Tales of Cotton Insects: Thursday June 13, 2024

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 10^th 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 15^th (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 1^st 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 2^nd 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 65^th Alabama Cotton Scout Schools kicked off this week in Headland. We have a few more opportunities to go.

June 25^th: EV Smith Research Center (4725 County Road 40, Shorter, Alabama 36075)

June 26^th: 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.

Tales of Cotton Insects: June 4, 2024

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 65^th Alabama Cotton Scout Schools kicked off this week in Headland. We have a few more opportunities to go.

June 11^th: Associated Growers Gin (15031 Brownsferry Road, Athens, Alabama 35611)

June 25^th: EV Smith Research Center (4725 County Road 40, Shorter, Alabama 36075)

June 26^th: 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.