Originally Posted by turfmd101
Explain how or why atrazine would burn please. I am just curious. What is atrazines mode of action.
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Atrazine inhibits photosynthesis; like all triazenine class of herbicides, it interferes with electron transport during photosynthesis and eventually leads to cell membrane destruction and cellular leakage.
Floratam, the most common St. Augustine cultivar in my area is tolerant of atrazine herbicides when temperatures are below 85°F.
The label clearly states:
"Do not apply when temperatures exceed 90o F. Use only on healthy turf grass which is not under heat or drought stress and reasonably free of infestations of insects, nematodes, and diseases. Use in the United States should be confined to Southeastern States only. Applications during the summer should be limited to spot treatment only."
In general, Atrazine results are inconsistent. Different St. Augustine cultivars have different tolerence levels, Floratam being the most tolerant. One cannot assume that an incidence of an application being well tolerated by a cultivar @102 degress indicates it is always appropriate to apply it under those conditions. Reasonable men would act on the side of prudence in it's application.
I would like to hear from others that they had sucess with Atrazine above 90 degrees without incuring damage to St. Augustine.