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The physical characteristics of a spray liquid are important in getting a good droplet formation and control efficiency over a particular target. As a function of these characteristics, it is possible to decipher which is the best adjuvant based on the respective concentration used during the spray. Therefore, ten spraying liquids were prepared, which varied in concentrations of pesticide lufenuron + profenofos, mineral oil, water and manganese sulfate. Pendant droplets formed from these mixtures were measured to examine their impact on surface tension. Droplets were applied to the surface of coffee leaves and the surface tension, contact angle formed and the leaf area wetted by the droplet, were measured. A smooth glass surface was taken as a comparative to the coffee leaves. The highest concentrations of oil resulted in lower surface tension, smaller contact angles of droplets on leaf surfaces and larger areas wetted by the droplets. Both surfaces showed hydrophilic behavior.KEYWORDS: surface tension, contact angle, wetted area, oil CARACTERÍSTICAS FÍSICAS DE CALDAS OLEOSAS E DE GOTAS FORMADAS EM SUPERFÍCIE DE FOLHAS DE CAFÉ E DE VIDRO RESUMO:As características físicas da calda de pulverização são importantes para que haja boa formação de gotas e eficiência de controle sobre determinado alvo. Em função dessas características, pode-se decidir sobre qual o melhor adjuvante, em sua respectiva concentração, poderá ser utilizado durante a pulverização. Para tanto, foram preparadas dez caldas fitossanitárias em que variaram as concentrações do inseticida lufenuron + profenofós, óleo mineral, água e sulfato de manganês. Gotas pendentes formadas a partir dessas misturas foram medidas em sua tensão superficial. Aplicaram-se gotas sobre a superfície de folhas de café e foram medidos a tensão superficial, o ângulo de contato formado e a área da folha molhada pela gota. Uma superfície lisa de vidro foi tomada como comparativo às folhas de café. As maiores concentrações de óleo resultaram em menores valores de tensão superficial, menores ângulos de contato de gotas com a superfície foliar e maiores áreas molhadas pelas gotas. Ambas as superfícies mostraram-se hidrofílicas. PALAVRAS-CHAVE:tensão superficial, ângulo de contato, área molhada, óleo.

For a crop protection product to achieve its goal, the product must be applied and remain on the leaves until it is absorbed. This situation may be compromised due to rainfall after spraying, thus necessitating reapplication which increase

The objective of this study was to evaluate the efficiency of application and the efficacy of control of water hyacinth (Eichhornia crassipes) with the use of the diquat herbicide done with two application volumes associated to three droplets classes. Three experiments were conducted; in the first, the application efficiency was evaluated; in the second, the control efficiency and; in the third, the droplet spectrum. They were conducted in a completely randomized design with five, four and six replicates, respectively. The treatments were arranged in a 2 x 3 factorial design, with two application volumes (100 and 200 L ha-1) and three droplets classes (fine, extremely coarse and ultra-coarse) to the first and second experiment and the third comprised two diquat concentrations in spray solution (2 and 4 g i.a. L-1) and three droplets classes (fine, extremely coarse and ultra-coarse). The application efficiency was determined by the coverage by droplets, spray deposition and active ingredient of the herbicide (diquat). The efficacy was measured by the control and the percentage of plants with regrowth at 50 days after application. The spectrum of droplets produced per each nozzle model used to obtain the droplets classes were analyzed. According to the parameters analyzed, using the droplets classes extremely thick and ultra thick can provide greater certainty in the application of diquat in the aquatic environment associated with the deposition of the active and sufficient coverage to control Eichhornia crassipes with both application volumes

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