During the heat of the summer your tall fescue lawn will be stressed. It does not like 117F heat during the day or at any time for that matter. When under stress, fescues will be prone to attack by lawn diseases. Makes sense, doesnt it? We are more prone to getting sick when we are under stress too.
This can become a big problem if the lawn is already stressed by a weak irrigation system, mowing the grass too short and even applying too much nitrogen 3 to 4 weeks before the onset of heavy stress. Lawns in parts of the yard where there is poor air movement are more prone to getting disease than those where air can move across its surface easily. Most plant diseases like it best when the humidity rises and there is poor air movement which fails to dry out the grass.
To help prevent disease in your lawn
- make sure the lawn is mowed at its proper height for fescue; no shorter than 1 1/2 inches. No taller than 2 1/2 inches this time of year
- keep mowers that were on diseased lawns from cutting your lawn or at least make sure the mower is clean when you start mowing
- don't apply nitrogen for at least four weeks prior to the onset of high temperatures; low nitrogen and high potassium fertilizers would be a better choice or using more expensive slow release fertilizers or manure-based fertilizers
- if your lawn is prone to disease in the past, apply a fungicide to your lawn now
- irrigate ONLY in the early moring hours just before sunrise. Never water in the beginning or middle of the night.