The relationship between wheat seed weight, infection by Fusarium culmorumor Microdochium nivale, germination and seedling disease

The distribution of seeds by weight for three lots of winter wheat cv. Aval on infected by Fusarium culmorum and three lots of winter wheat cv. Riband infected by Microdochium nivale was determined. The distribution of infecte d seeds within each seed lot was then determined by isolating F. culmorum f rom seeds on moist filter paper and M. nivale from seeds on potato dextrose agar. The distribution of M. nivale infected seeds between seeds of differ ent weight was similar to that of the seed lot as a whole, whereas the dist ribution of F. culmorum was greater in light seeds than heavy seeds. The pe rcentage germination of infected seeds decreased with seed weight. A simila r situation was found with respect to seedling emergence in compost for F. culmorum infected seeds. However, with M. nivale infection, similar numbers of seedlings emerged from both light and heavy infected seeds. Seed treatm ent with guazatine increased seedling emergence for both light and heavy se ed infected by M. nivale. However, seedling emergence from F. culmorum infe cted seed was poor even following treatment with guazatine. Poor emergence was most evident from light seed.