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UF/IFAS Indian River Research and Education Center (IRREC) Citrus Production and Other Tree Crops Research Laboratory 

UF/IFAS Indian River Research and Education Center (IRREC) Citrus Production and Other Tree Crops Research Laboratory 

The MAC Project 

The Indian River Region is historically known for its world-renowned grapefruit (Citrus paradisi) production. Since the detection of the HLB in Florida in 2005, grapefruit production, export, and quality declined steeply. HLB, also known as citrus greening, is a bacterial disease putatively caused by Candidatus Liberibacter asiaticus, and it is vectored by the Asian Citrus Psyllid (ACP, Diaphorina citri).

One of the challenges in the citrus industry is to keep a profitable crop with enough juice quality and little loss by diseases. To address this challenge, new varieties have been developed and needed to be tested in the field over several seasons to determine fruit and juice quality.

"The MAC Project” is a large variety trial established in 2018, focused on grapefruit, a prized crop in Florida that is in demand in Europe, Southeast Asia, and by consumers who celebrate our region’s premier grapefruit in the world. The goal of the project is to identify combinations that show HLB tolerance in endemic HLB environment.

Seven grapefruit scions and six rootstocks – including new potentially tolerant hybrids – totalizing 42 combinations were planted across the state in private citrus groves. A total of 40 blocks, each comprising 294 trees, were planted between 2020 and 2022. Of the 12,000 trees that are part of the trial, over 8,000 are measured bi-annually for plant response to disease, growth (via drone), annually for fruit and juice attributes. Fruit yield is a critical element of data collected and analyzed. Yield will determine if commercial production operations will be profitable for our growers.

 

 

On the left, Dr. Flavia Zambon processes leaf samples from experimental trees. On the right, Dr. Zambon works in a greenhouse with trees that were planted in groves that are part of The MAC Project. 

Collaborators' aims and funding sources 

The IRCL has been a collaborator since the inception of "The MAC project”, as more than a dozen citrus growers’ members of the IRCL have at least one experimental block on their land dedicated to “The MAC Project.” League members decide on cultural and chemical management practices. Such diversity on management is important since the experimental research blocks are in several Florida citrus production regions that represent different soils, microclimates, and irrigation systems.

“The MAC project” requires multiple years of production and data collection to establish reliable results. Researchers and growers alike believe multiple years of data will establish trustworthy recommendations for the industry to move forward with production of the world’s most coveted fresh grapefruit product.

The MAC Project was funded by the United States Department of Agriculture – Animal and Plant Health Inspection Service - Huanglongbing Multi-Agency Coordination (USDA – APHIS – HLB MAC) from 2018 to 2021.

The the Florida Department of Agriculture and Consumer Services (FDACS) funded The MAC Project in 2022. Since 2023, the Citrus Research and Development Foundation (CRDF) has funded The MAC Project.