2012年9月12 - 13日,
Target Spot of cotton, caused by Corynespora casiicola, is a recently-recognized disease that was prevalent and troublesome in the Southeastern U. S., especially Alabama, Florida, Georgia, and South Carolina in 2012 and 2013. In contrast to other foliar diseases of cotton, Target Spot is especially prevalent on well-fertilized, well-watered cotton. After row closure, brown concentric necrotic rings appear on leaves in the interior of the plant canopy. Thereafter defoliation may spread rapidly. At present we lack a quantitative means to relate disease symptoms to yield loss. Fungicide trials suggest that partial alleviation of disease symptoms may result in saving up to 200 lbs. of lint/acre in certain instances. The efficacy of the available fungicides is likely limited by our ability to apply the fungicide effectively to the interior of the plant canopy where the fungus is sporulating. Cotton Incorporated plans to increase research support on Target Spot in 2014.