YIELD AND QUALITY OF HUITLACOCHE ON SWEET CORN INOCULATED WITH USTILAGO-MAYDIS

Ear gall development was evaluated after inoculating sweet corn (Zea m ays L.) hybrids with Ustilago maydis (DC) Corda by injecting sporidial suspensions into silk channels when silks had emerged almost-equal-to 3 to 6 cm from ear shoots. Gall incidence was almost-equal-to 35% in two inoculation trials. About 0.5% of the noninoculated control plants was infected. Gall weight increased almost-equal-to 250% to 500% betw een 14 and 21 days after inoculation, reaching a maximum of almost-equ al-to 280 to 600 g. Gall tissue was nearly 100% black and had lost its spongy integrity 19 to 21 days after inoculation, when mycelial cells formed powdery teliospores. A 1- or 2-day harvest window during which huitlacoche yield and quality were optimized corresponded to the time at which 60% to 80% of the gall tissue was black. The optimal huitlac oche harvest time varied among hybrids from 17 to 19 days after inocul ation, but we suspect that optimal harvest time varies from almost-equ al-to 15 to 24 days after inoculation, depending on the growth stage a t which the host is inoculated and the environmental conditions follow ing inoculation. Differences among sweet corn hybrids in gall incidenc e, gall size, and coverage of mature galls by husk leaves were observe d and could be used to select sweet corn hybrids that are well suited for producing huitlacoche.