More Questions of the Week November 10, 2016
Here are four lawn-related questions I’ve heard repeatedly recently.
“What’s causing the round, brown spots in my St. Augustine, and what can I do about them?”
That’s a fungal leaf disease known as brown patch, and the circular spots (18 to 24 inches in diameter) that you described are telltale means of identifying it. You’ll also see where it has attacked the blades if you pull on them gently. They will separate from the runners, exposing the decayed tissues in the process. Apply a labeled fungicide, and water only in the morning. The grass will bounce back.
“Is it too late to apply weedkillers to my lawn?”
Yes, and no. It’s ten weeks too late to apply pre-emergent weedkillers to turf. That needs to be done in the first week of September. But you can apply post-emergent broadleafed weedkiller sprays now to control young seedlings of non-grassy weeds like clover, dandelions, henbit, chickweed, thistles, dichondra, oxalis and plantain. To be sure you’re in the right category of herbicides, you’re looking for one containing 2,4-D as an active ingredient. Your nursery professional can help you find it. Use a pump sprayer, and apply the herbicides carefully to the weed leaves. Results won’t be rapid, but the weeds will gradually fade away. This treatment must be made in dry, still conditions.
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“Is it OK to leave tree leaves on the lawn as a mulch?”
No. They keep the ground moist and warm, and that serves as an incubator for diseases like the brown patch we referenced earlier. Keep them picked up with your mower, and empty the bag into the compost pile. Don’t send them to the landfill.
“Should I leave my lawn a little taller as protection from the cold?”
No. Allowing the grass to stay taller won’t have any impact at all on its winter hardiness. But it will allow the weeds to develop more stems and leaves so they can take hold better. “Mowing high” is almost never a good plan. Mow at the recommended height for the type of grass that you’re growing, and stick with it every month of the year.