Last week,
aphids began to build in spots in fields statewide. Ordinarily, I would
recommend to let the natural fungus take out the aphids. However, each field
and season presents a different picture. The fungus always works, however
sometimes it is a week to 10 days later than we would like. Since we have a lot
of late maturing cotton this season, I don’t feel we need to let aphids set our
cotton back any further. Even if aphids do not cause yield losses, when an
entire field is drooped down from aphid stress, we are likely seeing some
maturity delay. For this reason, in 2018, I am suggesting that if a grower is
going over a field for weed control or PGR application, then I would add an
aphid control insecticide in the spray. We have some very economical choices
for aphid control when they can be piggy backed with a trip over the field for
another purpose.
Now on to
plant bugs – I say plant bugs because we could easily have both the tarnished
and the clouded species in some fields. In fact, I picked up some clouded
species in sweeps in cotton last week in central AL. Historically, we have had
more clouded in wet springs. Maybe because we get a better growth on button
bush, a wild host for clouded in wet seasons. Button bush is a plant that likes
low, swampy habitat, and excessive rainfall gives us that. No matter whether it
is TPB or CPB, our scouting thresholds and controls are the same.
Now let’s
talk about the TPB. The rainfall in the past month has kept their primary wild
host, daisy fleabane, fresh and it appears that 2 generations have developed on
fleabane. In mid May, we had mostly adults here in Central and South AL. Now,
in both South and North AL (including the TN Valley), we have another
generation that was just mid aged immatures the second week of June. This means
that we will likely have a migration from fleabane into cotton that will last
for 3-4 weeks. Therefore, feeding and egg laying in cotton by these migrating
adults will last 3-4 weeks. This will result in a long emergence of immatures
in cotton beginning about first bloom.
We may
need multiple applications pre bloom in some fields to control migrating adults.
Then we may also need multiple applications post bloom for the immatures as
they hatch. I hope I am over estimating what could be a bad plant bug year.
This is not what we needed on 2 gene cotton. Multiple plant bug sprays just
before the CEW flight comes from corn will result in more escape bollworms in
mid-late July.
One thing
we can do if this scenario happens is to use a plant bug application for adults
about first bloom and add the IGR Diamond to the tank mix. Diamond will add
residual control on hatching immature plant bugs for 10-20 days, depending on
the rate used.
I will be
focusing and making observations on plant bugs for about the next 3-4 weeks,
and I will keep everyone updated on what we are seeing. The first report of high
numbers of adult TPBs in cotton came from west central AL on June 19.
An
Extension publication overviewing plant bugs was prepared by Barry Freeman, our
resident plant bug expert in 1999 and can be found online at http://www.aces.edu/pubs/docs/A/ANR-0180/ANR-0180.pdf.
Life cycles, damage, scouting, and management have not changed over the years.
Every season and field are different, which requires close monitoring in order
to make the proper management decisions.
2018
Treatment thresholds and control recommendations can be found in ACES
publication # ANR-0415, “Cotton IPM Guide” available online at http://www.aces.edu/pubs/docs/I/IPM-0415/IPM-0415.pdf
If fieldmen,
growers, or consultants have plant bug observations, please call or text and
share with me at 334-332-9501. You may email me at smithrh@auburn.edu.
