For a citrus under protective screen (CUPS) production system to be profitable, the cost of the system must be offset by high yields of premium-quality fresh fruit with strong market prices.
Researchers at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) have expanded their CUPS research trials to investigate management strategies that improve fruit quality and yield.
Johnny Ferrarezi, assistant professor of citrus horticulture at the UF/IFAS Indian River Research and Education Center, presented research findings from multiple trials at the March 25 CUPS Field Day.
CANOPY MANAGEMENT TRIAL
Tree canopy and bearing volume are two important factors in fruit production and fruit quality.
The CUPS environment stimulates vigorous vegetative growth, posing operational challenges to mechanization that can be overcome by selectively controlling plant growth. Researchers evaluated a combination of treatments: hand pruning only after the bud-break stage, hand pruning at bloom and in late summer, mechanical hedging/topping at bloom and in late summer, and mechanical hedging and hand pruning at bloom and in late summer.
Findings revealed that canopy management increased yield without changing fruit quality. According to Ferrarezi, growers can multiply their labor costs by the time it takes to perform the pruning, and multiply yield by the current price to determine which technique is economically feasible for their operation.
COLORED SCREEN TRIAL
The next trial Ferrarezi shared looked at the effect of colored screens on tree growth and fruit quality. According to Ferrarezi, photoselective nets promote desired physiological responses in citrus such as modulated canopy growth, higher fruit Brix and fruit color.
Researchers compared red, blue and gray photoselective nets.
“Trees growing under the gray screen did not grow very well, despite the fact that there is data available with apples and pears indicating the gray screen induces higher yield in those crops,” Ferrarezi said.
He reported that the blue net reduced plant size and quality, but trees grown under the red net had increased growth and higher yields.