EFFECT OF POTASSIUM CHLORIDE, IMAZALIL, AND METHOD C IMAZALIL APPLICATION ON BARLEY INFECTED WITH COMMON ROO ROT

Two experiments were conducted at six locations in North Dakota in 1986 using Morex barley (Hordeum vulgare L.) as the test crop. The first consisted of a factorial combination of 3 KCl fertilizer rates (0, 50, and 200 kg ha −1 of KCl) by two rates of imazalil impregnated on the seed (0 and 0.1 g a.i. kg −1 seed). Potassium chloride application reduced plant nitrate concentrations at all sites, while imazalil had little effect. Imazalil reduced common root rot (CRR, incited primarily by Cochliobolus sativus) at four sites and KCl fertilization reduced CRR at two sites. At these latter two sites differing KCl × imazalil interactions were observed. At one site, KCl reduced CRR in the absence of imazalil but not in the presence of imazalil. Imazalil was quite effective in controlling CRR at this site, however. At the second site, both KCl and imazalil reduced CRR and their effects were complementary. Imazalil seed treatment substantially increased yield at one site where there was infection with take-all (Gaeumannomyces graminis) as well as CRR. Imazalil application significantly reduced yields at another site. Potassium chloride fertilization significantly increased yield at one site, but this yield increase could not be attributed to control of CRR. The second experiment compared seed impregnation with imazalil to impregnation of monoammonium phosphate fertilizer drilled with the seed. Fertilizer impregnation with imazalil eliminated all seedling toxicity associated with the fungicide, but imazalil-impregnated fertilizer was totally ineffective in controlling CRR.Key words: Chloride fertilization, fertilizer-fungicide interaction, fertilizer-pesticide mixtures, take-all, Cochliobolus sativus, Gaeumannomyces graminis, Hordeum vulgare