UF Researchers Work to Manage HLB in Grapefruit

By Jaci Schreckengost

Due to the rapid rate huanglongbing (HLB) has affected citrus, researchers are working on new management techniques for the disease.

Rhuanito “Johnny” Ferrarezi, assistant professor in citrus horticulture at the University of Florida/Institute of Food and Agricultural Sciences (UF/IFAS) Indian River Research and Education Center (IRREC), says research is being done to answer questions about how HLB has affected grapefruit.

Ferrarezi says even though UF/IFAS has the Citrus Research and Education Center in Lake Alfred, grapefruit is very important to the Indian River region of Florida, which is why research is being conducted at IRREC as well.

Grapefruit is less tolerant to HLB than oranges, Ferrarezi says. A large number of researchers are trying to answer questions about the disease and find the best techniques to manage it.

Researchers have been working on nutritional sprays, which Ferrarezi says could be foliar or through the soil. The UF/IFAS Citrus Initiative recently granted funds to test different nitrogen sources and micronutrient rates in three different locations. The purpose is to update UF/IFAS nutrient recommendations in the post-HLB era.

Ferrarezi says researchers are also trying to create a variety of grapefruit resistant to HLB. He says typically there are less varieties of grapefruit compared to other citrus, because there are fewer materials and it is a more difficult crop to breed.

Citrus under protective screening (CUPS) is an effective option for preventing HLB, however cost is a large stipulation. CUPS prevents HLB with a screen over the crops to keep the Asian citrus psyllid, which vectors the disease, out of the plants.

Ferrarezi says he is also involved in a 37-acre field variety trial at IRREC to help find the best types of grapefruit and rootstock combinations to grow in the Indian River area. He says just because one kind of grapefruit grows well in one part of the state, does not mean it will work everywhere.

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