A recent article provides estimates for the performance of Valencia orange grafted on new hybrid citrus rootstock cultivars developed by the U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS). These estimates can help growers decide which rootstocks to plant in HLB-endemic regions.
Authors of the article are Ariel Singerman of the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS), Kim Bowman of the USDA-ARS and Danelle Seymour of the University of California, Riverside.
TOP ROOTSTOCKS
The top two rootstocks were US SuperSour 4 and US SuperSour 5, which became commercially available in 2023. While the differences between the top rootstocks and sour orange become smaller in later years — suggesting that the advantage of the new rootstocks may decrease over time — the early differences are still valuable. They can lead to a quicker payback period and a higher return on investment when establishing a new grove.
The data consist of annual yields collected in a trial at the USDA Picos Farm in Fort Pierce, Florida. The trial consisted of 50 rootstocks including Swingle, sour orange, Cleopatra and ridge orange as standard rootstocks used in Florida for comparison. Trees were planted in 2014 at a density of 640 trees per hectare (approximately 260 trees per acre).
The authors calculated yield differences between each rootstock and sour orange because sour orange had the highest yield among the standard rootstocks in the trial.
YIELD RESULTS
The two top rootstocks — US SuperSour 4 and US SuperSour 5 — yielded 638 and 361 pounds solids per acre more over six seasons relative to sour orange, respectively.
For both rootstocks, the differences with respect to sour orange are largest (and statistically significant) in Years 4 and 6. It is clear that in Year 4, US SuperSour 4 and US SuperSour 5 perform substantially better compared to the previous year, whereas the performance of sour orange increases only moderately. In Year 6, US SuperSour 4 and US SuperSour 5 perform better compared to the previous year (although not as much as in Year 4), while the yield of sour orange decreases relative to the previous year. In Years 7 and 8, the yield differences between the US SuperSours and sour orange become smaller. Yield of all three rootstocks change by a similar magnitude in Year 8.
The 11 other rootstocks with positive cumulative differential pound solids per acre relative to sour orange were, in descending order: US-1672, US-1676, US SuperSour 3, US-2338, US-2111, US-2109, US-1649, US-1687, US-2137, US-1673 and US-2336. Their pound solids per acre differences relative to sour orange over six years ranged from 303.76 for US-1672 to 13.63 for US-2336.
REVENUE DIFFERENCES
US SuperSour 4 and US SuperSour 5 attained cumulative revenue differences over six seasons (expressed in 2022 dollar terms and using a 10% interest rate) of $2,307 and $1,291 per acre, respectively, compared to sour orange.
Source: UF/IFAS Citrus Magazine
Share this Post