Effect of an insecticide and fungicide seed treatment on canola production and yield under varying levels of precipitation

摘要

The effect of an insecticide/fungicide seed treatment on the performance and yield of winter canola (Brassica napus L.) was compared at 24 locations in 2002 throughout the southern United States. Canola seed of three winter-type varieties, 'Abilene','Plainsman' and 'Wichita' were either untreated or treated with a combination of the insecticide imidacloprid and fungicides thiram and metalaxyl. Imidacloprid is systemic and mainly targeted aphids on seedling plants. Fungicides prevented damping off and seedling blights. Treatments were planted in a randomized complete block design at 24 locations as part of the National Winter Canola Variety Trial. Precipitation both natural and irrigation from 1 July through 1 December 2002 was used to classify test locations as high, medium and low precipitation sites. Low precipitation conditions substantially reduced canola yields irrespective of seed treatments. The seed treatment prevented prevent loss of stand and grain yield in the high (＞370 mm) and medium (370 - 270 mm) precipitation regimes. However, at the 8 locations receiving less than 270 mm of autumn precipitation,an application of the seed treatment yielded did not significantly affect yield regardless of canola variety. Use of the seed treatment provided a clear benefit in wetter environments where autumn precipitation levels can normally be expected to exceed 270 mm.