Etiology and management of mango malformation

Mango malformation has been intriguing scientists for its cause and control for more than 100 years. The earliest hypothesis that mite causes the disorder could not be persued for long due to failure of miticide to control the disease. The role of mangiferin also did not persist for long in view of its presence in both healthy and malformed tissues and failure to control malformation by antimangiferin. Similarly deficiency or toxicity of nutritional elements were not proved. However, role of Fusarium spp. in the causation of malformation appears to be significant. Symptoms of vegetative and floral malformation appeared where mycelium of Fusarium species were present in the tissue at high concentrations. Fusarium spp. as well as malformed mango tissues contained malformins and malformins were not present in healthy tissues. Malformin concentration in malformed tissues correlated with the intensity of the disorder. Malformation-like symptoms were produced in young seedlings by soaking mango seeds in malformin solutions and symptoms disappeared as malformin concentration in the seedlings decreased. Malformation like-symptoms were also produced by paclobutrazol and ethephon in mango trees and seedlings. The malformation-like symptoms and malformin activity were counteracted in green house and field condition by high temperatures and chemicals. Malformation intensity was reduced along with malformin levels in high density Dashehari plantation and malformation was reduced to less than 0.1 percent by shoot pruning after crop harvest, and use of paclobutrazol. Fusarium concentration was also low in the xylem of the treated trees along with malformin levels. A hypothesis is proposed that the Fusarium spp. produces malformin and cause malformation in mango which can be controlled by annual pruning followed by paclobutrazol application in orchard soil near the collar zone of the trees.