STUDY ON THE WHEAT INFECTION AND DEXOYNIVALENOL ACCUMULATION RELATIVE TO THE FUSARIUM-GRAMINEARUM INOCULATION TECHNIQUE

Spring wheat (Triticum aestivum) cultivars Concorde, Laval-19, Frontana and Nobeoka Bozu were inoculated with a conidial suspension of Fusarium graminearum at two field sites. Inoculum was applied by spraying the spikes and by injecting the spikelets; check plants received natural inoculum only. Cvs. Concorde and Laval-19 were found susceptible to initial infection and to the spread of the infection. Cv. Frontana was fairly resistant to initial infection but was somewhat susceptible to the spread of the infection. Cv. Nobeoka Bozu was fairly resistant in all instances. A significant difference between deoxynivalenol concentrations in plants inoculated by spraying or inoculated by injection was detected in cv. Laval-19 only. The percentage of diseased spikelets and deoxynivalenol concentration in field-harvested grain were positively and significantly correlated for all cultivars. Deoxynivalenol concentration in glumes-rachis mixture was 5-10 times that found in the grain. From the practical point of view, simple spraying of spikes was as adequate as injection of spikelets to assess susceptibility to F. graminearum in wheat cultivars.