Seletividade e fitotoxidade de herbicidas na cultura da pitaia

Abstract

In Brazil, pitaya production has been growing in several regions of Brazil, especially in the state of São Paulo, which has the largest production of the fruit in the country. To obtain good productivity in the culture, the control of weeds is fundamental, however the use can allow phytotoxicity and loss in the development of the plants. Thus, the present work aimed to evaluate the effect of the application of different herbicides on red and white pulp pitaya on initial growth and the effects of phytotoxicity on seedling development. The experiment was conducted in the field, at the experimental station of the fruit growing sector of the Federal University of Lavras between the months of August 2020 to May 2021. Two experiments were carried out: the first using pitaya of red pulp, with seedlings of high rate of growth and several new shoots and the second with pitaya seedlings with white pulp with only mature cladodes and low growth rate. The experiment was arranged in a randomized block design, with four replications for red pitaya and three for white pitaya, with three plants per plot in both experiments. The treatments consisted of control, fomesafem, glufosinate ammonium, glyphosate, clethodim, carfentrazone-ethyl, imazethapyr and chlorimuron. Visual symptoms of phytotoxicity were evaluated at 7, 14, 21, and 28 days after herbicide application. At 30 and 60 days after application, the percentage of necrosis, cladode growth and number of new shoots were evaluated. For the red-fleshed dragon fruit, the herbicide cletodim during all evaluation periods did not present visual symptoms of phytotoxicity and necrosis in the seedlings and the highest growth of cladodes and number of shoots were in the treatments with cletodim, imazethapir and the control. For the white-fleshed dragon fruit, the herbicides cletodim, imazethapir, clorimuron showed lower phytotoxicity in the seedlings. The highest growth of cladodes was in the treatments with cletodim and the control at 60 days after application, and there was no growth of new shoots. For pitayas with red and white pulp, the herbicide cletodim becomes an alternative for use in controlling narrow-leaf weeds without causing severe visual damage to the seedlings.