Can the synergistic relationship between elemental sulfur and synthetic fungicides observed in the field be explained by their effect on the fungal growth of Northopassalaora personata?**


Sulfur is one of the oldest known fungicides used in peanut production to control late leaf spot disease (LLS) caused by the fungus Northopassalaora personata. Sulfur also exhibits properties that aid in making peanut plants greener, potentially increasing tolerance of peanut to LLS. In some situations, there is a synergistic reduction in LLS disease when synthetic fungicides are mixed with sulfur compared to these fungicides and sulfur alone. It is not clear whether the synergistic effect is due to sulfur’s activity on the host or the pathogen. A lab study is in progress to investigate how the fungicide-sulfur mixtures influence pathogen growth. Six treatments 1) nonfungicide control, 2) elemental sulfur, 3) Tebuconazole 4) sulfur mixed with Tebuconazole, 5) Azoxystrobin and 6) sulfur mixed with Azoxystrobin will be applied to the surface of Potato Dextrose Agar. Spores of N. personata will be placed on top of the treatments. Germination and hyphal growth will be quantified after 48 and 96 hours for at least 30 spores. If the hypothesis is true, spores exposed to the DMI sulfur mixtures will exhibit a greater than expected decline in hyphal growth based on how DMI’s target the pathogen, and spores exposed to the QoI sulfur mixtures will exhibit a greater than expected decline in germination based on how QoI’s target the pathogen. The experiment will include 3 replications and will be repeated twice.


Valdolsta State University University of Georgia

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