The attached pictures from today from Barnwell County complement the notice earlier this week of late leaf spot lesions having been found in Bamberg County. Initial visible lesions are often not evenly spread across a field, making it not unlike a labor of love to search out when it is first getting started. While there is not a set/magic number of locations that should be checked in a field to determine what the current leaf spot status is, the tradeoff of time invested helps pay back confidence of not having it sneak up on us. 10 to 20+ can be a good starting point as a rule of thumb.

With temps in the mid upper 90s to be upon us in the coming week+, in addition to stress from heat and drought where rains have been scarce, an opportunistic and less common disease that favors those conditions is Diplodia collar rot. Attached are a few pictures from several years back in case it shows up again. Affected laterals can have a papery flakiness to them, and crispy blighting can occur as well. The black pycnidia on killed laterals are a hallmark diagnostic feature, in addition to the spores inside those having a line/septum in the middle. Reducing stress, which is outside practical management options for dryland fields, is the most effective way to prevent/reduce this disease. Nevertheless, its general lack of economic impact can be a source of encouragement in the face of its less than pleasant appearance, should it develop. On the more common side, hot and stressful conditions are also favorable for our more familiar white mold/stem rot, particularly for fields with previous histories of it and long production backgrounds. While daytime temperatures in the mid upper 90s tend to be less conducive to LLS development, nighttime temps are cool enough and humidity is often ample enough to continue infection and spore production cycles. Due to this, I tend not to recommend a delay in fungicide programs during hot or dry spells, although where practical we can modify applications to take advantage of available rain, with the ideal balance of having enough time to provide foliar coverage (about a day) but if able to be washed in where white mold/stem rot management is a concern, timely washing in will give us benefit as well. We do not have a lot of acres sprayed during early AM/nighttime hours, but that is another option of increasing fungicide deposition near the soil line where extra help is needed in dryland fields.