Phytotoxicity of mixtures of phytosanitary products recommended for use in maize

ABSTRACT The use of tank mixtures has long been a practice in the phytosanitary management of agricultural crops. However, when different molecules are mixed in a tank, interactions may occur that reduce the efficiency of the products and cause a loss of selectivity in the crops. The aim of this study was to evaluate selectivity in maize, with a tank mixture of different phytosanitary products recommended for use with the crop. The following products were 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®. The experimental units consisted of 5-litre pots, containing two plants per pot, with the products applied at phenological stage V6. Assessments were made of phytotoxicity, transient chlorophyll a fluorescence, chlorophyll content and shoot dry weight. The data obtained in the experiment were submitted to ANOVA (p ≤ 0.05), and when significant, to the Scott-Knott test (p ≤ 0.05). The maize crop suffered phytotoxicity of up to 30%, with the plants recovering from 28 DAA. The phytotoxicity was caused by mixing the different products in the spraying solution, mainly due to the synergism caused by the mixture of the herbicides nicosulfuron and tembotrione with the insecticide chlorpyrifos and the fertiliser Kellus Manganese®, which aggravated the incompatibility of some treatments. The results of this study defined which phytosanitary products recommended for use with maize should not be mixed in the same spraying solution due to the possibility of damaging the crop.