Development of models to predict product deposition from coverage obtained on artificial collectors and their practical application

Cruz Garcerá,Enrique Moltó,Patricia Chueca

doi:10.5424/sjar/2014123-5186

Abstract

Models to relate the observed coverage on artificial collectors used in field tests (water-sensitive paper, WSP) and in laboratory bioassays of citrus pests (pieces of polyvinyl chloride sheets, PVC) with product deposition are described. Different solutions of plant protection products commonly used for pest control in citrus were sprayed in a Potter Tower on PVC and WSP under the same controlled conditions. These experiments led to the formulation of different basic models to relate coverage and deposition depending on the products and collectors. The best fitting model was selected from among those that had highest coefficients of determination (R2) and lowest estimation error (RMSEP), and at the same time resulted in a normal distribution of residuals. Finally, coverage on pieces of PVC sheets was related with coverage obtained on WSP by different equations depending on the product being applied. Such equations can be used to link laboratory and field results in order to assess the quality of a spray application in citrus cultivation.

Highlights

The goal of a pesticide spray treatment is to locate adequately the correct amount of active ingredient on the vegetation in the safest and cheapest way (Hislop, 1987)
This work opens the possibility to estimate the deposition of a plant protection product in field applications from coverage values measured on water sensitive papers (WSP) using the inverse of the function shown in Eq [1]
Nansen et al (2010) proposed a method to use WSP to estimate deposition of products, but their system was based on image analysis to measure the intensity of the blue colour generated on WSP, reporting that the major drawback of their method was its dependence on the lighting system and on the digitizer

Summary

Introduction

The goal of a pesticide spray treatment is to locate adequately the correct amount of active ingredient on the vegetation in the safest and cheapest way (Hislop, 1987). Many researchers have worked at assessing the real or potential effectiveness of spray applications of plant protection products by studying the deposition patterns of treatments on the surface of vegetation (Salyani et al, 1988; Ebert & Hall, 1999). There is a huge amount of research comparing deposition patterns of different machines, application techniques or operating conditions in order to assess the optimal way of distributing pesticides in the field (Cross et al, 2003; Farooq & Salyani, 2004). Spray deposition is often described in terms of coverage, which is the percent of surface covered by impinging droplets (hereafter called impacts), number of impacts per surface area and average size of impacts. Coverage is the most accurate parameter that can be estimated (Salyani & Fox, 1999). When impacts overlap, it is the only feature that is worth analyzing (Holownicki et al, 2002)

Objectives

Results

Conclusion