As the calendar turns to August the Alabama Cotton Insect
Situation has really started to heat up. Plant bugs are still heavy in
spots statewide, but stink bugs are becoming more and more of an issue
as the crop continues to bloom. Some heavy bollworm egg lays have also
been reported in parts of the Tennessee Valley. The overarching theme with many
of these pests appears to be the drawn-out planting of corn due to wet weather
this spring. Insect pests continue to trickle out of corn as the migrate into
cotton fields. Spider mites are also in fields and have reached treatment
levels over the past few days as well.
Plant Bugs
Plant bugs (tarnished and clouded) are still requiring treatments in some fields in Central and South Alabama. Cotton in the Tennessee Valley is under pretty substantial plant bug pressure. As we are now blooming, the black drop cloth is the preferred method to scout for plant bugs. Threshold is 3 tarnished plant bugs per 5 row feet. If clouded plant bugs are found, they should be counted as 1.5 tarnished plant bugs. Keep in mind that clouded plant bugs tend to do a little more damage to small bolls than tarnished plant bugs, thus the change in threshold.
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| Immature Clouded Plant Bug |
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| Immature Tarnished Plant Bug |
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| Adult Green Stink Bug |
Bollworms
We received reports of heavy egg lays in the TN Valley this week. No reports of escaped worms have been made (yet), but with 20%+ egg infested plants, there is a possibility. Outside of 2017, escaped worms have not been a big issue in Alabama but there can always be some fields that don’t go as planned. Aside from the terminals, bollworm moths seem to prefer to lay eggs on bloom tags (drying bloom petals). Thus, egg scouting efforts should be focused on in the terminals and the blooming zone (particularly on bloom tags). Currently, our recommended thresholds are based on the number of escaped worms found per 100 plants. Escaped worms may be found on bolls (often underneath the bloom tag), squares or white blooms. In Bollgard II and TwinLink technologies, escaped worms tend to be found in the blooming zone. Threshold is 5 worms (0.25 inches or bigger) per 100 plants. To date, we have seen no issues with 3 gene technologies (Bollgard 3, Widstrike 3, TwinLink Plus). We do not recommend treatment on these varieties. |
| Bollworm eggs on terminal. |
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| Escaped worm feeding under bloom tag. |
Spider Mites
We have received reports of spider mites from the Wiregrass
over the past week. Mites are in nearly every field statewide at some level all year long waiting for a hot,
dry stretch to “blow up.” As we write this, we don’t know what the incoming
tropical storm system is going to do, but it looks likely rain events are
coming. We do not know what that will do to spider mites approaching treatment
levels currently, so making applications in front of the storm may be
advisable. Treatment decisions require a bit of professional judgment.
Threshold is when mites and their injury is widely distributed across the
field. Coverage is critical for control of spider mites. Using the higher end
of labeled rates is advisable as cotton is into bloom.
Parting Shots
We still have another 4-6 weeks left to make cotton in
Alabama. Hopefully Tropical Storm Fred will bring some needed rain (but not too
much). Keep scouting and spraying fields as needed. Up-to-date thresholds and
insecticide recommendations visit the Alabama Cotton IPM Guide (IPM-0415).
We will continue to put out information through twitter, this newsletter and the
Alabama Crops Report Newsletter,
Podcast
and on the Pest
Patrol Hotline. As always, if we can ever be of any help please don’t
hesitate to let reach out.