| Mango
malformation - a review. |
| Sant
Ram,Yadav, V. K. |
| G.B. Pant
University of Agriculture & Technology, Pantnagar, India. |
| Mango
malformation has been intriguing scientists as to its cause and control
for more than 100 years. The earliest hypothesis that mites caused the
disorder did not last long as acaricides failed to control the problem.
The role of mangiferin also did not persist for long as a cause as it
was found in both healthy and malformed tissues and malformation could
not be controlled by antimangiferin. Similarly, nutrient deficiency or
toxicity were discounted. However, Fusarium subglutinans [Gibberella
fujikuroi var. subglutinans ] appears to have a significant role in
malformation. Symptoms of vegetative and floral malformation appeared
where mycelium of Fusarium species were present in the tissue at high
concentrations. G. f. var. subglutinans as well as malformed mango
tissue 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
greenhouse and field conditions by high temperatures. Malformation
intensity was reduced along with malformin levels in high density
Dashehari plantations and malformation was reduced to less than 0.1% by
shoot pruning after the 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 G. f. var. subglutinans
produces malformin and causes malformation in mango which can be
controlled by annual pruning followed by paclobutrazol application in
orchard soil near the collar zone of the trees or by solarization or
growing in greenhouses at high temperatures. |
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