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- Author or Editor: D. G. Finlayson x
The compatibility of 5 preemergence herbicides and 3 insecticides applied in silt loam was assessed in 4 brassica crops by comparing their effects on germination, plant stand, and yield. Several combinations were deleterious. The herbicides CDEC and DCPA in combination with the insecticide thionazin reduced plant stand in cabbage and cauliflower. Herbicide C-7019 in combination with the insecticide fensulfothion was incompatible for cabbage and broccoli. Cabbage germination was reduced; while with broccoli both the germination and crop yield were affected. C-7019 alone reduced the germination of cauliflower and in combination with fensulfothion the damage was increased. This herbicide was phytotoxic to rutabaga. When nitrofen was combined with the insecticides, plant stands of cauliflower and rutabaga were affected. Nitrofen and thionazin together reduced the plant stand of cabbage. Propachlor at 4 lb./acre was compatible with any of the three insecticides for the four crops. However, the plant stand and yields of all four crops were reduced in plots treated with propachlor at 6 lb./acre in combination with thionazin. Propachlor with the insecticide carbofuran injured only broccoli. The herbicides did not affect the efficacy of the insecticides.
Over a 6-year period (1969-1974) the efficacy of 25 herbicides and 3 insecticides and their interactions in combination were investigated when applied to field seeded rutabaga (Brassica napobrassica). Of 215 herbicide insecticide combinations tested only 29 resulted in phytotoxic interactions as measured by seedling emergence, plant height and marketable yield. Six combinations involved all the insecticides: thionazin, fensulfothion and carbofuran; 1 with carbofuran and thionazin, 1 thionazin and fensulfothion, 5 thionazin alone, and 2 fensul fothion alone. Only 6 herbicides were involved: alachlor, aziprotryn, pronamide, napropamide, prynachlor and chlorpropham; the last when combined with propachlor. Although fewer emergent seedlings were recorded with all insecticides in 1969 to 1971 only thionazin caused a significant reduction. Carbofuran and thionazin affected rutabaga growth detrimentally in the years 1969 to 1971, but in the following years carbofuran had no effect. Plant growth was not affected during any year by fensulfothion. In all years the insecticides resulted in significant increases in marketable yields of rutabaga, carbofuran was slightly better for control for cabbage maggot, Hylemya brassicae (Bouché) than either fensulfothion or thionazin. None of the herbicides showed any insecticidal properties, nor did they affect the efficacy of the insecticides.
Over a 6-year period (1969-1974) the efficacy of 3 insecticides and 24 herbicides and their interactions in combination were investigated when applied to field-seeded broccoli (Brassica oleracea L. Italica group), cabbage (Capitata group) and cauliflower (Botrytis group). Of these, broccoli was the most susceptible to injury. Of 212 herbicide-insecticide combinations, 26 caused phytotoxic symptoms in broccoli, 20 in cabbage and 8 in cauliflower. The insecticides, thionazin, fensulfothion and carbofuran, were each involved in 1 or more phytotoxic combinations in each of the 3 crops. Ten herbicides were involved in phytotoxic reactions: alachlor, aziprotryn, benefin, CDEC, chlorpropham, cycloate, prometryne, propachlor, prynachlor and PP493. Root maggot damage was reduced markedly by the insecticides. Carbofuran allowed less damage than either fensulfothion or thionazin. None of the herbicides showed any insecticidal properties, and some decreased the effectiveness of the insecticides.