Stink bug scouting aid developed

A pocket-size scouting decision aid was developed in 2010 for use in the Southeast to encourage 1) a higher adoption of stink bug scouting in cotton, 2) better field identification of stink bug-induced boll damage symptoms, and 3) use of recommended scouting procedures.

This article describes the decision aid and how to use it.

The aid relies on the latest dynamic threshold for stink bugs in cotton based on week of bloom. It provides the following scouting aids:

• A “dynamic threshold by week of bloom” table.

• Recommended scouting procedures.

• Measuring holes to help select the correct boll size range for damage assessments.

• Images of internal and external stink bug-in¬duced boll damage.

The aid should improve stink bug management, because the dynamic threshold is based on the cotton growth stages when the crop is most susceptible to stink bug damage. It relies on lower thresholds during weeks of maximum susceptibility (weeks 3 through 5 of the bloom period) and higher thresholds during stages of lower vulnerability (weeks 1 to 2 and weeks 6 to 9 of the bloom period).

The front side of the 3×6-inch decision aid provides recommended scouting procedures:

(1.) Select a random sample of the correct size bolls.

(2.) Assess an adequate number of bolls.

(3.) Sort the bolls into two piles, those with and those without obvious external damage lesions.

(4.) Crack bolls between the thumb and forefinger or cut them open with a knife and inspect all internal boll wall surfaces for internal warts (not just areas visible from the initial crushing or from the initial knife cut), and examine all locks for stained lint. (Helpful hint: Crack and inspect bolls with obvious external lesions first to determine if the internal damage threshold is met, as bolls with external lesions are more likely to be damaged internally; assessing these bolls first can save time.)

(5.) If the threshold is not met, check the remaining bolls for internal damage.

(6.) Treat only if the threshold has been met for that week.

The measuring holes provide cotton scouts with an efficient way to select correctly sized bolls. Scouts should target bolls with an outside diameter between 0.9 to 1.1 inches. Bolls of this size are best correlated with recent stink bug damage. The front side also lists the recommended dynamic threshold by week of bloom. The asterisks for weeks 4 and 5 of the bloom period permit nuances in scouting frequency recommendations by the various Southeastern states.

The reverse side of the aid provides images to help the scout properly identify stink bug damage: Internal warts, and stained lint; and external damage lesions. As explained in recommendation 3 above, external damage symptoms may be used to sort the pulled bolls into two piles.

Each decision aid is fitted with a lanyard that can be worn around the scout’s neck. The lanyard has a quick disconnect adjacent to the aid for removing the aid to size bolls.

Presently, these scouting templates are being distributed to county agents, consultants and scouts for use during the 2010 growing season. We are hopeful the use of these devices will lead to more cotton acreage being scouted, following correct scouting procedures, and more consistent, accurate scouting for stink bug damage.

This work was supported by the Southeast State Support Cotton Committees through Cotton Incorporated and by a Southern Regional IPM Capstone Grant. This work was a collaboration among Extension entomologists Jack Bacheler (North Carolina State University), Ames Herbert (Virginia Tech), Jeremy Greene (Clemson), and Phillip Roberts and Michael Toews (University of Georgia).

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