Breadfruit Disease Identification and Varietal Resistance in Hawai‘i

Breadfruit Disease Identification and Varietal Resistance in Hawai‘i

Breadfruit (Artocarpus altilis) plantings in Hawai‘i are growing exponentially, as research indicates over 2,500 trees have been established on commercial farms in the past 5 years and total plantings are expected to double further in the next 5 years (Langston and Lincoln 2018). A statewide assessment identified over 150 farms growing breadfruit and over 5,000 agricultural trees representing an estimated $1.5 million farm gate price once mature. This rapid development requires increased vigilance in disease monitoring to prevent crop losses and protect farm profitability. Diseases of breadfruit have caused widespread tree decline and death in Jamaica and the Pacific Basin (Trujillo 1971, Coates-Beckford and Pereira 1992), threatening local food production and the commercial breadfruit industry. This project addresses gaps in research on breadfruit diseases in Hawai‘i as well as varietal susceptibility and resistance to pathogens of the greatest concern. 

PIs worked with the Hawai‘i ‘Ulu Producers Cooperative and individual growers to identify and catalog Hawai‘i breadfruit diseases using producer reports, photographs, infected sample collection, and lab cultures. A total of 511 symptomatic samples were collected from 42 locations across Hawai'i State, with 468 samples yielding identification of potential causal agents. The project team conducted laboratory tests of varietal resistance and susceptibility for three diseases identified as major concerns for Hawai‘i breadfruit production - Colletotricum, Fusarium, and Phytophthora. Four strains of each of these genus were applied to the fruit and seedlings of five varieties in controlled settings. Varieties demonstrated significant differences in susceptibility to Fusarium and Phytophthora, but no symptoms were observed from the inoculations of Colletotricum. Findings were coupled with literature review and interviews with experts to produce an extension publication, technical factsheet, and outreach efforts to disseminate results. Results inform grower recommendations for varietal selection in Hawai‘i. These materials have and will be shared with producers and an extended network of international breadfruit researchers, producer groups and commercial manufacturers. While a relatively simple design and project, virtually no previous research has systematically confirmed pathogenicity for breadfruit diseases or examined differences in cultivar susceptibility (Lincoln et al 2018).

1. Through farmer network, identify and catalogue diseases affecting breadfruit (Artocarpus altilis) in Hawai‘i using reports from growers, photographs, infected sample collection, and lab cultures.
   July 2019 - January 2021

   1. Materials Produced: Hawai‘i Breadfruit Disease Catalog

   2. Field technician will work with farmer network to ship samples of infected fruit to CTAHR Phytomycology Laboratory where PIs Lincoln and Uchida will isolate, culture, and identify diseases. Collected diseases will be documented through farmer and PI photographs, field observations, and lab findings.

2. Conduct trials to determine susceptibility or resistance of five breadfruit varieties to three major diseases in Hawai‘i, including Phytophthora and Colletotrichum.

3. Develop and share Technical Factsheet on breadfruit diseases in Hawai‘i, including varietal resistance and susceptibility recommendations for specified diseases.

January 2021 - April 2021

1. Materials Produced: Technical Factsheet on breadfruit disease in Hawai‘i

2. Based on findings from Objective 2 above, PI Lincoln will develop varietal

   recommendations for Hawai‘i breadfruit growers. He will compile recommendations, disease documentation and photographs into a Technical Factsheet to help producers identify disease in their breadfruit trees. PIs will disseminate Factsheet to farmer and extension network.

4. Hold 2 on-farm workshops on breadfruit disease identification and management on major islands with commercial production, Hawai‘i and O‘ahu.
May 2021 - June 2021

a. PIs will lead two workshops on breadfruit disease identification on Hawai‘i Island and O‘ahu, distribute Technical Factsheet to participants, and evaluate participant subject knowledge before and after using SARE-approved surveys.