Before I describe pest pressure in the cotton crop, I would like to say that no two fields are similar and scouting is a must for good management of a crop. I don’t care if you do it personally, or hire a scout, just as long as it gets scouted properly. I briefly addressed the topics that I get contacted about the most.
Stinkbugs
It is important to scout quarter sized bolls for lint discoloration and/or warts on the boll wall. the threshold for damaged bolls is as follows: 10-15% week 3,4 and 5, 20% weeks 2 and 6, and 30%+ from week 7 and later. I have observed a fair amount of fields this year with stinkbug damage. All the more to justify scouting.
Two-Spotted Spider Mite
I have had a lot of phone calls on spider mite populations in cotton this year. If spider mite populations are present in a field, be careful not to flare them with insecticides. The threshold for spider mites is 50% of the plants in the field are infested and populations are increasing. Another tip is to look for areas that attract mites such as a dirt road or large tree on the edge of a field. Observe the populations in these areas and make sure that they do not start to expand.
Silverleaf Whitefly
I am happy to report that we are much better off than the unprecedented levels that our area experienced last year. Whitefly levels are currently low. Do scout for them as presence of whiteflies in cotton should directly impact your overall insect management decisions. The following are 3 factors that could potentially increase risk for presence of whitefly: proximity to watermelon, hairy leaf cotton, and late plantings. Also, make sure to terminate watermelon vines as soon as the crop is finished.
Foliar Diseases in Cotton
Initially, target spot was hard to find but that is not the case any more. Target spot is fairly easy to find in Turner County. Areolate mildew has been found in several counties but I have not seen it in Turner County. there is not a lot of data on treating for areolate mildew but generally it does not occur at levels that are yield limiting. The best window for treating target spot of cotton is the 1st-6th week of bloom. target spot combined with favorable weather in the 1st-3rd week of bloom is more of a concern than target spot during the 4th-6th week of bloom. Fungicides used for target spot do have activity on areolate mildew as well.