EVALUATION OF DILUTE vs. CONCENTRATE SPRAYER PERFORMANCE 



12 3 



Frank Drummond , James T. Williams , and Ronald J. Prokopy 



There has been debate during the past decade as to the effi- 

 cacy of low-volume spraying in comparison to dilute spraying in 

 orchard crop protection practices. The advocates of low-volume 

 spraying in orchards cite several advantages for this practice, 

 the most important of these being water conservation and greater 

 spray droplet deposition on the foliage (Brann 1964, Lewis et al. 

 1969, and Hall et al . 1981). Steiner (1976) reported that approx- 

 imately 701 of pesticide- active ingredients are deposited upon 

 target surfaces with low-volume spraying whereas only 55% is de- 

 posited with dilute spraying. However, growers as well as 

 researchers (Hall et al., 1975) have found that low-volume sprays 

 are not always deposited efficiently in all parts of the apple 

 tree canopy. Our objective in this study was to evaluate the 

 deposition of dye applied by 2 types of orchard sprayers on Cort- 

 land and Delicious trees 17 feet and 8 feet in height, respectively. 



The experimental design incorporated an early season trial on 

 May 4 (trees were in the pink stage of bud development) and a mid- 

 season trial on July 28. On May 4th the sky was overcast and the 

 temperature was in the mid 60's. The wind velocity averaged 15 

 mph from the northeast, with gusts up to 25 mph . On July 28, the 

 sky was clear, the temperature was approximately 74 F and the wind 

 velocity ranged 0-5 mph from the east. 



Both spray trials were conducted at Marshall Farms in Fitchburg, 

 Massachusetts. The treatments were applied with a Hardie sprayer 

 at 4X and 125 psi gauge pressure, and a Kinkelder sprayer at 25X 

 and 25 psi gauge pressure. The Kinkelder was used both with and 

 without the operation of an electrostatic charger. Each experi- 

 mental block consisted of a row of trees running north to south 

 from which subsamples of leaves were collected. The sprayers were 

 driven on each side of the treatment row. There were 2 buffer rows 

 between each treatment row to minimize the effects of drift. 



Spray deposition was measured by a method similar to that 

 used by Jubb (1980). A fluorescent dye. Dayglo* fire orange 

 (AX-14-N) was applied at the rate of 1 lb. /acre. Surfactants were 

 used to aid in incorporating the dye into water (1/2 pt./lOO gal. 

 Ajax* liquid soap for the first trial and 1 pt./lOO gal. Triton-B* 

 spreader sticker for the second trial) . The distribution and 



1 



Technical Assistant, Department of Entomology, University of Mass. 

 2 



Regional Extension Fruit Specialist, Middlesex County. 

 3 



Extension Entomologist, Department of Entomology, University of Mass 



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