We are transitioning out of the summer growing season, the days are getting shorter, and the nights cooler. As the days drop down into the low nineties farmers with Bermuda grass pastures or hayfields need to be vigilante in checking their fields not only for fall armyworms, but also yellowing spots where grass may be dying. Leaf Spot (also known as leaf blight) is a disease that typically appears in late summer when temperatures are between 75 and 90 degrees. Heavy infestations will decrease both yield and quality of your pasture or hay.
To identify leaf spot look for yellowing areas of you pasture and inspect the grass within this area. If the blades have brown irregular shaped spots then you most likely have a leaf spot infestation.
There are no fungicide recommendations for the treatment of leaf spot in your pasture or hay field. If you have a large or spreading infestation of leaf spot, it may be a symptom of another problem in your pasture. Nutrient deficiencies are commonly the problem that leads to a leaf spot infestation. Areas may be deficient in Magnesium, Sulfer, or Potassium. A soil test can be preformed in the affected areas to determine if this is the cause.
For fields with winter overseeds, try to minimize thatch (leftover residue from plants) in your field as. The decaying material can tie up nutrients, increasing the chances of having a leaf spot infestation. Burning off fields before Bermuda green-up can help minimize thatch.
Maintaining a proper cutting interval can help decrease your chance of having leaf spot. Proper cutting times can help maintain high nutritive value in the grass. Leaf Spot resistance moves from older tissue to younger tissue. By cutting at regular intervals resistance is indirectly increased.
If you are unsure if you have a leaf spot infestation, samples of the infected grass can be brought to the Extension office for identification. Soil boxes and forms can also be found at the Extension office.