Submitted to: Pacific Agriculture and Natural Resources
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2015
Publication Date: 7/2/2015
Citation: Keith, L.M., Matsumoto Brower, T.K., Suzuki, J.Y., Follett, P.A., Zee, F.T. 2015. Screening for powdery mildew resistance in ohelo berry germplasm in Hawaii. Pacific Agriculture and Natural Resources. 1:1-9.
Interpretive Summary: Ohelo berry is an endemic Hawaiian shrub and a food source of the endemic nene goose. To alleviate impacts to the environment during the wild gathering of fruits Ohelo cultivars for small-scale cultivation were selected. Powdery mildew was found to be the main disease affecting Ohelo. Plants were screened for potential sources of host resistance.
Technical Abstract: Ohelo, Vaccinium reticulatum (Smith), is an endemic Hawaiian shrub, less than 1 m (3.3 ft) tall, and grows between 640 and 3700 m (2,100 to 12,100 ft) elevation on disturbed volcanic sites on the islands of Maui and Hawaii. Concerns have arisen about human impacts to the environment during the wild gathering of fruits that include spreading of exotic weeds, damaging native vegetation, and reducing a food source of the endemic nene goose, Banta sandvicensis (Vigor). As an alternative to wild harvest, ohelo cultivars for small-scale cultivation as ornamentals and for edible berries in Hawaii were identified, evaluated and selected. The main disease pressure that may limit berry production and ornamental qualities was determined to be from powdery mildew. Numerous disease resistance screens of diverse ohelo berry germplasm were conducted to identify potential powdery mildew resistance. Controlled inoculations were made onto leaf discs and potted seedlings in a growth chamber. The results were compared with natural epidemics in two locations on Hawaii Island, Mealani and Lalamilo, approximately 55 miles north of Hilo. There was a good correlation of ratings between the field and growth chamber experiments. None of the selected ohelo accessions were resistant to infection. However, accession N09-16 was consistently rated as tolerant for the first month of testing regardless of location. The results emphasize the importance of uniform testing in multiple environments using the most appropriate host material available.