Conditions are ripe for target spot in cotton now. Growers are advised to begin carefully scouting a cotton crop at the approach of the first week of bloom, checking the lower canopy for tell-tale symptomatic leaves. If target spot is not identified after careful scouting, growers may delay a fungicide application and scout again in the coming weeks. The best timing of a fungicide application is often during the third week of bloom; where disease pressure is high, a second application may be beneficial two weeks later. Fungicides are not needed after the sixth week of bloom. Once defoliation has reached 20% or more, there is likely little chance to manage this disease.
One of the biggest challenges in protecting a cotton crop with a fungicide against target spot is that coverage is
needed deep the canopy. However, getting sufficient fungicide coverage there is a real challenge but can be improved by 1) increasing spray volume, 2) increasing spray pressure, and 3) making the first fungicide application early enough before the canopy of leaves is fully closed.
As in the slide below, there are a number of fungicides labeled for use on cotton to protect against target spot and also areolate mildew. For target spot, Priaxor has been the most important fungicide for growers to consider. Headline has also been quite effective and now Miravis Top seems to be among the most effective fungicides for management of target spot.
