Management of Meloidogyne mayaguensis in commercial guava orchards with chemical fertilization and organic amendments.

Abstract

In an effort to devise strategies to sustain guava production in the large Brazilian areas infested by M. mayagueusis, five treatments that combined chemical fertilization and organic soil amendments were assessed in a two year-experiment conducted in two locations: i) a newly planted orchard with light M. mayaguensis infestation, and ii) a mature, heavily infested, declining orchard. One of the treatments represented the routine practices of local growers: hand-spread soil and foliar fertilizations without previous fertility analysis, coupled with applications of cow manure (30 kg / tree) in a single spot under the tree canopy, twice a year. The remaining four treatments combined monthly soil and foliar fertilizations according to previous fertility analysis, coupled with quarterly applications of cow manure (applied either locally or homogenously under the canopy), sugarcane filter cake or a poultry compost (these applied homogenously under the canopy). These amendments were applied at 20 or 40 kg / tree in the young and mature orchards, respectively. The following variables were assessed along the experiment: number of second stage juveniles / 100 cm 3 of soil, number of root galls / 10 g of roots, and number of root galls and root mass per auger sampling (~ 500 cm 3 of soil), productivity in two harvests and fruit quality (°Brix and diameter). An economic analysis was conducted for each treatment considering the gross profit and the costs of guava production and of the different organic amendments. The poultry compost and the cow manure applied homogenously under the canopy provided the highest nematode suppression and productivity. The economic analysis indicated being unworthy to manage guava orchards which are heavily infested by M. mayaguensis. On the other hand, it indicated being feasible and profitable to manage moderately infested orchards with proper chemical fertilization coupled with applications of organic soil amendments, particularly poultry compost and cow manure spread evenly under the canopy.