|
Sci Tech
Applying pre-emergence herbicides
HERBICIDES ARE used to control weeds. Pre-emergence herbicides are those which are sprayed on soil uniformly before emergence of weeds. All weeds take five days to germinate and so pre-emergence herbicides are applied on third day after sowing.. There are herbicides specific to crops which have to be applied at recommended doses and at appropriate time.
The crops are planted after irrigating the field. For example in the case of sugarcane, ridges and furrows are formed first and sugarcane setts are placed on the ridges subsequently irrigation is given and planting is taken up in the furrows side by side. The pre-emergence herbicide Atrazine 50 per cent at 2.5kg per hectare is sprayed on third day after planting and life irrigation is given immediately.
In sugarcane, ridges and furrows are formed in advance and there will be a gap about 10 days as farmers have to wait for seed cane for planting.
During this time if rains come or portion of field got a wetting due to breach in irrigation channels, the weeds would germinate.
Afterwards if the farmer plants the cane and takes up herbicide spraying the weed control will be only partial. Hence the precautions to be taken are;
Farmers have to be careful before applying pre-emergence herbicides as they do not control the emerged weeds.
If weed emergence is noticed prior to planting it is better the field is ploughed again and then take up planting, to use pre-emergence herbicides.
If weed emergence is seen, don't spray pre-emergence herbicides; instead go for hand weeding when ploughing is not possible or if it involves additional cost like formation of ridges and furrows.
Avoid wetting the field before planting by keeping the channels in good condition. Similarly watch for rains even if it is of lesser quantity which can activate germination of weed seed as these are on the top layer of soil itself.
R. Jagannathan
H. Vijayaraghavan
& W. Wilfred Manuel
Sugarcane Research Station,
Sirugamani-639115.
Send this article to Friends by
E-Mail
Sci Tech
|
