seed treatment may raise germination rates by ten percent or more. However, when seed has a significant amount of mechanical damage, fungicide treatment may result in further damage to the seed. Also, do not subject damaged seed to additional mechanical handling if at all possible. Most seed dealers prefer not to treat, since any treated seed not sold must be destroyed. Therefore, farmer applied treatments might be an alternative. Most are inexpensive (less than $1.25 per acre). We might suggest as a rule, that growers planting in April consider the use of a fungicide seed treatment at planting. This year seed treatment might be good insurance for May and June planted beans as well.
ACTION STEPS:
More information on soybean diseases can be found at:
http://www.ces.ncsu.edu/depts/pp/notes/Soybean/soybean_contents.html
North Carolina Seed Testing Laboratory, North Carolina Department of Agriculture & Consumer Services (NCDA&CS):
http://www.agr.state.nc.us/plantind/Seed/Stest.htm
Seed Pathology Program, NCDA&CS:
http://www.agr.state.nc.us/plantind/Seed/Spath.htm
Send 2 pound soybean seed samples (sample size for other crops differ) to:
By U.S. Mail:
NCDA&CS
Plant Industry Division
Seed Testing Laboratory
P.O. Box 27647
Raleigh, NC 27611-7647
By UPS:
NCDA&CS
Plant Industry Division
Seed Section
Old Health Building
216 West Jones Street
Raleigh, NC 27603-1375
Phone: (919) 733-3930
Fax: (919) 733-1041
When sending a sample, please include:
Your name
Complete address
Telephone number
E-mail address
Kind, Variety and Lot number of each sample
New or old seed
Treatment (fungicide or insecticide) used
Also indicate any other individuals and their addresses to whom you would like sample report copies sent.
Please make your lot numbers distinctive. If we have many Lot 1's, etc., it is difficult to find your sample in our data base.
When submitting a mixture include a list of components and their percentages. This information is necessary for accurate testing.
The NCDA&CS Seed Testing Laboratory conducts:
Purity
Germination
Noxious weed seed examination
Cold test (corn)
Cool test (cotton)
Sand test
tetrazolium
They can also conduct by request:
Accelerated aging
Phenol (wheat)
Peroxidase (soybeans)
Hypocotyl color test
Fluorescence of ryegrass
All tests performed in the laboratory are free except for tetrazolium (TZ). There is a five dollar ($5.00) charge for each TZ test. Send at least 400 seed per TZ sample.
Be sure to package your sample securely. If a sample arrives damaged in transit, we might need to request a replacement sample in order to give you accurate test results.
Table 1. Some seed treatments available for soybean.
|
Brand Name |
Manufacturer |
Active Ingredients |
Application Method |
Diseases/fungi active against |
|
ApronMaxx RTA Flowable |
Syngenta |
Fludioxonil Mefenoxam |
On-farm With equipment |
sore shin pod and stem blight Phytopthora and/or Pythium damping off |
| SoyGard | Gustafson |
Azoxystrobin Metalaxl |
On-farm With equipment |
sore shin pod and stem blight Phytopthora and/or Pythium damping off |
|
Bean Guard Allegiance |
Gustafson TCI |
Vitavax Metalaxl Captan Molybdenum |
Hopper box |
sore shin pod and stem blight Phytopthora and/or Pythium damping off |
| Prevail |
Gustafson TCI |
Vitavax Metalaxl Terrachlor (PCNB) |
Hopper box |
sore shin pod and stem blight Phytopthora and/or Pythium damping off |
| Enhance |
Gustafson TCI |
Vitavax Captan |
Hopper box |
pod and stem blight sore shin |
|
Rival Flowable |
Gustafson |
Thiabendazole Captan PCNB |
Commercial |
purple seed stain frogeye leaf spot sore shin pod and stem blight |
These recommendations apply only to North Carolina. They may not be appropriate for conditions in other states and may not comply with laws and regulations outside of North Carolina. These recommendations were current as of October 2001. Individuals who use agricultural chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage regulations and examine a current product label before applying any chemical. For assistance, contact your county Cooperative Extension Service agent. The use of brand names and any mention or listing of commercial products or services in the publication does not imply endorsement by the North Carolina Cooperative Extension Service nor discrimination against similar products or services not mentioned.
Web sites to locate more information on seed treatments:
Trace Chemicals LLCA subsidiary of Gustafson LLC:
http://64.29.210.204/soybeans.asp
Gustafson:
http://www.gustafson.com/default.asp
Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age or disability. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.
Last modified on April 21, 2003 by Stephen J. Toth, Jr.