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Poster: Epidemiology: Risk Assessment


Weather patterns associated with Gibberella Ear Rot of Corn in Ohio
F. DALLA LANA (1), R. Minyo (1), P. Thimison (1), L. V. Madden (1), P. A. Paul (1) (1) The Ohio State University, U.S.A.

Gibberella ear rot (GER), caused by Fusarium graminearum is an important disease of corn. Since outbreaks of GER are sporadic, understanding the weather patterns associated with this disease is fundamental for GER risk assessment. The objective of this study was to determinate the association between weather conditions and GER intensity. During 2015, 15 hybrids were tested at 10 locations in Ohio. At the R1 growth stage, ten arbitrarily-selected primary ears per hybrid were inoculated in the silk channel with 2 ml of a spore suspension containing 2.5 x 105 macroconidia of F. graminearum per mL. Air temperature, relative humidity (RH), surface wetness, and rainfall data were collected at 15-min intervals using local weather stations. At R6 all inoculated ears plus five non-inoculated ears were hand-harvested to estimate the incidence and severity of GER. Symptomatic infection was not observed on non-inoculated ears of any hybrid at any location, indicating that natural infection likely did not occur. Two locations had relatively high GER incidence (18 to 25%), four had low incidence (0.7 to 1.4%), while incidence was zero at the other locations. A preliminary descriptive analysis of the data indicated that GER was associated with 3 to 5 rainy days during the 7 days before R1, moderate temperatures (approximately 20?C) during R1, and RH above 80% during the week after R1.