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ARS Home » Southeast Area » Poplarville, Mississippi » Southern Horticultural Research Unit » Research » Research Project #438108

Research Project: Management of Diseases, Pests, and Pollinators of Horticultural Crops

Location: Southern Horticultural Research Unit

2021 Annual Report

1. Develop environmentally friendly strategies for the control of small fruit diseases based on chemical, biological, and/or cultural control by conducting basic and applied research on the epidemiology, pathogenesis, and genetics of small fruit pathogens and their hosts. 1.1. Assess the effect of supplemental lights (LED, UV-B) on anthracnose pathogen growth in culture and on infection of greenhouse grown strawberries. 1.2. Assess the use of cover crops to reduce root rot pathogen populations in blueberry fields. 1.3. Develop a protocol to identify anthracnose resistant strawberry seedlings using non-viable culture filtrates of the anthracnose fungi. 2. Expand the scope and efficacy of plant pathogen sanitation technologies at multiple disease management scales involving propagation, general sanitation, and seasonal irrigation water treatment for ornamental production systems. 2.1. Evaluate spatial distribution of bacteria causing bacterial gall of Loropetalum in commercial nurseries and its association with stem cuttings used for propagation. 2.2. Determine rate activity responses for major commercial disinfestants against bacterial, fungal and viral plant pathogens. 2.3. Develop integrated preventive and reactive disease management strategies to control Pseudomonas, Colletotrichum, and Phytophthora in propagation facilities. 2.4. Develop concentration-time (CT) rates with water quality and temperature as covariates for treatment of Phytophthora nicotianae in irrigation water. 2.5. Model the relationship of seasonal dispersal of Phytophthora zoospores in recycled irrigation water with plant disease symptom development and weather conditions. 3. Discover, test, and develop new conventional and organic controls for the Spotted Wing Drosophila (SWD) and develop improved bee-safe practices for their application. 3.1. Discover and test erythritol, its derivates, essential oils, and insect growth regulators (IGRs) for control against SWD and other serious horticultural insect pests. 3.2. Test for additive or synergistic activity from combinations of select compounds from sub-objective 3.1 with biopesticides. 3.3. Test health safety of compounds from sub-objectives 3.1 and 3.2 to honey bees and important native bee crop pollinators. 4. Develop new management and conservation techniques for honey bees and important wild native bee pollinators for small fruit, vegetable and ornamental crop production. 4.1. Collect cocoons from trap-nests for managing orchard bees and chimney bees as fruit pollinators. 4.2. Develop and implement a pollinator release program. 4.3. Assess effects of common and new insecticides on these and other native bee pollinators of horticultural food crops. 4.4. Assess the use of soybean cultivars as bee forage for native and honey bees during the summer dearth along the Gulf Coast.

Evaluate influence of multiple light spectra, including UV-B light, on strawberry plant growth and as a way to inhibit germination and growth of anthracnose pathogens, thereby reducing disease. Assess effect of rotational cover crops (legume, brassica and grass), fallow and chemical treatments on Phytophthora populations in the soil and on severity of root disease on blueberry in replanted fields. Develop plant screening protocols using non-viable filtrates with presumed toxins of anthracnose pathogens to identify anthracnose resistance in strawberry seedlings. Sample for and analysis for distribution patterns of the bacterial knot pathogen on Loropetalum nursery stock to develop strategies for propagating pathogen-free plants. Identify differences in pathogen sensitivities, substrate demand loads and environmental factors that favor and interfere with disinfestant activity for several disinfestant chemical classes. Evaluate what combination of disease control practices allow for minimum levels of integrated management needed to control several major pathogens in woody plant propagation. Identify water quality and environmental factors that require adjustment in disinfestant concentration exposure to maintain control of Phytophthora in irrigation water. Monitor Phytophthora levels in pond water, the resulting disease progress on woody plants irrigated with the pond water and correlate these with favorable environmental conditions. Investigate how chemical formulation affects the activity of sugar alcohol pesticides, essential oils, and insect growth regulators applied to different stages of the spotted-wing Drosophila (SWD) fly. Identify what combination of chemicals previously tested by this research unit provide maximum mortality of SWD. Evaluate health effects on honey bees, orchard bees, chimney bees, and southeastern blueberry bees exposed to the chemicals evaluated by this research unit for SWD control. Collect orchard bees and chimney bees from across the southern U.S., establish them by commercial blueberry fields in Mississippi, determine their suitability as a pollinator and develop colony rearing practices. Establish orchard bee and chimney bee colonies near cooperating blueberry fields and monitor seasonal dispersal behaviors. Evaluate health effects on bee pollinators exposed to various insecticides, then assay for gene activity, enzyme activity and protein profiles. Evaluate the bloom period of soybean cultivars planted at several dates and monitor the feeding activity and health of native and honey bees.

Progress Report
An ARS plant pathologist at Poplarville, Mississippi in collaboration with university researchers at Tennessee State University, McMinnville, Tennessee documented efficacy of commercial disinfestant products to control two boxwood blight fungi, Calonectria pseudonaviculata and Pseudonectria foliicola, in solution, on blades of pruners and on boxwood greenery used as decorative products. An ARS plant pathologist at Poplarville, Mississippi performed systematic reviews and meta-analyses to summarize the existing knowledge on the efficacy of quaternary ammonium disinfestant compounds for controlling plant pathogens in agricultural and horticultural crop production systems. Results showed the current recommended rates for dose and contact time of commercial products are generally expected to result in effective disinfestation, but efficacy is expected to be influenced by the type of pathogen (bacteria, fungi, oomycete and virus), genus within pathogen type, the target material being treated, and by what generation QAC product is applied. An ARS plant pathologist and a plant geneticist at Poplarville, Mississippi collected diseased plant samples from a Christmas tree farm, extracted and sequenced RNA for collaborative research with researchers at Colorado State University involving annotation and transcript expression of Passalora sequoiae, the cause of Leyland Cypress blight. An ARS plant pathologist in Poplarville, Mississippi performed limited laboratory research on the activity of disinfestants on Colletotrichum camelliae, with effort initially requiring recovery, identification and pathogenicity testing of isolates. An ARS plant pathologist and a university researcher at Poplarville, Mississippi, reported that older declining rabbiteye blueberry bushes can be renovated by pruning bushes at 50-cm above ground level. In two consecutive years, bushes pruned at this height had much higher yields, and by the end of the study produced more canes than unpruned bushes. This resulted in more fruiting area and provided a substantial yield benefit. If blueberry growers prune old, nonproductive rabbiteye blueberry bushes at a 50-cm above ground level, they will have a greater potential for early economic returns compared to pruning bushes at ground level. ARS and Mississippi State University researchers at Poplarville, Mississippi, studied the effect of nitrogen levels on white drupelet disorder in ‘Sweetie Pie’ blackberry. Over two seasons one and five applications of the same amount of nitrogen decreased the percentage of white drupelet berries from 12.1% to 9.4% (one application) and 8.6% (five applications) compared to the control treatment of no additional nitrogen. The occurrence of white drupelets was also correlated with the number of rainfall events. It is likely that multiple factors are involved in development of white drupelets in blackberry fruit; however, application of additional nitrogen can reduce the problem and thus, increase the yield of market quality blackberry fruit. ARS scientists at Poplarville, Mississippi in cooperation with researchers from the University of Hawaii have identified two essential oils, pulegone and linalool, which, at a 1% concentration, killed 50% of Spotted Wing Drosophila (SWD) adults and eggs in a blueberry field, a level of control equal to the positive control, Entrust, an organic insecticide currently used for SWD control in blueberries. Commercial companies, OMEGA, LLC (Ontario, Canada and Delaware, USA) in cooperation with Bayer AgroScience are interested in developing and licensing these essential oils as agricultural insecticides. An ARS entomologist in Poplarville, Mississippi developed novel traps using plastic dome traps with a sugar-yeast bait for area-wide SWD suppression. Early tests showed that the yeast growth under warm conditions can fill traps and prevent fly capture. Field evaluation by ARS scientists in Poplarville, Mississippi of the traps in commercial blueberry fields has yet to conducted, but will commence during the next field season. ARS entomologists in Poplarville, Mississippi constructed a light-weight prototype trap for managing populations of an opportunistic cavity-nesting bee, Osmia ribifloris, a potential blueberry pollinator. This fiscal year, 85 standard wood blocks, each with 5 nesting cavities (425 nests total) were constructed with hanging hardware attached. Additionally, 4 large and 2 small coffee-can prototypes filled with cardboard nesting straws were completed along with 37 small hand-taped bundles of straws to be placed in precut PVC pipes. These straw-nest designs will be deployed and evaluated by ARS scientists in Poplarville, Mississippi in habitats containing the bee’s primary floral host, Agarita. Deployment of these nesting domiciles to Texas in the late winter and early spring was delayed due to early COVID restrictions. ARS entomologists in Poplarville, Mississippi determined that a number of commercial soybean varieties provided sufficient sources of nutrition for native bees and honey bees in the mid-southern United States. Varieties that were adapted to the Mid-South as well as some that were more adapted to subtropical areas including south Texas and Mexico, provided sufficient food sources for bees during periods of time where local flora where not readily available (i.e. summer dearth).


Review Publications
Stafne, E., Smith, B.J. 2021. Higher renovation pruning height improves early yields of ‘Woodard’ rabbiteye blueberry. HortTechnology. Volume 31:Issue 2/188-191.
Copes, W.E., Ojiambo, P.S. 2021. Efficacy of Hypochlorite in Disinfesting Nonfungal Plant Pathogens in Agricultural and Horticultural Plant Production: A Meta-Analysis. Plant Disease. 105:4084-4094.
Bika, R., Copes, W.E., Baysal-Gurel, F. 2021. Comparative performance of sanitizers in managing plant-to-plant transfer and postharvest infection of Calonectria pseudonaviculata and Pseudonectria foliicola on Boxwood. Plant Disease.
Lawson, A., Steckel, S., Williams, M., Adamczyk Jr, J.J., Stewart, S. 2021. Insecticide and Fungicide Residues Following a Foliar Application in Cotton and Soybean. Journal of Cotton Science. 24:159-167.
Goblirsch, M.J., Eakins, J., Rowan, N. 2021. Disease-Mitigating Innovations for the Pollination Service Industry: Challenges and Opportunities.. Current Opinion in Environmental Science & Health. S2468-5844(21)00037-4.
Meikle, W.G., Adamczyk Jr, J.J., Weiss, M., Ross, J.F., Werle, C.T., Beren, E.D. 2021. Sublethal concentrations of clothianidin affect honey bee colony growth and hive CO2 concentration. Scientific Reports. 11. Article 4364.
Alburaki, M., Chen, D., Dkinnrt, J.A., Meikle, W.G., Tarpy, D.R., Adamczyk Jr, J.J., Stewart, S.D. 2018. Honey bee survival and pathogen prevalence: from the perspective of landscape and exposure to pesticides. Insects. 9(2):65.
Meikle, W.G., Adamczyk, J.J., Weiss, M., Gregorc, A. 2018. Effects of bee density and sublethal imidacloprid exposure on cluster temperatures of caged honey bees. Apidologie. 49(5):581-593.
Zhu, Y., Yao, J., Adamczyk Jr, J.J. 2018. Long term risk assessment on noneffective and effective toxic doses of imidacloprid to honey bee worker. Journal of Applied Entomology. 143:118-128.
Gregorc, A., Sampson, B.J. 2019. Diagnosis and integrated control of Varroa mites (Varroa destructor) infesting honey bee (Apis mellifera) colonies – a review. Journal of Apicultural Research. 11.
Jurisic, S., Skerl, M., Gregorc, A., Sampson, B.J. 2019. Hydroxymethylfurfural Affects Caged Honey Bees (Apis mellifera carnica). Diversity Magazine. 12(1).
Strange, N.C., Moulton, J.K., Bernard, E.C., Klingeman, W.E., Sampson, B.J., Trigiano, R.N. 2020. Floral Visitors to Helianthus verticillatus, a Rare Sunflower Species in the Southern United States. HortScience. 55(12):1980–1986.
Gregorc, A., Sampson, B.J., Knight, P., Adamczyk Jr, J.J. 2019. Diet quality effects on honey bee (Hymenoptera: Apidae) mortality in laboratory conditions. Journal of Apicultural Research. 58:4, 492-493.
Alburaki, M., Gregorc, A., Adamczyk Jr, J.J., Stewart, S.D. 2018. Insights on pollen diversity of honeybee Apis mellifera L. colonies located in various agricultural landscapes. Southwestern Naturalist. 63/49-58.
Sampson, B.J., Easson, M.W., Stringer, S.J., Werle, C.T., Magee, D., Adamczyk Jr, J.J. 2018. Laboratory assessment of erythritol derivatives on the survival and reproductive rate of Drosophila suzukii (Diptera: Drosophilidae). Journal of Economic Entomology. 112(1)/173-180.