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 uri icon


  • 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.

published proceedings

  • 2000 Proceedings Beltwide Cotton Conferences

author list (cited authors)

  • Brown, R. S., Oosterhuis, D. M., Allen, C. T., & Bourland, F. M

complete list of authors

  • Brown, RS||Oosterhuis, DM||Allen, CT||Bourland, FM

publication date

  • January 2000