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Title: A NOVEL SEED TREATMENT WITH PRE-INFILTRATED SEEDS AND BIOCONTROL AGENTS TO REDUCE DAMOPING-OFF OF CORN (ZEA MAYS L.) CAUSED BY SPECIES OF PYTHIUM AND FUSARIUM

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

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/11/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Damping-off and root rot of corn caused by Pythium spp. and Fusarium spp. are destructive diseases affecting seedling stands and yield. This paper describes a novel seed treatment using biocontrol agents, alone or in combination, applied to field corn seeds, infiltrated with water, then dried, to reduce damping-off caused by Pythium and Fusarium. A combination nof a fungal and a bacterial antagonist applied to corn seeds increased the extent of disease suppression. Infiltration treatment enhanced disease reduction by reducing soluble substrates in or around the seed coat of corn which might be utilized by pathogens during seed infection. Thin-layer chromatography indicated that eight amino acids and three carbohydrates were present in the infiltration exudates. Application of this technology may be of interest and value to the corn seed industry and farmers to avoid use of chemical seed treatments.

Technical Abstract: Bioassays were conducted to determine the effectiveness of a novel seed treatment for the reduction of corn damping-off in a field soil artificially infested with a combination of the pathogens Pythium ultimum, P. arrhenomanes, and Fusarium graminearum at 3 inoculum rates (1/2, 1 or 2 X). Corn seeds were infiltrated with tap water, drained, air-dried, and then coated with biomass of Gliocladium virens isolate Gl-3, Burkholderia cepacia isolates Bc-B or Bc-1, or a combination of Gl-3 with each of the bacterial isolates. Treatments with biocontrol agents alone or in combination, as well as the fungicide captan, effectively reduced the disease at inoculum levels of 1/2 X and 1 X resulting in higher (P = 0.05) seed germination, plant height and fresh weight, and lower (P = 0.05) disease severity compared with the pathogen-infested control. At the highest inoculum rate (2 X), disease was decreased (P = 0.01) in all treatments. At this inoculum rate, coating seeds with Gl-3 + Bc-B reduced the disease better (P < 0.05) than that of other treatments, resulting in similar values for the parameters as that for the nonpathogen control. Pre-infiltration enhanced disease reduction with all treatments. Also, the exudate from a 2-hr infiltration of corn seed was added to the seeds during seed coating. Infiltrated seeds treated with the exudate had lower (P < 0.01) germination rates and plants had higher disease severity (P < 0.01) than those with infiltrated seeds alone. These results indicated that exudates in water after corn seed infiltration contained nutrients which might be used by pathogens during seed infection. Thin layer chromatography of the exudate showed the presence of eight amino acids and three carbohydrates.