Grapefruit grows better under screen houses than in unprotected groves because the indoor facilities keep out the insect that causes citrus greening, new University of Florida research shows.
Protecting citrus from greening is essential, UF/IFAS researchers say. The disease, first detected in Florida in 2004, has destroyed more than 250,000 acres of citrus trees in Florida – from 748,000 down to 480,000, according to the U.S. Department of Agriculture. That’s a 36 percent drop in planted area and a 68 percent reduction in yield, according to UF/IFAS research.
That’s why a system known as Citrus Under Protective Screen (CUPS) could be crucial to Florida growers, UF/IFAS researchers say. Although screen house cost is high and varies depending on facility size, two Florida commercial growers are using CUPS, said Rhuanito Ferrarezi, a UF/IFAS assistant professor of citrus horticulture and lead author of the new research.
“Growing young trees in screen houses may allow growers to produce greening-free trees,” said Ferrarezi, a faculty member at the UF/IFAS Indian River Research and Education Center (IRREC) in Fort Pierce, Florida. “We only tested grapefruit at the IRREC, but Arnold Schumann, a UF/IFAS soil and water sciences professor, is testing grapefruit, mandarin, orange and lime at the UF/IFAS Citrus Research and Education Center in Lake Alfred, Florida. The ultimate benefit of growing citrus trees in the screen houses would be increased yield and fruit quality.”
In two newly published studies, scientists at the UF/IFAS IRREC compared grapefruit grown in a screen house versus the fruit grown in open air. They also tested grapefruit grown in-ground against that grown in containers.
Among other advantages, screen houses keep out the Asian citrus psyllid, the pin-sized insect that can transmit the bacterium that causes citrus greening.
In one study, researchers found the screen houses reduced solar radiation and maximum wind gusts, among other environmental variables. In the other, they found the screen houses provided a better growing environment for in-ground grapefruit because the protected structures accelerated young tree growth compared with open-air plantings. They also protected trees from greening.
Ferrarezi cautions that it may be too early to conclude that if the trees grown in the screen house will be superior to trees grow in the open air. That will require more testing, he said.
“The results are still inconclusive because we conducted the trials with young trees, and the ultimate indicators of success are fruit yield and quality,” Ferrarezi said. “We don’t have enough years of data to guarantee the screen houses are superior – even though the results are showing that trend.”
The new studies are published in the journal HortTechnology.