Since 1994 the importance of tan spot of @entity3505 has increased in the @entity3505 growing areas of the Netherlands. The purpose of the present study was to determine inoculum sources of this disease caused by @entity47285 . Both in 1999 and 2000, the incidence of tan spot was assessed in 40 commercial fields of winter @entity3505 scattered over the main @entity3505 growing areas of the Netherlands. Adjoining fields were checked for presence of stubble or crops with straw covers and the surrounding vegetation was searched for grasses with leaf spots. Straw and affected leaves of @entity3505 and grasses were examined for @entity47285 . In greenhouse experiments the pathogenicity of isolates from alternative hosts was compared with that of isolates from @entity3505 . The possible development of @entity47285 perithecia on straw of crops other than @entity3505 was explored for @entity2247 , oat, rye grass and rape grown in fields nearby a tan spot affected @entity3505 field. Furthermore, dispersal of tan spot was studied in a field trial in which winter @entity3505 was sown leeward to stubble of above-mentioned severely tan spot affected @entity3505 crop. During the surveys three cases were found of @entity3505 crops adjoining fields with @entity47285 infested stubble or straw covers. It was only after flowering that the first symptoms of tan spot appeared in the three commercial @entity3505 crops. Couch grass (Elymus repens) was often found as host of @entity47285 . In the surroundings of more then half of the @entity3505 crops affected by tan spot this weed was also infected. @entity47285 isolates from couch grass were found to be as pathogenic to @entity3505 as isolates from @entity3505 to both @entity3505 and couch grass. The observations on straw of @entity2247 , oat, rye grass, rape and @entity3505 revealed @entity47285 perithecia only on @entity3505 straw. In the field trial with @entity3505 sown leeward to @entity47285 infested stubble, first symptoms of tan spot appeared on @entity3505 during April and May when the release of ascospores was at a maximum. Disease severity gradually decreased with increasing distance from the side adjoining the stubble. The results of this study indicate that straw covers and stubble from tan spot diseased @entity3505 crops and cough grass are inoculum sources of @entity47285 .

Inoculum sources of the tan spot fungus XXXX in The Netherlands.

@entity3505 :: ('4565', 'Species') :: ['wheat'] @entity2247 :: ('4513', 'Species') :: ['barley'] @entity47285 :: ('45151', 'Species') :: ['Pyrenophora tritici-repentis', 'P. tritici-repentis']
@entity47285 :: (45151,Species) :: ['Pyrenophora tritici-repentis']
