Misturas de produtos fitossanitários recomendados para a cultura da soja e do milho: interação e fitotoxicidade

Abstract

The use of tank mixtures has been used as a practice in the phytosanitary management of agricultural crops. Among the mixtures, we highlight the use of different phytosanitary products, such as herbicides, fungicides, insecticides, in addition to those intended for mineral nutrition. However, when mixing different molecules in a tank, physical-chemical interactions in the spray solution can occur, reducing the efficiency of the products and/or causing phytotoxicity in the crops. The objective of the work was to evaluate the interaction between different phytosanitary products (herbicides, fungicides, insecticides and nutrition) recommended for soybean and corn crops, as well as their effects on crops. Two experiments were carried out: I- evaluation of mixtures in the laboratory and II- selectivity for crops. Both trials were conducted at the Federal Rural University of Rio de Janeiro, Seropédica / RJ. The experimental design used was completely randomized, with four replications. Experiment I was carried out with two syrup volumes (150 L ha-1

and 80 L ha-1

) and one type of water (standard hard water). The physical-chemical interaction evaluations of the mixtures were carried out according to the Brazilian standard NBR 13875 (Pesticides and the like - physical-chemical compatibility assessment). For EI the phytosanitary products used for soybean cultivation were: herbicides - Verdict® , Pacto® , Flex® , Zapp Pro®

, fungicides - Fox®

, Orkestra®

, Dithane®,

insecticides - Benevia®

, Engeo Pleno® , Exalt®

and nutrition - Kellus Inox® , Kellus

Manganese®

. For the cultivation of corn, we used: herbicides - Sanson®

, Soberan®

, Callisto® ,

Zapp Pro®

, fungicides – Priori Xtra® , Nativo® , Tebufort®

, Aproach Prima®

, insecticides -

Connect® , Lorsban®

480 BR, Karate Zeon®

and nutrition - Kellus Manganese® , Kellus

Blindex® . Mixtures that did not show any incompatibility in syrup were selected for experiment II. In the EII, the experimental units were composed of 5-liter pots with soil classified as eutrophic haplossic planossol, containing two plants per pot, and the application was carried out at the phenological stage V6 of the corn crop and V5 of the soybean. At 7, 14, 21 and 28 days after the application of the mixtures (DAA), phytotoxicity, transient fluorescence of chlorophyll a, chlorophyll content, length of aerial part and dry mass of the aerial part of the plants were evaluated. The data obtained in the experiment were submitted to ANOVA (p ≤ 0.05), and when significant submitted to the Scott-Knott test at 5% probability (p ≤ 0.05). The incompatibilities between the mixtures for both crops occurred mainly due to the different formulations of the products, where most of them are very concentrated when mixed, and by the reduction of the syrup volume, being accentuated for the soybean crop that presented 54% of incompatibility only with the reduction. The soybean crop did not suffer significant phytotoxicity. However, the corn crop suffered phytotoxicity of up to 30%, with recovery of the plants observed at 28 DAA. This phytotoxicity was caused by the different products mixed in the syrup, mainly due to the synergism caused by the mixture of the herbicides nicosulfuron and tembotrione with the insecticide chlorpyrifos, and the fertilizer Kellus Manganese® that aggravated the incompatibilities in some treatments. The results of this study defined which phytosanitary products recommended for soybean and corn crops should not be mixed in the same application solution, due to incompatibility problems or the possibility of damage to crops.