Cowpea cover crop mulch for weed control in desert pepper production

A 2-year field project was conducted in Thermal, Calif,, to investigate cow pea [Vigna unguiculata (L.) Walp.] mulch as an alternative weed control opt ion in pepper (Capsicum annuum L.) production. Treatments included: bare gr ound (BG) with hand weeding, BG with no weeding, cowpea mulch (CM) with han d weeding, and CM with no weeding. Cowpea was seeded in July on 76-cm beds and irrigated with buried drip line. Two weeks prior to transplanting peppe rs, irrigation water was turned off to desiccate the cowpea plants, In Sept ember, cowpea was cut at the soil line, mulch was returned to the top of th e bed, and pepper plants were transplanted into the mulch and fertilized th rough the drip line, Every 2 weeks, the number of weeds emerged and pepper plant height were recorded. Fruit production, pepper plant dry weight, and weed dry weight were recorded at harvest in December. Fewer weeds emerged i n CM than in BG, The final weed population in nonweeded CM was reduced 80% and 90% in comparison with nonweeded BG in 1997 and 1998, respectively. Wee d dry weights in nonweeded CM were 67% and 90% less than those in nonweeded BG over the same period,In 1997 and 1998, respectively, pepper plants prod uced 202% and 156% more dry weight, as well as greater fruit weight, in CM than in BG, There were no differences in mean fruit weight, Cowpea mulch pr ovided season-long weed control without herbicides while promoting plant gr owth and fruit production.