Weed management objectives

From the standpoint of crop protection, weed management has three principal objectives (1) Weed density should be reduced to tolerable levels. Experimental studies with a range of species indicate that the relationship between crop yield loss and weed density can be described by a rectangular hyperbola (Cousens, 1985 Weaver, Smits & Tan, 1987 Norris, 1992 Blackshaw, 1993 Knezevic, Weise & Swanton, 1994 Chikoye,Weise & Swanton, 1995).The specific parameters of this relationship change...

Thermal and electric weeders

Thermal Weeder

Flame weeders briefly expose weeds to a propane or butane flame at 800-1000 C Ascard, 1995a , which disrupts cell membranes and leads to rapid dehydration Ellwanger, Bingham amp Chapell, 1973 Ellwanger et al., 1973 . A bank of burners can flame a wide area to kill weeds before crop planting or crop emergence, or to defoliate plants prior to harvest Tawczynski, 1990 . Shielding such machines to contain the heat increases their efficiency. Irrigation a few days before planting ensures that the...