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

Spring wheat (Triticum aestivum) cultivars Concorde, Laval-19, Frontan a and Nobeoka Bozu were inoculated with a conidial suspension of Fusar ium graminearum at two field sites. Inoculum was applied by spraying t he spikes and by injecting the spikelets; check plants received natura l 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 concen trations in plants inoculated by spraying or inoculated by injection w as detected in cv. Laval-19 only. The percentage of diseased spikelets and deoxynivalenol concentration in field-harvested grain were positi vely and significantly correlated for all cultivars. Deoxynivalenol co ncentration 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.