Location: Southern Horticultural Research2011 Annual Report
1a. Objectives (from AD-416)
The objectives are to develop new and improved crop production practices and disease and insect control practices for ornamental, small fruit and other horticultural crops adapted to the U.S. Gulf Coast region. The developed management techniques are needed to minimize production losses and improve crop quality and yield for the purpose of increasing net income.
1b. Approach (from AD-416)
Identify and evaluate nutritional and cultural requirements, non-Apis pollination efficiency, insect pest problems, and plant disease problems to improve orchard establishment, human health benefit, crop yield, and post-harvest quality of fruit crops. Management techniques to be evaluated include planting systems, irrigation systems, fertilizer selection and timing, non-Apis bee colony establishment, suitability of bio-control organisms, pesticide selection and timing, cultivar selection, fruit handling, and post-harvest storage conditions. Identify and evaluate different organic substrates, insect pest problems, and plant disease problems to improve production options and crop quality of ornamental plants. Management techniques to be evaluated include irrigation and nutritional requirements of plants grown in different organic substrates, suitability of bio-control organisms, cultivar selection, pesticide selection and timing, pesticide application technology, disinfestant selection, and sanitation practices.
3. Progress Report
Progress in small fruit physiology research involved fertility studies. In a nutrient study, blueberry plants were sampled and mineral analysis completed. In a fertigation rate and timing trial, treatments were applied to blueberry plants, data collected, and samples prepared for analysis. Progress in entomology research included population assessment of parasitoids of blueberry gall midge in commercial and organic blueberry fields and development of native bee crop pollinators. Three parasitoids were abundant in 75% of blueberry fields. Collaborative work was done with California blueberry growers in developing a pollinator management program. Cinnamomum oil was shown to be effective as a quick-acting biopesticide that killed 100% of azalea lace bugs within 1 hr of exposure; comparable to Geranium and neem oils. Progress in small fruit plant pathology research included the isolation of Phytophthora species from symptomatic blueberry plants and identification of 19 Phytophthora cinnamoni isolates. Pot grown blueberry plants were inoculated with five Phytophthora cinnamoni isolates for the purpose of developing a method to screen blueberry germplasm for resistance to Phytophthora root rot. Treatments to control root rot were applied to blueberry plants in a field infested with Phytophthora spp. Treatments were applied to muscadine grapes to determine the effect of nitrogen fertilizer on disease incidence and severity. Strawberry germplasm was screened for the presence of two disease resistance markers. Blackberry cultivars were established in the field to evaluate their susceptibility to rosette and orange rust. Progress in ornamental horticulture research included studies evaluating irrigation volume and substrate suitability for greenhouse production of Boston fern, and the phytotoxic effects of wood-based substrates on seed germination and seedling growth of ornamental plants. Wood-based materials were acquired for future experiments. Progress in ornamental plant entomology research involved use of a pheromone for monitoring and controlling damage caused by leaf beetle pests in commercial nurseries. Progress in ornamental plant pathology research involved development of an integrated disease control strategy. Scouting protocol and use of environmental predictors were tested to determine the stage of disease development most responsive to fungicide treatment in nurseries. The influence of different forms of moisture on web blight development was modeled. Impact of hot water treatment used to kill Rhizoctonia was evaluated on root formation and development of azalea stem cuttings. Floor of nursery propagation houses were sampled for Rhizoctonia, and pathogen survival was evaluated on the floor of empty propagation houses. Irrigation was installed and trap-structures constructed to collect Camellia twig blight spores during rain and wind events.
1. Many food crops annually suffer yield losses due to inadequate pollination. A decline in honey bee populations is making it difficult for farmers to secure enough strong honey bee colonies. It may be prudent for farmers to first assess levels of free pollination services being provided by wild native bees. Crops better served by native bees would therefore require few if any honey bees as supplemental pollinations. More honey bee colonies could then be made available for pollinating larger and needier monocultures such as California almonds and cherries. It was discovered that a native bee crucially pollinates squash and pumpkin crops throughout the U.S. Native bees crucially pollinate U.S. fruits and vegetables. ARS scientists assessed the relative importance of wild bees and honey bees as pollinators of U.S. fruits and vegetables. ARS researchers in Poplarville, MS, and Logan, UT, confirmed that both male and female Peponapis pruinosa, an unmanaged solitary bee, were the most efficacious and reliable pollinators of cucurbit crops and that the prophylactic use of honey bees as pollinators would provide no additional profit to most cucurbit farmers.
2. The pathogen that causes azalea web blight lives on plant tissue all year in the southeastern U.S., although it only causes plant damage in July and August. Healthy appearing azalea stem cuttings collected for propagation in May to June may harbor the pathogen, which then multiplies in the propagation house to infest next year’s crop. Stem cuttings of twelve diverse azalea cultivars developed normal root systems after submersion in 122°F water for 20 minutes, a treatment that will kill the fungus that causes web blight. An ARS scientist in Poplarville, MS developed this knowledge in cooperation with scientists associated with Mississippi State University at Poplarville, MS; North Carolina State University at Raleigh, NC; Akita Prefectural University at Akita, Japan. Hot water is an environmentally friendly control practice. It is one part of a developing integrated disease management strategy to significantly reduce plant damage and reduce routine fungicide usage. The same disease problem occurs on multiple other woody shrub genera, such as holly.Copes, W.E., Rodriquez-Carres, M., Toda, T., Rinehart, T.A., Cubeta, M.A. 2011. Seasonal prevalence of species of binculeate Rhizoctonia fungi in growing medium, leaf litter, and stems of container-grown azalea. Plant Disease. 95:705-711.