Epidemiology and Management of Plant-parasitic Nematodes in Winegrapes

Nematodes are root feeding organisms that can cause direct damage and can also be a virus vector. Nematodes can severely limit the successful establishment of vines and vineyards and impact production yields by 5-20%. There are several products available to growers to assist in managing Nematode populations and increase successful vine establishment. This research evaluates combinations of synthetic (at half the recommended commercial rate) and biological nematicides to reduce populations of plant-parasitic nematodes, and increase populations of free-living beneficial nematodes and to increase vine productivity.

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Heat stress in wine grapes: acclimation and potential mitigation

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.

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Enhanced IPM of Rose Stem Girdler, an Emerging Pest of Pacific Northwest Caneberries

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.

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Attraction and retention of beneficial insects through enhanced plant biodiversity in irrigated vineyards (Vitis vinifera L.)

The success of both integrated pest management and organic production is critically dependent on naturally occurring insect biological control agents. Numerous studies (including some in vineyard systems) have indicated that populations of beneficial insects can be increased by increasing plant diversity (e.g., through cover cropping). Research targeted specifically at the situation in eastern Washington irrigated vineyards is therefore urgently needed.

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Biology and Management of Cutworms in Washington Vineyards

Cutworms are capable of causing severe damage in vineyards during the early spring months when vines buds and tender shoots are at their most vulnerable. Damage to buds can cause severe crop loss in Washington vineyards, and this study supports the idea that the Cutworm species found on vineyard floors (on weeds, etc.) are a minor component of the fauna that actually damages grapevines. Vineyard sites with a large number of Cutworms on the vineyard floor did not necessarily sustain major bud damage. Conversely, sites with small numbers of Cutworms sometimes sustained major bud damage. This appeared to be related to ground cover presence/absence and/or type, but was also, in view of the rearing data, a consequence of most ground-dwelling species preferring to remain on the ground and not climb up grapevines.

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