What ’s the effect of foliar fungicides on kernel diseases of wheat?
Black point and red smudge are common kernel diseases of wheat (Triticum spp.) in Saskatchewan (Fernandez, et al., 1994). Black point is a dark discoloration of the germ end and surrounding area, but can also extend into the crease. Alternaria spp. and Cochliobolus sativus (Ito & Kurib.) Drechsl. ex Dastur (anamorph Bipolaris sorokiniana (Sacc. in Sorok.) Shoem.) have been most commonly associated with black point, although many other organisms have been isolated from affected grain. Red smudge is a pinkish or reddish discoloration over part or most of the seed coat or in the crease. It is mostly associated with Pyrenophora tritici-repentis (Died.) Drechsl. (anamorph Drechslera tritici-repentis (Died.) Shoem.). Black point and red smudge cause downgrading of grain (Canadian Grain Commission, 1991). For Canadian Western Amber Durum, 0.25% of red smudge or 10% combination of black point and smudge will lower the grade from No. 1 to No. 2, representing an average loss of $12 per tonne. It is therefore of interest to determine if fungicide applications aimed at controlling leaf spotting diseases in wheat could protect the grain from kernel discoloration. Few studies have been done in this area. Conner and Kuzyk (1988) did not get a consistent control of black point from foliar application of various fungicides. Other studies (Gooding et al., 1993; Ellis et al., 1996) found that fungicide applications increased black point for some cultivars, but not for others. Ellis et al. (1996) indicated that an increase in black point could be related to an increase in kernel weight. There has been no research on the effect of fungicides on the incidence of red smudge. This study was undertaken to determine the effect of fungicide application on black point and red smudge, differences among cultivars, and relationship to plant growth.
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