Rootstocks US-812, US-942 Hold Promise

Ernie NeffRootstocks


The rootstocks US-812 and US-942 seemed to offer promise in early economic performance evaluations that economist Ariel Singerman discussed at the 2021 Citrus Expo. Singerman is a University of Florida Institute of Food and Agricultural Sciences Extension economist at the Citrus Research and Education Center in Lake Alfred.

Singerman analyzed yield and economic performance of rootstocks in commercial settings during the 2018-19 and 2019-20 seasons. The rootstocks were grafted with Valencia orange, and growers ran the side-by-side trials.

The trials were in Lake Placid, where the planting was 240 trees per acre; Babson Park, 303 trees per acre; and Felda, 202 trees per acre. Each site was managed by a different grower. Within each site, all major sources of variability were held constant; only the rootstocks varied.

At each site, the rootstocks UFR-2, UFR-3, UFR-4, UFR-16, US-812 and US-942 were evaluated. Additionally, US-897 was evaluated in the Babson Park site. Control rootstocks were sour orange in Lake Placid, Carrizo in Babson Park and Swingle in Felda.

In Lake Placid, US-812 and US-942 attained positive revenue differences compared to the control. Singerman said US-812 seems to be a better choice because in 2019-20 the positive difference with respect to the control was larger.

In Babson Park, US-812 and US-942 attained positive revenue differences compared to the control. US-812 attained a cumulative revenue that doubled that of US-942.

In Felda, UFR-2 performance was similar to the control but with an intrinsic higher risk because its performance through time is still unknown. While UFR-4 did not attain large differences, the differences increased over time. US-812 and US-942 obtained the largest differences in yield and revenue compared to the control, but those differences decreased considerably in 2019-20.  

See Singerman’s Citrus Expo presentation.

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About the Author

Ernie Neff

Senior Correspondent at Large