Soybean loopers are the dominant caterpillar species occurring over a multi state area of the southeastern United States. Several states, including Arkansas, Georgia and the Carolinas are all experiencing looper outbreaks. I observed my first soybean field with treatable levels of loopers in Baldwin county on 8/26. Based on what is happening over a large area, Alabama growers need to be very alert for looper outbreaks.
Soybean loopers may occur at damaging levels in soybeans, peanuts, or late maturing cotton fields. Looper eggs are deposited on the underside of leaves in the lower part of the crop canopy. The tiny, hair like, early instar larvae can go undetected for several days. As they mature they move up the plant canopy with their defoliation. Therefore, the foliage loss is often unnoticeable for a week or more. A high percent of the total foliage consumed is during the last 3-4 days of the larval cycle. I have always considered somewhere between 5 and 8 larvae per row foot as an economic level. The amount of canopy available in a crop like soybeans would have some bearing on the economic threshold. I will have to depend on my entomology friends to set a sweep net threshold for drill soybeans. I’ll be checking around for that threshold since late planted drill beans behind wheat may be at the greatest risk.
Insecticides that work well on soybean looper are: Steward, Intrepid, Tracer, and recently labeled Belt. Both Diamond and Dimilin (Insect Growth Regulators) also give adequate to good suppression. Products like pyrethroids, Lannate, Larvin, Sevin, Lorsban and methyl parathion do not give measurable control of soybean loopers in Alabama.
Monday, August 30, 2010
Wednesday, August 25, 2010
Cotton
Many fields are beginning to open and the plants have few developing bolls near the terminal. Therefore, insects are of little concern. The extreme heat coupled with drought a few weeks back took care of our top crop. Late maturing fields that caught a scattered thunderstorm should be watched for stink bugs until the last bolls we expect to harvest are 20-25 days old. Several growers have expressed concern about the number of hard locked lower bolls due to boll rot. What began as a promising cotton crop has turned into a below average yield potential for the state as a whole. The southwestern region of the state had the best rainfall pattern and will likely have the best yields.
Soybeans
A sub-threshold level of several caterpillar species can be found in most fields statewide. These include green cloverworms, soybean loopers, podworms, fall armyworms, and in the southern areas of the state, velvetbean caterpillars.
If the fall armyworms should occur at treatable levels, growers need to know that they are likely the “grass” strain which can be controlled rather economically with pyrethroids, Intrepid or Dimilin.
Stink bugs, especially the brown species, are at treatable levels in some bean fields. Growers should remember that stink bugs affect the quality of beans more so than the yield. Where brown stink bugs are the primary target, I would suggest a high rate of one of the labeled pyrethroids. These include: Baythroid XL, Brigade (Discipline), Prolex, Karate Z, or Mustang Max. Several of these have multiple generic brand names.
If the fall armyworms should occur at treatable levels, growers need to know that they are likely the “grass” strain which can be controlled rather economically with pyrethroids, Intrepid or Dimilin.
Stink bugs, especially the brown species, are at treatable levels in some bean fields. Growers should remember that stink bugs affect the quality of beans more so than the yield. Where brown stink bugs are the primary target, I would suggest a high rate of one of the labeled pyrethroids. These include: Baythroid XL, Brigade (Discipline), Prolex, Karate Z, or Mustang Max. Several of these have multiple generic brand names.
Peanuts
Many of the same caterpillar species found in soybeans are also at sub-economic levels in peanuts. The one exception is fall armyworm. Another “flush”, about 20-30 small larvae per row foot, was found in peanuts near Shorter, AL (Macon county) yesterday (August 24). These armyworms do not always occur in all fields on a given farm. The same products – pyrethroids, Intrepid and Dimilin also provide good control of fall armyworms in peanuts. The quickest kill will come from pyrethroids while the longest residual will come from Intrepid and Dimilin.
Recent Field Tours
More than 100 growers, ag suppliers and related agencies were in attendance at a recent Field Day. The 34th annual East Central Tour was held on August 13th. This tour began 34 years ago primarily to view the “magic” cotton insect control obtained with Ambush, Pounce and Pydrin pyrethroids. They provided better control than anything that generation of growers had ever observed.
The annual Wiregrass Research Farm field day was held on August 20th. The latest research results on peanuts, cotton, corn and soybeans were presented.
The annual Wiregrass Research Farm field day was held on August 20th. The latest research results on peanuts, cotton, corn and soybeans were presented.
Twin Link Field Day
I had the opportunity to participate in the Bayer Twin Link dual-Bt technology field tour near Blackville, SC, on August 23rd. Research on this technology was observed on the Clemson Edisto Research and Education Center and on the Carolina Ag Research farm (Dr. Mike McCarty). Both locations have had some of the highest bollworm pressure I have ever observed. Untreated conventional cotton had 100% boll damage and some foliage loss to bollworms. The Bayer Twin Link Bt technology did not give perfect control under this level of pressure but showed impressive results.
Monday, August 16, 2010
Insect Blog 8-16-10
Weather- Temperatures remain high 90-95 degrees Fahrenheit and rainfall extremely scattered statewide, as of today (8/16). Hay, pastures, peanuts and soybeans in many areas would profit greatly from rainfall. Most cotton fields are beyond benefit from water.
Fall Armyworms- Populations continue in hay, pastures and peanuts. However, in many south Alabama locations the previous generation has cycled out. Another generation may be possible 2-3 weeks ahead.
Tobacco Budworms- An extremely heavy moth flight and egg lay was observed on cotton in Seminole County, GA on 8/11. Only late planted conventional cotton will be at risk from this pest. However, it might be noted that budworms are now infesting soybeans in sizable numbers in some southern locations.
Podworms/Soybeans- Soybean growers should be very alert for corn earworm infestations on beans that are anywhere from R1-R7 (blooming to filled pods that are still green).
Bean Leaf Beetles/Soybeans- Several Tennessee Valley fields have subeconomic levels of bean leaf beetles in soybeans.
Lesser Corn Stalk Borer/Peanuts- Dr. Ayanava Majumdar, Extension peanut entomologist, has issued a high alert for LCSB in peanuts based on a sharp increase in moth numbers captured in traps. Counties in extreme southeastern Alabama are also very hot and dry, which is ideal weather for LCSB outbreaks.
New Registration (Belt)- Belt insecticide, marketed by Bayer, received registration on soybeans on 8/12. The label rate is 2-3 oz per acre. Belt has activity on most all caterpillar pests and is at its best on foliage feeders.
Fall Armyworms- Populations continue in hay, pastures and peanuts. However, in many south Alabama locations the previous generation has cycled out. Another generation may be possible 2-3 weeks ahead.
Tobacco Budworms- An extremely heavy moth flight and egg lay was observed on cotton in Seminole County, GA on 8/11. Only late planted conventional cotton will be at risk from this pest. However, it might be noted that budworms are now infesting soybeans in sizable numbers in some southern locations.
Podworms/Soybeans- Soybean growers should be very alert for corn earworm infestations on beans that are anywhere from R1-R7 (blooming to filled pods that are still green).
Bean Leaf Beetles/Soybeans- Several Tennessee Valley fields have subeconomic levels of bean leaf beetles in soybeans.
Lesser Corn Stalk Borer/Peanuts- Dr. Ayanava Majumdar, Extension peanut entomologist, has issued a high alert for LCSB in peanuts based on a sharp increase in moth numbers captured in traps. Counties in extreme southeastern Alabama are also very hot and dry, which is ideal weather for LCSB outbreaks.
New Registration (Belt)- Belt insecticide, marketed by Bayer, received registration on soybeans on 8/12. The label rate is 2-3 oz per acre. Belt has activity on most all caterpillar pests and is at its best on foliage feeders.
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