The genetic diversity, epidemiology, and chemical control of the causal agent of pecan anthracnose, Colletotrichum
Ingram, Thomas William
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New genetic data shows pecan anthracnose to be caused by species within the Colletotrichum gloeosporioides species complex. Conidial germination, appressoria formation, and latent infections are all higher at 20 °C and 25 °C, compared to 30 °C and 35 °C. Latent infections were found in south Georgia orchards in late July 2011, and early June in 2012. Symptoms did not always develop, even when numerous latent infections were present. Field applications of strobilurins, triazoles, phosphites and organotin combinations were effective in significantly reducing the number of foliar latent infections in 2011 and 2012. In the greenhouse the fungicides Super-Tin, Quadris Top, and ProPhyt significantly reduced the number of foliar latent infections in pre- and post-inoculation treatments. A range of sensitivities to the triazoles, strobilurins or organotins was found in 39 isolates tested, but only 3 were completely resistant to thiophanate-methyl.