The first point is when to back off of stink bug controls. Our early April cotton is beyond the eighth or ninth week of bloom with few to no 10-12 day old bolls remaining. In fact, my test plots of PHY 375 planted April 9 had several open bolls per plant early last week. Even with cotton that still has a few 10-12 day old bolls remaining, stink bug numbers are so low in most fields that a stink bug threshold could never be reached. I would not be concerned at all with 10-20% internal damage as cotton is maturing out and beginning to open. For those who would be spraying with ground equipment, and that would consist of the majority of growers in Alabama, a ground rig going through mature cotton would destroy far more good bolls than the few smaller bolls near the top of the plant that stink bugs might injure.
Spider mites populations held steady last week but did not
seem to increase, likely due to the frequent thunderstorm occurrence. I would
just keep an eye on them and delay treatment decision as long as the current
weather pattern holds.
One of the heaviest tobacco budworm flights seen in several
years has been ongoing in the southern counties. Moths, eggs, and small larvae
have occurred in high numbers from Dothan in the southeast to Fairhope in the southwest.
This will have no impact on cotton with Bollgard or WideStrike technology.
However, conventional varieties are a different story. I was in research plots
of conventional cotton with no insect technology at Fairhope, AL on August 7
and found 32% worm square damage with 9% of the squares containing live larvae.
Who says the technology has less value than it once did? In the old days, what
would we do under this level of pressure, with thunderstorms occurring every
afternoon?
Growers that may be impacted by this budworm pressure are
soybean and peanut producers. If these crops are infested with budworms then
the newer chemistry will be required because pyrethroids would not perform at
all.
Chemical choices would be, in alphabetical order: Belt,
Steward, or Tracer and possibly Lannate. Some might include Intrepid with this
group but I do not know how effective it would be on budworms. Peanut growers should monitor their fields closely for the next 7 to 10 days for budworm numbers. New growers applying
a fungicide to soybeans should not automatically add a pyrethroid for insurance purposes.
If an insecticide is added in a preventative mode, I would suggest Dimilin at
2 oz. for future foliage feeders.
One other soybean pest that I will mention in closing is
soybean loopers. Most soybean fields have a few green cloverworms or an
occasional looper. However, one field in Baldwin County was observed last week
with about 10 loopers per foot with about 10-15% foliage loss already.
Therefore, all fields are not alike and must be scouted to stay on top of the
soybean insects.
