A Comparison of Ground-Based Air-Blast Sprayer and Aircraft Application of Fungicides to Manage Scab in Tall Pecan Trees

Abstract

Pecan scab (caused by Venturia effusa) is a destructive disease of pecan in the southeastern United States. Susceptible cultivars must be sprayed with fungicide every 10 to 21 days to ensure yield and kernel quality. Fungicide is most often applied using large orchard air-blast sprayers. Pecan trees grow tall, and air-blast sprays result in a gradient in spray deposition and consequently of scab. Aerial fungicide application is also practiced. Disease distribution and spray deposition of the two methods have not been compared but will provide information aiding decisions on spray application methods. We compared air-blast, aerial, and air-blast + aerial applications for efficacy controlling scab at five heights in the canopy of 25-m cultivar Schley pecan trees. There was a negative relationship between scab severity and height in control trees, a positive linear relationship with height in air-blast treated trees, and a generally negative linear relationship between scab severity and height in aerially treated trees. Air-blast + aerial treatments resulted in low severity of scab at all heights. Spray deposition on water-sensitive cards indicated a declining gradient with height using an air-blast sprayer, whereas aerial applications resulted in a low deposition at all sample heights. Air-blast sprays tended to result in less good control at heights >12.5 m, and aerially treated trees at ≤7.5 m. The results provide insight into the efficacy and advantages of these methods for applying fungicide to control scab in tall pecan trees; further research is needed to better understand the impact of frequency and timing of these two methods.

Droplet Distribution of an Autonomous UAV-based Sprayer in Citrus Tree Canopy

“…Pesticides applied by ground-based or backpack sprayers in orchards might meet the requirements of droplet distribution in the inside and bottom part of the canopy because they are flexible to change the direction of spraying angle than UAV-based sprayers. However, a high-volume spraying method is commonly adopted when ground-based machine or knapsack are used as sprayers, which might result in significant pesticide wastes [8][9]. Furthermore, ground-based sprayers for pesticide application are subject to terrain restrictions and are labourconsuming in small or hilly orchards.…”

Phone App to Perform Quality Control of Pesticide Spray Applications in Field Crops

“…A recent study confirmed that water-sensitive spray cards can be used to obtain spray coverage data in the strawberry canopy, and also identified nozzle height above the canopy, spray volume, and pressure as important factors that affect spray coverage [41]. In addition, there are numerous studies in which water-sensitive spray cards have been used to describe spray coverages in orchard crops [2,[42][43][44][45]. Under favorable spray application conditions, i.e., high temperature, low wind, and low ambient relative humidity, spray coverage patterns on water-sensitive spray cards typically show a clear distinction between blue/purple spray droplets and the background (yellow spray card) (Figure 2a,b).…”

Design, development and evaluation of a tractor mounted air blast sprayer for coconut and arecanut

“…An air-assisted spraying system could improve the pesticide deposit levels and the coverage rate on leaves, increase the penetration of the spray droplets into the canopy and reduce the spray loss. 4 Many tractor operated air-assisted sprayers were developed for the height of 15 m for better deposition and coverage of pesticide throughout the canopy 5 , 6 but very limited work has been reported in the air assisted sprayers above 15 m for tall crops like coconut field. 7 – 9 Arecanut ( Areca catechu L.) is a profitable plantation crop widely grown in India and Tropical Asia.…”