SEED TREATMENT WITH A FUNGAL OR A BACTERIAL ANTAGONIST FOR REDUCING CORN DAMPING-OFF CAUSED BY SPECIES OF PYTHIUM AND FUSARIUM

Bioassays were conducted under greenhouse conditions to test the effic acy of antagonists applied to corn (Zea mays) seed for protection agai nst seed rot and seedling damping-off at 18 and 25 degrees C in a fiel d soil artificially infested with a combination of Pythium ultimum, P. arrhenomanes, and Fusarium graminearum. Biomass of Gliocladium virens isolates G1-3 or G1-21, Trichoderma viride isolate Tv-l, or peat-base d slurry of Burkholderia cepacia isolates Bc-B, Bc-T, or Bc-1 was coat ed individually onto corn seeds in one test, and G1-3 or Bc-B at four inoculum levels was used in another test. Seed treatments with most of the biocontrol agents, as well as with the fungicide captan, signific antly (P less than or equal to 0.05) increased seedling stand, plant h eight and fresh weight, and decreased root rot severity compared with untreated seeds in pathogen-infested soil. Coating seeds with the bioc ontrol fungus G. virens isolate G1-3 was the most effective treatment, resulting in greater (P less than or equal to 0.05) seedling stand, p lant height, and fresh weight, and lower (P less than or equal to 0.05 ) severity of root rot than those parameters from seeds treated with c aptan or other antagonists at both temperatures. The results from the seeds treated with G1-3 were similar to those of untreated seeds in no ninfested soil. In treatments with Bc-1, Bc-T, Bc-B, or Tv-l, incubati on temperature affected plant emergence, root rot severity, plant heig ht, and fresh weight (P less than or equal to 0.01). Conversely, in se eds coated with G1-3 or G1-21, these parameters were similar at both t emperatures. The minimum number of propagules needed per corn seed to obtain plant emergence comparable to that from captan-treated seeds wa s between 10(4) and 10(5) CFU for G1-3 and >10(8) for Bc-B. When propa gules of G1-3 were applied at a rate >10(6) CFU per seed, seedling eme rgence was greater (P less than or equal to 0.05) than that from capta n-treated seeds.