Protecting Trees: Beyond CUPS and IPCs

Many Florida citrus growers have been using individual protective covers (IPCs) for several years primarily to protect trees from HLB-spreading Asian citrus psyllids (ACP). Smaller but increasing numbers of growers are utilizing the more expensive citrus under protective screen (CUPS) system to protect trees from ACP and HLB.

Recently, Fernando Alferez informed growers in a virtual presentation about some other tree protection systems being used around the world. Alferez is a University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) citrus horticulturist at the Southwest Florida Research and Education Center.

Screening over multiple trees is being used in Valencia, Spain, to exclude bees in an effort to avoid cross-pollination and seeds in fruit, Alferez said. Shading is used over many contiguous acres of trees in Spain and Morocco to avoid sunburn. Thermic mesh bags are protecting trees from freezing temperatures in California and Spain; Alferez said they might be useful in North Florida and South Georgia citrus plantings.

Alferez also discussed the IPCs and CUPS most familiar to Florida growers. In an experiment he has been conducting for three years, trees under IPCs are still negative for HLB. Those trees have also experienced improved growth, he said. Learn more about Alferez’s IPC findings.

In CUPS, citrus has been planted at high densities of 1,361 Murcott trees per acre and 871 Ray Ruby grapefruit trees per acre, Alferez reported. Murcott and Ray Ruby are UF/IFAS researcher Arnold Schumann’s favored varieties to grow in CUPS; learn more here.

CUPS research Alferez is conducting includes bloom induction through deficit irrigation, fruit set assessment and treatments, and fruit yield and quality assessment. Planned CUPS experiments include trellis-assisted tree training, hand pruning to maximize production, and efforts to improve external fruit color. Alferez referred to those issues he and fellow researchers are working on or plan to research as “some unsolved questions for citrus growing in CUPS.”