The cotton insect control season is basically over. I say that realizing that there are a few late maturing fields within the state that may still need a stink bug spray. There are even fewer fields that have high numbers of tarnished and clouded plant bugs present. Where growers are attempting to make a top crop, in fields that have exceptional yield potential, plant bug controls may still be applied. Our greatest concern now in cotton is boll rot and disease. The past few days of overcast skies and rain showers have increased boll rot. The next weeks forecast is much the same. Other than a few southwestern counties, the state was spared from the excessive rainfall from Isaac.
At present, the insect action is primarily happening in
soybeans and to a limited degree in peanuts. The lep feeders are occurring on
soybeans state wide. We have more soybean loopers on beans in the Tennessee
Valley area of North Alabama than I can ever remember. This complex also
includes the green cloverworm statewide and the velvetbean caterpillar as far
north as Selma and Montgomery in central Alabama.
Loopers, (all are the soybean looper, more difficult to
control) are occurring at 1 to 8 or more per sweep. Most of our beans are drill
so we cannot use a drop cloth. Our threshold experience with loopers using drop
cloths is well established at 5-8 per row foot. We are wrestling with a sweep
net threshold. Two loopers per sweep are not causing more than 5% foliage loss
while 8 per sweep is causing 30-35% foliage loss. Our threshold is 20% foliage
loss with beans at the stage they are now. So somewhere between 2 and 8 loopers
per sweep is a treatable level. Based on my field observations I would treat in
the neighborhood of four loopers per sweep.
Stink bugs are increasing in beans and will likely continue
to do so in the days ahead. Therefore, in many fields a stink bug material
(pyrethroid) or acephate (Orthene) may need to be added as we treat for loopers
with the recommended insecticides of Tracer (Blackhawk), Intrepid, Steward or
One or more soybean fields in Southwest Alabama are infested
with the garden fleahopper at damaging levels. This is a first for this insect
on soybeans. They occurred on peanuts in that area a couple of weeks ago.
Some peanut fields are also infested with this mix of
caterpillar pests. In this mix we are also finding fall armyworms, southern
armyworms, corn earworms, cutworms, yellow striped armyworms and immature
Both soybeans and peanuts need to be scouted weekly for the
remainder of this season and future seasons. The old method of spraying an
insecticide on soybeans or peanuts when fungicides are applied is really just a
stab in the dark. The odds of this being good timing for insect control is
somewhere between slim and none. With the price of beans we have to do a better
job with insect control than automatic sprays based on the stage of the beans.
Most of our comments in the next week or so will be directed
towards soybeans and peanuts.