Methods of weed control in Cassava

ALL CROPS ARE SUBJECT TO WEED COMPETITION FOR LIGHT, WATER AND NUTRIENTS. THE CRITICAL PERIOD OF COMPETITION FOR CASSAVA CONTINUES UNTIL THE CANOPY HAS FORMED AND CAN LAST UP TO 120 DAYS. WEEDING AFTER 120 DAYS DID NOT INCREASE PRODUCTION. TWO WELL-SPACED WEEDINGS PRODUCED 75% OF THE MAXIMUM YIELD. CROP DENSITY IS ALSO IMPORTANT. UNDER WEED FREE CONDITIONS A CROP MAXIMIZES ITS USE OF ESSENTIAL NUTRIENTS, WATER AND LIGHT, AND A LOW CASSAVA POPULATION CAN YIELD AS MUCH AS HIGHER ONES. HIGHER CROP DENSITY WILL COMPENSATE FOR THE EFFECTS OF WEED COMPETITION. FOUR TRIALS WERE CONDUCTED TO SCREEN HERBICIDES. EIGHTEEN PRODUCTS WERE FOUND TO CAUSE NO INJURY TO CASSAVA EVEN AT THREE OR FOUR TIMES THE RECOMMENDED RATE. THE REPORT ALSO DISCUSSES INCORPORATED HERBICIDES AND THE PLANTING SCHEMES, POSTEMERGENCE HERBICIDES, AND INTEGRATED CONTROL. THERE IS A TABLE SHOWING THE CHEMICAL WEED CONTROL RECOMMENDATIONS FOR CASSAVA. TO ARRIVE AT THESE RECOMMENDATIONS, THE EFFECTIVENESS, SELECTIVITY, AVAILABILITY, AND COST OF EACH PRODUCT WAS TAKEN INTO ACCOUNT. RARELY WILL A SINGLE APPLICATION OF HERBICIDE GIVE SUFFICIENT WEED CONTROL UNTIL THE CANOPY CLOSES SO EACH FIELD MUST BE OBSERVED CLOSELY TO DETERMINE WHEN COMPLEMENTARY HAND OR MECHANICAL WEEDINGS SHOULD BE PERFORMED.