Pacific Northwest Potato Research Articles

Managing Plant‐Parasitic Nematodes in Pacific Northwest Potatoes

AbstractSeveral plant‐parasitic nematode species are found in Pacific Northwest potato fields, and they can potentially cause agronomic damage alone or, in some cases, in conjunction with diseases. Because of interactions with other host crops and pathogens, not to mention fumigant costs, managing the soil‐borne pests requires a combination that may include soil sampling, crop rotation, nematicides, fumigation, and biofumigation. Earn 1 CEU in Integrated Pest Management by reading this article and taking the quiz at https://web.sciencesocieties.org/Learning‐Center/Courses.

Improving Soil Health in Pacific Northwest Potato Production: a Review

Many factors are driving interest in improving soil health in potato production systems in the U.S. Pacific Northwest and beyond, including the need for enhanced sustainability and economic viability, and consumer preferences. Potato production poses a particular challenge in terms of soil health due to intensive tillage, minimal residue left on fields, short rotations, and the importance of managing soilborne pathogens. This review discusses existing soil health assessment methods and their relevance for the region and summarizes results of studies conducted in the Pacific Northwest and beyond, examining practices aimed at improving soil health and their effects on soil health, soilborne pathogens, yield and quality of potatoes, and net returns in potato production systems. These practices include reducing tillage; adjusting crop rotation length and species composition; reducing fumigation; and using cover crops, green manures, and organic amendments.

Susceptibility of Weedy Hosts from Pacific Northwest Potato Production Systems to Crop-Aggressive Isolates of Verticillium dahliae.

Verticillium wilt, caused by Verticillium dahliae, is a disease of dicotyledonous crops such as potato and has a wide host range and persistent, long-term survival structures called microsclerotia that can persist in soil for up to 14 years. Some V. dahliae isolates are particularly aggressive on a specific plant host while retaining the ability to infect a wide range of other hosts. Weeds can serve as hosts for V. dahliae but whether they serve as sources of inoculum for aggressive isolates of V. dahliae to crop hosts is unknown. The goal of this research was to quantify V. dahliae microsclerotia obtained from 16 weeds which were grown in the greenhouse. Potting medium was infested with one of eight V. dahliae isolates from potato, mint, sugar beet, sunflower, tomato, and watermelon. The isolates from mint and potato were aggressive on the host from which they were originally isolated. All 16 weeds were infected by at least one V. dahliae isolate, although the number of microsclerotia produced from some infections was relatively low (≤5 microsclerotia/g of dry plant). Black nightshade yielded greater numbers of microsclerotia of the V. dahliae potato isolate than any other isolate in three of four trials in the greenhouse (second trial false discovery rate, adjusted P ≤ 0.0158; third trial, P ≤ 0.0264; and fourth trial, P ≤ 0.0193). Litchi tomato yielded greater numbers of microsclerotia of the V. dahliae potato isolate than any other isolate in one of four trials (first trial, P ≤ 0.0149). A V. dahliae isolate from tomato yielded greater numbers of microsclerotia in large crabgrass and wild oat in a second trial (P ≤ 0.0158). Weeds, depending on the species, grown during and between potato crop rotations may increase the number of microsclerotia of the potato-aggressive isolates of V. dahliae.

Mountain Gem Russet: a Potato Variety with High Early and Full Season Yield Potential and Excellent Fresh Market and Early Processing Characteristics

Mountain Gem Russet is a potato variety notable for having both high early and full-season yields of oblong-long, medium-russeted tubers with higher protein content than those of standard potato varieties. Mountain Gem Russet has greater resistance to soft rot, tuber late blight, growth cracks and second growth than Russet Burbank. Mountain Gem Russet produced greater total and U.S. No. 1 yields than Ranger Russet and Russet Norkotah in early-season trials conducted in Idaho, Oregon and Washington over a 3 year period. In full-season trials conducted in five western states over a 4 year period, average total and U.S. No. 1 yields for Mountain Gem Russet were almost always higher than Ranger Russet and Russet Burbank, with specific gravities averaging between these two standard cultivars. It maintains acceptable reducing sugar concentrations and fry quality when stored at 8.9 °C and has displayed a high level of fry color uniformity from tuber stem to bud end providing good potential for early processing. High fresh merit ratings and taste panel sensory scores comparable to Russet Burbank indicate good fresh market potential for Mountain Gem Russet. It was released in 2015 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington, and is a product of the Pacific Northwest Potato Variety (Tri-State) Development Program.

Teton Russet: An Early-Maturing, Dual-Purpose Potato Cultivar Having Higher Protein and Vitamin C Content, Low Asparagine, and Resistances to Common Scab and Fusarium Dry Rot

Teton Russet is an early-maturing, medium-russeted, potato cultivar with high merit for both fresh-pack and processing. In early harvest trials in the Pacific Northwest, Teton Russet had total yields similar to Russet Norkotah, and higher than Ranger Russet and Russet Burbank. Marketable yield of Teton Russet in the early harvest trials was also comparable to or higher than Russet Norkotah in Washington and Oregon, and higher than Ranger Russet and Russet Burbank at these sites, as well as in Idaho. In full-season trials, while total yield of the earlier-maturing Teton Russet tended to be lower than Ranger Russet and Russet Burbank, marketable yield was generally higher than Russet Burbank across the majority of sites due to its higher percentage of U.S. No. 1 tubers. Teton Russet is suitable for processing, with acceptable fry color following up to 8 months of storage at 8.9 °C. Uniformity of fry color was also very consistent. Teton Russet has shown lower levels of the amino acid asparagine relative to Ranger Russet and Russet Burbank which may contribute to lower acrylamide levels in French fries and other processed potato products. Teton Russet is notable for having resistance to common scab (Streptomyces spp.) and Fusarium dry rot, and is moderately resistant to tuber net necrosis. Analyses have also shown Teton Russet to have significantly higher protein levels than Russet Norkotah, Ranger Russet, and Russet Burbank, as well as higher vitamin C content than Russet Norkotah and Russet Burbank. Teton Russet was released in 2011 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington, and is a product of the Pacific Northwest Potato Variety (Tri-State) Development Program.

Comparison of field methyl isothiocyanate flux following Pacific Northwest surface‐applied and ground‐incorporated fumigation practices

A fumigant volatilization emission was conducted in Washington State in the fall of 2008 to estimate flux following applications of metam sodium by modified low-boom-height (LBH) center-pivot chemigation and soil-incorporated shank injection. This study was performed in a commercial potato field circle to assess emission rates and total cumulative field loss of methyl isothiocyanate (MITC) (the biologically active conversion product of metam sodium) under conditions typical for fall Pacific Northwest potato preplant fumigation. This assessment provides regionally specific MITC emission rate information for modeling appropriate field-edge set-back buffer distances for bystander protection. Soil-incorporated shank injection appreciably reduced MITC emissions, with lower periodic flux compared with low-drift surface-applied LBH chemigation during treatment applications and over the 4 day post-fumigation experimental timeframe. The estimated total cumulative fumigant loss was 13% by shank injection compared with 47% by LBH chemigation over the application/post-application monitoring period. The greater adoption of shank-injection fumigation will immediately aid in reducing bystander inhalation exposure to MITC, especially in high-soil-fumigation regions existing at the rural-urban interface.

Palisade Russet: A Late Blight Resistant Potato Cultivar Having a Low Incidence of Sugar Ends and High Specific Gravity

Palisade Russet is a medium-late maturing, lightly russeted potato cultivar notable for its resistance to late blight (Phytophthora infestans) infection of foliage and tuber. Palisade Russet is suitable for processing with low tuber glucose concentrations observed following long-term storage at a temperature as low as 5.6°C with consistently acceptable fry color scores (USDA value ≤2.0) following storage at temperatures of 5.6 to 8.9°C. Reducing sugars are also maintained uniformly throughout the tuber, resulting in a low incidence of sugar ends in French fries relative to standard processing cultivars such as Russet Burbank and Ranger Russet. Palisade Russet has shown high specific gravities in western production regions of the U.S. which may limit its acceptance by the western processing industry. However, in potato production regions with inherently low specific gravities, Palisade Russet could have potential as a processing cultivar. In full-season trials conducted in Idaho, Oregon, and Washington over a 5 year period, the average total yield of Palisade Russet across all three states was very similar to yields observed for Ranger Russet and Russet Burbank. However, the U.S. No. 1 yield of Palisade Russet was 3% and 31% higher relative to Ranger Russet and Russet Burbank, respectively. In addition to late blight, Palisade Russet is also resistant to Verticillium wilt, black dot, and pink rot, and has a moderate level of resistance to net necrosis, PVY, and early blight of both the foliage and tuber. The disease resistances of Palisade Russet make it a good candidate for organic production, or for use by growers seeking reduced pesticide inputs. Palisade Russet displays a low incidence of second growth and growth cracks, especially relative to Russet Burbank, and is intermediate between Ranger Russet and Russet Burbank for incidence of hollow heart/brown center. Blackspot bruise expression for Palisade Russet is less pronounced than for either Ranger Russet or Russet Burbank, however it is slightly more susceptible to shatter bruise. Palisade Russet was released in 2011 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington, and is a product of the Pacific Northwest Potato Variety (Tri-State) Development Program.

Vitamin B1 Content in Potato: Effect of Genotype, Tuber Enlargement, and Storage, and Estimation of Stability and Broad-Sense Heritability

Thiamine pyrophosphate (vitamin B1) is an essential nutrient in the human diet, and is often referred as the energy vitamin. Potato contains modest amounts of thiamine. However, the genetic variation of thiamine concentrations in potato has never been investigated. In this study, we determined thiamine concentrations in freshly-harvested unpeeled tubers of 54 potato clones, the majority of them originating from the Pacific Northwest Potato Development Program. Tubers from 39 clones were collected from four different environmental conditions. Thiamine concentrations ranged from 292 to 1,317 ng g−1 fresh weight, which gives a good estimate of the genetic variation available in Solanum tuberosum ssp. tuberosum. Thirteen clones/varieties contained >685 ng g−1 fresh weight and four had >800 ng g−1 fresh weight over multiple harvests, indicating that these genotypes would contribute a significant amount of thiamine in the diet (>10% of the Recommended Daily Allowance based on a 175- or 150-g serving, respectively). Broad-sense heritability for thiamine content was calculated as 0.49 with a 95% confidence interval of 0.21–0.72, suggesting that genetic variation accounted for about 50% of the observed variation. There were significant clone and clone x environment effects. After accounting for environmental variation, 25 clones were unstable across environments. Tubers harvested at a mature stage late in the growing season had higher amounts of thiamine than tubers harvested at a young stage early in the season. Storage at cold temperature did not lead to significant thiamine loss; instead, thiamine concentrations slightly increased during storage in some genotypes. These results suggest that increasing the concentration of thiamine in potato is feasible and that all potato varieties may one day be a significant source of thiamine in the human diet.

Clearwater Russet: A Dual-Purpose Potato Cultivar with Cold Sweetening Resistance, High Protein Content, and Low Incidence of External Defects and Sugar Ends

Clearwater Russet is a medium-late maturing, russet-skinned, potato cultivar suitable for processing or fresh pack. It is notable for having a low incidence of external defects that contributes to its high U.S. No 1 yield relative to the dual-purpose industry standard, Russet Burbank. Clearwater Russet also maintains low glucose concentrations in its tubers during long-term storage making it an exceptional processing variety. With its low incidence of sugar ends and cold-induced sweetening resistance, Clearwater Russet can be stored at a temperature of 7.2°C for up to 250 days without the need for reconditioning; fry color from this storage regime is consistently ≤1.0 (USDA Fry Color Scale). This cultivar is also notable for its high tuber protein content, which was 33% greater than that of Russet Burbank. In full-season trials conducted over a 3-year period in California, Colorado, Idaho, Oregon, and Washington, Clearwater Russet had total yields slightly lower than Ranger Russet and Russet Burbank, but averaged 1% and 33% higher U.S. No. 1 yields, respectively, across all states. Average specific gravity of Clearwater Russet is comparable to Ranger Russet and significantly higher than Russet Burbank. Clearwater Russet is resistant to potato virus X (PVX) and tuber late blight and is moderately resistant to Verticillium wilt, common scab, and the common strain of potato virus Y (PVYO). Symptoms of infection with two necrotic strains of PVY were not observed in tubers of Clearwater Russet or Russet Burbank, but were observed in Ranger Russet. Blackspot bruise reaction for Clearwater Russet is less pronounced than for either Ranger Russet or Russet Burbank. The incidence of hollow heart in Clearwater Russet is intermediate between Ranger Russet and Russet Burbank. Internal brown spot has been noted as a problem for Clearwater Russet in the Columbia Basin of Oregon, but has not been observed as problematic in other growing regions. Clearwater Russet was released in 2008 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington, and is a product of the Pacific Northwest Potato Variety (Tri-State) Development Program.

Role of Hairy Nightshade in the Transmission of Different Potato virus Y Strains on Solanum tuberosum (L.)

The complexity of the Potato virus Y (PVY) (Potyviridae: Potyvirus) pathosystem is affected by the presence of several virus strains that differ in their ability to produce tuber necrosis and by the presence of an alternate host that could increase the amount of inoculum in potato fields. Solanum sarrachoides (Sendtner) is an invasive weed from South America present in Pacific Northwest potato agro-ecosystems. It serves as reservoir of PVY and its most efficient vectors: the green peach aphid, Myzus persicae (Sulzer), and the potato aphid, Macrosiphum euphorbiae (Thomas). The role of S. sarracoides as vector and virus reservoir in PVY epidemiology was investigated through a series of laboratory and greenhouse experiments. We studied the symptoms produced in S. sarracoides upon infection with necrotic and non-necrotic strains of PVY and looked at the percentage of infection and titer accumulation of these strains. PVY infection in S. sarrachoides produced symptoms similar to those produced in PVY-infected potato plants. Mottling and yellowing were the main symptoms of infection observed in S. sarrachoides plants, especially by PVYO and PVYNTN infection. Greenhouse transmission studies revealed that PVY-infected S. sarrachoides increased the transmission rate of PVY necrotic strains by M. persicae. The necrotic strain PVYNTN reached higher titer in S. sarrachoides than in potato plants when compared to PVYO and PVYN:O These findings have broadened our understanding of the role and importance of S. sarrachoides in the PVY epidemiology in the potato ecosystems and could potentially be included in the development or optimization of virus management programs. Accepted for publication 15 March 2010. Published 26 May 2010.

Validation and Implementation of Marker-Assisted Selection (MAS) for PVY Resistance (Ry adg gene) in a Tetraploid Potato Breeding Program

The gene Ryadg from S. tuberosum ssp. andigena provides extreme resistance to PVY. This gene has been genetically mapped to chromosome XI and linked PCR-based DNA markers have been identified. Advanced tetraploid russeted potato clones developed by the U.S. Pacific Northwest Potato Breeding (‘Tri-State’) Program with Ryadg PVY resistance were used in this study. The objective of this work was to assess the usefulness of molecular markers linked to Ryadg as a tool for selecting PVY resistance in a tetraploid potato breeding program. To achieve this, a full-sib tetraploid population segregating for Ryadg was screened with molecular markers linked to Ryadg, artificially inoculated with PVYO and evaluated in the greenhouse. A large percentage (96.4%) of the segregating lines showed coincidence between molecular markers and ELISA results at 40 days after inoculation. This justifies the use of molecular markers as an alternative to artificial inoculation followed by ELISA. Segregation (resistant vs. susceptible) based on ELISA and molecular marker results in the full-sib population indicated the presence of Ryadg as a simplex in the PVY resistant parent OR00030-1. Additional full-sib populations segregating for the Ryadg gene coming from OR00030-1 and from a related clone, AOR00628-3, were evaluated under field conditions. MAS can be used as a fast and efficient tool to select for PVY resistance, reducing the number of PVY susceptible lines retained for succeeding field evaluations, and thereby increasing the odds of generating PVY resistant potato varieties.

Hairy Nightshade as a Potential Potato leafroll virus (Luteoviridae: Polerovirus) Inoculum Source in Pacific Northwest Potato Ecosystems

Hairy nightshade, Solanum sarrachoides, is a solanaceous weed found abundantly in Pacific Northwest potato ecosystems. It serves as a reservoir for one of the important potato viruses, Potato leafroll virus (PLRV) (Luteoviridae: Polerovirus), and its most important vector, the green peach aphid, Myzus persicae (Homoptera: Aphididae). Laboratory research indicated an increased green peach aphid settling and performance on S. sarrachoides than on potato. It also revealed that green peach aphids transmitted PLRV more efficiently from S. sarrachoides to potato than from potato to potato. To test the efficiency of S. sarrachoides as an inoculum source in the field, a two season (2004 and 2005) trial was conducted at Kimberly, Idaho. Two inoculum sources, PLRV-infected potato and PLRV-infected S. sarrachoides, were compared in this trial. Green peach aphid density and temporal and spatial PLRV spread were monitored at weekly intervals. Higher densities of green peach aphids were observed on plots with S. sarrachoides and inoculum sources (PLRV-infected S. sarrachoides and potato) than on plots without S. sarrachoides and inoculum sources. PLRV infection in plots with PLRV-infected S. sarrachoides was similar to or slightly higher than in plots with PLRV-infected potato as an inoculum source. Temporal and spatial PLRV spread was similar in plots with either inoculum source. Thus, S. sarrachoides is as efficient as or a better PLRV inoculum source than potato.

The economic impact of investment in the Pacific Northwest potato variety development program

Genetic improvement has been the principle contributor to productivity growth in almost all field crops. The Pacific Northwest (PNW) had the highest rate of potato yield growth combined with the least amount of varietal change in any specialized major field crop-producing region in North America. A coordinated potato variety development program, jointly funded by the USDA, the three land grant universities, and the potato industry in the PNW, was established in 1984. The program developed 17 new potato varieties during the 1989–2001 period, two of them are emerging as successful processing varieties.

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