The effect of different spray liquids on the foliar retention of agricultural sprays by wheat plants in a canopy

Abstract

The aim of this work was to examine the effect of liquid properties on spray retention in a range of situations representative of practical pesticide application. Liquids with different physical properties were sprayed with conventional flat-fan and air-induction nozzles onto outdoor-grown wheat plants (Triticum aestivum L cv Axona) at growth stages between GS 22 and GS 35. Since total retention is affected by leaf surface as well as plant growth stage and canopy density, the experiments included spraying both single leaves and groups of plants with different canopy densities. Retention on whole plants was strongly influenced by plant growth and canopy properties. Individual leaf surfaces were not as water-repellent as was found previously for younger indoor-grown plants, reducing the effect of dynamic surface tension on retention. This, combined with the increased probability of droplets hitting foliage in a denser canopy, gave reduced differences in retention between liquids when compared with similar measurements made previously on younger plants. With a leaf area index greater than 7, retention on whole plants was almost independent of liquid. Air-induction nozzles gave lower levels of retention than flat-fan nozzles, with this difference greatest when spraying high dynamic surface tension liquids and at low crop densities.

Spray droplet impaction outcomes for different plant species and spray formulations

“…The retention of most plant protection products on plant leaves is a key to their efficient use. Retention efficiency can be between 10% to 100%, depending on the application technique and plant properties (Butler Ellis et al, 2004;Knoche, 1994). Several factors contribute to the variability of spray retention by plants.…”

Dose e taxa de aplicação de fungicida no controle da ferrugem da folha (Puccinia triticina) e da mancha amarela (Pyrenophora tritici repentis) do trigo

“…A taxa de aplicação (L.ha -1 ) utilizada é o principal fator inerente ao deslocamento das gotas pulverizadas até o alvo, influenciando, assim, nos percentuais de cobertura, penetração e deposição das gotas sobre o dossel da cultura e, por conseguinte, na ação protetora e/ou curativa dos fungicidas (BUTLER ELLIS; WEBB; WESTERN, 2004;MENEGHETTI, 2006;PANISSON et al, 2003;HALLEY et al, 2008;FRITZ et al, 2007).…”

Experimental method for the assessment of agricultural spray retention based on high-speed imaging of drop impact on a synthetic superhydrophobic surface

“…52 Butler Ellis et al (2004) examined the effect of liquid properties and application technology 53 on spray retention in a range of situations representative of practical pesticide application. 54 Retention on whole plants was strongly influenced both by plant growth and plant canopy.…”