CHEMICAL CONTROL OF WEED IN COWPEA Vigna unguiculata (L.) Walp. IN TWO PRODUCTION LOCATIONS, PANAMA.

Abstract

The use of herbicides for controlling weeds has been spectacular in the last few years due mainly to its selectivity and effective and rapid action at relatively low doses. In commercial cultivation of cowpea bean Vigna unguiculata (L.) Walp, located in the Districts of Bugaba and David, Province of Chiriqui, Republic of Panama, an experiment was carried out to evaluate the effectiveness of pre and post emergent herbicides in different concentrations and combinations and its effect on the production of grain. The results indicated that imazethapyr herbicide applied in pre emergence at doses of 0.2 kg a.i./ha presented a prolonged effectiveness in the control of weed up to 60 days after the emergence. The cominations of the herbicides imazethapyr/paraquat (0.1/0.4 kg a.i./ha) and imazaquin/paraquat (0.15/0.4 kg a.i./ha) applied in directed (30 days after emergence) pre emergence and post emergence, respectively, and the combination of the post emergents paraquat/fluazifop butyl (0.4/0.25 a.i/ha) applied at 30 days and 35 days after emergence produced the highest values of effectiveness at the end of the cultivation cycle. The greatest production of bean (1423 kg) was obtained by managing the weed with the herbicides imazethapyr/paraquat (0.1/0.4 kg a.i./ha) in directed (30 after emergence) pre emergence and post emergence. This treatment presented a marginal return rate of 751%; that is, in addition to recovering the balboa invested, the treatment yielded and aditional 7.51 balboas.