The cotton situation is all over the board right now in Alabama. Plant bugs are building in some areas statewide and relatively quite in others. Overall, stink bugs have been low but are now beginning to build. Monitoring the situation and only treating fields with damaging levels will be the only way to maximize inputs from now on. With the current futures outlook on price, we need to ensure every dollar spent brings back more.
We have also received a few spider mite calls and questions
have revolved around when to walk away. This can be a tricky call (as can be
when to treat in general). A threshold for spider mites of 30-50% infested
plants showing injury is the best we have. Some considerations for terminating
treatments include age of the cotton and how bad the infestation is. Bolls that
are expected to be harvested should be protected from mites until they are
about 20 days old. How bad is too bad? This is hard to say, but you cannot walk
away from a disaster. If mites are turning leaves red and defoliation can
happen, action is needed.
Soybean Update (Scott Graham and Caitlyn Lawton)
Over the past week, we have received multiple reports of
fall armyworm outbreaks in double cropped soybeans. In nearly every case, the
armyworms started on volunteer wheat or on grass weeds and moved to beans after
a herbicide application, or total consumption of the grass.
In 2021, we faced an epic fall armyworm outbreak, basically
nationwide. We began hearing about pyrethroids missing worms in Texas as early
as May that year. This year, while we have not hide widespread misses, we have
received reports from north, south and central Alabama of control failures. So,
what do we do in these situations?
Our general recommendation is still to use a pyrethroid,
particularly if tank-mixed with a herbicide application targeted at killing
grass weeds. Other options if pyrethroids fail or there is concern they won’t
get the job done include:
acephate (0.75 lb)
Besiege (7 oz)
Diamond (6 oz)
Elevest (5.6 oz)
Intrepid 2F (4 oz)
Intrepid Edge (4 oz)
Vantacor (1.2 oz)
Soybeans can withstand a fair
amount of defoliation in the vegetative stage (30%) and the reproductive stage
(20%). However, we do not want these late beans to be anymore delayed than
necessary. Scout fields and be prepared to treat when needed. We do not have a
threshold for sweep-nets or the number of FAW per foot, however some recommend
action in double crop beans if 25% of plants are infested.
We have also begun receiving reports
of stink bugs and soybean loopers infesting fields and requiring treatment. In
addition to our traditional stink bugs species, we have also heard of some
redbanded stink bugs in fields in central Alabama. In most cases, they are just
part of the complex and not the dominate species. Threshold for stink bugs is 4
per 25 sweeps until R6. At R6 threshold is doubled to 8 per 25 sweeps for the
next 7-10 days.
Our threshold for defoliating
caterpillars (loopers, cloverworms, velvetbean caterpillars) is to avoid 20% defoliation
during reproductive stages. For soybean loopers (SBL), treatment is recommended
if 18 loopers (> 0.5 inch) is found per 25 sweeps. Velvetbean caterpillar
(VBC) and green cloverworm (GCW)threshold is 36 per 25 sweeps. Most labeled
insecticides do a good job controlling VBC and GCW, while newer materials (Vantacor,
Besiege, Intrepid Edge, etc.) are needed to control SBL.
Pastures and Forages (Lawton)
Reports and infestations of fall armyworm are even higher in
pastures and forages than soybeans. Our threshold in these situations is an
average of 2-3 worms per square foot. As with soybeans, we have received
sporadic reports of pyrethroids missing worms. In addition to pyrethroids,
Intrepid 2F, Besiege, Vantacor and Dimilin are labeled for control. Keep in
mind that Dimilin is a growth regulator and will be slow. Dimilin should be
targeted at worms less than 0.5” long. Refer to the Pasture and Forage Crops
IPM Guide (IPM-0028)
for rates, other recommendations and preharvest/grazing intervals.
Regardless of the crop, we are likely to see at least one
more generation of FAW this year, as their lifecycle is about 30 days long.
Keep scouting and monitoring fields weekly to ensure you have not missed worms.
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). To stay
up-to-date on the Alabama insect situation, subscribe to the Alabama Cotton
Shorts Newsletter,
Alabama Crops Report Newsletter,
and the Syngenta Pest Patrol Hotline.
