Study of the Effects of Adjuvants Associated With Insecticides on the Physicochemical Properties of the Spray Solution and Characterization of Deposits on Wheat and Maize Leaves Under Simulated Rain

Abstract

The association of adjuvants with phytosanitary products has been tested for several years but is commonly recommended without considering technical and scientific criteria. This study aimed to evaluate the influence of the association of insecticides with different adjuvants on surface tension, contact angle, coverage, hydrogen ionic potential (pH), and the formation of deposits exposed to rain. The insecticides thiamethoxam, imidacloprid, and lambda-cyhalothrin were tested at doses of 75 g ha-1 , 150 g ha-1 , and 150 g ha-1 , respectively, with a spray volume of 200 L ha-1. Break-Thru 240 ® , Break-Thru 233 ® , Break-Thru Union ® , Oleo FC Agraröl ® , and Naturo'il ® were added to each of these spray solutions. The results showed that the addition of adjuvants reduced the surface tension and contact angle, and consequently, increased droplet coverage. No deposit pattern was found in the thiamethoxam, imidacloprid, and lambda-cyhalothrin insecticides associated with the adjuvants and a higher amount of residue was observed on wheat leaves than on maize leaves. The use of adjuvants can be an alternative to improve the efficiency of insecticides, allowing the product to achieve its full control potential.

Adjuvant interference on spray solution properties of 2,4-D and dicamba herbicides and their efficacy for Ipomoea SPP. control

“…Similar results can be found in the literature, as Silwet ® L-77 also caused a large decrease in surface tension when added to glyphosate or saflufenacil herbicides (CASTRO et al, 2018). It should be noted that such decrease in surface tension caused by adjuvants could potentially increase the amount of pesticide active ingredient which gets retained at the foliage and improve its efficacy, as has been shown for the insecticide chlorantraniliprole when sprayed onto maize (Zea mays L.) plants (MELO et al, 2019). Accordingly, better retention of herbicide molecules onto the leaf surface could lead to greater weed control levels, since a lack of proper coverage is known to lead to poor weed control (BUTTS et al, 2018).…”

“…This demonstrates the potential for adjuvants to play a major role in increasing the biological efficacy of pesticides, especially herbicides. Some benefits resulting from adjuvant usage derive from processes taking place in the spraying tank-mix, such as pH and droplet size and quantity alterations, and reduction of surface tension (GIMENES et al, 2013;MELO et al, 2019).…”

Spray Retention on Coffee Leaves Associated With Type and Concentration of Adjuvants

“…The lower values of spray retention with lower SST solutions may be explained by the follow steps: (1) adding surfactant in deionized water provided a SST reduction of spray solution ( Figure 1); (2) the lower SST provided a lower contact angle between the droplets and leaf surface (Melo et al, 2019) increasing the wetted leaf area (Lin et al, 2016;and (3) due the greater droplet spreading area, the coalescence between the droplets increased the wetted area on the leaf surface (Xu et al, 2010) with a low quantity of solution and consequently, provided a run-off (Prado et al, 2016).…”

Control decision‐making systems for Anacampsis phytomiella in cashew orchards as a function of insecticide spray method and irrigation use

“…Another critical insecticide spray product used for A. phytomiella management in cashew orchards is a lipophilic adjuvant (Mesquita et al, 2022b). This type of adjuvant allows the insecticide to penetrate through the superficial waxy layer of the chestnut and, thus, reach the pest larvae inside this plant part (Congreve & Cameron, 2019; Melo et al, 2019).…”