Influence of Environment on the Spread of Barley Stripe Disease in California. L. F. Jackson, Extension Agronomist, University of California, Davis 95616. R. K. Webster, Professor of Plant Pathology, University of California, Davis 95616. Plant Dis. 72:406-408. Accepted for publication 2 December 1987. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0406.

Barley was grown at five sites in California and exposed to the same sources of inoculum of barley stripe disease at each site to determine the effect of environment of seed production on floral infection. Seed samples were taken from plots of barley planted with seed originating from two seed lots known to be infested with Drechslera graminea. Source seed lots from cvs. Prato and Kombyne had 15 and 70% infestation, respectively, and were either treated with fungicides to control barley leaf stripe or left untreated. Percentage of infection in plots from the untreated seed was 50% for untreated Kombyne and ranged from 1 to 10% for untreated Prato. Fungicide treatment reduced disease levels to 1% or less in the remaining plots. Seed samples from the plots grown in 1984 at each site were planted in replicate 2.4-m rows at the University of California at Davis in 1985 to determine the amount of floral infection that had occurred in 1984. Infection percentages varied from 0 to 50%, with significant differences in infection between sites of origin of seed lots. Gradients of infection frequency with distance from heavily infected source plants varied according to site of origin of seed.