An individual grower’s response to pests and diseases in their vineyard can have consequences for an entire growing region. Collective action strategies can help align grower responses to achieve better regional disease control. Ways in which we identify, approach, and address manager opinions regarding cooperative management efforts influences the success of collective action strategies. A Q-method survey was conducted to investigate the adoption obstacles of wine grape growers to regionally collective actions for managing pests and diseases. Qualitative information from the western US (n = 17 participants) was used to generate 36 statements describing opinions on collective management action and general disease management. A second set of grape producers (n = 59) were asked to rank these statements relative to each other. Participants perceived that collective management action would be worth the extra associated time or costs. Four prominent archetypal perspectives arose from the Q-method analysis explaining 66% of the variance in expressed opinions. Archetypes were termed, “The Cooperators" (14 of 59), “The Quasi-Individualists” (9 of 59), “The Mid-Level Pragmatists” (8 of 59), and “The Bottom-Line Focused” (5 of 59). These groups were split across the demographic information collected; archetypes explained more variation between responses than demographic information. Overall, participants were likely to agree that cooperation was important, but they were more concerned about their individual vineyard economic and crop health concerns. Thus, suggesting that if outreach professionals want to increase the likelihood of grape grower participate in collective pest management actions, they should emphasize the individual benefits of participation.

Knowledge about how producers subjectively assess and communicate about different information resources can help optimize Agricultural Extension efforts. In particular, how do growers use different information resources when making decisions on pest and disease management? Using pest and disease management in wine grapes ( Vitis vinifera) as a case study, three surveys were conducted among grape producers in the western United States to qualitatively explore resource options ( n = 15), examine the relative importance of the 23 different information resources identified ( n = 63), and investigate the social networks where information is passed within and between regions ( n = 65). Five different informational archetypes emerged, demonstrating different preferences for information resource use, which explained 66% of the variance in survey responses. Personal connections (e.g., discussion with professional network, with field foreman and supervisors, and with an Extension agent) were extremely important to the participants. In the communication network analysis, 65 participants were used to form a 324-actor network with 448 links, which were then subdivided into intra-state networks. The networks show evidence of structures that facilitate information diffusion and cooperation between independent producers. Additionally, even with networks much smaller than the grape producer populations in these states, influential individuals could be identified. These individuals, when targeted by outreach professionals, could assist with information dissemination and facilitate changes in opinion or behaviors in the region. [Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 “No Rights Reserved” license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2024.

Anisogramma anomala, a biotrophic ascomycete, causes eastern filbert blight (EFB) of hazelnuts (Corylus spp.). EFB is endemic in eastern North America, preventing the commercial production of European hazelnut (C. avellana L.). In contrast, the historic absence of A. anomala in the Pacific Northwest (PNW) supported the development of a robust hazelnut industry. Circa 1960, A. anomala was inadvertently introduced into southwestern Washington, causing orchard devastation. Distribution of the pathogen in the PNW has been hypothesized to be the result of a single-point introduction. This study aimed to investigate the single-point introduction hypothesis of A. anomala by comparing the genetic diversity of A. anomala samples from the PNW and New Jersey (NJ). Specimens from the main PNW production region (n = 60) and an area within the pathogen's native range, NJ (n = 151), were genotyped using 15 simple sequence repeat (SSR) markers. The following were used to assess genetic diversity and population structure: allelic summary statistics, discriminant analysis of principal components, network median-joining tree, analysis of multilocus genotypes, and allelic population diversity analysis. Analyses separated the samples into one cluster containing all the PNW isolates, and five clusters of NJ isolates. The PNW samples were nearly genetically uniform, and the NJ isolates were diverse. These findings support the hypothesis that A. anomala in the PNW was derived from a single-point introduction and corroborate previous studies that have shown A. anomala is very diverse in NJ. This indicates that maintaining restrictions on the movement of Corylus into the PNW is important to prevent the introduction of new populations of A. anomala, thus protecting the PNW hazelnut industry.

Eastern filbert blight (EFB) and pacific flatheaded borer (PFB) are two problems of Pacific Northwest orchard and nursery production. Fungicides and insecticides used to manage these issues are typically applied to plant tissues with minimal foliage present that can result in considerable spray waste or drift. The Intelligent Spray System (ISS) is a laser-guided, variable-rate sprayer that detects objects in the target zone and releases spray volumes proportional to the density of plant tissues, thereby increasing application efficiency and reducing waste. However, the ISS has not been tested when targeting low-foliage plant tissues such as emerging shoots and trunks. Three experiments were conducted from 2018 to 2021 to evaluate the potential use of the ISS for EFB and PFB management by assessing spray coverage on emerging hazelnut shoot tips, hazelnut tree trunks, and maple tree trunks. On hazelnut shoot tips, coverage was <10% of the shoot on both adaxial and abaxial sides, with the highest coverage on the adaxial side (9.5%) resulting from spraying in standard mode (no sensors) at 3.1 kph. On hazelnut trunks, application at the slowest tested speed (3.1 kph) in intelligent mode resulted in spray coverage greater than or equal to that applied in standard mode at 5.1 kph. In addition, coverage was significantly higher on cards placed on the ground between trees when the sprayer was used in standard mode, indicating higher amounts of wasted spray and drift over intelligent mode. On maple trunks, the slowest speed tested (3.1 kph) resulted in the highest coverage of tree trunks facing the sprayer that were two and three rows away from the sprayer, with the highest coverage levels on the row of trees closest to the sprayer occurring at the highest tested speed of 6.4 kph. On cards placed on trunk sides not facing the sprayer, the slowest tested speed of 3.2 kph resulted in significantly higher coverage than both treatments at 6.4 kph and intelligent mode at 4.8 kph in the tree row closest to the sprayer. This work has demonstrated a baseline of coverage that hazelnut buds receive when spraying for EFB, illustrates that the ISS was able to effectively target trunks, and could be an alternative to drenches for PFB control.

There are over 35 known virus and virus-like diseases of sweet cherry (Prunus avium), some with potential to cause severe economic impact by reducing vegetative growth, vigor, or fruit quality. Oregon is the second-ranked state for sweet cherry production in the United States. Statewide surveys were conducted in Oregon sweet cherry orchards for virus and virus-like diversity and distribution. Orchards in key production regions with suspected virus disease symptoms were sampled. Virus-specific enzyme-linked immunosorbent assay, isothermal amplification, or quantitative real-time PCR were used to test for the presence of common or economically important sweet cherry pathogens, including cherry leaf roll virus (CLRV), little cherry virus 2 (LChV2), prune dwarf virus (PDV), prunus necrotic ringspot virus (PNRSV), tomato ringspot virus (ToRSV), and ‘Candidatus Phytoplasma pruni’. CLRV, a new virus of sweet cherry in Oregon, was found associated with enation and dieback symptoms in The Dalles. Some viruses were found in new regions, which included Hood River (PDV, PNRSV, and ToRSV) and the Umpqua Valley (PDV and PNRSV). A subsequent survey was conducted in the Mid-Columbia production region for the presence of little cherry symptoms associated with little cherry and X-Diseases. All symptomatic samples from The Dalles and Mosier, OR, or Dallesport, WA, tested positive for ‘Ca. P. pruni’ but not LChV2. These findings provide a foundation for the current understanding and management of virus and virus-like diseases of sweet cherry in Oregon and context for further studies into these pathogens and their vectors.

Organic blueberry production in the PNW has many challenges, including diseases like mummy berry caused by the fungus Monilinia vaccinii-corymbosi (Reade) Honey. Management recommendations focus on reducing overwintering pseudosclerotia, however, it is unknown how long they survive. Based on qualitative observations pseudosclerotia are hypothesized to survive multiple years after contact with the soil surface. The development of apothecia from M. vaccinii-corymbosi pseudosclerotia was evaluated over multiple years at a location without a history of blueberry production. A total of 1,000 pseudosclerotia were placed on field soil plots in 2018 and replicated eight times. Another 100 pseudosclerotia were placed in wire corrals on field soil and replicated fifteen times. Plots and corrals were regularly examined each spring for the emergence of apothecia. The pseudosclerotia were able to survive, germinate, and produce apothecia for up to five years after their placement. Very few pseudosclerotia produced apothecia in any year, varying from 0 to 18 at any observed time. Pieces of partial or whole pseudosclerotia were observed for up to three years after placement. Our study shows that a pseudosclerotial “seed bank” exists under blueberry bushes, necessitating a long-term implementation of mummy berry cultural management tactics.

Boxwood blight (BB) caused by Calonectria pseudonaviculata (Cps), an economically devastating disease affecting everyone in the supply chain from growers to gardeners, was first officially documented in the United States in 2011. This disease has taken a heavy toll on boxwood, an iconic landscape plant and the number one evergreen nursery crop. Instead of abandoning boxwood production and switching to other evergreens, growers in the United States, informed by the latest research, have elected to combat this disease. One of the strategies employed has been to shift boxwood production from highly susceptible to less-susceptible cultivars. The objective of this study was to investigate the ongoing shift by comparing boxwood sales of 17 selected nurseries from seven states across the country in 2011, 2016, and 2021. Results revealed an additional 21.24% (from 38.58 to 60.04%) in sales of less-susceptible boxwood cultivars in 2021 compared with 2016. The less-susceptible cultivars responsible for increased boxwood sales are 'Winter Gem', 'Wintergreen', 'SB 300' (Freedom), 'SB 108' (Independence), and 'Little Missy'. The potential for long-term positive impact on sustainable boxwood production and plantings in the United States through the use of less-susceptible cultivars is discussed. This shift in boxwood choices builds crop health into new plantings of this landmark plant and sustains growth in demand for boxwood. This sets a new example of sustainable protection for a crop that is under serious pressure from an invasive pathogen.

The hazelnut (Corylus avellana) cultivars ‘Ennis’, ‘Jefferson’, and ‘McDonald’ were inoculated with various doses of Anisogramma anomala ascospores to determine whether high concentrations of ascospores resulted in eastern filbert blight (EFB) cankers. Trees at budbreak or early shoot growth were inoculated with 0, 10 4 , 10 5 , 10 6 , and 10 7 ascospores/ml, placed in a mist chamber for 72 h, and held for 1.5 years for canker development. Ennis trees became infected when the concentration was at least 10 4 ascospores/ml whereas resistant trees became infected only when the concentration was 10 6 or 10 7 ascospores/ml. The progression of EFB symptoms in a 10-ha Jefferson hazelnut orchard was also documented over a 5-year period from 2010 to 2014. EFB cankers were first observed fall 2010, averaged 7 cm in length, and were characterized by longitudinal cracks and flat or slightly sunken areas on trunks. Some cankers had a few small stromata with viable ascospores. Cankers on 143 trees were measured after leaf fall each year. Comparison between the initial canker size and the final size measured in 2014 indicated that 49% of the cankers continued to get larger but there was no indication of whether the cankers would increase or decrease in size over time. Growers should use fungicides the first few years after planting until trees are established and vigorously growing. Cankers that develop on resistant trees should be removed and destroyed prior to budbreak in the spring.

In this Short Communication we describe the occurrence of mummy berry associated with huckleberry (Vaccinium membranaceum) caused by Monilinia spp. in Oregon. To our knowledge, this is the first report of a Monilinia spp. associated with mummy berry of huckleberry in Oregon. Sequence data from our specimens reveal the closest identity was Monilinia vaccinii-corymbosi, a pathogen of commercial blueberry (Vaccinium corymbosum). This may be a new species of Monilinia, not previously reported on huckleberry, and further investigation is needed. Of specific importance, the huckleberry holds cultural importance as a sacred First Food of the Confederated Tribes of the Umatilla Indian Reservation and other Pacific Northwest tribes. Although plant pathogen management in natural landscapes presents unique challenges, we will work with tribal authorities to determine whether cultural management techniques may mitigate yield loss due to Monilinia spp.

To optimize pesticide applications to the canopies of deciduous perennial crops, spray volume should be adjusted throughout the year to match the changes in canopy volume and density. Machine-vision, computer-controlled, variable-rate sprayers are now commercially available and claim to provide adequate coverage with decreased spray volumes compared with constant-rate sprayers. However, there is little research comparing variable- and constant-rate spray applications as crop characteristics change throughout a growing season. This study evaluated spray volume, spray quality (e.g., coverage and deposit density), and off-target spray losses of variable- and constant-rate sprayers across multiple phenophases in an apple (Malus domestica) orchard and a grape (Vitis vinifera) vineyard. The variable-rate sprayer mode applied 67% to 74% less volume in the orchard and 61% to 80% less volume in the vineyard. Spray coverage (percent), measured by water-sensitive cards (WSC), was consistently greater in the constant-rate mode compared with the variable-rate mode, but in many cases, excessive coverage (i.e., over-spray) was recorded. The variable-rate sprayer reduced off-target losses, measured by WSC coverage, up to 40% in the orchard and up to 33% in the vineyard. Spray application deposit densities (droplets per square centimeter) on target canopies were typically greater in variable-rate mode. However, the deposit densities were confounded in over-spray conditions because droplets coalesced on the WSC resulting in artificially low values (i.e., few, very large droplets). Spray efficiencies were most improved early in the growing season, when canopy density was lowest, demonstrating the importance of tailoring spray volume to plant canopy characteristics.

Hazelnut kernel mold, caused by a number of fungal species, has been a chronic problem in Pacific Northwest hazelnut production areas for many years. Two highly susceptible breeding selections and two commercial cultivars were used to investigate kernel mold development over time and possible correlations with rainfall. Nuts were allowed to naturally fall onto orchard soil, regularly collected, cracked open, and evaluated for kernel mold. Disease progress for each selection or cultivar was evaluated each year with both linear and exponential models. The general progression of kernel mold was similar for the two breeding selections and cultivars Ennis and Lewis, where kernel mold increased slowly during the nut dropping period but more rapidly after normal harvest. An exponential model described disease progress better than a linear model for 8 of the 10 significant disease progress curves examined. Although some years had significantly higher estimated rates of disease increase, this parameter was inversely related to the area under the disease progress curve (AUDPC). The incidence of kernel mold did not significantly increase over time for 8 of the 18 disease progress curves examined, including 6 of 8 curves for commercial cultivars. The relationship between initial kernel mold incidence and AUDPC was described well with a simple linear model indicating that initial disease incidence appeared to be a good predictor of AUDPC. The longer nuts remained on the ground, especially after harvest, the higher the incidence of kernel mold. Kernel mold incidence was not significantly correlated with rainfall totals for any period of time from flowering to harvest. Multiple harvests ending shortly after all nuts have fallen should result in lower incidence of kernel mold for growers.

Bacterial blight ( Xanthomonas arboricola pv . corylina ( Xac )) of hazelnut ( Corylus avellana L.) was described first in Oregon in 1915 and is now recognized as a damaging disease of young hazelnut trees worldwide. Thousands of hectares of new hazelnut cultivars that are resistant to eastern filbert blight ( Anisogramma anomala ) are being planted in the Willamette Valley of Oregon, where 99% of the US hazelnut crop is grown. Reports of bacterial blight on young hazelnut trees have increased but information about the causal pathogen is limited. Isolates were recovered from tissues with bacterial blight symptoms that were then characterized for their ability to grow on semi-selective media, their nutrient utilization profiles using Biolog GN2, quinate metabolism, copper tolerance, hypersensitive response on tobacco, and pathogenicity on hazelnut. Additionally, isolates were identified with a duplex PCR assay ( ftsX and qumA ), 16S rRNA sequence, and multi-locus sequence analysis (MLSA) using rpoD and gyrB . Pathogenic isolates were identified as Xac using morphological, biochemical, molecular, and host assays. Using MLSA, Xac isolates from Oregon separated into two clades, one clade with the type strain and a second clade previously described using isolates from Europe. The phylogenetic diversity of Xac observed in other countries also is present in Oregon.

Many specialty crops are susceptible to insects and diseases, and as such are reliant on regular canopy pesticide applications to achieve quality attributes required for salability. The majority of specialty crop producers continue to use antiquated pesticide application technologies for directed canopy spraying such as the radial air blast sprayer that has been associated with chemical wastage and off-target drift of around 40% and 15% of total applied spray volume, respectively. However, precision sprayers are available that result in remarkable improvements to these parameters. The wide-scale adoption of precision sprayers by specialty crop producers remains low. Reasons for the continued dominance of old technologies include risk averseness of farmers and regulatory bottlenecks. However, as farm labor becomes more expensive, less available, and consumers and regulations favor sustainably produced products, motivations to improve spray application efficiency are increasing. While there are many opportunities and future directions application technology may take, sensor-controlled sprayer technology that applies a proportionate amount of spray will likely be the primary technology of precision sprayers going into the future. (c) 2020 Society of Chemical Industry

Boxwood blight, caused by Calonectria henricotiae and C. pseudonaviculata, is an extremely destructive disease of cultivated and native Buxus species (boxwood) worldwide. The disease is widespread in North America, Europe, and Southwest Asia. Early and accurate diagnosis of boxwood blight is the most effective tool used to prevent spread of the disease, and it is the first step for development and implementation of appropriate control measures. This diagnostic guide provides up-to-date information on how to diagnose and identify boxwood blight and also offers an overview of methods used to isolate the pathogen, store cultures, and evaluate pathogenicity of the causal agents.

Wine grapes are an important agricultural commodity in the Pacific Northwest, where grape powdery mildew (GPM) is one of the main disease problems. The efficacy of various sulfur concentrations and output volumes from an air blast sprayer retrofitted with the Intelligent Spray System (ISS) were evaluated for the management of GPM. The ISS consists of a LiDAR sensor, Doppler speed sensor, embedded computer, flow controller, and individual pulse-width-modulation solenoid valves at each nozzle. GPM cluster severity ranged from 55 to 75% across all trials in the study when the ISS was used at its default spray rate of 62.5 ml/m3 with micronized sulfur at 6 g/liter, which was significantly higher than all other fungicide treatments but lower than nontreated controls. Similarly, leaf incidence values were highest on nontreated vines, followed by micronized sulfur at 6 g/liter applied at 62.5 ml/m3, with all other fungicide treatments being significantly lower in all trials. Using the ISS at the 62.5 ml/m3 rate and a rotation of locally systemic fungicides resulted in the lowest observed GPM leaf incidence and average cluster severity of 11% in both 2019 and 2020, the lowest cluster severity of all fungicide treatments tested. GPM control with the ISS and micronized sulfur was equivalent to a constant-rate air blast treatment at 6 g/liter when the spray rate of the ISS was increased to 125 ml/m3 or the concentration of sulfur was increased to 24 g/liter. In those cases, the amount of sulfur applied to vines was at or above the minimum label rate from bloom until the end of the season, or the entire season, respectively. This study has shown that sufficient disease control cannot always be expected when pesticides are mixed at the same rate as would be used for a constant-rate sprayer in a variable rate sprayer, especially when contact fungicides such as sulfur are used. With appropriate adjustments, the variable-rate ISS can be a useful tool to reduce pesticide quantities, water needed for mixing, and as a result labor, because fewer trips to refill for a given spray event are needed.