High yields of HLB-free fruit can hypothetically be sustainably produced in citrus under protective screen (CUPS), Arnold Schumann said at a Dec. 14 field day at the Citrus Research and Education Center (CREC). He backed that up with data showing high yields from Ray Ruby grapefruit planted at high densities and fertigated in CUPS. Trees in his CUPS facility are planted at 4-foot by 8-foot and 5-foot by 10-foot spacings.
Schumann is a University of Florida Institute of Food and Agricultural Sciences professor at the CREC in Lake Alfred. Here are highlights he reported after 8.5 years of growing citrus in CUPS at the CREC:
- 99.5% of trees remain HLB-free.
- Psyllids only infested the trees during rescreening. HLB spread was minimal, and psyllids were eliminated.
- Cumulative grapefruit yields over seven years of production totaled 5,929 boxes per acre. Fruit quality is enhanced by fine-tuning fertigation.
- There is no citrus canker in CUPS.
- The CUPS structure suffered moderate damage from three hurricanes from 2017 to 2022, but trees and crops were undamaged and required no post-hurricane recovery.
Schumann said the 5,929 cumulative boxes produced over seven years of production would yield $106,722 per acre at a price of $20 per box with a conservative packout rate of 90%. He said packout actually exceeds 90% in CUPS. Packout is the percentage of harvested fresh fruit that winds up being marketed after culling out fruit that is blemished or of substandard quality.
That $106,722-per-acre cumulative revenue over seven years is equivalent to 40 years of conventional HLB-endemic grapefruit producing 267 boxes per acre at a 50% packout rate and $20 per box, Schumann said. The 267 boxes per acre he cited is the U.S. Department of Agriculture-reported Florida grapefruit yield for 2018–19.
Schumann also noted that a conventional grower would have faced 40 years of caretaking costs, fertilizer, irrigation, insurance and environmental impacts versus only seven years of those costs in CUPS.
Learn more here about the CREC CUPS research.
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