Tarnished Plant Bug Management In Pre-Bloom Cotton
DR. DAWSON KERNS
BATON ROUGE, LOUISIANA
Tarnished plant bugs are among the most important pests of cotton in Louisiana. Injury inflicted by plant bugs results in square loss which has a direct impact on yield. Silking corn, blooming soybeans, and other flowering hosts all contribute to a growing plant bug population over the course of the growing season. Once cotton begins to square, adults will migrate into cotton and begin feeding. Before bloom, the goal is to maintain at least 80% square retention. Therefore, monitoring square retention is the best way to determine if early-season management of plant bugs is adequate. If square retention is at risk of falling below 80%, then treatment may be warranted. Additionally, a sweep net can be used to monitor adult plant bugs migrating into the field. However, it is important to consider that plant bugs will move in and out of cotton quickly during the pre-bloom window, so it is not uncommon to find poor square retention with little or no plant bugs present in the field.
ThryvOn cotton should be monitored just as non-ThryvOn cotton. The ThryvOn trait provides some suppression of adult plant bugs, but it is still prone to heavy square loss, especially when large infestations of plant bugs occur. The biggest benefit provided by ThryvOn is in the reduction of immature plant bugs during bloom.
Neonicotinoids such as Centric at 2.5 oz/a or imidacloprid at the highest labelled rate are early season options for tarnished plant bugs, but follow-up applications may be needed to maintain adequate control. Other options for plant bug control include: acephate which carries the risk of flaring spider mites or aphids, Vydate which is effective but has a limited residual of only three days, Bidrin which is not labelled for plant bugs before bloom, and Transform which is very effective, but may best be saved for the blooming window. The third week of squaring to first bloom window is the best time to begin applications of Diamond. Applications of Diamond targets immatures and will help prevent establishment of plant populations that require repetitive insecticide applications. ∆
DR. DAWSON KERNS: LSU AgCenter