Critical Window for Early Planted Cotton in Central and North Alabama
The plant bug situation has exploded over the week in
Central and North Alabama. Based on reports and observations from about Montgomery
north through the TN Valley and NE Alabama, all cotton planted on or before ≈May 10th likely
needs a plant bug spray. Overall, square retention is still high, but with
some of the numbers reported, it will start dropping quickly if action is not
taken (goal is to maintain 80%). Overall, pressure appears to be lighter in
cotton planted on or after ≈May
15th (much of that is just starting or not squaring yet). Note:
Reports are that adult plant bug numbers are similar in ThryvOn and Non-ThryvOn
cotton in most areas. This is not unexpected as most of ThryvOn’s impact is against immature plant bugs.
Multiple reports from Cherokee county are that the earliest
planted fields are running anywhere from 20-35 adult plant bugs per 100 sweeps
(threshold = 8). In these situations, imidacloprid alone may not be enough to
preserve square retention. Adding mid-rates of acephate or a pyrethroid
(depending on location) may improve control. Centric is another option for
control.
In most situations populations are above threshold but in
more manageable numbers. Our May 1st planted cotton at Prattville
averaged ≈12 adults per 100
sweeps this week and ≈9
per 100 sweeps at TN Valley. We have received some reports from the field of
similar populations and that some fields are receiving a 2nd adult application
this week (following applications last week). High rates of imidacloprid alone,
Centric (2 oz), acephate (0.5-0.67 oz) or pyrethroids (highest labeled rate, dependent
on location) should suppress populations and preserve square retention. Keep in
mind that no insecticide will provide more than 2-3 days of residual control
for adults and square retention is the best way to determine efficacy, adult
numbers can rebound from week to week as more move into fields.
Thus far, reports from south Alabama are that plant bugs are
scattered here and there, but few fields are above threshold. These fields should
be closely monitored as the migration will likely begin soon.
The next 10-14 days will be critical for plant bug
management in central and north Alabama cotton. Timely applications of recommended
insecticides will preserve square retention and reduce egg lay and nymphs
hatching out in the coming weeks. Consider being prepared to make an
application of Diamond with a knockdown insecticide ≈10-12 days following the adulticide applications
going out now. One consideration for the “automatic” follow up may be weather.
If fields do not receive rain in the next couple weeks, that may impact immature
plant bug populations in our favor. Plant bug nymphs do not seem to handle hot,
dry conditions very well. Particularly in the hatchling stage.
Reminder: The 65th Alabama Cotton Scout
Schools kicked off this week in Headland. We have a few more opportunities to
go.
June 25th: EV Smith Research Center (4725 County
Road 40, Shorter, Alabama 36075)
June 26th: McCord’s Fire Station #1 (1150 County
Road 157, Centre, Alabama 35960)
If we can be of any help, please don’t hesitate to reach out
and let us know (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.
