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Title: INSECTICIDE RESISTANCE MANAGEMENT: STRATEGIES OF USING IGRS VS. PYRETHROIDSFOR INITIAL APPLICATIONS AGAINST SILVERLEAF WHITEFLY

Author
item AKEY, DAVID
item ELLSWORTH, PETER - UNIV OF AZ, MAC, AZ
item DENNEHY, TIM - UNIV OF AZ, TUCSON, AZ
item HENNEBERRY, THOMAS

Submitted to: Silverleaf Whitefly: 1997 Supplement to the Five Year National Research and
Publication Type: Abstract Only
Publication Acceptance Date: 8/1/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: We determined if control is more efficient if pyrethroids are used first, then followed by insect growth regulators (IGR) or vice versa, what effects do pyrethroid first sequences vs IGRs first sequences have on resistance management, and will a more efficient ground spray result in significantly higher yields at the UofA, MAC, Maricopa, AZ. The experimental factorial was 2 x 2 x 3 replicates. Planting was on a 6-plant/2-skip row with an actual plant of 45 ac. There were 12 plots of 3.3 ac each for a total of 45 ac of land actually planted and 60 ac occupied. An additional 20 ac in the same 2 fields as the experimental plots were treated at the same time to insure integrity of the experiment. Over a 12 week sampling period, the following statements can be made. For eggs, by week 3, twice as many eggs were present in IGR first plots sprayed at 40 psi than in the other treatments. By week 6, continuing through week 9, all treatments were approximately the same. However, for weeks 10-12, pyrethroid first treatments had twice as many eggs as the IGR first plots. The highest number of eggs at the end of the trials was approximately 2000 per 3.88 sq. cm. for pyrethroid first plots sprayed at 40 psi. Large nymphs peaked at week 2 with highest numbers in pyrethroid first plots. IGR first plots treated at 225 psi had approximately 200 large nymphs compared with greater than 300 large nymphs for the plots treated at 40 psi.