Agfax Buzz:
    July 4, 2014
    bollworms-sweep-net-gus-lorenz-08292013-feature

    Virginia Peanuts: Worm Potential This Season, Be Vigilant

    AgFax.Com - Your Online Ag News Source

    By Ames Herbert, Virginia Extension Entomologist

    Reports are coming in about infestations of both beet armyworm and tobacco budworm in peanut fields in Georgia and South Carolina. These are pretty early reports and could signal trouble to come.

    Although we get both species in this area of Virginia, it has been several years since we have experienced severe infestations of either.

    Beet armyworms seem to be cyclic, occurring only once every few years, with no pattern that we understand. Moths migrate into the area from the south and are particularly attracted to pigweed species. Often, the caterpillars will be found feeding on pigweeds on field edges or wherever the weeds are growing.

    They feed on pigweed plants then move to nearby crop plants. So, peanut, cotton or soybean fields bordered by a lot of pigweeds or with a lot weeds in the field are particularly vulnerable to beet armyworm infestations.

    Tobacco budworm is known to be an occasional pest of cotton, peanuts and soybeans in this area. Caterpillars are easily confused with corn earworm, a different but related species. Adult moths of these species look very different, but the caterpillars are almost identical except for features that require some knowledge and good magnification.

    We separate these species by holding large sized caterpillars under a microscope and inspecting the shape of the mandibular ridge the inside jaw of the mouthparts. Obviously, this is not something that can be done in the field.

    Budworms are not a big threat to peanuts or soybean, as they are leaf feeders only, and it takes a lot of feeding to do economic damage. They do no more damage than corn earworm, the more common of the two species.

    In peanut and soybean fields, both budworm and corn earworm can occur at the same time, but typically corn earworm is the dominant pest making up 70% or more of the total. In cotton, budworms can be troublesome as they feed on young developing squares.

    Another difference between these species is the timing of the infestation. In some years we see budworm infestations early, before corn earworm. This seems to be the case this year, at least in states south of us. Corn earworm moths are starting to show up in Virginia. We are catching 10 to 20 moths per night in our local pheromone traps, which isn’t a lot compared to what we will see later in the season, but enough to result in some possible small outbreaks of worms.

    Beet armyworm, tobacco budworm and corn earworm are strictly leaf feeders in peanut so any decision to treat a field should be based on:

    • The number of worms per row foot.
    • The degree of defoliation compared to the total foliage of the canopy.

    The threshold for worms for this time of year is 4 per row foot (total, all species). If you sample using a drop cloth, after slapping plants on both sides of a 3 foot long cloth you would need to see at least 12 worms. The likeliness of actually finding this many worms is very low, and it is pretty rare to find threshold levels of worms in any peanut field.

    But is always pays to be vigilant.

    Check fields periodically throughout the season for pests. If after checking you find at or near thresholds of any pest, select a product that fits the need. For example, if you do find a field at threshold for a combination of beet armyworm, tobacco budworm or corn earworm, pyrethroids would not be the best choice. These species would be controlled better with non-pyrethroids like Steward, Belt, Prevathon, or Blackhawk.


    Tags: , , , , , , ,

    Leave a Reply

    Name and Email Address are required fields. Your email will not be published or shared with third parties.

    AgFax Peanut News

    Alabama: Dry Conditions Push Crop Maturity, Harvest – USDA9-22

    Arkansas: Wet Weather Slows Harvest – USDA9-22

    Oklahoma: Wheat, Canola Planting Active – USDA9-22

    Georgia: Some Insect, Disease Problems Reported — USDA9-22

    Texas: Rains Benefit Crops, Soils, Delay Cotton Harvest – USDA9-22

    Florida: Peanut Harvest Continues in Panhandle – USDA9-22

    North Carolina: Corn Harvest Over 60% Complete – USDA9-22

    Peanuts: Salmonella Trial Results in Federal Convictions – AgFax9-22

    Keith Good: Ethanol Industry Enjoys Big Year, but Uncertainties Linger9-22

    Peanut Harvest: More Digging In SE; Western Growers Gearing Up – AgFax9-20

    Georgia Peanuts: Some Dryland Fields Will Make, Some Won’t9-19

    Georgia: Rains Falling at the Wrong Times9-19

    Florida Peanuts: Spiderling is Emerging Weed Problem9-19

    USDA: Peanut Price Highlights9-19

    Virginia Peanuts: Checking on Maturity9-19

    Keith Good: Soybean Futures Hit 4-Year Low; Wheat, Corn Tumble, Too9-19

    Most Farmers Willing to Take More Steps to Improve Water Quality, Says Study9-18

    U.S. Drought Outlook: Improvements in Texas, Southwest9-18

    Harvest Approaches in Iowa; Time for More Planting in Florida — DTN9-18

    U.S. Energy: Shale-Focused Companies’ Financial Performance Improves9-18

    Gasoline Prices: Average Falls 5 Cents9-18

    Propane Stocks: Rise by 1.4M Barrels9-18

    Diesel Prices: Decrease by a Penny9-18

    Florida Peanuts: When it Rains it Pours9-18

    Keith Good: USDA Approves Use of Dow’s New GMO Corn, Soybeans9-18

    Georgia Peanuts: Keep Eyes Open for Spider Mites9-17

    Georgia Peanuts: Dryland Digging Considerations9-17

    DTN Fertilizer Trends: Rabobank Forecasts Higher 3Q Retail Prices9-17

    Keith Good: 18.3B Bushels of Corn, Soybeans — Where to Put it All?9-17

    Non-Land Production Costs Unlikely to See Much Decline in 20159-16

    USDA: Weekly National Peanut Prices9-16

    Keith Good: USDA Rates Corn Crop 74% Good or Excellent, Soybeans 72%9-16