Fitonematoides x cana-de-açúcar : ocorrência populacional em áreas de estados do nordeste brasileiro e a avaliação de piraclostrobina como indutor de resistência

Abstract

Brazil stands out as the world's largest producer of sugarcane. However, the northeastern region presents low productivity when compared to the center-south of the country. This low productivity is related to several factors, among them abiotic and biotic, mainly phytonethoid diseases. The knowledge of the occurrence of diseases, and of the population levels of the pathogens involved, is important for the direction of the activities and in the aid of appropriate management measures to be adopted. To take effective measures in phytonuthoid management, it is essential to consider not only the species of the pathogen, but also how much of it is present in the area. To know the effects of management attributed to sugarcane in northeastern conditions, and the dynamics of populations of phytonematoids, especially those of the genus Meloidogyne and Pratylenchus and the responses of plant defenses mainly through the induction of resistance, are fundamental for understanding of the population changes of these organisms and consequent effects on agricultural productivity. The objective of this work was to study the population fluctuation over nine years of Meloidogyne and Pratylenchus in sugar cane fields, cultivated with the varieties RB813804, RB867515, RB92579, SP791011, SP813250, in the States of Rio Grande Norte, Alagoas and Pernambuco. and the application of pyraclostrobin in plant cane in the management of phytonematoids. Sampling for survey was carried out in five plants in the states of Rio Grande do Norte, Alagoas and Pernambuco. The varieties cultivated over the years in these plants with greater predominance were RB813804, RB867515, RB92579, SP791011, SP813250. For the application of pyraclostrobin, the study was conducted at the Santa Teresa plant in the city of Goiana-Pe. The results for the survey of the largest nematode populations of both genus Meloidogyne and Pratylenchus were observed in the years of 2009, 2014, 2015, 2016, 2017 and 2018. For the analyzed varieties those that presented the highest population densities Pratylenchus was SP813250, RB92579, RB867515. And for the genus Meloidogyne, the varieties with the largest populations were RB813804 and SP791011. The surveys showed that nematode populations increased over the years being influenced by cultivated varieties. Regarding the application of pyraclostrobin in sugarcane, the product had no effect on the treatments, without influencing the crop productivity or nematode population densities.