Varieties and Rootstocks Reviewed

In his virtual Citrus Expo presentation, Jude Grosser reviewed varieties and rootstocks showing promise for productivity in the face of HLB. Grosser is a University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) plant breeder. His presentation was based on work done by him and fellow UF/IFAS researchers Bill Castle and Fred Gmitter.

Grosser said UF/IFAS released OLL-20 “based solely on its exceptional (orange) juice flavor.” The variety also produces high solids, he said, adding, “You can look forward to being able to plant this in the near future.”

Bingo is “a fantastic piece of fruit that could really make Florida competitive in the Cuties/Halos market,” Grosser said. But he noted that Bingo has issues with early dieback and inconsistent fruit set and sizing. Progress is being made on addressing those issues, he said.

Grapefruit remain difficult to grow in the face of HLB. Grosser said dark red Flame is “showing recovery from HLB,” and that UF 914 has had exceptional fruit quality.

UF/IFAS is working on developing lemons, especially those with high levels of oil. “Since lemons are so tolerant of HLB, there’s a renewed interest in them in Florida,” Grosser said. Researchers are focusing on developing varieties with high oil production and seedlessness.

Turning to rootstocks in the St. Helena trial, Grosser said his favorite has been Orange 1804 from Argentina. But researchers likely can’t get the seeds for that variety imported, so are working on making it available through tissue culture micropropagation. Grosser’s second-favorite rootstock in that trial is UFR-14 and his third-favorite is Amb+HBLJ-2.

A slide in Grosser’s presentation asked, “Can new rootstocks in the citrus breeding pipeline confer (HLB) resistance to susceptible scions?” The answer was, “Maybe! Especially if trees are grown with optimized nutrition.”

See Grosser’s full presentation here.

All Citrus Expo presentations and the continuing education units that can be earned by watching them will remain available through the end of 2020.