Submitted to: Plant Disease
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/5/2005
Publication Date: 9/5/2006
Citation: Carson, M.L. 2006. Yield loss potential of phaeosphaeria leaf spot of maize caused by phaeosphaeria maydis. Plant Disease. 89:986-988. Interpretive Summary: Phaeosphaeria leaf spot is a relatively new disease of corn in the U. S., being confined to southern Florida at the present time. To determine if this disease has the potential to reduce corn yields, field trials were planted in southern Florida. Yields of artificially inoculated plots were compared to those of uninoculated plots. Only the most susceptible hybrid in the trials suffered a small, but significant yield loss. These data, along with previous studies that indicated most U. S. corn hybrids are resistant to this disease, suggest that this disease has limited potential for causing damage to the U. S. corn crop. This information will be useful to corn breeders and plant pathologists in the public and private sectors in setting priorities in corn improvement programs. It will also be useful to extension personnel and growers seeking additional information on this new disease.
Technical Abstract: The ability of Phaeosphaeria leaf spot (PLS) to reduce yields of maize was evaluated over two winter growing seasons in southern Florida. Nine commercial maize hybrids, that varied in their reaction to PLS, were planted in a split-plot design with hybrids as whole plots and inoculated vs. uninoculated treatments as sub plots. The most susceptible hybrid, Pioneer brand 3489 sustained a significant reduction in grain yield (11-13%) and 400 kernel weight (8-10%) in the trials. Regression analyses indicated that grain yields and 400 kernel weights were reduced 0.23 and 0.16%, respectively, for each percent increase in PLS severity at the mid-dent stage. Because most maize hybrids in the U.S. are resistant, and PLS develops late in the grain-filling period, its potential to cause substantial losses appears limited.