RESPONSE OF WINTER CEREALS, WHEAT, RYE AND TRITICALE, TO CEPHALOSPORIUM GRAMINEUM INFECTION
Institute of Soil Science and Plant Cultivation, 24-100 Pulawy, Poland
Background and objectives
Cephalosporium stripe is a severe systemic disease of cereals caused by the soilborne fungal pathogen, Cephalosporium gramineum Nisikado & Ikata. Although C. gramineum has a wide host range within the Gramineae, environmental conditions restrict infection to winter crops. The pathogen infects plants during winter or early spring through roots that have been predisposed by freeze stress and severed by frost-heaving of soil. This disease can cause serious yield losses in winter cereals grown in a continuous cropping system or in short rotations. Extensive research on the ecology of the pathogen and crop susceptibility has been done in the United States, but mainly with respect to winter wheat . No such information was available for winter triticale and rye which are important cereal crops in Poland and elsewhere. In Poland Cephalosporium stripe disease was first found in 1988 on winter triticale and rye, and a preliminary pot experiment indicated substantial differences in susceptibility of winter cereals to C. gramineum. The experiments reported here were carried out under field conditions on soil inoculated with the pathogen and were designed to compare the response of 3 winter cereals, wheat, rye and triticale, to C. gramineum infection.
Materials and methods
The experiments, conducted during 1989-95, were estabilished on a brown soil (pH 6.7; 1% org. C; 51% sand, 31% silt and 18% clay) using a split-plot design with C. gramineum inoculated soil and uninoculated controls as the main plots replicated 4 times. The subplots of cultivars and lines consisted of three 1 m rows of plants. At growth stage (OS) 10.5.4 of the Feekes' scale one row of each cereal was pulled out and the incidence of Cephalosporium stripe was recorded as the percentage of plants infected (striped and blighted plants) and the percentage of plants killed by the pathogen. After harvest grain yields were determined.
Results and conclusions
The results of these experiments indicate that Polish cultivars of winter wheat possess relatively good tolerance to Cephalosporium stripe, while rye and triticale are much more susceptible to this disease. Higher resistance of the tested wheat cultivars was connected mainly with slow development of disease symptoms . For example, while many infected plants of rye and triticale had already been killed at OS 10.5.4., none of the infected wheat plants was dead by this stage of plant development. Severeley infected plants of rye and triticale may be destroyed by the pathogen at early tillering or shortly alter heading. It seems that winter rye possesses also some resistance to the disease which is expressed as a generally lower percentage of plants undergoing infection by C. gramineum, though infected tillers of rye are usually quickly killed by the pathogen. According to our results winter triticale appeared to be more susceptible to Cephalosporium stripe than its parental species since it had a high percentage (genarally higher than wheat and rye) of plants undergoing infection, with many infected plants being quickly destroyed by the disease. Under high disease incidence (80-100% infected plants) the grain yield losses ranged from 24% to 62% for wheat cultivars, 63% to 86% for rye cultivars and 85% to 95% for triticale cultivars. Marked differences in susceptibility to C. gramineum found among the tested cultivars of triticale suggest that selection of relatively tolerant lines of this new cereal is possible. For example, in the case of Malno, the most resistant cultivar of triticale, disease progress was much slower than in the case of other triticale cultivars tested.
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