From the Archives
of the Rare Fruit Council of Australia
From the Tropical Fruit News, Rare Fruit Council International Miami RFCI
Mineral Treatment for Mango Decline
Scientific Name: Mangifera indica
Family: Anacardiacea
Agricultural
researchers, stymied for years by a mysterious ailment that has killed
hundreds of South Dale mango trees, say they have found a partial
solution to the problem.
But it's a costly remedy, and the researchers still haven't found the cause of the disease, called 'mango decline'.
Researchers
at the University of Florida's Tropical Research and Education Center
in the Redland have been studying the problem since it first hit South
Dade's fruit groves in the late 1970s, but for years they came up with
no answers, said Carl Campbell, a researcher at the center. Then in
1988, scientists began treating affected trees with micronutrients
zinc, iron and manganese.
The results have been encouraging.
Trees that aren't severely diseased recover with the treatment, said
Bruce Shaffer, a University of Florida plant physiologist supervising
the research project. He presented his findings, which will later be
published in a scientific paper, to members of the Florida Mango Forum
Tuesday at the Redland Golf and Country Club. Dade's backyards are full
of trees with mango decline, Campbell said. Homeowners can buy the
micronutrients to treat diseased trees and, possibly, to prevent
healthy trees from succumbing to the ailment. Some mango growers who
are members of the forum have donated more than $6,000 to speed up and
broaden the scope of the center's project, said John Himburg, the
forum's secretary. They have a lot at stake. Dade County growers
produce 95 percent of the nation's mango supply on a little more than
2,000 acres, bringing in $5 million to $6 million annually.
At
least 400 acres of groves have been affected by the disease, Campbell
said. Mango decline damages the root systems of young trees and causes
their leaves to yellow and fall off and their twigs and branches to
die. Sometimes the trees die. Other times they weaken and produce
little or no fruit, Campbell said.
About a quarter of 400 acres
of mangoes owned or managed by J.R. Brooks and Son have been affected
by the decline, said Mike Hunt, production manager for South Dade's
largest tropical fruit farming company. "It's difficult to put into
dollars, but there's been a significant reduction in yield. I would
guess we were losing 15,000 to 20,000 bushels a year. That's a couple
of hundred thousand dollars," Hunt said.
"All of our groves have
had some degree of decline," said Gerald Jones, grove manager for Bill
Krome, who has nearly 100 acres of mangoes. In one 20-acre grove, four
acres of trees were killed, he said. New trees take five years to begin
bearing fruit. "You have to start all over again. It's a very serious
problem," he said. Several growers who have tried the micronutrient
treatment told Schaffer their trees are recovering. But the nutrients
are expensive: Iron, for example, is about $10 a pound, compared with 8
to 12 cents a pound for fertilizer, Hunt said. That means it would cost
about $75,000 a year to treat Brooks' 25,000 affected trees with the
micronutrients.
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