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Fall 2021 Newsletter

Masthead: WSU NWREC News & Notes

Fall 2021 Edition

Director's Message

Dr. Carol Miles

It has been a busy summer and we have lots of good work to report at WSU NWREC as you will see in the program highlights. A highlight for our Center was the ribbon cutting ceremony in early August to officially open the Ruth Wylie Headhouse, which is Phase I of our Plant Growth Facility. We were joined by County Commissioners Lisa Janicki and Ron Wesen and also Interim Dean Rich Koenig as well as the extended Wylie family. The Wylie Headhouse provides us with much needed desk space for six personnel, a Zoom meeting room, and a soil field lab that provides us essential space for our research programs. Funding for the Wylie Headhouse was provided by a Skagit County Economic Development/Public Facilities Project grant and a generous gift from Nancy Kercheval. We are also very pleased to announce that we have received another Skagit County Economic Development/Public Facilities Project grant and a private donation for the Plant Growth Facility Phase II greenhouse. While more funding will be needed to complete Phase II, we will begin the project in steps that will enable us to move forward as funds become available.

Six people cutting ribbon to dedicate a building.
Ruth Wylie and Chad Kruger cutting the ribbon in August for the official opening of the Wiley Headhouse, Phase I of the Plant Growth Facility.

And for more good news, we have received approval to hire a new entomologist at NWREC. We recognize that insect pests present a primary threat to production sustainability and resiliency of agricultural industries in our region. Thus this was our top priority position to refill following the retirements of Dr. Lynell Tanigoshi in 2017 and Dr. Bev Gerdeman in 2020. This faculty position will have responsibilities for teaching and applied research for all aspects of insect management in regional crops of significance, including but not limited to blueberry, raspberry, potato, vegetable seed, flower bulbs, tree fruit and greenhouse production. Other program areas for this position include biological control, management of native pollinators, and testing products through the IR-4 program. We look forward to recruiting and interviewing candidates for this position and welcome all of you to participate in the candidate seminars when the time comes. Please look for these announcements in a few months and keep in touch if you have any questions.

Feature Focus: Biodegradable Plastic Mulch

Raspberry seedling grows through biodegradable plastic mulch sheet.
Figure 1. ‘WakeHaven’ raspberry planted with plastic mulch. Photo by L.W. DeVetter

About 57,152 metric tons (~126 million pounds) of polyethylene (PE) mulch is used annually in specialty crop production in the United States and use is expanding nationally and globally. Waste generated after using this important but non-degradable material causes concerns regarding environmental plastic pollution. Carol Miles, Vegetable Horticulturist, and her graduate students have been carrying out field research on soil-biodegradable plastic mulch (BDM) with vegetable crops for the past 20 years to reduce plastic waste generation and disposal challenges while maintaining crop productivity. In these studies, BDM has provided the same benefits as PE mulch including weed control, soil temperature modification, soil moisture retention, and increased crop yield and quality, with the added advantage of being tilled into the soil at the end of the season, thereby reducing the costs for removal and disposal.

BDM products are tested for biodegradability under controlled laboratory conditions that resemble but do not duplicate real field conditions. An international biodegradability standard (EN-17033) requires that BDMs degrade by 90% within two years under these controlled temperature and moisture conditions. A team led by Deirdre Griffin-LaHue, Soil Health Program, recently ‘dug’ into NWREC field data to compare degradation rates of five BDM films with this standard test. BDM recovery from soil was measured every six months from fall 2016 to fall 2020, and through modeling we estimated that these mulches would take up to 2.4 times longer to degrade than occurs in the lab biodegradability test. We also found better agreement with the lab test when we measured time by cumulative degree days rather than calendar days, indicating temperature plays a key role in biodegradation under field conditions. These BDMs are biodegradable but this work highlights how important it is to develop field tests for biodegradability that account for site-specific environmental conditions that will impact the rate of biodegradation.

Lisa DeVetter, Small Fruit Horticulturist, and her team of graduate students and technical staff compared several BDMs and PE mulch to bare ground cultivation in spring- and late-summer planted raspberry established from tissue culture transplants in Whatcom County. Overall, they found in spring-planted raspberry that BDMs and PE mulch performed the same with regards to yield, and both types of mulches increased yield compared to bare ground cultivation that uses tillage and herbicides for weed management. There was no impact on yield due to BDMs and PE mulch in late-summer raspberry plantings and mulch improved weed management. However, growers have concerns about BDM deterioration over time and in-soil biodegradability. Thus many have adopted PE mulch instead of BDMs and the estimated acreage of raspberry grown with PE mulch in Washington increased from 10-15 acres in 2016 to approximately 400 acres in 2021.

Field of strawberry plants.
Strawberries are grown with soil-biodegradable plastic mulch. Photo by L.W. DeVetter

BDM is also a promising alternative to PE mulch in commercial strawberry production. In a field trial with day-neutral strawberry at NWREC, this collaborative team found BDM produced fruit yield and quality similar to PE mulch. Our team has been collaborating with commercial strawberry growers and research and extension specialists in the Watsonville area of California, which is a national leader in strawberry production. Since 2020, five strawberry growers have been trialing 1.1, 1.3, 1.6 and 2.0 mil BDM with the goal of reducing plastic waste generation in this farming system. In California strawberry production, about 845 lbs of plastic per acre is used each year (drip tape, mulch, fumigation tarp), most of which is landfilled after use. Our WSU team recently went to California to co-host a field day and observe these grower trials. After 10 months in the field, the BDMs had minimal deterioration and growers reported comparable weed control and fruit yield and quality for BDM and PE mulch. Field trials are expanding in California as interest builds after these promising first year trial results. The value of collaborative research is highlighted through our BDM research as our sphere of impact is increasing, which will translate into reduced plastic waste generation for specialty crop producers while maintaining yields and on-farm profitability.

For more information on BDMs, please visit the Small Fruits website and follow us on Twitter @Mulch_Matters.

Lunch & Learn Seminars

There are no upcoming events at this time.

Program Highlights

Berry and Potato Pathology

Petri dishes stacked in a metal cabinet.
Petri plates with fungal isolates obtained from diseased potato samples.

During this field season, Chakradhar Mattupalli has been visiting with potato and blueberry growers and stakeholders, collecting research data through grower field visits to identify disease issues and obtain disease samples for pathogen isolations. We submitted proposals to Washington state blueberry and potato commissions, with a focus on developing strategies for managing mummy berry in blueberries and silver scurf on potatoes. We obtained funding from Northwest Center for Small Fruit Research to monitor Botrytis fungicide resistance on blueberries in Washington and Oregon. This work will be performed in collaboration with Dr. Virginia Stockwell, USDA researcher from Oregon. We are also glad to welcome Alec Blue, an M.S. in Ag student, into our program. Alec’s non-thesis research will explore the effects of fumigation on infestation levels of hemipteran pests of potato as well as identify knowledge gaps for conducting future research in this area. Furthermore, we are building our team as we are in the process of hiring a lab technician and recruiting new graduate students.

WSU Breadlab

Combine works in wheat field.
Wheat harvest in western Washington.

WSU Breadlab continues to be one of the only wheat breeding programs in the nation that breeds specifically for climate crisis. We do not breed for commodity systems or a new, smaller version of monoculture. We breed for improved farming and food systems and for small grains that are able to adapt to a changing environment. The lab currently has four Ph.D. students working on colored and perennial wheat, wheat for increased nutrition and fiber content, colored barley for malting, and rye. Each has a unique project focused on grains that are outside of the commodity system, are highly diverse and thrive in organic farming systems. We have 60 members in 27 states and six countries that have joined Breadlab Collective and are selling the Approachable loaf—our soft, sandwich style bread that is made with no more than seven ingredients, no non-food and is at least 60% whole wheat. Thanks to Skagit Community Foundation, we are doing monthly production bakes of 50 loaves for Friendship House in Mount Vernon, who provide two emergency shelters, one transitional house, one permanent low income shared living house, a daily meal service (where the bread gets used for sandwiches or garlic bread), and an employment training program.

Cider Education

As of Fall 2021, we are now teaching our sixth cohort of students in our course Online Cider & Perry Production – A Foundation. The online version of the course spans eight to 16 weeks and is taught in collaboration with our partners at the Cider Institute of North America (CINA), Brock University, and Cornell University. Since we pivoted to an online model due to the pandemic, we have taught a total of 206 aspiring cider professionals from 34 U.S. states, six Canadian provinces and territories, and three countries outside of North America (spanning Africa, Europe, and South America). Students have indicated high satisfaction with the online version of the course, and many are planning to continue their education with the Advanced certification level. The Fall 2021 course is already full, but those interested in the 12-week Spring 2022 session can secure their spot by registering online. These classes do fill up, so it’s advised to register sooner rather than later.

We are looking forward to returning to in-person coursework hopefully sometime in 2022. For those who have completed the Foundation level certification, we are currently working on finding more ways to deliver our Advanced curriculum online. Please visit the CINA website for the most up-to-date information on courses, certifications, and other CINA resources.

Small Fruit Horticulture

Five people wearing white jumpsuits, another person in a jacket stand just outside a blueberry field.
The team wearing PPE because we were collecting data after a pesticide application (dressing in compliance with the label to allow re-entry).

From May through August, we collected pollination data from 19 blueberry field sites across the state, counted honeybees and blueberry flowers, opened honeybee hives to conduct quality assessments, and measured productivity and fruit quality. Dr. Maxime Eeraerts (postdoctoral researcher) led the majority of our pollination experiments and completed the identification of a new specimen set that includes wild pollinators collected from Washington blueberry fields. Dr. Bob Gillespie, a member of the WSU NWREC Pollinator Working Group, also supported our pollination studies. Qianwen Lu, Ph.D. student, completed her studies to investigate impact of different fertilizer-nitrogen on crop productivity, fruit quality, and soil health. Brenda Madrid, M.S. student, collected her final project data to test products to enhance degradation of soil-biodegradable plastic mulches and interviewed stakeholders regarding their perceptions of risk and uncertainty for the adoption of plastic mulches in raspberry production. May Wang, M.S. student, completed our strawberry-lettuce double cropping study in collaboration with Srijana Shrestha, M.S. student in Vegetable Horticulture. May also collaborated with Drs. Lydia Tymon and Gary Chastagner, WSU pathologists, to understand how different mulches impact the dispersal of pathogens that cause gray mold in strawberries.

Raspberry fruit with heat damage (white patch).)
Sunscald of raspberries. Photo by L.W. DeVetter

Extreme heat in late June caused significant crop damage. We collaborated with other regional scientists, plant breeders, growers, and industry members in the PNW to develop strategies to mitigate heat damage in berry crops. Our program also worked extensively with organic blueberry growers and we harvested experiments on organic blueberry fertilizer nitrogen in Prosser and presented at two blueberry field days in Oregon.

Soil Health

Soil sample in a probe; vineyard in background.
Grad student Kwabena Sarpong collecting soil samples in a wine grape vineyard for the Soil Health Program’s ‘State of the Soil’ assessment. (Photo by Molly McIlquham)

The Soil Health Program has had a busy and productive summer, which included work on two projects supported by the WA Soil Health Initiative. We completed Year 2 of our ‘State of the Soils’ soil health assessment, which is a close collaboration with soil scientists at WSDA’s Natural Resources Assessment Section. Grad students Kwabena Sarpong and Molly McIlquham, along with collaborators, traveled around the state sampling on nearly 200 farmer’s fields across potato, onion, sweet corn, wine grape, hops, and pulse systems. This dataset, along with 100 sites sampled in 2020, will be used to calibrate soil health scoring curves to be relevant for Washington’s soils and systems.

We also established the NW Washington Long-Term Agroecological Research & Extension (LTARE) site at NWREC. This site will be an important place to investigate short- and long-term impacts of soil management on soil health, disease pressure, and productivity in NW Washington’s annual cropping systems (see Soil & Water program update for more info). Additionally, we completed the first year of a long-term trial in Douglas County, WA looking at the synergistic soil health benefits of biosolids & cover crop grazing, and another studying the connections between soil health and crop nutritional quality using quinoa as a model crop.


Soil & Water

Aerial photo of farmland.
A birds-eye view of the Long-term Agroecological Research & Extension site established this spring with support from the WA Soil Health Initiative (Photo by Kwabena Sarpong)

We are excited to report that the Mount Vernon LTARE site has been fully established in collaboration with Deirdre Griffin LaHue’s Soil Health program and Chris Benedict, WSU Extension. The experiment is based around a four-year potato rotation (including winter wheat, silage corn, barley, and grass/clover hay as rotational crops) with a gradient of organic matter inputs (crop residue, cover crops, compost) and soil disturbance (tillage and perennial vs. annual rotational crops). The first growing season is just wrapping up and we’d like to say a special thanks to Bob Hulbert for farming the crops in the trial and to our Stakeholder Advisory Committee for their guidance and assistance.

Soil & Water program personnel have led projects across the state this summer, including assessing the contribution of soil organic matter and organic fertilizers to nitrogen supply in blueberry production, evaluating the effects of irrigation and nitrogen management on onion bacterial diseases in the Columbia Basin, working with farmers to support efforts to experiment with irrigation management, evaluating irrigation thresholds for spinach seed production, assessing the influence of soil organic matter on resistance to soil compaction and water-holding capacity, exploring the impacts of controlled drainage and subirrigation in dairy forage systems, and contributing to a synthesis of knowledge about water supply and demand in the Skagit River basin. We look forward to seeing many of you at Extension and outreach events in the near future and working together to improve irrigation, nutrient management, and soil physical health in northwestern Washington and beyond.

We welcome Harmony Varner to our program! Harmony graduated from WSU in May 2021 with a B.S. in Organic and Sustainable Agriculture, and immediately joined us as an M.S. student. Harmony’s work focuses on farmer-led experimentation with irrigation, with the goal of generating research results that are relevant to a farmer’s individual field and that, in aggregate, can help us make better informed recommendations.

Vegetable Horticulture

Man writing on clipboard beside ordhard.
Aidan Kendall, MS student, measuring shoot biomass removed from mechanical hedging at WSU Mount Vernon NWREC.
Four people picking cataloupe in field.
Cantaloupe harvest at WSU Mount Vernon NWREC.

Cantaloupe and sweetpotato are high value crops, but as both are warm season crops that grow well in the temperature range of 30‒35 °C, our climate limits their production. In cool regions such as NW Washington, cantaloupe experiences sudden vine wilt due in part to the environmental stress of cold soil. Our cantaloupe research is focused on grafting with cold-tolerant rootstocks to ensure a productive crop. Additionally, we are testing the use of plastic mulch to elevate soil temperature for both cantaloupe and sweetpotato. Further, we have been testing soil-biodegradable plastic mulch (BDM) as an alternative to polyethylene (PE) mulch, to increase soil temperature and crop productivity while resolving plastic waste and disposal challenges. Our studies have shown that grafting cantaloupe with cold tolerant rootstocks and growing with BDM can overcome sudden vine wilt and produce marketable size fruits without compromising fruit quality. For sweetpotatoes, our research is in line with other studies that found sweetpotatoes grown with plastic mulch in northern climates have higher yield than in the southern U.S. Our study has also found comparable sweetpotato yield between BDM and PE mulch. This year our sweetpotato research is focusing on testing new varieties and breeding lines for wireworm resistance. All of this work is being carried out by M.S. student Srijana Shrestha, while M.S. in Ag student Ann Kowenstrot will be starting a new project to map the prevalence of turnip mosaic in rhubarb in Alaska.

In our research cider apple orchard, M.S. student Aidan Kendal continues to evaluate ways to optimize productivity while minimizing labor in our medium-density orchard of 65 different cider cultivars. We are testing: chemical blossom thinning, summer mechanical hedging, stop-drop chemicals, fruit maturity indices using non-destructive handheld meters, and mechanical over-the-row harvest. Additionally, our research on reduced irrigation in cider-apple production continues to show that reduced irrigation can be effective for establishing orchards in our region.

Vegetable Seed Pathology

Beet seeds collected on white sheets.
Beet seed harvested and drying.

The Vegetable Seed Pathology program has been busy with field research, the start of harvest season, and greenhouse and lab trials. We had six onion bacterial disease field trials in Pasco this season along with a survey of onion bulb crops for bacterial pathogens as part of the ‘Stop the Rot’ onion bacterial project funded by USDA NIFA Specialty Crops Research Initiative. To find out more, visit the Alliumnet website, including a video on the project. The carrot cavity spot field trial is in full swing with harvest and evaluation of the roots of ~80 carrot cultivars scheduled for October and November to determine which cultivars have some resistance to cavity spot, a soilborne disease caused by species of Pythium. This is a collaborative project with Dr. Phil Simon, USDA ARS carrot breeder at the University of Wisconsin-Madison, and is funded by the California Fresh Carrot Advisory Board. We swathed the beet seed crop field trial of Marilen Nampijja, Ph.D. student, on Sep. 7, just prior to the onset of rain. Marilen inoculated the trial with the bacterial leaf spot pathogen, Pseudomonas syringae pv. aptata to assess its development on the crop and colonization of the seed by this important seedborne pathogen. This project is funded by a USDA NIFA Specialty Crops Research Initiative grant. On Sep. 11, we planted a very large greenhouse trial to screen ~650 sweet corn breeding lines and accessions for resistance to the soilborne fungus Fusarium verticillioides. This project is funded by the USDA NIFA Specialty Crops Research Initiative and was carried out by postdoctorate Dr. Sanjaya Gyawali. Ph.D. students are carrying out studies, Alex Batson with spinach Fusarium wilt and Kayla Spawton with spinach Stemphylium leaf spot.

Tomasita Villaroel
Tomasita Villaroel

We welcome Tomasita Villaroel to our program. Tomi grew up in Venezuela, then resided in Washington DC for 25 years before moving to Anacortes with her family in 2019. Tomi is excited to be a part of our program and support the various research projects on bacteria, fungi, and other pathogens, and their effects on the food we eat. She has already been a tremendous help with all the projects in progress.

Weed Science

Two men on a boat. Man in forground using binoculars.
Steven Seefeldt and Brian Maupin stalking the wild reed canarygrass around Ross Lake, WA.

The Weed Science Program had a busy year as we worked to finish up our studies and put the program into hibernation as Steve Seefeldt will be retiring at the end of 2021. From these studies we determined that different cover crops impact weed populations differently. Once the analyses are finished, our goal is be able to recommend a cover crop based on the weed species in a field. We showed that in raspberry fields lower rates of chlorsulfuron carefully applied in the autumn will reduce horsetail and will not result in residues in raspberry leaves and fruit the following year. A model for determining when to control wild buckwheat and pale smartweed before they begin to set seed has been developed and a beta version has been entered into AgWeathernet’s AWNfarm package. This research will give growers a timing plan to try to keep these weeds from adding any seed back into the soil. Preventing seed production could lead to near eradication of these plants in about five years. And finally, a report to the National Park Service is almost done and will provide a way forward to manage reed canarygrass in the North Cascades National Park. It has been a joy working with all the farmers, WSU faculty and staff, and students at the NWREC. I will miss the interactions with all of you, but I am looking forward to the next phase of life.

Employee and Graduate Student Highlights

New Arrivals

Graduate Students

  • Alec Blume, M.S. in Ag student. Effects of soil fumigation on hemipteran pests of potato.
  • Madeline Desjardins, Ph.D. student. Impacts of biosolids and cover crop grazing on soil health in dryland systems.
  • Evan Domsic, Ph.D. student. Investigating the effects of soil management and variety selection on quinoa nutritional quality.
  • Ann Kowenstrot, M.S. in Ag student. Evaluating yield and quality of rhubarb germplasm collection in Alaska.
  • Harmony Varner, M.S. student. Farmer-led irrigation experimentation: A model for learning and adaptation.


  • Robbie Andrus, postdoctoral scholar (School of the Environment). Recovery of forests from disturbances (bark beetles, fire) in the context of climate change.
  • Logan Clark, Technical Assistant
  • Jeff DeLong, USDA-ARS supporting research scientist for Dr. Virginia Stockwell, USDA Plant Health National Program with a focus on small fruit crops.
  • Dakota McFadden, Research Assistant
  • Teal Potter, postdoctoral scholar. Managing the potato microbiome for improved soil and potato health.
  • Tomasita Villaroel, Service Worker
  • Ryan Yamamoto, Technical Assistant


Departing Staff

  • Congratulations to Dr. Sanjaya Gyawali, Research Associate in the VSP program, on being hired as a plant pathologist with Sakata Seed America. Sanjaya is based at the Sakata research facility in south Mount Vernon, and will no doubt be collaborating with the Vegetable Seed Pathology program as he’ll be working on many of the same crops and diseases in his role at Sakata. Sanjaya has been with the VSP program since January 2018. We will miss his presence in the program but wish him all the best in his new role at Sakata.


  • Pinki Devi, Ph.D., graduated from the Vegetable Horticulture program. Dissertation: Optimizing watermelon grafting to enhance grafting efficiency and its impacts on fruit maturity and quality.
  • Cheyenne Sloan, M.S. in soil science, graduated from the Soils & Water program. Thesis: Nitrogen supply from soil organic matter: Predictors and implications for nutrient management in northern highbush blueberry. Cheyenne will be joining Michigan State University (her alma mater) as a Blueberry and Small Fruit Extension Educator.
  • Toby Una, M.S. in soil science, graduated from the Soil Health program. Thesis: Winter cover crop suitability for improved soil health in Northwestern Washington. Toby will soon begin her Ph.D. with Dr. Sally Brown at the University of Washington.

Educational Events

Bob Gillespie, a member of our Pollinator Working Group at WSU NWREC, led an excellent pollinator workshop on Aug. 6, 2021. Cheyenne Sloan, Maxime Eeraerts, and Lisa DeVetter supported implementation of this event and Maxime Eeraerts shared information about native pollinators. Maxime’s presentation included showcasing his native pollinator collection sampled from blueberry fields in Washington. We had approximately 13 participants for this full-day workshop, which was one of the first events we’ve had since the lockdown.


  • Belo, T., du Toit, L., Waters, T., Derie, M., and LaHue, G. 2021. Effects of irrigation frequency and final irrigation timing on onion bacterial diseases in the Columbia Basin of Washington, 2020. Plant Disease Management Reports 15:V109.
  • Bhasin, A., J. Davenport, S. Lukas, Q. Lu, G. Hoheisel, and L.W. DeVetter. 2021. Evaluating postharvest organic nitrogen fertilizer applications in early fruiting northern highbush blueberry. HortScience. In press.
  • Block, A.K., Tang, H.V., Hopkins, D., Mendoza, J., Solemslie, R.K., du Toit, L.J., and Christensen, S.A. 2021. A maize leucine-rich repeat receptor-like protein kinase mediates responses to fungal attack. Planta 254:73.
  • Buajaila, F., J. Cowan, D. Inglis, L. Carpenter-Boggs, and C. Miles. 2021. Tomato growth, yield and quality response to mixed chemical-organic fertilizers and grafting treatments in high tunnel environment. Canadian Journal of Plant Science. Just-IN,
  • Cai, Y., F. Takeda, B. Foote, and L.W. DeVetter. 2021. Effects of Machine-Harvest Interval on Fruit Quality of Fresh Market Northern Highbush Blueberry. Horticulturae 7(8): p.245.
  • DeVetter, L. W., S. Galinato, T. Kortus, and J. Maberry. 2021. Alternate-year production Is not profitable in Washington floricane red raspberry systems. HortTechnology. doi:
  • Devi, P., L.W. DeVetter, S. Lukas, and C. Miles. 2021. Exogenous treatments to enhance splice-grafted watermelon survival. Horticulturae 7(7):197.
  • du Toit, L.J., Derie, M.L., Gundersen, B., Waters, T.D., and Darner, J. 2021. Effects of late-season cultural practices on bacterial leaf blight and bulb rot in an onion bulb crop in Pasco, WA, 2020. Plant Disease Management Reports 15:V100.
  • du Toit, L.J., Derie, M.L., Gundersen, B., Waters, T.D., and Darner, J. 2021. Efficacy of bactericides for management of bacterial leaf blight and bulb rots in an onion crop in Pasco, WA, 2020. Plant Disease Management Reports 15:V107.
  • du Toit, L.J., Derie, M.L., Gundersen, B., Waters, T.D., and Darner, J. 2021. Efficacy of disinfectants applied to onion bulbs in storage for control of bacterial bulb rots, Pasco, WA, 2020-2021. Plant Disease Management Reports 15:V102.
  • du Toit, L., and Waters, T. 2021. To disinfect or not? Can postharvest applications of disinfectants reduce bacterial bulb rots in storage? Onion World, July/August 2021:6-9.
  • Grant, K.J., L. DeVetter, and A. Melathopoulos. 2021. Honey bee (Apis mellifera) colony strength and its effects on pollination and yield in highbush blueberries (Vaccinium corymbosum). PeerJ. 9:e11634.
  • Griffin-LaHue, D., S. Ghimire, Y. Yu, E.J. Scheenstra, C.A. Miles, and M. Flury. 2021. In-field degradation of soil-biodegradable plastic mulch films in a Mediterranean climate. Science of The Total Environment, 150238.
  • MacKay, H., and du Toit, L. 2021. Progress report. Stop the Rot: A national collaboration to research, combat bacterial diseases of onion. Onion World, May/June 2021:12-14.
  • Jonathan Yoder, Siddharth Chaudhary, Brittany Duarte, Correigh Greene, Jordan Jobe, Gabe LaHue, Cindy Maroney, Guillaume Mauger, Harriet Morgan, Julie Padowski, Kirti Rajagopalan, Crystal Raymond, Matthew Rogers, Nathan Rossman, Navdeep Singh, Britta Timpane-Padgham, Chad Wiseman, Jason Won. 2021. Skagit Water Supply and Demand Synthesis. Story Map Series Prepared for the State of Washington Joint Legislative Task Force on Water Supply.
  • Wohleb, C.H., Waters, T.W., and du Toit, L.J. 2021. Washington State University Extension Onion Alerts. Contributed articles and photos, and edited WSU Onion Alerts released online on 9 Jun. and 1 Sep. 2021. and
  • Zhang, H., C. Miles, B. Gerdeman, D.G, LaHue, and L.W. DeVetter. 2021. Plastic mulch use in perennial fruit cropping systems – A review. Scientia Horticulturae, 281, p.109975.