Long-Term Rootstock Evaluation Is Best

A variety of different findings in recent rootstock trials led to a conclusion that long-term evaluation of rootstocks is necessary to assess economic benefits to growers. That conclusion was part of a take-home message in Ute Albrecht’s virtual Citrus Expo presentation. Albrecht is a researcher with the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS).

Her report was on findings from trials established in 2015 by fellow UF/IFAS scientists Bill Castle, Fred Gmitter and Jude Grosser in collaboration with the grower Lykes Bros. The trials evaluated rootstock effects on Valencia and Hamlin orange performance under HLB-endemic conditions. The Valencias and Hamlins were planted in Polk and Highlands counties on 30-plus rootstocks. The rootstocks came from the University of Florida, California, Spain and the U.S. Department of Agriculture.

Here are Albrecht’s take-home messages:

• Tree size can be considerably influenced by rootstock.

• In 2018-19, the largest, best-looking trees were not necessarily the most productive. In 2019-20, however, the largest, best-looking trees were often the most productive.

• In 2018-19, several of the small tree size-inducing rootstocks were very productive and yield efficient. But in 2019-20, few of the small tree size-inducing rootstocks could compete in productivity with the large tree size-inducing rootstocks.

• Rootstocks that induce small, yield-efficient trees can be planted at higher density and may be profitable during the early production years. But growth and productivity may change as trees mature. It was following this message that Albrecht suggested long-term evaluation is necessary to assess economic benefits.

• For some rootstocks, effects on tree size and yield varied between the two trial locations. For some rootsocks, effects on tree size and yield varied between the two scion cultivars.

• Many factors need to be considered when choosing the right rootstock.

• Choosing the right rootstocks will result in higher profit at no additional cost.

See Albrecht’s full presentation here. The presentation, and the continuing education units available to those who watch it, will remain online through the end of 2020.

Read more on Albrecht’s rootstock research.