Plant bugs, stink bugs, bollworms, spider mites (cotton), velvetbean caterpillars, corn earworms soybean loopers (peanuts and soybeans) and stink bugs (soybeans) have been reported this week. In some places, cotton looks good and has good moisture, in others it’s scary dry and blooming out the top.
Bug Complex
Reports of green and southern green stink bugs have picked
up this week statewide. After wondering if they would ever show up, they are here
now. As we mentioned last week, our tests in south, central and north Alabama, are
running 30-50% internal boll damage in untreated plots. We have started hearing
reports from scouts and consultants that damage has jumped from less than 10%
to 30% or more in the past week. While our older cotton is safe from bugs,
later planted cotton (probably about mid-May on) is still at risk. The
threshold is 10% damage weeks 3-6 of bloom and 30-50% in weeks 7-8.
Plant bugs are becoming a little spottier but are still
heavy in some places. A lot of acres have received multiple applications of
Diamond and that has helped keep populations manageable. Keep the fight up
until cotton reaches NAWF 2, at that point, we should be free to cut it lose.
Spider Mites
We have received reports of spider mites across the state this
week. In some cases, these are in fields that have been hammered for plant
bugs, but not in every case. Historically, rain has helped reduce the impacts
of mites, but that hasn’t seemed to hold true the last couple of years. We are
not sure why this is, but it seems to be real. Look for signs of injury, then flip
leaves over to confirm you have an active infestation. At this point in the season,
we have a few options (abamectin, Zeal, Portal, Oberon), with abamectin being
the most common used. There are varying levels of resistance, so if you have
used some earlier this year, watch closely behind another application.
Regardless of the product, we feel that higher rates give us better control
later in the season as coverage is difficult with bigger plants and more
canopy. One of the bigger questions we have gotten is when to cut lose spider
mites. Research from the mid-south suggests mites can cause yield loss until
about NAWF 2, so keep after them until at least that stage.
Soybeans
We have gotten several calls on defoliating caterpillars and
stink bugs with some podworms mixed in. In some cases the soybeans are around
the R5 stage and highly susceptible to all three, in others they are mid R3 and
relatively safe from podworms and stink bugs. While pyrethroids provide good
control of stink bugs, cloverworms and velvetbeans, they are an excellent way
to create a soybean looper problem. Scout closely and make sure you don’t have
loopers before spraying a pyrethroid. Our looper traps have picked up across the
state this week and we expect to start finding worms really picking up over the
next 7 to 10 days. Remember loopers have 2 pair of prolegs, VBC have 4 and GCW
have 3. In fields with loopers, consider using a diamide insecticide like
Besiege, Elevest or Vantacor, or a product like Intrepid Edge. If stink bugs
are in the mix, I would consider adding the needed pyrethroid to make a full
labeled rate for Besiege/Elevest, or adding a full labeled rate to Vantacor or
Intrepid Edge.
Peanuts
Like with soybeans, defoliating caterpillars are starting to
build in some areas. Peanuts are tough and can withstand quite a bit of defoliation.
Be on the lookout but don’t treat if threshold isn’t met (4-8 per row foot). As
dry as we are in some places, we do not want to make an unnecessary application
an create a spider mite issue.
As always, if we can ever be of any help, or if you would
like to provide input on the situation in your area, please don’t hesitate to
reach out (Scott Graham: 662-809-3368; Ron Smith: 334-332-9501). For more
information on thresholds and insecticide recommendations, visit the Alabama
Cotton IPM Guide (IPM-0415). To
stay up-to-date on the Alabama cotton insect situation, subscribe to the
Alabama Cotton Shorts Newsletter,
Alabama Crops Report Newsletter,
and the Syngenta Pest Patrol Hotline.
