Effect of Unmanned Aerial Vehicle Flight Height on Droplet Distribution, Drift and Control of Cotton Aphids and Spider Mites

Abstract

Unmanned aerial vehicles (UAVs), as emerging plant protection machinery, have the advantages of high operational efficiency, high speed, and low drift. The current study aimed to elucidate the characteristics of droplet distribution and drift, control efficiency on cotton aphids and spider mites, and attachment and absorption of cotton leaves during UAV spraying. Kromekote card and filter paper are used as samplers to collect droplets, and the droplet density, coverage rate, deposition, and drift percentage are statistically analyzed. The pooled results showed that the droplet uniformity, the droplet coverage rate, the deposition, and the drifting ability are higher when the UAV flight height was 2 m. The control effects by UAV spraying on cotton aphids and spider mites were 63.7% and 61.3%, respectively. These values are slightly inferior to those obtained through boom spraying. Cotton leaf attachment and absorption of spirodiclofen after UAV spraying were slightly lower than those after boom spraying, therefore, the control efficiency of cotton pests is slightly different. According to the different flight height operations by the UAV sprayer, the drift capability of the droplets at 2 m flight height was large, and the droplet uniformity and deposition were satisfactory. The research results could provide the theoretical basis and technical support for UAV operation.

Droplet Deposition and Control of Planthoppers of Different Nozzles in Two-Stage Rice with a Quadrotor Unmanned Aerial Vehicle

“…Compared with ground equipment, the biggest difference is the volume of pesticide sprayed per unit area. The average application of ground application equipment (knapsack-type sprayer and boom sprayer) in dry crops (wheat and cotton) is 300-450 L per hectare, and 750 L/hectare was used by stretcher-mounted sprayer in rice, while the average application of drone is 15 L-30 L currently in China [12,14,15,17,18]. Spraying limited volumes while ensuring proper application coverage and pest control is a challenge for UAV applications.…”

Unmanned Aircraft System (UAS) Technology and Applications in Agriculture

“…Therefore, the many disadvantages involved with chemical use should be constrained as much as possible. Unmanned aircraft systems equipped for chemical spraying have been proven to eliminate many of these disadvantages such as terrain limitations of ground-based sprayers [61]; chemical exposure risks for farmers/workers [59]; and with proper use, UAS sprayers can be more effective and economical than traditional methods [59,60,62]. For example, Mink and his colleagues were able to save 90% of herbicide in maize fields and 43% of herbicide in sugar beet fields by using site-specific weed control methods via UAS [50].…”

“…For example, Mink and his colleagues were able to save 90% of herbicide in maize fields and 43% of herbicide in sugar beet fields by using site-specific weed control methods via UAS [50]. From the literature, it appears that Asia is leading the way in this area of research, with a great deal of research focus upon droplet distribution and drift [60][61][62][63][64]. According to Pederi and Cheporniuk, approximately half of all Japanese rice fields currently use UAS for spraying purposes [59].…”

“…The UAS platform needs to be equipped with three main components: a tank to hold the liquids, a nozzle to guide the spray pattern, and a pump to move pressurized fluid through the nozzle. Common tank sizes used aboard UAVs range from a couple liters to upwards of 10 L for larger rotorcrafts and fixed-wing platforms [59,62,76], with a few setups incorporating multiple smaller tanks capable of handling different chemicals [50]. There appears to be two dominant types of nozzles used: centrifugal for a more circular pattern and flat fan for dispersal in a straight line [65].…”

“…Traditional statistical analysis is also commonplace in some areas of research. Common methods in this category include the use of extremum estimators, spatial statistics, linear classifiers, image statistics, and focal statistics [4,9,21,31,62].…”