Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2004
Publication Date: June 20, 2004
Citation: Olanya, O.M., Larkin, R.P., Honeycutt, C.W. 2004. Comparison of late blight suppression by natural products and the impact of genotype diversity on disease development and control. American Phytopathological Society Abstracts.vol 94 (6): pg S77-S78. (#P-2004-0525-AMA) Technical Abstract: The potential use of natural products for late blight management can promote reduced inputs and enhance sustainability of potato production. The objective of this research was to determine late blight control by non-conventional products on Phytophthora infestans isolates with diverse genotypes and quantify epidemic components under controlled conditions. Growth of isolates of different genotypes was evaluated in petri-dish assays when Rye B media was amended with essential oils (Lavender, Thyme, Thyme Borneal, Oregano); and Serenade (Bacillus subtilis strain QST 713). The percent reduction of in-vitro growth differed significantly among fungal genotypes. Inhibition of in-vitro growth was highest on the 100/111/122 genotype and least on the 100/100 genotype. The reduction of fungal growth was best achieved when media was amended with Oregano and Serenade. In growth chamber studies, components of epidemic development (incubation & latent periods, lesion size, sporulation capacity, disease severity) incited by diverse fungal genotypes were evaluated on the variety Shepody. Incubation and latent periods ranged from 2-7 and 5-9 days, respectively. Average disease severity, lesion size and numbers were significantly impacted by fungal genotypes and isolates, with the 100/111/122 genotype being most virulent. Foliar application of natural products prior to inoculation with isolates of diverse genotypes resulted in variable disease suppression. These results suggest that genotype diversity affects disease development; however, disease suppression was not genotype specific.