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Priorities for use of micronized sulfur for management of peanut leaf spot – Dr. Culbreath

In recent years we have had very encouraging results with micronized sulfur used as a mixing partner with several different fungicides for leaf spot control.  In many cases, mixing with sulfur has provided control comparable to (and sometimes better than) as mixing with 1 pint of a 720 formulation of chlorothalonil for leaf spot control and often for less cost.  I do not understand what is happening with those mixtures, because sulfur alone does not provide adequate leaf spot control under the pressure we have in our tests.  We still have a lot to learn, but sulfur has done especially well when mixed with Umbra, Excalia, or azoxystrobin (Abound and various products).  All three of these products are used for management of soilborne diseases, but are not adequate alone under heavy pressure for leaf spot control.  Mixing with chlorothalonil is certainly a viable option with any of these, but these products would be my top priorities for mixing with sulfur.   Our work with sulfur as a mixing partner was prompted largely by a shortage of chlorothalonil a few years back, and concerns about the future of chlorothalonil.  Currently, chlorothalonil is still an effective option as either a stand-alone treatment or mixing partner. Therefore, when a mixing partner is needed, growers might consider using sulfur mixtures with some applications and chlorothalonil mixtures with others.  Currently, I would also prefer chlorothalonil as a mixing partner with Topsin.   Based on our results, sulfur is not as effective as  chlorothalonil as a stand-alone treatment.