Unique Citrus Variety Standing Up to Deadly Disease

Unique Citrus Variety Standing Up to Deadly Disease

Sugar Belle oranges

‘Sugar Belle’
Photo courtesy of UF/IFAS

Recent studies are indicating UF/IFAS scientists have developed a mandarin hybrid (‘LB8-9,’ aka, ‘Sugar Belle’) that appears to be tolerant of the devastating citrus greening disease. Now, researchers are taking next steps to find out what makes this sweet mandarin such a standout.

In a field study led by Nabil Killiny, UF/IFAS Assistant Professor of plant pathology, researchers at the UF/IFAS Citrus Research and Education Center in Lake Alfred focused on identifying the chemicals found in ‘Sugar Belle’ trees that have been shown to fight against diseases in other plants.


They found ‘Sugar Belle’ is high in several volatiles and beneficial compounds known as phenolics. Volatile and non-volatile metabolites of the greenhouse-grown mandarin trees were tested. Among other traits, volatile metabolites emit odors, while non-volatile metabolites do not.

Using gas chromatography – mass spectrometry to analyze metabolites, researchers found ‘Sugar Belle’ mandarins to be relatively tolerant to disease pressure. Other newly released mandarins should be further evaluated using greenhouse-controlled studies, the research concludes. If tolerance of these hybrids is confirmed, they could be used to replace the traditionally susceptible cultivars.

According to UF/IFAS Horticultural Sciences Professor Fred Gmitter, in 2016, Florida citrus nurseries grew more ‘Sugar Belle’ trees than any other mandarin hybrid except for one, demonstrating grower interest in the variety.

Gmitter and UF/IFAS Professor Jude Grosser, co-authors on the new study, which is published in the journal Plant Physiology and Biochemistry, developed and released ‘Sugar Belle’ in 2009.