Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 19, 2002
Publication Date: N/A
Interpretive Summary: Peanut is one of the major cash crops in the southeastern United States. Insecticides and fungicides have traditionally been applied to peanuts many times per year as foliar sprays. The spray application costs are a major production expense. There has been very little research to enhance the placement and efficacy of insecticides and fungicides using fan pattern nozzles for different size canopies during the growing season. In this study, different hydraulic nozzles were compared to improve spray penetration performance for peanut canopies. The peanut plant structure characteristics was also measured at the time of spray application. Spray penetration into peanut canopies could be improved by increasing nozzle size from low volume to middle volume but could not be improved by increasing the nozzle size from middle volume to high volume after plants were 68 days old. Also, during the later growing stage, spray deposits on the top of canopies were considerably higher than at the middle position and much higher than at the bottom position. Spray deposits at the bottom and middle of peanut canopies tended to decrease linearly as the combination of plant height, width, leaf area index and foliage density increased.
Technical Abstract: Three spray penetration tests were conducted 48, 68, and 109 days after peanuts were planted on single- and twin-row beds. Spray was applied with flat fan pattern nozzles 8001VS, 8003VS, and 8005VS at 276 kPa pressure. Leaf area index, foliage density, and plant height and width were measured for each test and correlated with spray deposits at the bottom and middle of peanut canopies. Tests to compare spray penetrations by adjusting spray inclination from vertical to 15° toward travel direction were also conducted when peanut plants were 68 and 109 days old. Data showed that spray penetration into peanut canopies could be improved by increasing nozzle size from 8001VS to 8003VS but could not be improved by increasing the nozzle size from 8003VS to 8005VS after plants were 68 days old. Spray deposits on the top of canopies from the 8003VS nozzle were 10.5 times higher than at the middle position and 62 times higher than at the bottom positions when plants were 109 days old. The average spray deposits at the middle of canopies from the 8003VS nozzle were 1.251, 0.721 and 0.552 L/cm2 when plants were 48, 68, and 109 days old, respectively. Spray deposits at the bottom and middle of peanut canopies tended to decrease linearly as the plant structure indicator of growth (square root of the product of plant height, width, leaf area index and foliage density) increased. Inclining nozzles to discharge sprays from vertical to 15° toward travel direction did not significantly improve spray penetration.