FIELD ASSESSMENT OF MEAT AND BONE MEAL FOR MANAGEMENT OF GUAVA ORCHARDS AFFECTED BY GUAVA DECLINE [EVALUACIÓN A CAMPO DE HARINA DE CARNE Y HUESO PARA EL MANEJO DE PLANTACIONES AFECTADAS POR EL DETERIORO DEL GUAYABO]

Abstract

Guava decline is a disease complex involving Meloidogyne enterolobii and Fusarium solani, which causesroot rot, defoliation and death of guava trees within months from onset of symptoms. Since no resistant cultivaror rootstock is available nor are there nematicides registered for this crop, management strategies for this diseaseare needed. Meat and bone meal (MBM) was applied to the soil of a commercial guava orchard affected by guavadecline, in three dosage/regime applications: i) quarterly applications of 12.5 Kg/tree, ii) quarterly applications of 25Kg/tree, and iii) semiannual applications of 50 Kg/tree. During this 24 month-experiment, the following variableswere assessed: M. enterolobii and other soil plant-parasitic and free-living nematodes presence and populationdensity, Fusarium sp. density in soil and guava roots, release of ammonia in the soil upon MBM decomposition,and productivity in two harvests. The quarterly application of 25 Kg/tree was further assessed in three differentorchards, which were clearly distinct in age and in the levels of disease severity and agronomic care. The lowlevels of ammonia observed in the soil upon MBM decomposition in all three dosage/regime applications likelyexplain the modest reduction of second-stage juveniles of M. enterolobii in soil and other minor plant-parasiticnematodes. The parasitism by M. enterolobii, expressed as density of root galls, and density of Fusarium sp. insoil and roots were unaffected by MBM applications, which led to progression of guava decline and reduced theorchard productivity. This work shows the difficulty in management of plant-parasitic nematodes when organicamendments are applied in soil, particularly in the control of disease complexes as guava decline.