Influência de sucessões de cultivos na severidade da murcha-de-fusário do caupi

Abstract

The cowpea is very important for the poor populations of the North and Northeast of the Brazil. Several factors corroborate to production low of the culture, among them we can quote the disease, focusing on cowpea Fusarium wilt , caused by the fungus Fusarium oxysporum f.sp. tracheiphilum. This study aimed to evaluate the influence of incorporation of crop succession on the severity of cowpea Fusarium wilt. In all experiments we used soil without previous history of cultivation with this culture. There were no observed F. oxysporum populations indigenous in the soil. The experiments were conducted in microplots of concrete pipes containing soil artificially infested with the pathogen structures, the density of 5x103 cfu g-1 of soil. The experiment consisted of three cultivation cycles being: (i) cowpea, (ii) succession cultural and (iii) cowpea. The culture succession were: corn - MI, sorghum - SO, cotton - AL, castor - MN and sunflower - GI; legumes: Crotalaria juncea - CJ, Crotalaria spectabilis - CS, bean-pig - FP, pigeon pea Dwarf - GA, lab-lab - LA and black velvet - velvet MP and dwarf - MA. There were still some treatments: plots with cowpea without inoculum of F. o. f. sp. tracheiphilum - TEST, plots of cowpea inoculated with F. o. f. sp. tracheiphilum (cowpea) - CA, and plots infested with the pathogen in fallow system - PO. The incorporation of succession before of the cowpea planting provided a range in the disease severity of 56.67% to 26.33%. Among the legumes studied the FP and MP were the most suitable for reducing the severity of the disease and offer better grain yield. For succession crops to the OS and GI showed a greater reduction in severity of Fusarium wilt of cowpea.