Weed management in tomato

WEED INTERFERENCE is one of the factors responsible for the low yield of tomato in Tamil Nadu. Wider spacing, frequent irrigations and non-judicious use of manures and fertilizer encourage luxuriant weed growth. Broad spectrum of weed species Trianthema portulacastrum, Digera arvensis, Amaranthus viridis, Gynandropsis pentaphylla, Parthenium hysterophorus. Flaveria australasica were found to occur in tomato ecosystem.

Chemical and non-chemical methods of weed control viz., herbicides, mulches and allelopathic plant products were evaluated in transplanted CO3 tomato.

The herbicides were pendimethalin 1.0 kg ha- 1, oxyfluorfen 0.15 kg ha-1, metribuzin 0.50 kg ha-1 (pre and post emergence); the plant products were sunflower residue leachate (20 per cent w/v), eucalyptus fresh leaf leachate (20 per cent w/v), eucalyptus oil (0.4 per cent), palmarosa oil (0.4 per cent); and the mulches were black polythene mulch (50 ), white polythene mulch 50 and these treatments were compared with farmer's method of hand weeding twice and an unweeded plot.

Black polythene mulching registered maximum tomato yield (27.59 t ha-1) by virtue of reduced weed growth and increased nutrient uptake by the crop.

It was followed by pre-emergence application of pendimethalin 1.0 kg ha-1 and metribuzin 0.50 kg ha-1 combined with a earthing up at 40 DAT, with the yield of 24.60 and 23.82 t ha- 1 respectively.

The fruit yield with conventional method of hand weeding twice was only 20.82 t ha-1.

All allelopathic plant products and white polythene mulching failed to control weeds effectively and thus resulted in poor yield and economic returns.

Considering the economic indices, highest net return and B:C ratio (3.22) was obtained in pendimethalin 1.0 kg ha-1.

It was followed by pre-emergence metribuzin application 0.50 kg ha-1, which recorded a net return of Rs. 48,483 and B:C ratio of 3.11. Though, black polythene mulching resulted comparatively highest yield, it only resulted in lower economic returns viz., lower not return and B:C ratio due to increased cost of polythene sheet.

P. Saravanane & O. S. Kandasamy

Department of Agronomy

TNAU, Coimbatore

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