Nematode and fungal communities associated with mango decline of southern Punjab

Plant parasitic nematodes and fungal pathogens associated with decline of mango (Mangifera indica L. Family-Anacardiaceae) were assessed within southern Punjab plantations. The fungi most often isolated from symptomatic terminal branches of decline mango trees were Alternaria alternata, Ceratocystis fimbriata, Colletotrichum gloeosporioides, Fusarium spp., Botryodiplodia theobromae, and Nattrassia mangiferae. Three fungal pathogens viz., B. theobromae, C. fambriata, and N. mangiferae were also identified from roots, barks and vessels collected from the stem and the collar region. Incidence of B. theobromae was 87% of sampled trees, whereas incidence of C. fambriata and N. mangiferae was relatively low (ca 5.5%). Plant parasitic nematodes associated with declining trees included Criconemella sphaerocephala, Helicotylenchus dihystera, Hemicriconemoides mangiferae, Hoplolaimus indicus, Meloidogyne spp., Pratylenchus brachyurus, Rotylenchulus reniformis, Trichodorus spp., Tylenchorhynchus claytoni, Tylenchus filiformis and Xiphinema spp. Populations of H. mangiferae, Macroposthonia spp. and Rotylenchulus reniformis were very high. Possible factors contributing to mango decline must include H. mangiferae and R. reniformis. Association of fungi with tissues symptomatic of mango decline in the presence of none to high population levels of plant parasitic nematodes is an area in need of further study to understand the relationship between nematodes and fungal pathogens in inducing decline syndrome in mango.