Plant Bugs Invading Alabama Cotton
Over the couple days, we have received multiple reports or observed adult tarnished plant bugs in April or early May planted cotton across central and north Alabama. In most cases, populations were below threshold, and a few squares were missing. However, some fields are at threshold and treatments are going out. Thus far, reports from southwest and southeast Alabama are that few or no plant bugs are being observed.
As our earliest fields begin to square, monitor pinhead
square retention on the upper 2 or 3 nodes of plants. Our goal is to maintain
80% of these first position squares (closest to the mainstem). The reason to monitor
the upper 2 or 3 nodes each week is that these are the “new squares” that were
put on in the current week (added since last week’s scouting trip). In addition
to monitoring square retention, a sweep-net is a good monitoring tool to
determine the level of adult plant bugs in the field (threshold is 2 adults per
25 sweeps). Even if square retention is above 80%, we recommend treating adults
because they will start feeding on pinhead squares and depositing eggs that
will hatch in the following 7 to 10 days.
Our general recommendation for adult plant bug control is
the high rate of imidacloprid or 1.75-2oz of Centric. In some areas, bifenthrin
is also an option. In cases of high pressure, acephate may also be considered
or tank-mixed with imidacloprid. We generally try to stay away from acephate
and bifenthrin to preserve better beneficial insects and for resistance management,
however under heavy pressure we need to worry about plant bugs and deal with
other issues if/when they arrive.
Based on our observations in daisy fleabane this spring, we
suscept this could be a multiple spray year for adults in June, particularly
for early planted cotton. Remember that as long as square retention is at or
above 80% a previous application “did its job” and more adults have moved into
the field. Also keep in mind that June applications for adult plant bugs can
set the tone for the rest of the season. By knocking back adults, we are
reducing egg lay and nymphs that hatch out later as blooms begin to appear.
Reminder: The 65th Alabama Cotton Scout Schools
kicked off this week in Headland. We have a few more opportunities to go.
June 11th: Associated Growers Gin (15031
Brownsferry Road, Athens, Alabama 35611)
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.
