Abstract
ABSTRACT The use of insecticides is common in pest management in wheat crops but may lead to higher production costs and environmental contamination. Therefore, a more comprehensive and uniform distribution of plant protection products in the desired target is recommended. The objective of this study is to evaluate the effect of different spray nozzles, application rates, and adjuvants on droplet spectrum and spray deposition in wheat crops. The physicochemical characteristics of the spray mixture, droplet spectrum, and spray deposition in wheat plants were evaluated. The lower application rate (75 L ha−1) combined with the use of the twin flat fan tip AS7030 and the adjuvant sodium lauryl ether sulfate (SLES) yielded droplets with a larger diameter. However, insecticide spraying using hollow cone tip MGA 015 without adjuvants provided the highest percentage of droplets susceptible to drift. SLES significantly decreased the percentage of drift by increasing droplet size, and the adjuvant silicone, d-limonene, and polyester copolymer increased spray deposition. The evaluated adjuvants increased the electrical conductivity and reduced the surface tension of the spray mixtures. These results indicate that it is possible to reduce the application rate from 150 to 75 L ha−1 without affecting spray deposition on wheat leaves.
Highlights
The cultivation of wheat (Triticum aestivum L.; Gramineae, Triticaceae) is of great relevance to agricultural production in Brazil
The objective of this study was to evaluate the effect of different spray nozzles, application rates, and adjuvants on droplet spectrum and spray deposition in wheat crops
The average values of pH, electrical conductivity, dynamic viscosity, density, and surface tension of the spray mixture as a function of the application rates and adjuvants in wheat crops are presented in Tables 2 and 3
Summary
The cultivation of wheat (Triticum aestivum L.; Gramineae, Triticaceae) is of great relevance to agricultural production in Brazil. Despite estimates of record production, Brazil has not yet reached self-sufficiency in producing wheat because crop yield is affected by abiotic factors, including climate, soil, and nutrition, and biotic factors, especially pests and diseases. The green aphid (Schizaphis graminum Rondani, 1852) (Hemiptera: Aphididae) is the main pest insect responsible for causing significant economic losses to wheat crops, primarily by injecting toxins into plant tissues during feeding, causing yellowing, drying, and plant death. Chemical control is common to avoid high infestations of aphids but increases production costs, environmental contamination, and public health problems. Insecticide application is a relevant factor when choosing the application technology to be employed and should guarantee the efficient deposition of the chemical product in the desired target to avoid insecticide drift (Van Zil et al, 2013)
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