Survey of blueberry (Vaccinium spp.) problems in the Gulf South.
The blueberry (Vaccinium) industry in Mississippi has been steadily increasing since the early 1980s, but some plants in older fields are now in decline. The root rot pathogen, Phytophthora cinnamomi, is endemic in the southeastern United States and has caused severe losses to blueberries in North Carolina and Arkansas. Because the warm, humid climate of Mississippi, with periods of high precipitation, provides a favorable environment for Phytophthora root rot disease, it was suspected to be the cause of plant decline in older blueberry fields. Members of the Gulf South Blueberry Growers Association were mailed surveys to determine cultural practices and the extent of losses in their blueberry fields. The survey was written in partial, open-ended question format with 33 questions pertaining to cultivars, number of hectares planted, cultural practices, overall health of the blueberry plants, and losses due to diseases, insects, or other problems. Fifty-eight of 146 surveys (40%) were completed and returned. 89% of respondents grew rabbiteye (Vaccinium ashei) cultivars and the balance grew southern highbush (V. corymbosum hybrids) cultivars. The average number of plants per hectare was 1523 with the majority of plants 10-20 years old. 79% of the growers described the overall condition of their plants as average, healthy, or vigorous. The most common cause of plant death cited was environmental with damage caused by the 2004 and 2005 hurricanes at the top of the list. No major diseases were reported by 36% of the respondents, while mummy berry (Monilinia vaccinii-corymbosi [Reade] Honey), leaf spots (many causal organisms), and root rot (Phytophthora cinnamomi Rands) were noted as problems by 22, 15, and 10% of the growers, respectively. Phytophthora species were isolated from root and soil samples collected from symptomatic plants on three farms. Weeds were listed as problems on 100% of the surveys. 47% of the respondents plan to increase their blueberry plantings mainly with rabbiteye cultivars.