biological control of dodder (cuscuta campestris l.) by fungi pathogens

parasite weeds are the most important yield reducing factors, and among them dodder (cuscuta campestris l.) is an obligate parasite of many plant families. in order to find a suitable biocontrol agent for dodder a study was conducted based on a randomized complete design with four replications at research greenhouse of faculty of agriculture, ferdowsi university of mashhad, iran during 2007-2009. diseased dodders sampled from sugarbeet farms of chenaran, iran. after culturing and isolating exiting fungi from infected tissues of dodder, fusarium sp., alternaria sp. and colletotrichum sp. were recognized. inoculation of isolates was carried out with concenteration of 1×108 spores per ml sterile water at different growth stages of dodder in labratoary and greenhouse. among different fungi, isolate of 323 of f. oxysporum showed an effective control on germination of dodder seeds and the highest level of plant pathogencity was before the contact of dodder with host and infection in older plants decreased. infection of this isolate with crops such as sugarbeet (beta vulgaris l.), alfalfa (medigago sativa l.), basil (ocimum basilicum l.), wheat (triticum aestivum l.) and barley (hordeum vulgare l.) showed no symptoms.