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Old 08-26-2012, 03:19 PM
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turfmd101 turfmd101 is offline
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Originally Posted by jvanvliet View Post
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:

Atrazines mode of action to my knowledge is growth accelerator. Growing weeds through their life cycle at a speeded rate. That's why most applicators and homeowners notice the weeds get "bigger "after a couple of weeks. Atrazine takes about 3 to 4 weeks to complete this process. Thats why sometimes some weeds die some look yellow and some look fine. Different weed species different results. Short life cycle weeds easy to kill one app longer life cycle ones harder. That can be seen in medium size dollarweed. Sometimes after 4 week cycle its just bigger. A follow up app insurers this process finishes the weed life cycle. Another reason follow up apps are more important than 1st apps sometimes.

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.
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