Although thrips are still a struggle for a few growers and although some cotton has been beaten up by our recent rainy weather, most cotton is now beyond the thrips-susceptible stage of four true leaves.
In our thrips tests at Rocky Mount, N.C., all cotton planted with any seed treatment that required a foliar application is now safe from further thrips damage. This high moisture and warm days and nights really has cotton growing rapidly with squaring less than a week away for a few producers.
Abundant host growth: Although predicting what and how many insects will show up in the coming weeks and months is close to pure speculation, due to high moisture levels throughout much of the state, we have a large biomass of plant material in CRP land, ditch banks and in the general landscape. Many weed species are excellent hosts for plant bugs and stink bugs. A healthy corn crop with high soil moisture levels is also an excellent host for plant bugs.
Plant bug increases? In recent years, surveyed consultants have reported a significant increase in plant bug treatments, with approximately 6 percent of our cotton acreage treated from 2004 to 2007 and 16 percent treated averaged over the past two years. I realize these numbers would not impress our Mid-South brothers who sometimes are faced with 4 to 8 plant bug sprays annually (boll weevil reminiscing, anyone?), but it will still be interesting to see if our trend toward increasing levels and associated and damage continues.
Decision aid tool
Stink bug decision aid tool: With stink bugs in cotton, we now have a very straightforward scouting tool in the form of a field decision aid to help scouts select correct boll sizes for examination, recognize the appropriate internal boll wall damage and follow a dynamic boll damage threshold that changes by week of bloom.
It’s helpful to remind scouts and producers that stink bug damage often varies greatly from year to year and from field to field. Our best bet in economically managing stink bugs is to make threshold-based spray decisions. In a given year it’s not unusual for threshold-based sprays to vary between zero and three or four applications throughout the state depending on stink bug levels and cotton plant susceptibility.
Web-based stink bug app: We hope to have a web-based stink bug decision aid app (an on line version of the field card with significantly more information) posted in the next 4 weeks, accessible from laptops, desk tops, tablets smart phones and other internet enabled devices. This app will provide a stink bug ID guide, list scouting steps, illustrate internal boll damage symptoms, list thresholds by week of bloom and link to other related areas of interest. More on this in the coming weeks.
Cotton and soybean scouting schools: Beginning with next week’s Pest News, we will begin listing the locations, dates and times of our upcoming July cotton and soybean insect scouting schools.
Insect updates: To listen to our Wednesday cotton insect updates, just go to the Cotton Insect Hotline or call the Extension Teletip number 1-800-662-7301 and press “2” at the prompt (pressing “1” will take you to a soybean rust update last recorded by Jim Dunphy in 2011).
For more on crop conditions and advice, visit http://www.nccrops.com/.
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