Location: Horticultural Crops Research Unit
2019 Annual Report
Objectives
Objective 1. Determine the water and nutrient requirements needed to produce highquality temperate fruit and nursery crops in the Pacific Northwest.
• Sub-objective 1.1. Develop water and nutrient guidelines to improve fruit and wine quality in Pinot noir.
• Sub-objective 1.2. Characterize the interactions between water and nutrient use
efficiency and plant quality in container-grown nursery plants.
• Sub-objective 1.3. Identify salinity thresholds associated with compost and fertilizer use in highbush blueberry and basil.
• Sub-objective 1.4. Determine temperature thresholds for sprinkler frost protection in cranberry.
Objective 2. Evaluate the impact of soil microbes on crop water and nutrient use in grape and other specialty crop production systems.
• Sub-objective 2.1. Characterize taxonomic and functional diversity of indigenous arbuscular mycorrhizal fungi (AMF) in vineyards.
• Sub-objective 2.2. Determine the effects of AMF on interactions among plant development, resource allocation, and product quality in specialty crops.
Objective 3. Develop irrigation and nutrient management practices and strategies that enhance crop productivity and quality with efficient use of water and fertilizers in berry and woody nursery crop production systems.
• Sub-objective 3.1. Identify cover crop practices that enhance vineyard establishment and improve fruit quality in cool-climate wine grapes.
• Sub-objective 3.2. Evaluate the potential benefits of using organic mulches under weed mat and identify the right source(s), time (fall vs. spring), and place (surface vs. incorporation) for organic compost application in highbush blueberry.
• Sub-objective 3.3. Develop irrigation practices to reduce heat-related fruit damage in highbush blueberry.
• Sub-objective 3.4. Develop nutrient management methods to increase cold tolerance in container-grown nursery crops.
Approach
Experiments will be conducted in the greenhouse and field on small fruit and nursery crops, including Pinot noir wine grape, highbush blueberry, cranberry, and container-grown Rhododendron, Vaccinium, Salix, Euonymous, floral geophytes (e.g., lily), and basil. For objective 1, relationships among soil N, P, and K
availability, vine growth, and fruit quality will be determined in wine grape and
used to develop leaf and petiole nutrient standards for production of Pinot noir and cool-climate cultivars in the Pacific Northwest. The extent to which berry quality of Pinot noir is altered by soil water deficits will also be investigated to provide benchmarks that relate specific indicators of vine water status such as leaf water potential and stomatal conductance to fruit quality. Greenhouse studies will be designed to test whether excess N availability reduces plant quality and water use efficiency in container-grown nursery plants and to identify salinity levels that limit shoot and root growth and function and lead to leaf necrosis in blueberry and basil. Critical temperatures for freeze damage in the region will be likewise determined for cranberry using combination of laboratory measurements on excised plant tissues and temperature-control units on the plants in the field. For objective 2, root and soil samples will be collected from plants grown in both field and greenhouse experiments to test if diversity of arbuscular mycorrhizal fungi (AMF) is a function of sampling location, soil depth, and cover crop use in grape roots; and to ascertain whether AMF improve quality of floral geophytes by enhancing P uptake and allocation. For objective 3, field studies will be designed to determine whether alleyway cover crops and residue placement in vine rows increases root production, AMF colonization, and plant growth and nutrient uptake in young grapevines; if using organic mulches (sawdust or compost) under weed mat will enhance soil conditions, including availability of water and nutrients, and result in more growth and production in highbush blueberry; and whether overhead cooling with sprinklers or misters reduce heat damage in blueberry fruit when applied correctly at the proper temperature, rate, and frequency. Can-yard studies will likewise be designed to test whether increased N availability reduces cold tolerance or, alternatively, if application of cation fertilizers (K, Ca, Mg) increase cold tolerance in container-grown nursery plants. Measurements in the studies will include standard techniques for measuring plant water status (pressure chamber, porometer), photosynthesis (gas-exchange), photosynthetic efficiency (fluorometer), fruit quality (refractometry, acid titratation, colorimetry, HPLC), root production and turnover (minirhizotrons, soil cores), mycorrhizal colonization (microscopy), DNA sequencing (PCR), soil pH and EC, soil water content (TDR, tensiometers), and plant and soil nutrients (CNS analyzer, ICP). Data will be analyzed using ANOVA, ANCOVA, nonparametric, and regression techniques. In some cases, studies may need to be repeated due to poor weather conditions or the need for a wider range of treatments.
Progress Report
This report documents progress for the bridging project 2072-21000-053-00D which began in December 2018 and continues research from project 2072-21000-048-00D that was terminated December 2018.
A study to address how nitrogen management in both the vineyard and winery can be manipulated to obtain optimal fruit quality in red and white grape cultivars was continued in fiscal year 2019. This on-farm trial involves collaborators from Oregon State University and industry. Plant productivity, nutrient and water status, gas exchange, and solar exposure of fruit are being monitored periodically in the vineyard in response to vineyard soil and foliar nitrogen (N) applications. Must nitrogen is being manipulated in the winery, and fermentations are monitored by our collaborators. Early results indicate that soil nitrogen application was more effective than foliar nitrogen in boosting vine N status in both varieties. Soil nitrogen was also more effective than foliar nitrogen in raising must (freshly crushed juice from entire grape bodies) yeast assimilable nitrogen (YAN) levels in Chardonnay, but both soil and foliar nitrogen had a similar effect in Pinot noir. The rate of fermentation in Chardonnay was dictated by must YAN level, irrespective of where the nitrogen came from. Vineyard nitrogen applications were more effective in boosting the rate of fermentation than winery nitrogen additions.
New studies were initiated to assess how nitrogen use alters fine root growth and the extent of mycorrhizal colonization of roots in grapevines. ARS researchers in Corvallis, Oregon, set up a vineyard versus winery nitrogen trial by collecting data from mature vineyards and conducting greenhouse trials to examine how rates of soil or foliar applied nitrogen affect vine growth, mycorrhizal colonization, and whole plant nutrient uptake. Results suggest that nitrogen application in the vineyard reduces mycorrhizal colonization and interferes with phosphorus uptake, but more data is needed to confirm these findings. Nitrogen application to young vines in the greenhouse, however, did not reduce mycorrhizal colonization. Further experiments are being planned to better understand how nitrogen use and plant nitrogen status influences the regulation of mycorrhizal fungi and the benefits derived from them. This information is important in developing sustainable vineyard nutrient management strategies that can reduce inputs and potential nutrient losses to the environment.
Vineyard preparation for a new study that will examine how canopy architecture, vine density and crop level alter productivity and quality of Pinot noir was continued. Since the vines struggled last growing season after carrying their first substantial crop, vines will be grown for another growing season at a typical crop load for the region before starting the crop load aspect of the experiment. This project will provide a large-scale test of whether increasing midday solar capture by opening up the top of the canopy can improve the quantity of fruit produced without compromising quality or long-term vine health.
Work was initiated to examine how different grapevine rootstocks respond to the northern root knot nematode with collaborators at Washington State University. While rootstocks are still not used in Eastern Washington vineyards due to concerns over winter kill of scions, the industry is interested in using rootstocks in future vineyard replanting scenarios where the northern root knot nematode has become established at very high levels. A trial to examine how different rootstocks performed under varying levels of nematode density was recently established and much of the field data was collected. Preserved root samples were prepared and stored for subsequent analysis of various root developmental characters and colonization by mycorrhizal fungi. Understanding how different rootstocks respond to this nematode under field conditions and whether mycorrhizal colonization is impaired are important to the success of vine establishment.
New studies were initiated to evaluate the impact of water and nutrient management practices on the tolerance of nursery crops to withstand abiotic and biotic stresses. Experiments initiated in 2018 to understand how the nursery production environment (irrigation, fertilizer, fungicide, and temperature) affects emerging and new pathogens prevalent in the region were continued. Results from these experiments will be used to develop new management practices and disease control strategies to minimize pathogen damage and losses for woody nursery plants. A new series of experiments were started to define salinity thresholds for specialty crops grown in different production systems. Results from this research will be used by growers to reduce losses of planting stock, mitigate the impact of salinity on quality, and broaden the use of salt tolerant species in environments that are not suitable for production of other crops. A new experiment was started to evaluate water and nutrient management practices for specialty crops grown in soilless substrates in the field. Results from these experiments will be used to develop management options for this type of high-value production system.
Work was continued to evaluate alternative soil amendments for highbush blueberry. Plants were grown in soil amended with biochar alone or in combination with bokashi (fermented wheat bran) at rates of 10 percent and 20 percent, by volume, and compared to those grown in soil only. Biochar was also tested with or without bokashi under field conditions in a new planting. In this case, the use of biochar was evaluated for two years and compared to the conventional practice of incorporating douglas fir sawdust in the row or using soil only. A third study was conducted to evaluate the potential of using ammonium-enriched organic materials as soil amendments for production of blueberry. Results indicate that biochar could be a good soil amendment for commercial production of highbush blueberry. Benefits include more plant growth and higher yield in soil with biochar, as well as much greater levels of root colonization by mycorrhizal fungi when the plants were grown in a sandy soil. Biochar also improved soil aggregation and had relatively little effect on soil pH. Adding biochar to the planting hole was considerably more economical than applying it to the row and cost $1,320/hectare less than the industry standard of incorporating sawdust in the row. These findings indicate that biochar is a promising soil amendment for commercial production of highbush blueberry. Ammonium-enriched Douglas fir sawdust and wood chips were also excellent amendments for improving growth and nitrogen (N) nutrition in highbush blueberry. Both substrates are highly porous in nature and work well as biofilters. Woody biofilters are highly efficient for treating odors associated with animal farms, biogas plants, and composting facilities, including ammonia gas and volatile organic sulfur compounds. Once enriched with adsorbed N, these biofilters could be used as excellent sources of nutrients and organic matter for blueberry.
Research was initiated to evaluate new remote sensing techniques for assessing the need for irrigation, including multispectral and thermal imagery. The images are collected using a small unmanned aerial system and analyzed to develop robust field-specific estimates of crop development and irrigation water requirements for highbush blueberry and red raspberry in the Pacific Northwest. The images are also useful for identifying weak zones in the field caused by poor irrigation or disease issues, such as Phytophthora root rot.
New studies were initiated to evaluate new practices for reducing irrigation water use in berry crops, including deficit irrigation in blueberry and pulsed drip irrigation in raspberry. Initial findings suggest that reducing irrigation, either during early stages of fruit development or after harvest, may have a minimal effect on yield or fruit quality in blueberry. Use of deficit irrigation would lead to immediate water savings and when coupled with remote sensing technology could enable growers and irrigation managers to optimize on-farm and regional water use. When managed properly, pulsing could increase plant growth and production relative to applying water all at once each day or two and can greatly reduce runoff, evaporation, and leaching.
Work was continued to evaluate whether fertigating with potassium, phosphorus, or boron fertilizers is more effective than traditional methods of fertilizer application in highbush blueberry. The results indicate that potassium thiosulfate is a good source of potassium for fertigation and can be used with urea on soils with optimum pH for blueberry (4.5-5.5) and with ammonium sulfate on soils with pH greater than 5.5. Fertigating with potassium fertilizers containing organic acids or their derivatives is also useful, particularly for increasing availability and retention of potassium in the soil. However, there was no benefits to date from fertigation or granular application of potassium fertilizers on fruit production in two mature blueberry fields. The fertilizers had an immediate effect on pH and availability of potassium and other nutrients in the soil and after two years are beginning to influence the nutrient status of the plants. Early results in phosphorus and boron trials are limited at this point, but strongly suggest that fertigation with boron is more effective than using a single spring application of granular boron fertilizer. The project builds on our previous work on nitrogen and will be used to develop complete guidelines for fertigation of highbush blueberry. The results will help growers improve production in the crop and enhance fruit quality for consumers.
Accomplishments
1. Life cycle model developed for the northern root-knot nematode in Washington vineyards. Wine grape growers in Washington do not have adequate methods to manage plant parasitic nematodes. ARS scientists in Corvallis, Oregon, and researchers from Washington State University, characterized the development dynamics of the most numerous nematode parasite in Washington vineyards, the northern root-knot nematode, over two years at multiple sites. This nematode produced only one generation per year in Washington wine grape vineyards. By gaining insight into the biology of this pest in production vineyards, it is now possible to improve time management strategies. For example, it is now known that the susceptible stage of this nematode is most abundant in soil in the spring and fall. These findings will benefit wine grape growers by offering better time control strategies to reduce the impact of this damaging pest.
2. Salinity levels negatively impact phenolic yield of basil without altering biomass. Decreasing availability and rising costs of high-quality water for irrigation results in more frequent use of saline water sources in many crop production systems. The effects of salinity on crop biomass yield has been the focus of most salinity studies, and a few studies have reported how salinity influences crop qualities, such as polyphenolic composition. ARS researchers in Corvallis, Oregon, assessed yield and composition of basil when grown hydroponically with different levels of salinity from sodium chloride (NaCl). Hydroponic solutions with high salinity had no impact on leaf biomass after 71 days. Salinity altered leaf composition at lower salinity levels than those that influenced biomass yield. Our data suggest that water sources with salinity less than 5 deciSiemens per metre (dS/m, electrical conductivity units) can be used by greenhouse producers to grow basil hydroponically with little effect on leaf chemistry.
3. An important root rot pathogen in Oregon nurseries has low genetic diversity but a broad range of fungicide sensitivity. Recent sampling of Pacific Northwest nurseries frequently encountered the root rot pathogen, Phytophthora plurivora, and it has been shown to be among the most damaging Phytophthora pathogens on ornamentals. ARS researchers in Corvallis, Oregon, characterized the genetic variation of P. plurivora from Oregon nurseries. Population structure suggested the presence of one dominant clonal lineage in all nurseries, as well as isolates of cryptic diversity mostly found in one nursery. Within the clonal lineage, there was a broad range of sensitivity to the two most common fungicides available to growers. There was also a correlation between sensitivity to the two fungicides. The broad range of fungicide sensitivity within the P. plurivora population has important implications for managing this key pathogen by Pacific Northwest nursery producers.
4. Nursery plants grown in biodegradable paper biocontainers use more water than plants grown in plastic containers. The plastic containers used in production of most nursery crops are costly, and many of them are not recyclable. Biodegradable containers that can reduce the environmental footprint of nursery plant production without impacting crop quality will make production systems more sustainable. Plant growth, water use, and performance of hydrangea plants grown in plastic containers were compared to those grown in a paper biocontainer by ARS researchers in Corvallis, Oregon. Plants in the biocontainers required more water, indicating that this specific container may not be a satisfactory alternative to traditional plastic containers. The nursery industry can use these findings to improve sustainable production practices.
5. Suitability of different composts identified for blueberry. Organic blueberry growers often use compost to supply nutrients and improve soil health, but the pH and salts in many composts are too high and result in poor plant growth or death. ARS scientists in Corvallis, Oregon, and collaborators from Oregon State University, evaluated the suitability of diverse composts for blueberry. Plant growth was best when compost pH was less than 7.0 and improved consistently when the composts were acidified with elemental sulfur. The most favorable composts were those made from 80 percent grass seed hulls and 20 percent peppermint hay, horse manure with pelletized wood bedding, a mix of 60 percent Douglas fir bark, 20 percent fine sawdust, and 20 percent digested, dewatered municipal wastewater treatment biosolids, chipped deciduous tree leaves from municipal street sweeping, and ground urban yard debris (grass, leaves, woody debris). Availability of most of these composts may be limited in many regions, but yard debris composts are widely available from commercial vendors and can be used by blueberry growers to build soil organic matter without supplying excessive salts.
Review Publications
Scagel, C.F., Lee, J., Mitchell, J.N. 2019. Salinity from NaCl changes the nutrient and polyphenolic composition of basil leaves. Industrial Crops and Products. 127:119-128. https://doi.org/10.1016/j.indcrop.2018.10.048.
Carleson, N.C., Fieland, V.J., Scagel, C.F., Weiland, G.E., Grunwald, N.J. 2019. Population structure of Phytophthora plurivora on Rhododendron in Oregon nurseries. Plant Disease. 103(8):1923-1930. https://doi.org/10.1094/PDIS-12-18-2187-RE.
East, K.E., Zasada, I.A., Schreiner, R.P., Moyer, M.M. 2019. Developmental dynamics of Meloidogyne hapla in Washington wine grapes. Plant Disease. 103(5):966-971. https://doi.org/10.1094/PDIS-07-18-1195-RE.
Costello, R.C., Sullivan, D.M., Bryla, D.R., Strik, B.C., Owen, J. 2019. Compost feedstock and compost acidification affect growth and mineral nutrition in northern highbush blueberry. HortScience. 54(6):1067-1076. https://doi.org/10.21273/HORTSCI13599-18.
Li, T., Bi, G., Harkess, R., Denny, G., Scagel, C.F. 2019. Effect of nitrogen fertilization and irrigation frequency on plant growth and nutrient uptake of hydrangea using traditional and sustainable alternative containers. HortScience. 54(1):167–174. https://doi.org/10.21273/HORTSCI13513-18.
