http://www.theledger.com/article/20090819/NEWS/908195031/1178?Title=Rebel-With-A-Cause-May-Yield-Greening-Breakthrough

2009 citrus expo
Rebel With A Cause May Yield Greening Breakthrough

By Kevin Bouffard
THE LEDGER
Published: Wednesday, August 19, 2009 at 6:08 p.m.
Last Modified: Wednesday, August 19, 2009 at 6:08 p.m.

FORT MYERS | Felda citrus grower Maury Boyd no longer seems like a renegade.

"He pursued his ideas on his own, and I give him credit," Tim Spann, an assistant professor of horticulture at the University of Florida's Citrus Research and Education Center in Lake Alfred, told The Ledger. "He's shown his method could do a lot of good."

Spann was referring to Boyd's once unconventional ideas for battling the fatal citrus greening disease that threatens to destroy the state's signature agriculture industry.

Boyd believes the progress of greening in the tree can be stopped or slowed by applications of various nutritional and anti-bacterial chemicals, including an aspirin-like substance.

The most controversial aspect of the Boyd method is the refusal to remove greening-infected trees as recommended by almost all state and federal citrus scientists. He insists the nutritional and other sprays will prolong the tree's life and production.

Spann reviewed current research into the Boyd method on Wednesday before about 500 growers at the 2009 Citrus Expo in Fort Myers, which annually attracts more than 1,000 citrus people and exhibitors from related industries, such as farm equipment providers and chemical companies.

Spann opened his talk with the disclaimer he is not advising growers to stop removing greening-infected trees. But the research shows Boyd's method does improve the health of both infected and non-infected trees.

Scientists know greening significantly reduces levels of calcium, magnesium and boron and raises phosphorous levels, Spann said. The sprays appear to restore the balance of those tree nutrients.

In a grove with a 40 percent infection level, removing infected trees reduces fruit yields by 40 percent, he said. But in the same grove using the Boyd method, fruit yields dropped just 20 percent.

A major reason for that result is that the nutritional sprays boosted fruit yields in non-infected trees by 10 percent, Spann said. If nothing else, Boyd's method appears to benefit normal trees.

Even in the infected trees, however, the yield loss comes from branches damaged by the disease, thus incapable of producing mature fruit, he said. But non-damaged limbs of infected trees produce good fruit in yields comparable to the healthy trees in the same grove.

"Under average to good management infected trees don't appear to decline as rapidly as we first assumed," Spann said. "Under poor management, they decline rapidly."

The unresolved questions include how leaving infected trees in a grove affects the spread of the disease within the grove and to neighboring groves, Spann said.

At issue is controlling populations of citrus psyllids, a host for the greening bacteria and primary cause of the disease's spread. Scientists argue keeping infected trees increases the probability psyllids will pick up the bacteria from those trees and transmit it elsewhere.

Whether a grower removes infected trees or not, the main factor affecting greening's spread is keeping psyllid populations down, Spann said. Boyd's program includes regular pesticide spray to control psyllids.

Theoretically effective psyllid control would limit greening spread whether the grower removes infected trees are not, Spann told The Ledger.

But proving that scientifically will require many more years of collecting data from Boyd's groves and others using his system, he said.

Other speakers on Wednesday included Nate Jameson, owner of Brite Leaf Citrus Nursery of Lake Panasoffkee, who counterintuitively advised growers to delay replanting trees lost to pest and diseases in some cases.

The greening threat means growers must manage new plantings more intensively, including frequent pesticide and fertilizer applications, Jameson said. If labor and materials aren't available, it may make more sense to delay replanting.

"Because of (greening), costs are higher today. Historically we've replanted immediately, but times have changed, and we may have to do something different," he said.

Jameson also advised growers to consider planting smaller "dwarf" trees instead of full-sized traditional varieties because they grow faster and produce a commercial crop sooner.

Florida growers have resisted dwarf trees so far because of lower fruit yields per tree.

Better to have some production per acre than no production, Jameson said.

The Expo runs through today at the Lee Civic Center.

[ Kevin Bouffard can be reached at kevin.bouffard@theledger.com or 863-422-6800. ]