The past week has brought slightly cooler temperatures across much of Alabama, resulting in cotton that is not growing off as quick as we would want in some areas. We also have some pockets that are getting dry, further exacerbating the issue.
Overall,
thrips pressure has not been too bad this year, but we are starting to see
pressure pick up in some areas. For the most part, our at-plant treatments have
been holding on pretty well, but some of the seed treatments are starting to
break. In “normal” conditions, we don’t see yield loss after about the 4th
or 5th leaf stage. However, in fields where cotton is not growing,
foliar applications may still be warranted. Remember that acephate is
effective, but is highly sensitive to wash off after rain and may flare spider
mites. Intrepid Edge has better rainfastness and is less likely to flare mites.
TCAH Damage in Cotton
We have also seen and heard reports of three-cornered alfalfa hoppers in some fields. TCAH tend to be worse in dry spells, when weedy hosts are drying down and tender cotton plants are the best thing around. They are usually worse on field borders, however in no-till, high residue fields they may be distributed across the field. Usually, we do not recommend spraying for TCAH because adults are so mobile and reinfest so fast that controls are difficult to evaluate. Typically, cotton plants damaged by TCAH die, and surrounding plants usually compensate for any loss. One consideration for treatment would be in fields with very low plant populations or in fields with spotty stands. Pyrethroids and acephate provide good control, but again adults can continue to move into fields. Generally, cotton is “safe” from TCAH around the 6-8th node. Cotton plants that have been injured from TCAH appear stunted, leaf veins begin to turn dark red, and leaves take on a red/orange appearance. There will also be a knot or multiple knots on the stem usually below the cotyledons.
One other
report we have gotten over the past week is high numbers of stink bugs in corn.
Corn is highly susceptible to stink bug injury just prior to tassel (V14-VT). A
well timed pyrethroid application will help corn and likely reduce populations
moving into cotton later in the season as well.
Plant Bugs: Although we shouldn’t have any cotton squaring
(yet), I want
to go ahead and mention plant bugs. We have a graduate student (TJ Douglas) traveling
the state making collections of adult plant bugs from daisy fleabane for
resistance monitoring. The fleabane is loaded with all ages and stages of plant
bugs across Alabama. Keep an eye on ditch banks and field edges with fleabane
on it. As long as rains persist, and fleabane is healthy, plant bugs will
likely stay there. Once the fleabane begins to dry down, plant bugs will start
moving to the most mature cotton in the area (first planted cotton). Scout this
cotton weekly as soon as squares are in the field. Threshold is 8 bugs per 100
sweeps -OR- maintain 80% square retention. Older fields (later planted)
should be monitored for plant bugs as well, but early season populations tend
to build most heavily in the earlier planted fields.
Cotton Scout
Schools: We have 4 programs planned across the
state this year. You can click the link on Agenda for details on each location.
We published a story on the longest consecutive running program in Alabama
Extension here.
Southeast Alabama
— Cotton and Peanut
June 6
Wiregrass Research and Extension Center
Headland, Alabama
Central and West
Alabama — Cotton and Soybean
June 8
Autauga County Agricultural Center
Autaugaville, Alabama
Tennessee Valley
— Cotton and Soybean
June 14
Tennessee Valley Research and Extension Center
Belle Mina, Alabama
Northeast Alabama
— Cotton
June 22
McCord’s Fire Station #1
1150 County Road 157
Centre, Alabama
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 Podcast, and the Syngenta Pest Patrol Hotline.