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ARS Home » Research » Publications at this Location » Publication #70823
Title: SEED TREATMENT WITH A FUNGAL OR A BACTERIAL ANTAGONIST FOR REDUCING CORN DAMPING-OFF CAUSED BY SPECIES OF PYTHIUM AND FUSARIUM

Author
item Mao, Weili
item Lewis, Jack
item HEBBAR, PRAKASH - OICD
item Lumsden, Robert

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/24/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Biological control using beneficial microbes alone or with minimal use of pesticides to suppress various crops diseases has become important in recent years. Corn damping-off caused by species of Pythium and Fusarium are the most destructive diseases affecting seedling stand and yield. Fungicides are the major weapon used for controlling the diseases. However, none of the fungicides are effective under high disease pressure and may cause some side effects, such as environmental pollution. Bioassays of seed treatment with biocontrol agents (Trichoderma spp., Gliocladium spp., and Burkholderia spp.) for protection against damping-off of field corn were determined at two temperatures (18 Deg and 25 Deg C). All seed treatments with antagonists reduced disease severity and increased germination rate, which were comparable to that achieved with the fungicide captan. The fungal antagonist G. virens (G1-3) was the most effective isolate to reduce disease at both temperatures compared to the other antagonists and was superior to captan. Results of the study also indicate the minimum number of propagules needed per corn seed to obtain a germination rate comparable to that of captan-treated seed. The information can be utilized by the seed industry for commercial seed application and the technology can be adapted for disease control of other crops such as soybean, wheat and rice.

Technical Abstract: Biocontrol agents, Gliocladium virens isolates G1-3 or G1-21, Trichoderma viride isolate Tv-1, or Burkholderia cepacia isolates Bc-B, Bc-T or Bc-1 were coated individually onto corn seed in one test, and G1-3 or Bc-B at four inoculum levels were used in another test. Bioassays were conducted in a greenhouse at 18 Deg and 25 Deg C with field soil artifically infested with a combination of Pythium ultimum, P. arrhenomanes, and Fusarium graminearum. Seed treatments with all biocontrol agents, as well as with the fungicide captan, significantly (P < 0.05) reduced disease severity and increased seed germination, plant height and fresh weight compared to the pathogen-infested control. Coating seed with G1-3 was the most effective treatment, resulting in greater (P < 0.05) germination rate, ,plant height, fresh weight, and lower (P < 0.05) disease severity than those seeds treated with captan or other antagonists at both temperatures. In treatments with Bc-1, Bc-T, Bc-B, Tv-1, or the non-pathogen control, incubation temperature affected seed germination, disease severity, plant height and fresh weight (P < 0.01). Conversely, in treatments with G1-3 or G1-21, these parameters were similar at both temperatures. The minimum number of propagules needed per corn seed to obtain seed germination comparable to that of captan-treated seed was between 10**4 and 10**5 colony forming units (cfu) for G1-3, and > 10**8 for Bc-B. When propagules of G1-3 were applied at a rate > 10**6 cfu per seed, seed germination was greater (P < 0.05) than that of captan-treated seed.