- Cotton -

COTTON: Gossypium hirsutum L.,     ‘Deltapine 51’                         

  Bollworm (BW); Helicoverpa zea (Boddie)                           
  Tobacco budworm (TBW); Heliothis virescens (F.)                      
  Beet armyworm (BAW); Spodoptera exigua (Hübner)              
  Fall armyworm (FAW); Spodoptera frugiperda (J. E. Smith)
  Cabbage looper (CL); Trichoplusia ni (Hübner)

  Cotton aphid (CA); Aphis gossypii Glover

CONTROL OF INSECT PESTS ON COTTON IN SOUTHEAST OKLAHOMA, 1999:  Cotton seed was planted in July in rows on 36 inch centers.  The experimental design was a RCB with 5 replicates and 8 treatments.  Plots were treated with a tractor-mounted sprayer operated at 40 psi with an output of 36 gal/acre from 3 hollow-cone nozzles per row.  Plots were 3 rows wide by 50 ft long.  Plots were treated on 7, 15, 22 and 29 Sep and 6 Oct.   Insects and damage to buds and bolls were monitored on 14, 21 and 28 Sep, 5 and 12 Oct by counting insects or buds and bolls on plants in the middle row.  Visual surveys of 3 plants per plot were made to determine CA abundance and bud and boll damage and beat sheet sampling of 3 row ft was used to determine lepidoptera larva abundance.  On  21 Oct ten plants were selected from the middle row in each plot and examined to determine total number of bolls and damaged bolls per plant from which data the percentage damaged bolls (%DAM) was calculated.  Data from individual survey dates were summed across dates prior to analysis.  Abundance of all lepidoptera larvae (LEP) was calculated by summing numbers of BW, TBW, BAW, FAW and CL to provide an indication of toxin activity to lepidoptera.    Data were analysed using ANOV and a means separation test to determine treatment effects.

CA were very abundant in many of the treated plots and lepidoptera larvae were moderately abundant.  CA were significantly more abundant in plots treated with Karate than in plots with all other treatments.  Thiodan and Proclaim treated plots had significantly fewer CA than the untreated plots.  There were significantly fewer LEP in plots treated with Tracer and with Karate than in the untreated, Dipel, Thiodan, and Proclaim treated plots.  At the end of the season there was significantly less boll damage (%DAM) by LEP in the Proclaim and Dipel treated plots than in the untreated and Confirm treatment plots.

Means in the same column followed by the same letter are not significantly different, LSD, P=0.1.

^aAphid data were transformed to log10 values prior to analysis but non-transformed means are reported in the table.  %DAM data were transformed to arcsine values prior to analysis but non-transformed means are reported in the table.