Location: Horticultural Crops Disease and Pest Management Research Unit
Project Number: 2072-22000-046-000-D
Project Type: In-House Appropriated
Start Date: May 8, 2022
End Date: May 7, 2027
Objective 1: Improve and expand knowledge of the prevalence of genotypic and phenotypic diversity in existing and emerging plant pathogens of small fruits and nursery crops. Sub-objective 1.A: Evaluate boxwood blight in Oregon nurseries. Sub-objective 1.B: Develop molecular diagnostics and tools to facilitate research on a nematode/virus disease complex. Sub-objective 1.C : Identify factors that cause blueberry shock virus recurrence in commercial fields and blueberry breeding lines. Objective 2: Understand how pathogen biology and diversity interacts with environmental factors to cause disease of small fruits and nursery crops. Sub-objective 2.A: Influence of plant spacing and irrigation frequency on the spread of boxwood blight from infected plants to healthy plants. Sub-objective 2.B: Cellular level response of Meloidogyne spp. to nematicides. Objective 3: Develop chemical and host resistance disease management strategies for nursery crops and small fruits. Sub-objective 3.A: Evaluate newer fungicide chemistries for control of Phytophthora root rot of rhododendron by sensitivity assays. Sub-objective 3.B: Novel nematicide discovery: Solanum sisymbriifolium as a source of nematicidal compounds. Sub-objective 3.C: Screen selected Rubus idaeus (red raspberry) accessions for resistance to raspberry bushy dwarf virus Objective 4: Develop robust and reliable diagnostic assays for plant virus detection in small fruits. Sub-objective 4.A: Compare graft indexing, RT-PCR, and high-throughput sequencing methods for virus detection in strawberry. Sub-objective 4.B: Compare graft indexing, RT-PCR, and high-throughput sequencing methods for virus detection in Rubus.
The long-term goal of this project is to develop sustainable disease management strategies that are based on a knowledge of the identity and biology of the causal agent(s) and on knowledge of pathogen co-infections and interactions with the environment. This will be accomplished by: (1) determining the prevalence of key pathogens and nematodes constraining production of nursery and small fruit crops; (2) understanding how environment and management practices influence disease; (3) identifying new pesticides and disease resistant crop genotypes for the management of nursery and small fruit diseases; and (4) developing pathogen detection protocols for nursery certification and quarantine plant material. Knowledge about the prevalence of fungal pathogens, nematodes, and viruses in agricultural systems is key for establishing effective disease control methods. Surveys will be conducted to assess the incidence of fungal pathogens in nurseries, and viruses and nematodes in small fruit research and production fields. Molecular diagnostic tools will be developed to evaluate the ability of nematodes to vector plant viruses and to assess for virus coinfections in small fruit crops. Pathogen and nematode prevalence is influenced by their response to multiple environmental factors. Therefore, studies will be established to assess the influence of irrigation and plant spacing on the spread of fungal plant pathogens in outdoor container trials, and on the effect of nematicides on nematode fitness in laboratory trials. New pesticide chemistries are needed because multiple oomycete pathogens have developed resistance to fungicides and many traditional nematicides have been phased out because of harmful environmental and human health effects. New pesticide chemistries will be evaluated for their efficacy against oomycete plant pathogens and nematodes in laboratory, greenhouse and field experiments. In addition, host resistance plays a crucial role in successful disease management and diagnostic assays are needed to allow growers, regulatory agencies, and diagnosticians to quickly and accurately identify the pathogens causing disease. Small fruit genotypes from grower fields, breeding programs, and national germplasm collections will be screened for resistance or tolerance to key viruses and both traditional bioassays and modern DNA- or RNA-based technologies will be compared for their ability to detect a wide range of viral pathogens for the small fruit industry. Together, results from this research will identify chemical and nonchemical practices to reduce plant disease, and that can be deployed in horticultural systems in the future.