Revista Brasileira De Herbicidas 2002; 3(1): 17-22
Diquat defoliation effieiency on pre harvest bean crop
DOI: 10.7824/rbh.v3i1.366
The best time to harvest the bean crop is after the occurrence ofphysiological maturation, when the seeds vigour, the gemination and the weight of dry matter are high. To carry out mechanical harvesting at this moment is difficult because a high number of leaves is still green. Besides, the mechanical injuries may be inflicted on the seeds. The use of defoliation can minimize this occurrence, promoting uniformity of plants maturity at harvest with grains maintaining low moisture. ln order to evaluate the agronomic efficiency on defoliation of diquat at pre harvest ofthe bean crop, an experiment was carried out in Ponta Grossa (PR), during 1999/00, using the cultivar FT Nobre. The experimental design was a randomised block with six treatments and four replications. The following treatments were tested with applications 14 days before harvesting: diquat (200,300,400 and 500 g1ha), ammonium-glufosinate (400 g1ha) and controI. Diquat at doses equal to or higher than 300 gI ha and ammonium-glufosinate showed efficiency in the control (or defoliation) of Bidens pilosa, Eleusine indica and Digitaria horizontalis. AlI treatments showed efficiency for plant defoliation after four days of application, indicating the possibility of anticipation ofharvest. Differences in seed germination, vigour, health and even on the yield among the treatments, including the control were not observed.
556