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Read more about the article Optimizing Nutrient Management for Organically Grown Blueberries East of the Cascade Range

Optimizing Nutrient Management for Organically Grown Blueberries East of the Cascade Range

Northern highbush blueberry (Vaccinium corymbosum) production east of the Cascade Range is an important contributor to the national supply of organic blueberries. However, native soil conditions are alkaline, have high free calcium content, and low in organic matter. Although growers amend soils to lower pH and provide organic matter, these soil characteristics influence nutrient cycling and availability. Growers need data-driven guidelines on how to optimize nutrient management for their unique growing conditions, but few studies have been conducted in this important region. This project addressed that need with an emphasis on organic nitrogen fertility practices by evaluating the effects of commercially available organic nitrogen fertilizer sources applied at low, medium, and high rates on blueberry yield, fruit quality, and various plant and soil variables. Organic fertilizer nitrogen mineralization dynamics were also characterized via a laboratory incubation study at different temperatures.

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Read more about the article Risk assessment of nematode-transmitted viruses of small fruit crops in the Pacific Northwest

Risk assessment of nematode-transmitted viruses of small fruit crops in the Pacific Northwest

The Pacific Northwest (PNW) maintains a $840 million small fruit industry susceptible to nepoviruses, which are viruses that are transmitted by dagger nematodes. The association of viruses with nematodes is complicated with many nepoviruses, taxonomic confusion among vector nematodes, and limited data on the ability of Xiphinema spp. populations to vector many of the nepoviruses. Research was conducted to provide an up-to- date assessment of the problem in the region and to develop new molecular tools to improve detection of this disease complex. Over two years, 96 small fruit fields and vineyards were sampled in the PNW. In total 43 vineyard, 24 blueberry, 15 raspberry, 8 blackberry, 5 strawberry and one ribes fields were assessed for dagger nematode and nepoviruses. The highest incidence of dagger nematode was found in grape vines (79 %) followed by raspberry and blueberries. The population densities were 56 and 37 nematodes per 250 cc of soil in grapes and blueberry, respectively. Tomato ringspot virus (ToRSV) was found in three blueberry fields, while, in grape, raspberry and ribes only one field each. Tobacco ringspot virus (TRSV) was found in six vineyards.

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Read more about the article Evaluating Commercially Available Technologies for Weed Management in Blueberries: Saturated Steam and Rotary Brush

Evaluating Commercially Available Technologies for Weed Management in Blueberries: Saturated Steam and Rotary Brush

Washington and Oregon account for 85% of national raspberry production and 15% of worldwide production. Growers from Washington and Oregon harvest over 80 million pounds of raspberries on about 12,000 acres. Tomato ringspot virus (ToRSV) continues to be a problem in raspberry production in the Willamette Valley in Oregon, and in southern Washington. The predominant mode of spread of ToRSV is via the nematode vector Xiphinema americanum, also known as “Dagger” nematodes. Methyl bromide is often a method of choice for managing ToRSV and other nematode-borne plant viruses because it kills the nematode vectors. However, ToRSV often reappears within 3-4 years of fumigation with methyl bromide.

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Read more about the article Development of alternate fertilization programs to mitigate nutrient problems found in long-term organic production systems

Development of alternate fertilization programs to mitigate nutrient problems found in long-term organic production systems

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.

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Read more about the article Diversity of Pseudomonas syringae and diagnosis and management of bacterial canker on blueberry

Diversity of Pseudomonas syringae and diagnosis and management of bacterial canker on blueberry

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.

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