Utilização de medicamentos homeopáticos como alternativa para redução da taxa de progresso da murcha bacteriana na mandioca

Abstract

The bacterial blight of cassava, caused by the bacterium Xanthomonas axonopodis pv. manihotis, is considered the most important disease and constitutes a serious economic problem for cassava in Brazil, since there are no efficient commercial products to manage the disease. Considering the benefits observed for agriculture through the application of homeopathy, this can become a low-cost strategy for cassava producers, because it is an environmentally correct and not residual. So, this work aims to evaluate the action of homeopathic drugs on the bacterium, the severity of the disease and on the development of cassava plants. The treatments included two homeopathic drugs (Sulphur and Silicea terra), a drug homeopathic based on Propolis, the isotheraphy in the form of nosode of X. axonopodis pv. manihotis (XAM) and hydro-alcoholic solution (30% ethyl alcohol). The dynamization undertaken were 6CH, 12CH, 18CH, 24CH and 30CH. The estimate of the antimicrobial activity in vitro was by antibiogram, using the technique "pour plate", and the bacterial growth count by the “spread plate” technique. For in vivo evaluations, cassava branches of the variety Caiuá (Olho Junto), were used in two trials. The first test was carried out with the inoculation of bacteria prior to the application of the treatments, in order to obtain curative action, and the second test was carried out the inoculation after the application of the treatments, aiming at preventive action. The results were submitted to analysis of variance by the F test and comparison of means by the Scott-knott test, both with levels of 5% of significance. In the in vitro assays, the homeopathic drugs did not present inhibition by the antibiogram, however, for bacterial growth and colony count, Sulphur treatments 12CH and 18CH, Propolis 6CH, 12CH, 18CH and 30CH, isotherapic XAM 6CH and 18CH, in addition to all the dynamizations of hydroalcohol solution caused inhibition. For the in vivo assay, the treatments interfered in the physiological activities of the plants, being the preventive application more efficient than the curative mode, in the management of the bacterial blight of cassava. The treatments Silicea terra 12CH and Sulphur 24CH, for the curative and preventive trials, respectively, favored the development of the pathogen, causing death of the plants. The treatments with Alcohol 30CH and Propolis 6CH were efficient in reducing the severity of the disease in both trials. In general, preventive homeopathic treatment tends to reestablish plant homeostasis more efficiently than curative treatment, as well as to accelerate sprout budding and increase the height of cassava plants.