Pathogens Identified as Cause of Citrus Fruit Drop

Learn About Results and Solutions on July 25 at the KeyPlex Citrus Symposium at Seven Sebring Raceway Hotel

WINTER PARK, FLA. — Eleven years of research conducted in EU have determined causes of fruit drop on citrus, and the results will help to guide the citrus industry into the future. Fruit drop, in particular, was thought to be caused by physiological conditions and other pathogens, such as huang long bing (HLB). However, research sponsored by the European Union and KeyPlex at the University of Torino in Italy has clearly identified Colletotrichum gloeosporioides and further fungal pathogens as playing a major role.

Since fruit drop causes significant crop loss in oranges, lemons, grapefruit, limes, and other types of citrus, it is a major concern for the industry. Dr. Vladimiro Guarnaccia, associate professor of Plant pathology at the University of Torino and a lead researcher on this project, will present the methods and results of his team’s two years of work at the third and final KeyPlex Citrus Symposium on July 25, 2024, at Seven Sebring Raceway Hotel in Sebring, Florida. Most importantly, he will present solutions to aid citrus growers, such as agronomic practices and control methods based on his observations and preliminary tested conclusions.

“We started hypothesizing that Glomerella cingulata — the sexual phase of C. gloeosporioides — was the main cause of early fruit drop in citrus, not HLB, as has been long presumed,” says Gerald O’Connor, CEO of KeyPlex. “We scoured the world looking for information on this and came across Dr. Guarnaccia, who was already working on it at the University of Torino. We are excited to present the results of this groundbreaking research — the result of many years of work — that will help the citrus industry.”

Email Gerald O’Connor at for a personal invitation.

Read the full report of :
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Stem-End Rot of Sweet Orange, Citrus sinensis, in Florida

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