AN INOCULATION DEVICE TO EVALUATE MAIZE FOR RESISTANCE TO EAR ROT ANDAFLATOXIN PRODUCTION BY ASPERGILLUS-FLAVUS

Fifteen commercially available maize hybrids were evaluated for variat ion in susceptibility to Aspergillus flavus and aflatoxin production u sing an inoculation technique that wounds kernels and injects a suspen sion of A. flavus conidia under the husk. The inoculator consists of s even rows of 23 pins mounted in an aluminum bar, with 0.8 cm of the po int ends exposed. Located in the center of the pins is a larger needle through which a spore suspension is injected under the husk. The inoc ulator is mounted at the end of a spray gun which is attached to a bac kpack sprayer. The inoculator is aligned with the ear axis, the pins a re forced through the husk into kernels, and inoculum is injected unde r the husk. Hybrid rank for ear rot was significantly correlated betwe en inoculations done in 1990 and 1991. Aflatoxin values, however, were not significantly correlated between years. All 15 hybrids were consi dered moderately to highly susceptible to A. flavus ear rot and aflato xin accumulation. The inoculating device allows for more rapid evaluat ion of resistance to A. flavus ear rot than do some previous technique s. A time-of-inoculation study conducted in 1991 indicated that inocul ations at 17, 20, and 23 days after midsilk result in the severest ear rot.