Effect of insecticide termination at 250, 350, and 450 heat units on carbon partitioning from upper canopy leaves to the developing boll load
Conference Paper
Overview
Additional Document Info
View All
Overview
abstract
The crop monitoring program COTMAN uses the concept of 350 heat units after anthesis of the last effective flower population at NAWF=5 for termination of insecticide applications. It has been reported that terminating insecticides at 350 heat units after NAWF=5 results in a higher yield than when terminating at either lower or higher heat unit values, although evidence is lacking. It is hypothesized that insect damage to upper-canopy (above NAWF=5) squares results in improved partitioning of carbon to lower developing bolls. Two field studies were conducted to determine how removing upper-canopy fruit at different heat units affected yield, as well as boll weight and fiber quality of first position bolls at NAWF=5. Treatments consisted of a control with no fruit removal and hand removal of all upper-canopy fruit above NAWF=5 at 250, 350, and 450 heat units. The data from the 1998 season supported the COTMAN concept of insecticide termination at 350 heat units after NAWF=5. However, the results from the 1999 study did not support insecticide termination at NAWF=5 +350 H.U., in fact, yield and fiber quality were the highest when fruit was not removed. Further field verification is required.
