During the past ten years, Target Spot in cotton has continued to increase in Georgia. Currently, with warm weather, good canopy growth, and scattered rainfall the conditions are favorable for Target Spot. Of course, when we receive consistent rain showers the cotton experiences better growth and increased periods of leaf wetness which permits the risk of Target Spot development. Concerning Target Spot management, as it relates to yield, we have only had small amounts of data and often times conflicting data to refer to. However, we do know that Target Spot responds to fungicide applications and fungicides can reduce disease severity. The most difficult aspect of fungicide application and control is obtaining the necessary coverage. For this reason, in order to get the fungicide down into the plant, we begin to spray early in the cotton growth stage (first week of bloom).
We should take several factors into consideration when determining if we should spray or at least be aware of possible needed fungicide applications.
1. Is there a history of past problems or disease.
2. Does the cotton have rank growth and what is the current/future weather forecast.
3. Has Target Spot actually been discovered in the field.
4. What is the growth stage of the cotton. Fungicides should not be sprayed until the first week of bloom, no application is needed prior to this growth stage. The optimal time for a two application spray program is: first spray during first-second week of bloom and second fungicide application three weeks later. For a one application spray program, the most beneficial time is third week of bloom.
Fungicides that may be considered for application include: Headline @ 6 oz. rate, Quadris @ 6-9 oz. rate, and Twinline @ 7-8.5 oz. rate.
Please refer to the chart below for scoring/ranking of Target Spot Risk Factors.