Evaporation and wettability of fungicide spray, with or without adjuvant, on leaves of vegetables

Abstract

On tomato, cucumber and bell pepper cultivation, commonly large quantities of plant-protection products are applied, to control pests and diseases, as a way to guarantee better productivity and final product quality. The knowledge of spreading and evaporation time of spray droplets is fundamental to understand the interaction between fungicides and target surface for proper distribution of this fungicide. This study was installed to determine the wetting area and droplet evaporation of sprays containing the fungicide Cabrio Top, with or without adjuvant Nimbus®, deposited on leaves and artificial surfaces (glass slide). A system was used which analyzes images composed of a droplet generator, a stereoscope camera for capturing images and a climatic chamber for controlling temperature and relative air humidity. Droplets of 600 µm in diameter containing spray solution were deposited on leaf surfaces and on glass slide and sequential images were used to quantify the wetting area and the evaporation time. The spray solution and the target surface are determinant for wetness and droplet evaporation after deposition. Evaporation time and surface tension were inversely proportional to the wetting areas. Addition of adjuvant Nimbus® (0.5%, v/v) reduced the surface tension and provided an increase in the wetting surface area, except on tomato leaves which had shown low wetting capacity in both fungicide solutions applied.

Application of ultra‐low‐volume spray for the control of vegetable disease in greenhouse: Investigation of formulation performance and potential dermal exposure

“…The leaves were then inoculated with a 5 mm diameter tomato-gray-mold fungal cake and incubated at 28 °C, 95%-100% relative humidity, and in total darkness until the control was fully developed; three replicates of each treatment and one replicate per leaf were performed. The spot diameter was measured by the cross-cross method, and the control effect was calculated according to Eqn (6), where D c is the lesion growth diameter of the control, and D t is the lesion growth diameter of the treated sample.…”

“…[3][4][5] Application of fungicides is still the most efficient way to control vegetable diseases. 6 However, traditional application methods such as the use of backpack sprayers with water-diluted pesticides have certain drawbacks, e.g., uneven distribution, high labor intensity, and safety risks. 7 Spraying with pesticide increases the greenhouse humidity, which is conducive to the occurrence of many vegetable diseases.…”

“…For example, gray‐mold diseases, root‐rot diseases, viral diseases, and powdery mildew have become more severe in Solanaceae vegetables 3–5 . Application of fungicides is still the most efficient way to control vegetable diseases 6 . However, traditional application methods such as the use of backpack sprayers with water‐diluted pesticides have certain drawbacks, e.g., uneven distribution, high labor intensity, and safety risks 7 .…”

Effect of Adjuvant, Concentration and Water Type on the Droplet Size Characteristics in Agricultural Nozzles

“…2022, 12, 5821 2 of 10 affecting the contact angle and surface free energy, which in turn control the leaf surface wettability [2]. Adding adjuvants to the spray solution reduces the droplet surface tension [3][4][5][6][7][8], contact angle values [3,6,7] and pH values [3]. Adjuvant addition enhances spray deposition and electrical conductivity [4], and improves the control efficacy of pesticides [9].…”

“…Adjuvant addition enhances spray deposition and electrical conductivity [4], and improves the control efficacy of pesticides [9]. Moreover, adding adjuvants results in a higher wetting surface area [5] and increases the density and viscosity of the spray solution [6]. The concentration of adjuvant within the spray solution affects different parameters.…”