COMPARISON OF SINGLE-CHISEL AND DOUBLE-CHISEL INJECTION METHODS FOR THE CONTROL OF ROTYLENCHULUS-RENIFORMIS IN PINEAPPLE

The efficacy of 1,3-dichloropropene (1,3-D) applied with one or two ch isels was determined for control of Rotylendulus reniformis on pineapp le. The soil was fumigated with 1,3-D at 157 liters/ha with either a s ingle chisel 46 cm deep or two chisels 41 cm deep in replicated experi ments conducted in four commercial fields. Soil samples were collected before fumigation and 45 days afterward from three depths and three p ositions. The three depths were 0-15, 16-30, and 31-45 cm; and the thr ee positions were the center of the bed, plant line, and interbed area . The single-chisel injection was comparable to the two chisels in per centage control of R. reniformis. Satisfactory control was achieved in three fields (percentage reduction from untreated = 79, 81, and 83) b ut not in the fourth field. The highest level of control was at the lo west soil depth (31-45 cm) nearest the points of injection. Among the sampling positions, control in the interbed area was generally the low est. A single-chisel injection may be recommended because of the sligh tly enhanced control.