Questions About Spraying for Leaf Spot in Dry Weather Peanut Notes No. 152

— Written By Barbara Shew and last updated by

I’ve been getting a lot of calls about whether to spray in areas that have not received rain in the past few weeks. There are good reasons to hold off spraying in dry weather. The risk of leaf spot tends to be low under hot, dry conditions, whereas spraying increases the risk of spider mite outbreaks.

However, we can still have several hours a day of high humidity even during very dry weather, and leaf spot fungi can infect during these periods. The best way to determine if it is safe to delay a spray is to check disease advisories since these are based on hours of high humidity.

Today is July 21. As of today, the last effective spray date at all advisory locations is between July 3 to July 6. If you sprayed two weeks ago on July 7, you have sprayed since the last effective spray date and it’s safe to wait a few more days to spray. Conditions may warrant a spray in isolated areas that have received rain.

You can receive advisory updates from your Count Agent, or contact me ( if you want to be added to the peanut disease advisory mailing list.

Reminder: This is a critical time for stem rot control. A stem rot fungicide should be applied with the next leaf spot spray.