EFFECT OF DOSE, VOLUME AND TIME OF APPLICATION OF NON-SELECTIVE HERBICIDES AGAINST WEEDS IN ORCHARDS

摘要

Glyphosate @ 0.82% (Roundup 2.0%) solution applied in citrus (1999) and grape orchards (2000) being superior to its lower dose (0.41% with and without surfactant) resulted into 83-95 and 70-90 % control of majority of the weeds including Cynodon dactylon up to 90 days after treatment (DAT) when sprayed in high (625 L/ha) and low (250 L/ha) volumes, respectively. The toxicity levels of glyphosate were almost identical at three times of its application (last week of June, July or August). Single application of paraquat @ 0.1% (Gramaxone 0.5%) in the month of June, July or August was significantly less effective compared to glyphosate. However, repeat spray of paraquat @ 0.1% i.e. in July and August could control the weeds equivalent to lower dose of glyphosate but that too only up to 30 DAT in both orchards. Similarly, in ber orchard, glyphosate @ 0.82% being at par with its application at 0.62 and 1.2%, and also with MON-8793 and MON-8794 each @ 2.7 kg/ha caused 80-86 and 85-98 % toxicity up to 90 DAT on Cyperus rotundas and other weeds, respectively. Glyphosate applied at 0.82 % in ber orchard during 2000 was superior to its lower doses (0.2 and 0.41%) and all applications of paraquat (0.06 and 0.12 %) and glyphosate @ 0.075, 0.15 and 0.3% (Basta, 15% SL). The treatment of two hand weedings in ber orchard could not control C. rotundas as effectively as glyphosate at 0.82per cent.