14 research outputs found
Effects of sharp eyespot (Rhizoctonia cerealis) on yield and grain quality of winter wheat
Effects of sowing date and volunteers on the infectivity of soil infested with Gaeumannomyces graminis var. tritici and on take-all disease in successive crops of winter wheat
Size, shape and intensity of aggregation of take-all disease during natural epidemics in second wheat crops
The contribution of ground-level inoculum of Fusarium culmorum to ear blight of winter wheat
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Effects of straw and silicon soil amendments on some foliar and stem-base diseases in pot-grown winter wheat
Four foliar and two stem-base pathogens were inoculated onto wheat plants grown in different substrates in pot experiments. Soils from four different UK locations were each treated in three ways: (i) straw incorporated in the field at 10 t ha−1 several months previously; (ii) silicon fertilization at 100 mg L−1 during the experiment; and (iii) no amendments. A sand and vermiculite mix was used with and without silicon amendment. The silicon treatment increased plant silica concentrations in all experiments, but incorporating straw was not associated with raised plant silica concentrations. Blumeria graminis and Puccinia recondita were inoculated by shaking infected plants over the test plants, followed by suitable humid periods. The silicon treatment reduced powdery mildew (B. graminis) substantially in sand and vermiculite and in two of the soils, but there were no effects on the slight infection by brown rust (P. recondita). Phaeosphaeria nodorum and Mycosphaerella graminicola were inoculated as conidial suspensions. Leaf spot caused by P. nodorum was reduced in silicon-amended sand and vermiculite; soil was not tested. Symptoms of septoria leaf blotch caused by M. graminicola were reduced by silicon amendment in a severely infected sand and vermiculite experiment but not in soil or a slightly infected sand and vermiculite experiment. Oculimacula yallundae (eyespot) and Fusarium culmorum (brown foot rot) were inoculated as agar plugs on the stem base. Severity of O. yallundae was reduced by silicon amendment of two of the soils but not sand and vermiculite; brown foot rot symptoms caused by F. culmorum were unaffected by silicon amendment. The straw treatment reduced severity of powdery mildew but did not detectably affect the other pathogens. Both straw and silicon treatments appeared to increase plant resistance to all diseases only under high disease pressure
Development of disease symptoms and fungal pathogens on shoot bases in continuous winter wheat, and effects of fungicides
Field plots in three consecutive crops of winter wheat were sampled at approximately 2-week intervals from April to July in 1989, 1990 and 1991. Culm and stem bases were examined for symptoms of eyespot, sharp eyespot and brown foot rot. The W-type and R-type of Pseudocercosporella herpotrichoides, P. anguioides, Fusarium culmorum, F. avenaceum and Microdochium nivale grown from this plant material on agar were identified. Eyespot was most severe in 1991, when plant development was least rapid following cool weather in late winter and the summer was relatively cool and wet. Sharp eyespot was most severe in 1990, which had a warm summer with moderate rainfall. The other warm summer, 1989, was drier and these conditions favoured late development of brown foot rot, associated mainly with F. culmorum which was scarce at other times. Sharp eyespot sometimes increased where prochloraz, which decreased eyespot, was applied. Distinct symptoms of more than one disease occurred less frequently on the same stem than expected from the individual total occurrences, but co-occurrences of different fungi were often more frequent than expected. In July 1990, Fusarium spp. co-occurred with R-type, but not W-type, P. herpotrichoides more frequently than expected, and in July 1990 and 1991 M. nivale and both W-type and R-type co-occurred more frequently than expected. Fusarium spp. and M. nivale were more frequent, especially in the earlier samples, on nodes than on internodes, whilst P. herpotrichoides normally infected at the internodes. The results suggest that stems weakened or altered by a primary colonizer are often a suitable substrate for a secondary colonizer, often a Fusarium sp., which may begin infection at a distance from the original lesion and often not cause distinct symptoms itself