Completed or Ongoing Research
Heat stress poses challenges for the sustainable production of premium wine grapes in the Pacific Northwest. The intensity of heat waves has been increasing. For example, the series of heat wave events in 2021 broke temperature records in many locations in this region, and heat waves were again common during the 2022 and 2023 growing season. Growers need knowledge of how grapevines adjust to heat waves or sudden temperature changes to make informed management decisions. We grew potted grapevines in environmentally controlled growth chambers under different temperature regimes (simulating cool and warm growing seasons) before exposing the vines to sudden temperature changes with maximum temperatures varying from 77°F to 104°F. Photosynthesis measurements showed that grapevines might tolerate a sudden rise in temperature better in a warm than a cool season. During extended heat waves, however, the cool season-acclimated vines recovered faster than the warm season-acclimated vines.
Rose stem girdler (RSG) is an invasive beetle pest of caneberry crops that is becoming increasingly problematic for Pacific Northwest (PNW) growers. It has progressively become naturalized throughout the northern Willamette Valley northward to the south Puget Sound region throughout the 2000s-present due to abundant wild bramble hosts. Grower reports of damage to crops has been variable, but with incidental claims of up to ~70% crop loss in a given year due to cane girdling by the beetle’s larvae. Control has been difficult and inefficient due to narrow windows of time for effective control (after adults emerge from canes, but before egg-laying begins 7 days later), and the lack of region-specific information to predict emergence and longevity of egg-laying activity. Our project objectives were: 1) to refine determinants of risk to PNW caneberry plantings from RSG through coordinated regional pest surveys, 2) to develop an enhanced integrated pest management (IPM) program with refined information on RSG detection methods, life cycle, and development of a pest management prediction model, and 3) to investigate biocontrol potential of a parasitoid wasp that may mitigate RSG’s viability and play a role in future IPM programs.
In long-lived organic blueberry production systems, nutrient imbalances caused by some fertilization and mulching practices can reduce yield and plant health. The ability to balance nutrient levels and thus improve productivity over time was evaluated in a mature planting of ‘Duke’ and ‘Liberty’ that had previously been used to study different mulching practices and various rates and sources of fertilizer. The prior fertilizer treatments were feather meal and fish emulsion, each applied initially at “low” and “high” rates of nitrogen (N), 29 and 57 kg·ha-1 N in 2007–08 and then increased incrementally as the planting matured to 73 and 140 kg·ha-1 N in 2013–2016. Mulch treatments included sawdust (9-cm deep), yard-debris compost (4-cm) + sawdust (5-cm) and weed mat. In winter 2016-17, existing weed mat was removed from plots where it was present, and new weed mat was installed on top of any existing organic mulches – thus changing the mulch treatments to weed mat (over bare soil), weed mat over sawdust, and weed mat over compost + sawdust from 2017–2020.
Black raspberry is a well-known Pacific Northwest specialty crop with unique flavor and nutritional attributes, but also unique vulnerabilities. A prominent threat facing the crop is the aphid-vectored Black Raspberry Necrosis Virus. Natural genetic resistance to aphids has been identified in black raspberry germplasm in Maine (ME), Michigan (MI), and Ontario (ON), Canada.
In a collaboration between OSU and USDA-ARS researchers, genetic linkage mapping found three separate but linked genetic loci on Rubus Linkage Group 6 (RLG 6). Attempts to target these loci with genetic markers could not clearly distinguish the three from each other.
Bacterial canker caused by the bacterial pathogen Pseudomonas syringae is characterized by killed buds and stems. The disease can be severe when environmental conditions support growth and infection of tissues in the fall and spring. The disease is especially damaging to young succulent plants. Copper is sprayed onto plants to control the growth of the pathogen and the development of bacterial canker. P. syringae actually refers to a complex group of pathogens, with individual members that have either a wide host range or narrow host range. Surprisingly, little was known about P. syringae causing bacterial canker on blueberry.
It was not known if only a single type of P. syringae with a narrow host range caused bacterial canker or if multiple types of the pathogen complex caused bacterial canker. P. syringae can use many traits to cause plant diseases, such as the production of plant toxins or the ability to nucleate ice formation.
