MINERAL TREATMENT FOR MANGO DECLINE
SCIENTIFIC NAME: Mangifera indica
FAMILY: Anacardiaceae
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.
DATE: November 1988
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