Tarnished plant bugs have continued to be a problem in flowering cotton in some Virginia cotton fields. This week, scouts found 10 out of 30 fields above the bloom threshold of 2-3 plant bugs per drop cloth sample across Virginia’s cotton-growing region. Six of these fields averaged above the bloom threshold for the past two weeks (see map below). Dirty blooms may indicate plant bugs are present but should not be used as a threshold for spray decisions. Cracking bolls and observing internal boll injury in small dime and quarter-sized bolls is also a great indicator bugs may be present and causing significant damage. Internal boll injury includes raised warts or outgrowth on the carpel wall, small black punctures that usually match an external lesion, and stained lint. We recommend observing at least 25 bolls per field for internal injury in addition to drop cloth sampling to make informed spray decisions. Plant bug populations have peaked in mid-August over the past few years in Virginia so we recommend continued scouting during the coming weeks. Check out this video if you would like to see a short tutorial on drop cloth sampling.

Plant bug density averaged over two weeks from 24 July to 02 August 2018.

Plant bug internal boll injury symptoms.

Plant bug nymph feeding on a dirty bloom.