| Abstrakt: |
Two tests were conducted to determine the effects of insecticide treatments on cotton growth, yield, and economic return. Test 1 was conducted to compare the effects of insecticides on cotton fleahopper numbers and subsequent impact on plant fruiting, yield and economic return. All insecticide treatments significantly reduced fleahopper numbers compared with those in nontreated cotton on all post-treatment inspections except for counts made 8 days after treatment 3 (8 DAT-3) in Intruder 70WP (0.6 oz/acre) and Orthene 97 Pel. treatments. Centric was the only treatment that maintained fleahopper numbers below the threshold level of 15/100 plant terminals on all inspection dates. Significantly greater numbers of squares, retained fruit, and greater retention of fruit on the first 10 fruiting branches were found on insecticide treated cotton as measured during the 4th week of bloom. Lint yield was significantly improved by all but one insecticide treatment, and dollar returns above the nontreated cotton ranged from $7.69 to $40.60 per acre. In Test 2, fleahopper numbers were above the established treatment threshold beginning in the first week of squaring, but the cotton vegetative internodes were short due to cold weather suggesting that fleahopper treatment would not be economical and treatment should be delayed a week. Therefore, a field experiment was conducted to evaluate the consequences of the suggested delayed treatment. Treatments were initiated beginning late in the 1st week of squaring followed by initiation of additional plot treatments on about a weekly basis thereafter. One set of plots was treated only during the 2nd and 4th weeks. All insecticide treated cotton was treated during the 4th week. Fleahoppers were reduced to very low numbers following initiation of treatments for the insect. Cotton growth, fruit retention and location, plant height, lint yield, and dollar returns were all affected by the treatments. Plants in the insecticide treated cotton had significantly more squares and bolls when plant mapped during the 4th week of bloom and produced significantly more cotton lint than the nontreated cotton. Plant mapping data at harvest revealed effects on internode length, number of main stem nodes, boll load location, and percentage boll retention at different locations on the plants. Insecticide treated plants averaged 11.6 inches shorter than nontreated based on final field measurement. The lowest yield and dollar return among the insecticide treatments was the cotton treated 4 times beginning late in the 1st week of squaring. This treatment produced a $43.16 per acre dollar return, whereas, the 3 remaining insecticide treatments averaged $86.90 per acre return over the nontreated cotton. [ABSTRACT FROM AUTHOR] |
