Production and dispersal of conidia of Leucostoma cinctum in peach and cherry orchards under irrigation in eastern Washington

The objectives of this study were to determine the seasonal production patterns of Leucostoma cinctum conidia in peach and cherry orchards and the effects of irrigation on dispersal of conidia. Conidia were trapped throughout the year and were present in highest numbers during spring and summer on both cherry and peach. The pathogen was dispersed 1.0 m by water drops that simulated irrigation drops that would impact cankers during over-the-canopy irrigation. Spore production and dispersal also resulted from the use of over-the-canopy and under-tree impact sprinklers. Although the two irrigation methods were not directly compared, the latter mode dispersed propagules of L. cinctum over horizontal distances of about 6 m, a distance sufficient to account for the movement of the pathogen between trees within and across orchard rows. It is concluded that disease management could be improved by alteration of horticultural and irrigation practices.