The biggest concern this week for producers is the potential landfall of either Hurricane Marco or tropical storm Laura. As of Sunday August 23, the latest tracks show both storms making landfall in Louisiana within 48 hours of each other. Marco is expected to make landfall Monday evening followed by Laura on Wednesday.
In terms of cotton and peanut production, cotton crops in southwest and south-central Alabama appear to be most at risk. Alabama peanuts will be less impacted, but we may see an increase in leaf spot diseases. Alabama producers should keep a close eye on the track of the storms and plan fungicide applications accordingly.
For foliar diseases, if the last fungicide application was applied 7 or more days ago and the track for the tropical storm shifts back towards AL, producers should consider an additional fungicide application before the storm system comes ashore. However, keep in mind that fungicides need to dry fully to provide full efficacy and any rain events immediately following application can wash off fungicides.
For early and late leaf spot diseases of peanuts, Miravis and Priaxor are good options for producers as they have activity beyond 14 days. Conditions will also be very favorable to white mold (see picture above) and producers MUST keep the disease contained by making timely applications of good fungicides (ACES Peanut IPM guide).
If white mold is not managed properly, the disease will spread quickly up and down the rows making it difficult to control.
In terms of cotton, producers should scout fields for target spot and areolate mildew as warm, wet weather is conducive for disease development. Last week, areolate mildew (see pictures below) was found in a cotton variety research trial at the Wiregrass Research and Extension Center in Headland, AL.
So far there have been no additional reports of the disease in Alabama, but it has the potential to spread over the coming week in late planted cotton due to the potential wet weather. Early planted cotton is too mature to see significant yield losses due to the defoliation caused areolate mildew or target spot. Producers should scout their cotton for areolate mildew and consider a fungicide application if:
1) they are further than 4 weeks from defoliation
2) the crop has good yield potential
3) the disease has not spread to far
4) weather conditions favor disease spread (which it will this week)
Although we have limited efficacy data, we believe that the disease can be controlled with strobilurin products such as Headline or Quadris or mixed products like Priaxor or Elatus. Target spot is also still a concern for cotton and has been seen in our research trials in Prattville, Headland, and Fairhope. The best window of opportunity for managing target spot is from the first week of bloom to sixth week of bloom.
For additional information of fungicides, please consult the ACES Cotton IPM guide.
