For the most part, soybean insect problems remain sporadic. But keep up with your scouting!
There are treatments being made for some pests, and as usual, you should expect problems to intensify over the next several weeks.
I’ve made comments about three-cornered alfalfa hopper in another article, but below are some other observations.
• There have been a few reports of green cloverworms at treatment level. Treatment is recommended when larval counts exceed 38 per 25 sweeps or if defoliation is greater than 20-25 percent. This pest is easy to control with pyrethroids and many other insecticides. I am also seeing or hearing about scattered fall and beet armyworm larvae (but not at treatment levels)
• Green stink bug populations are building. Remember that populations often start increasing rapidly when soybeans approach R5. Co-application of insecticides with fungicides at R3 are usually too early to prevent this. The recommended treatment threshold is 9 stink bugs per 25 sweeps.
• Corn earworms are being reported more commonly, although few fields have treatment level infestations. I don’t expect widespread problems, but this pest is potentially too damaging to make assumptions. Treatments are being made to the south and west of Tennessee, so I’m sure we have some fields at risk. Pay particular attention to late maturing fields. The treatment threshold is 9 larvae per 25 sweeps. The sweep net will not be as efficient in tall, canopied beans. So, you may have to part the canopy to visually check for larvae or pod damage if you are seeing corn earworms in the sweep net.
• Soybean loopers are being treated in Mississippi and southern Arkansas. Thus, there is potential for infestations in Tennessee beginning later this month. We can avoid some problems by keeping beneficial insects in the system where possible. Avoid making pyrethroid applications just because. Make treatments for stink bugs, corn earworm or other pests only if populations are above threshold. If treatment for corn earworm is needed, consider using Belt SC (2 ounces per acre), Steward (6-8 ounces per acre) or Tracer (1.5 ounces per acre). These treatments have minimal effects on populations of beneficial insects.