Soybean: There have now been a few reports of treatable numbers of corn earworm in soybean. Treatment is warranted if an average of 9 or more larvae are found per 25 sweeps. Infestations are being reported in the latest and shortest bean fields. This is one pest I would consider reducing the threshold to 6 larvae per 25 sweeps if a fungicide were being applied. I’ve discussed treatment options previously, but the higher the pressure, the more I suggest using products such as Belt SC, Prevathon, Besiege, Steward, etc. The pyrethroid insecticides are not reliable enough to take the chance on controlling heavy infestations. They also can flare outbreaks of soybean loopers which are most likely to occur on these same late maturing fields.
There has also been a few reports of green cloverworm and/or loopers at numbers high enough to cause 20% defoliation or more. Stink bugs are currently not as bad as I expected, but a few fields are being treated, and this will increase over the next several weeks.
Sorghum: Reports of corn earworms and fall armyworm feeding in heads are pretty typical (meaning pretty common). If you go by the book, treatment is recommended when an average of 2 small larvae (< 1/4 inch) or 1 large larvae is found per head. My recent data suggests a better threshold would be to treat if one larva of any size was present per head. Sample by shaking heads into a bucket or sweep net, but be sure to carefully look for small larvae in the debris. Infestations typically start building towards the end of flowering. You can be more friendly to the bees by waiting to treat until flowering is mostly complete or spraying late in the day. A complete list of recommended insecticides for control of headworms can be found on UTcrops.com (link here). However, I would discourage the use of pyrethroid insecticides unless premixed or tank mixed with other insecticides.
Sorry folks … the pyrethroid insecticide have value in the right situation for the right pest, but gone are the days when we could use them for just about anything.
