Abstract
2 Former assistant professor and associate professor, Dep. of Plant Pathology and associate professor, Dep. of Agronomy, respectively, Kansas State Univ., Manhattan, KS 66506. Current address of senior author: College of Agriculture, King Saud Univ., Gassim, Saudi Arabia. Reprint requests may be directed to the second author.
Eighty percent of the 486 000 ha of corn production in Kansas is irrigated and Fusarium stalk and root rots (primarily incited by Fusarium moniliforme Sheld.) is the most damaging diseases of irrigated corn with estimated annual statewide losses ranging from 5 to 10%. The purpose of this study was to investigate the effects of seedborne, airborne, and soilborne F. moniliforme inoculum and irrigation scheduling on F. moniliforme colonized root and crown tissue, grain yields and stalk rot incidence. Parameters included four levels (0, 12.5, 25, and 50%) of F. moniliforme infested seed lots and four irrigation schedules: 1) non-irrigated; 2) irrigating when the available soil moisture was 50% depleted as determined by a neutron probe; 3) 50% depleted as determined by a computer model; and 4) 35% depletion until tasseling, then 65% until harvest as determined by a computer model. Colonization of the root and crown tissue by F. moniliforme increased nearly three-fold during the growing season as the fungus was detected in 23.1% of the corn plants in May and 62.5% in August. Fungal colonization of plant tissue could not be correlated to infested seed lots or irrigation schedules. Stalk rot incidence and grain production were not significantly influenced by the various levels of infested seed lots. Yields were increased nearly 85% with a concomitant decrease (59.8%) stalk rot incidence in the irrigated plots. The highest levels of soilborne inoculum (210 propagules/g of soil) and airborne inoculum (0.3 propagule/L of air) were found near the end of the growing season.
Key Words: Zea mays L. • Fusarium stalk rot • Water management • Seedborne inoculum
1 Contribution no. 82-674-J from the Dep. of Plant Pathology, Kansas Agric. Exp. Stn., Kansas State Univ., Manhattan, KS 66506. Research reported in this paper was supported in part by a grant from the Kansas Corn Commission.
Received for publication January 24, 1983.