Effective utilization of distillation waste as organic mulch for weed management in the aromatic grass, Citronella java']java

Organic mulch (distillation waste of Citronella java with similar to 20% moisture) 5 and 7.5 t ha(-1), diuron 1.5 kg ha(-1), diuron 1.5 kg ha(-1) plus organic mulch 5t ha(-1) and intercropping of blackgram( Vigna mungo L.) were evaluated against the conventional method of weed control (three spade-hoeings year(-1)) in perennial Citronella java (Cymbopogon winterianus Jowitt) (Poaceae) during the first harvest years (planting year) in 1988-89 (July-June) and 1989-90. The residual effects were studied during the second harvest years in 1989-90 and 1990-91 at the research farm of Central Institute of Medicinal and Aromatic Plants, Lucknow. Weeds caused 48% reduction (average 2-year) in herb and oil yields in the first harvest year as against 18% in the second. Organic mulch, at both levels of application (5 and 7.5 t ha(-1)), was highly effective in arresting weed growth, producing herb and oil yields comparable with repeated manual weeding, and increased the net economic return by 560-600% and 80-85% in the first and second harvest years, respectively, over the conventional method of weed control. Diuron 1.5 kg ha(-1) was phytotoxic during 1989-90 when there was rainfall immediately after its application, suggesting a narrow range of selectivity of diuron to C. java. The conventional method of weed control and blackgram intercropping did not give the desired weed control. Weed control in the planting year had a distinct advantage in the second harvest year. Distillation waste of C. java, with no purchase cost and ready availability to the growers, is recommended for efficient weed management in C. java.