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POSTERS: Biological control

Biocontrol potential of Streptomyces isolates on fungal pathogens (Helminthosporium solani, Pythium ultimum.) of potatoes
Shae Taylor - Brigham Young University. Brad Geary- Brigham Young Univ, Christopher Clarke- Virginia Tech

Pythium leak, caused by Pythium ultimum, and silver scurf, caused by Helminthosporium solani, are fungal pathogens that significantly reduce yields and lower quality for the potato industry. They are not controlled effectively by current methods. Streptomyces spp. are recognized as producers of antimicrobial and antifungal secondary metabolites. Previous studies have lacked analysis of more than two or three isolates of Streptomyces. By looking at more than 70 isolates, we seek to set a foundation to determine what Streptomyces make a viable biological control and what secondary products are effective control mechanisms. We have conducted bioassays on Streptomyces isolates against P. ultimum and against H. solani. The bioassays are conducted by placing Streptomyces in the center of a Petri dish. Plugs of P. ultimum and H. solani are placed around the Streptomyces. The growth of the fungi toward the Streptomyces is then measured, and compared, to the growth away from the Streptomyces. Several isolates of Streptomyces significantly inhibited P. ultimum growth with ME02-6988A causing inhibition at 67%. More Streptomyces isolates caused significant inhibition of H. solani. The range of percent inhibition ranges between 14-59% with strain ID-05-47c causing inhibition at 59%. More research should be done in determining what secondary metabolites are causing this inhibition and what genes are encoding for the secondary metabolites.