Influence of seed treatment with imazalil on common root rot and the size of the subcrown internode of wheat.
Common root rot (Cochliobolus sativus) ratings of Neepawa wheat grown at 2 locations from seed treated with imazalil at 0.3 g a.i./kg seed averaged 5% for seedlings and 16% for mature plants, compared with 32% and 51%, respectively, for those from nontreated seed. In 3 tests, with several wheat cvs., soils and treatment rates in the glasshouse, imazalil lowered disease in the seedlings. The level of control increased with dosage. The internodes of mature plants from treated seed in the field experiment averaged 14.7% larger than those from nontreated seed. In one glasshouse test they were 12.8, 27.2 and 37.1% larger, respectively, when dosages of 0.1, 0.2 and 0.3 g a.i./kg seed were applied to Neepawa. Similar increases occurred with the cv. Cypress. The relationship of the differential response of subcrown internode growth to imazalil and the control of common root rot is discussed.