Sweet corn diseases and their management in the PNW: seed treatment evaluations and development of Fusarium-free seed (2013)

Research report to the Oregon Processed Vegetable Commission

Cindy Ocamb  
OSU Dept. of Botany and Plant Pathology

Sweet corn is susceptible to pathogenic Fusarium species that incite seed rot and seedling blight and rots of roots, crowns, stalks, and ears.  We evaluated pesticide combinations on sweet corn 'GSS1477' for the control of seed rot and seedling blight.  We also examined the effect of biocontrol applications on sweet corn seed inbreds and the hybrid seed produced.  In the fungicide study, stand counts were generally greater among the treated seed compared to the nontreated control, except when seed was treated with Allegiance, which had significantly lower stand counts than the seed treatments of Stamina, Dynasty, or Dynasty+Allegiance+Maxim.  The majority of each primary root was rotted in all treatments by the time of sampling (79 % of the root length rotted) and no treatment significantly reduced primary root rot compared to the nontreated control.  When seed was treated with 42-S Thiram, Stamina+ Maxim+Allegiance, or  Captec+Thiram+MicroAF, less rot of the seminal roots was found relative to nontreated control plants or plots treated with Dynasty, Raxil, or Captec+Thiram.  When the inbreds of 'Jubilee' were treated with an experimental biocontrol formulation, little difference was found in root rot severity between the biocontrol and nontreated Jubilee seed parent plants, but stalk node rot was significantly more severe in the nontreated plants. Biocontrol applications resulted in a significant increase in ear weights compared to conventional treatment, both for the primary ear and total ear yield per plant.  During the two years of study, the husked weight of primary ears averaged 18 to 27% greater with the biocontrol treatment while the total ear weight produced per plant was increased by 74 - 104%, compared to the treatment in which no biological control was applied.