All posts by scherrm

People: California Grown Grad Student Studies Plant Physiology Drought Responses

Sadie Keller

My path to pursuing a Master of Science in Horticulture has not been straight and narrow. Ironically, growing up in California’s Central Valley, I wasn’t aware of the career possibilities in agriculture and horticulture. I’d always possessed an affinity for plants and the outdoors for as long as I can remember. My earliest memories involve working in our backyard garden with my dad and raising chickens.

I graduated high school with a love of science and headed to college to pursue an engineering degree. After two years of struggling with my major, it was time to come home and assess my options. I started attending classes at a local community college and found a job working farmers markets on the weekends. Little did I know, this experience would change the rest of my life. I loved this job and it showed me what I was passionate about; the environment, sustainability, irrigation efficiency, and building climate resilient landscapes and agriculture systems.

Keller measures stem water potential using pressure bomb method
Sadie measures stem water potential using a pressure bomb.

I transferred to California State University, Stanislaus to obtain a Bachelor of Science in Agriculture. From this point on, I have thrown myself into every possible internship and work experience to expand my skills and deepen my knowledge. I’ve worked as a nursery technician, a field scout, a CSA assistant, a standards program aide for the county, a trapper, an inspector, and research assistant. In February of 2020, I was selected to attend the Future Leaders in Agriculture Program in Washington D.C. with 20 other students from around the U.S. where my eyes were opened to the vast opportunities available in agriculture.

Now, as a Graduate Research Assistant in the Nackley Lab, I study ornamental plant vascular systems responses to drought conditions and stem hydraulics. Being at Oregon State and a member of the Nackley Lab, I feel like I am getting the most hands-on experience and interdisciplinary education possible. I am getting lab experience working for Dr. Carolyn Scagel at the USDA-ARS Horticulture Crops Research Lab where I support her plant physiology research by helping with tissue and water sample collection, processing, and laboratory analyses related to plant water relations and plant mineral nutrition. With Dr. Nackley, I am getting to explore my interests in remote sensing technologies and learning how I can incorporate these technologies into my thesis project. I am also a TA for his Plant Nursery Systems class this Spring. My favorite part about doing research is working at NWREC over the summer with our lab team and other graduate students.

computers and equipment used for plant physiology studies
Sadie’s work settings, her home away from home.

Pest Management: The Enemy of My Enemy

Melissa Scherr

There is an often-referenced but under-implemented army of spineless mercenaries wandering our nurseries in search of glory and fame.

Ok, that might be a bit melodramatic, but it’s not necessarily untrue. Natural enemies – that is, the natural enemies of PEST insects – are a naturally occurring force for good in production systems, feeding on every stage of many of our most economically important pests. Just as the pest insects invade when we supply an abundance of leafy hosts, the natural enemies of those pests respond to the abundance of prey. However, waiting and hoping these beneficial insects appear in sufficient numbers to manage a pest outbreak doesn’t always seem like a safe bet, which is why methods for enhancing the efficacy of natural enemies have become a staple in Integrated pest management strategies.

Utilizing natural enemies in crops has become increasingly popular as more species are available for mass releases from commercial suppliers – everything from the predatory mites that feed on the eggs and young of soft-bodied insects and other mites, to the above-pictured green lacewing, the juveniles of which not only appear as a tiny alligator, but feed just as voraciously (image right).

photo: juvenile lacewing feeding on a caterpillar;
cr. Ralph Berry, OSU Entomology

Understanding both the pest and the natural enemies in your system is key to utilizing the natural enemies as a pest management resources. It’s important to target all stages of the pest insect, which means identify the natural enemies that attack the different stages and encouraging the natural enemy populations at the right time. There are three main strategies for encouraging natural enemies:

  1. Conservation. Conserving the natural enemies that already exist in the production zone includes providing habitat and alternate food resources, so that when they prey numbers decline, the natural enemies don’t leave the area. This could mean providing debris for overwintering or alternate host plants that will not only attract pest *away* from crops but give predators a continual food resource.
  2. Augmentation. Once you’ve identified the natural enemies in your system, you can temporarily boost the population size by augmenting with commercially available NEs to create more pressure on the pest population. This can be used to target adults during mating season to limit reproductive success, or used to target egg and juvenile stages to limit damage later in the season. Understanding pest biology will help make decisions on how and when to use this strategy. Combined with conservation strategies, this can provide long term suppression, potentially lasting more than a single season.
  3. Inundation. This strategy is similar to augmentation but is usually implemented in artificial settings, such as greenhouses, when natural enemy populations are usually low or non-existent. Introducing a natural enemy at a high density to control a pest population can provide rapid suppression, though in this strategy, it usually is less reasonable to expect the natural enemies to remain once pest numbers are low. This is usually implemented with the expectation that natural enemies will need to be reintroduced as need.

Of these strategies, augmentation is the most ideal place to start – harnessing the natural enemies already occurring in your production zone. In 2021, the Nackley Lab released the pocket guide to Common Natural Enemies in Nursery Crops and Garden Pests (image right, click to download) to aid in identification and to help with decision-making when it comes to using natural enemies in pest management strategies. With color images showing distinguishing characteristics, commonly mistaken species and information on scouting for these natural enemies, it can help you get started with natural enemies in your crop.

common natural enemies cover
Common Natural Enemies cover, publication EC 1613

People: The Meeting of Plant Physiology and Tech

Dalyn McCauley

Backpacking in the Sawtooth mountains
during an unexpected blizzard.

I was born and raised in Southern Oregon (Central Point, OR). I grew up with a family that spent a lot of time outdoors, and almost always around water. White water rafting, crabbing trips, skiing, surf lessons, and sailing was how I spent most weekends and summers. Not much has changed. I have always been a tinkerer and love being creative, solving problems and building. My up bringing, laced with unintentional physics lessons, paired with a love for math and science led me to pursue a degree in Mechanical Engineering at Oregon State University.  

During undergrad, my path of study provided me with many unique and exciting opportunities. My favorite of which was studying abroad at the University of New South Wales in Sydney, Australia. This was such an incredible experience that widened my world view and got me passionate about international travel. I then got involved in the OSU chapter of Engineers Without Borders, and in my last year of undergrad I traveled to rural Cambodia on an assessment trip to plan out the design for a water distribution and filtration system for a small village. It was a powerful and transformative experience, as I was able to see the complexity and challenges of water resource issues globally. We learned a lot from the community and local NGOs about project management, engineering in low-resource environments, and the challenges associated with regulating a common-pool resource like water. Ultimately, it was during this experience that I realized I wanted to be in a profession where I could contribute to solving global environmental problems, which led to my M.S. in Water Resource Engineering with a research focus on precision agriculture from the University of Idaho.

Now, as an FRA in the Nackley Lab working on sensor-controlled irrigation techniques, I am lucky to have found a niche career path that combines engineering and environmentalism. I investigate and develop automatic irrigation systems that use real-time feedback from plants, soil or weather (or a combination thereof) to control irrigation and conserve resources. My favorite thing about working in agricultural research and extension is the great potential for impact. At the extension level, we are at the very important nexus of academic research and on-farm adoption. Working closely with growers to develop pertinent research questions, and having growers anticipate our experimental results gives our work tangible purpose and keeps things exciting.

Installing sensors for a crop water stress study at NWREC
At work, you can find me amongst the hemp in the lysimeter-controlled irrigation set up at NWREC

Pest Management: Springtime, the calm before the grape growing season storm

By Brent Warneke

In early spring in western Oregon many orchard crops are breaking bud, bulbs are showing off in gardens and perennials are bursting into spring glory. Wine grapes, however, are late to break bud, with average dates at our research vineyard in Corvallis of about mid-April each year. The month period between mid-March to mid-April is a good time to check off a number of tasks before vines break bud and attention needs to turn to managing vine growth.

Controlling weeds is easiest to do when everything is growing slower such as in winter and early spring.

When the grapes start dripping, bud break is around the corner.

If there are any weeds below vines that have established over winter, control these with herbicides such as glufosinate, glyphosate, or paraquat. After existing weeds have been managed, applying a pre-emergent herbicide helps prevent future weeds from establishing by creating a protective layer of herbicide in the soil. Products such as Casoron and Goal work well, with Casoron being a granule and Goal being a liquid product. For some pre-emergent herbicides, precipitation is needed after application to wash the product into the soil for maximum efficacy. Always carefully read the product label before making an application of any pesticide.

Control establishing weeds then apply a pre-emergent to prevent further weed establishment.

Before vines get growing is a great time to go through the vineyard and remove or destroy vines with galls or cankers. Look for growths such as crown gall at the base of vines or open cuts on cordons or vine trunks. Crown gall can girdle vines, starving the vine of nutrients and water, and is particularly harmful to young vines. Vines infected with crown gall or with open cankers should be removed and burned or transported away from the site and destroyed. Care should be taken when removing vines with crown gall as it can be spread on tools.

Prevention of trunk diseases is key to vineyard longevity, and extended wet periods in spring are perfect conditions for trunk disease pathogens to establish. The pathogens that cause trunk diseases release spores during extended wet periods, and spores are then spread by rain and wind to open pruning cuts. Consider applying protective fungicide applications to cover recently opened pruning wounds to prevent infection. A chemical free way to prevent infection by these pathogens is called double or delayed pruning. A pruning cut is made to vines leaving longer stubs than needed. Later in the season when rains have stopped a second cut is made to the desired length to allow the vines to heal without rain and thus decreasing the chance of infection by trunk pathogens.

Once the grapes get growing it’s hard to keep up so inventory pesticides, PPE and other inputs and place orders for anything that is needed. Calibrate your sprayer, make sure your tractor is functioning well, and order any extra parts that might be needed for the season. A little preparation goes a long way in a successful season, best of luck to all in 2022!

Left: Crown gall makes disorganized, bumpy growths typically located at the base of vines. Remove all affected vines (including as much roots as possible) and destroy, while trying not to contaminate other adjacent vines. Decontaminate tools with 10% bleach or 70% ethanol.

People: The Serious Bees-ness of Bugs

Melissa Scherr

Melissa is Greek for “honey bee”, but I’m pretty sure my parents hadn’t given me the name expecting I’d take it quite so literally. Though when I’m hand-pollinating my corn in the summer to make sure I get well-fertilized, full cobs I thoroughly enjoy the irony. Even as a kid, one of my favorite hobbies was flipping over paving stones to capture worms and “rolly pollies” and other small insects in the unused canning jars in the garage… much to the horror of my parents when canning season came back around. Though I don’t think I was the only kid doing things like that, I have noticed that the Entomology community isn’t as big as it would be if all the kids grew up to become insect specialists.

Becoming an entomologist wasn’t exactly the dream I had growing up, either, and in all honesty, I didn’t even know it was a career path until college. In fact, I’d started university in the music program with a scholarship for Vocal Performance but not really knowing what I wanted for myself as a career. The biggest mistake of that career was testing into General Biology for Majors, because in my first term of classes I knew Biology was where I belonged. I finished my first year at college taking the minimum required credits to maintain my scholarship while doubling down on my biology, chemistry, and math courses. I began my second year as a biology major.

With my limited exposure to careers in science, I began exploring specialties through the courses I took at Oregon State University during my undergrad years. I took an Aquatic Entomology class that finally lit up all the ideas and passion that I felt for science, and it didn’t take long for me to decide that insects and ecology were going to be my path. I became fascinated with the interaction between insects and their environments, the way they could be used as living indicators, and tracked to understand weather patterns and the ecologies of other organisms.

Above: Fender’s Blue Butterfly, found only in the Willamette Valley; right: Mating Silvery Blue butterflies

From there, my desire to understand the way insects behave in response to changes in the environment evolved and I began to examine insects in changing landscapes of the Pacific Northwest: insect community aggregation in timber lands, pollinators in degraded and then restored landscapes, and channeled river systems in agricultural lands.

Dr. Scherr sampling insects in lavendar

Working in Nursery production is very similar. In every ecosystem, the part of this job I enjoy the most is the new mystery and the strange way insects have adapted to life with humans in our tiny corner of the world. There are more questions than answers, and insects find a way to surprise and amaze me in every project – sometimes not in the best of ways, like when they disappear the same year a major grant is funded – but always in ways that make my job interesting and compelling. I plan to always be found crawling through the foliage, shaking leaves and scratching the soil, searching for tiny answers.

Plant Health: Shade Trees Can Chill Out Better than Expected

Lloyd Nackley

Nackley Lab field-grown shade trees at the last week of planting. Blocks of 10 trees from left to right Maple, Crabapple, Oak, Serviceberry, Honey Locust, and Kentucky Coffeetree, distinguishable by leaf color and canopy structure. Rows from top to bottom week of planting (March-June) distinguishable by different stage of canopy development.
  • Oregon growers may have to store trees longer than usual when spring storms in the Midwest and Northeast limit shipping and planting.
  • We assessed the effects that longer storage has on the health of trees and found that properly stored shade trees were not negatively impacted by longer storage.
  • Our results indicate a wider window for shipping is possible.

Most of the trees grown in Oregon Nurseries are shipped to the Midwest and Northeast US. In the spring, massive storms in the Midwest and Northeast can put a freeze on trucking and transplanting of bareroot shade trees just as shipping season for Oregon Nurseries heats up. Oregon growers are faced with the question of will increased storage time impacts the quality of the bareroot as the frequency and severity of spring storms increase with Climate Change.

First week of planting at the Nackley Lab field at Oregon State University North Willamette Research and Extension Center (Aurora, Oregon).

Deciduous trees, such as maples, crabapples, oaks, and others are some of the most valuable and most common types of trees grown in Oregon. The Oregon nursery industry takes advantage of plant dormancy periods to dig, store, and ship trees. Large cold storage facilities give nursery growers some flexibility to ship trees when the conditions on the consumer’s end are suitable for planting. For example, trees destined for the Midwest can be held until the region’s colder, longer winter is over.

Trees brought out of cold storage by our grower cooperator, J. Frank Schmidt and Sons.

How long trees can be stored is one of the key physiological questions for optimizing nursery production. Even dormant trees have limits to the length of time they can be kept in cold storage. Dormant trees rely on carbohydrate reserves for respiration and tissue development. The two key risks of storage are desiccation and carbon starvation due to respiration. We must understand the limits to cold storage so that growers can ensure they are shipping healthy, high-quality trees to their customers.

Dr. Rebecca Sheridan using a pressure chamber (model 1505D-EXP, PMS Instruments, Albany OR) to measure stem water potential of trees brought out of storage before being planted.

With support from the Oregon Association of Nurseries research committee and considerable help from the J. Frank Schmidt and Sons crew, we conducted a study, recently published in Frontiers in Plant Science[NL1] , in which we studied the impact of prolonged storage on six genera: Maple, Crabapple, Oak, Serviceberry, Honey Locust, and Kentucky Coffeetree. For each cultivar, we measured stem hydraulic conductance and vulnerability to embolism. Every week for 14 weeks (March–June), we removed trees of each cultivar from cold storage (1–2°C). Each week and for each cultivar, we measured stem water potential and water content. We planted trees each week to track survival and growth. Our results showed that for four cultivars (Maple, Crabapple, Oak, and Serviceberry), the stem water potentials measured in trees removed from storage suggest that the water transport system remains intact during storage. For two cultivars (Honey Locust and Kentucky Coffeetree), the water potential measured on trees out of storage exceeded safe values. However, planted Honey Locust and Kentucky Coffeetree trees from all weeks survived and grew to suggest that these species can repair or rebuild hydraulic function. Overall, the results show that the trees did not experience detrimental water relations or carbon starvation thresholds. Our results suggest that many young deciduous trees are resilient to conditions caused by prolonged dormancy and validate the current storage methods.

Red maples beginning to show true colors towards the end of the growing season.

More info:

Front. Plant Sci. Sheridan and Nackley 2022 https://doi.org/10.3389/fpls.2022.818769

Digger Magazine: http://www.diggermagazine.com/the-cold-shoulder-season/  2021

People: The Life of Brian

I was born in the small farming village of Los Angeles. I lived in the city doing office type jobs until I turned 25 and read a book about the soil microbial community; and everything changed. This book, ’Teaming with Microbes’ by Jeff Lowenfels, is responsible for my complete career change. It was written so the first half taught the science behind soil and plant interactions while the second half explained how to use this knowledge in a home garden.

At the time I lived in a 3rd story apartment building with a balcony that, in no time, was overflowing with vegetable plants and bubbling buckets of compost tea. The success of the garden was directly related to my new-found understanding of soil. I moved out of California and went back to school at the age of 30 to follow my new found passion. My first class was Soil 101 at the local community college in Clackamas. Learning about the “why” behind life science fascinated me. I quickly finished a two year degree and transferred to Oregon State University.

Majoring in Crop and Soil Science while working in a soil microbiology lab took up all my time; when I wasn’t on my daily commute of 160 miles or staying up all night with two young daughters who didn’t like to sleep. After completing my bachelor’s degree, I joined the Dragila Lab and began working on my master’s degree in Soil Physics. I loved doing research and worked on a large, multi-department thesis project studying the effectiveness of soil solarization in Pacific Northwest nurseries. Soil Solarization required a tilled row of soil to be tightly wrapped in clear plastic sheeting. The clear plastic would use the greenhouse effect to super heat the soil, killing soil pathogens and weed seeds. During the three year project, I installed over 600 soil sensors for monitoring soil moisture and temperature movement under the plastic treatments, while other departments assessed the mortality to the weeds and pathogens. At the end of my thesis work, I had produced a model for predicting weed seed mortality from solarization.

Upon completion of grad school, I went into extension where my passion for science communication was used in combination with my knowledge of technology in horticulture. I have been working for OSU at the North Willamette Research and Extension Center since 2019. In the Nackley Lab as a Faculty Research Assistant I set up experiments that explore greenhouse and nursery production. Current projects include: flying UAV’s with near red spectrum cameras to look for plant stress from the sky, VWC sensor base irrigation of shade trees and lysimeter controlled irrigation for indoor hemp production. I am also part of OSU’s Intelligent Spray Project where an air-blast sprayer that has been retrofitted with a LiDAR system is evaluated for efficacy and pesticide savings in the nursery industry. My favorite part of doing research is setting up a new experiment in a way that will hopefully show differences in plant growth based on different treatments. The challenge of working with Mother Nature while manipulating the factors of plant growth fascinates me, especially when there are visual growth differences attributable to the experiment’s set up. These days I can be found either fiddling with technology, setting up overly complicated irrigation systems or at a podium giving talks about what information has been gained from the results of my trials. Where ever you do find me, you can be sure I am on a passionate course for understanding the whys behind growing plants.

Sunset on the Gravel pad at NWREC in Canby, Oregon

Brian, showing off the fruits of a season’s labor at NWREC

Irrigation: Going LOCOS for On-Site Weather Data

How we are using low-cost and open-source weather stations for decision support 

Dalyn McCauley

On-farm weather data can provide valuable information to growers including informing irrigation scheduling, tracking plant growth indices, and mitigating damaging events like frost, heat waves or disease. Weather can vary widely across landscapes, even across a single field, and we have found that there is value in having multiple distributed weather stations on-farm to capture variability across small spatial scales. To do this cost effectively, I developed a low-cost open-source weather station (LOCOS) for my M.S. thesis at the University of Idaho that uses low-cost sensors and an Arduino microcontroller for data logging. By distributing multiple LOCOS across a vineyard, we found that there were distinct micro-climates that had varying susceptibility to grape powdery mildew disease. From calculating a Powdery Mildew Risk Index at each station, we saw that some vineyard blocks could benefit from unique fungicide application schedules. You can read more about this project here.

Figure 1: The first iteration of the LOCOS design installed at a vineyard in 2019 (Julieatta, Idaho).
Figure 1: The first iteration of the LOCOS design installed at a vineyard in 2019 (Julieatta, Idaho). 

Since then, the LOCOS have been adapted to study crop water stress. In the summer of 2021, we used LOCOS equipped with infrared thermometers to develop a crop water stress index (CWSI) for hazelnuts. The CWSI is based on leaf temperature and weather data (air temperature, relative humidity, wind speed, and solar radiation). Leaf temperature is a known indicator of plant stress. When a plant is actively transpiring the leaves will be cooler than the surrounding air because of the evaporative cooling effect of transpiration. Whereas a plant that is stressed and not transpiring will have a warmer canopy that is closer to the ambient air temperature. The CWSI varies from 0 to 1, where 1 indicates a stressed, non-transpiring plant, and 0 indicates a well-watered plant transpiring at max potential.  

We used the LOCOS to collect canopy temperature of the hazelnut trees from June to September, 2021. The trees were subject to three different irrigation treatments, over watered, moderate water, and no water (dryland) so we could get a range of canopy temperatures to incorporate into our model. We also collected data on leaf water potential, leaf transpiration and leaf conductance to validate the index against. We found that the CWSI we developed was closely correlated with leaf water potential (r2 = 0.84), leaf conductance (r2 = 0.75) and leaf transpiration (r2 = 0.72). These are exciting results because it shows that the LOCOS could provide continuous data on crop water stress that can be used to inform irrigation decision in near real-time. This summer, we will use the LOCOS in another study to develop a CWSI for red maples. 

Figure 2: LOCOS installed in a hazelnut orchard for CWSI study in 2021 (Aurora, OR).  

Pest Management: Pesticide Redistribution, an important feature of synthetic pesticides

Brent Warneke

I have been working on the Intelligent Sprayer (ISS) project with the Nackley lab investigating management of plant diseases such as grape powdery mildew while also investigating ways to improve spray coverage and efficacy of the ISS on hazelnuts and nursery crops. I was recently invited to write an article for Sprayers101.com, a resource used globally to inform and provide resources to producers, to discuss my work exploring pesticide redistribution in plant tissues following application.

Pesticide redistribution is a characteristic of many modern synthetic pesticides that aids in their efficacy and reliability. Pesticide redistribution is the movement of pesticide away from its point of deposition to a different spot on or in the plant where it retains its activity against the pest or pathogen of interest. While many pesticides have redistribution properties, they are often under-studied and not always considered when choosing a pesticide product for an application.

One example of a type of pesticide redistribution is “translaminar redistribution”. This occurs when a pesticide is applied to one side of a plant (for example, a leaf) and absorbs through the plant tissue to protect the other side that did not directly receive spray (Figure 1). This can help make a pesticide application more effective especially when the crop contains dense or complex growth that is difficult to fully cover with pesticide when spraying. There are other types of redistribution that each are effective in their own way such as xylem systemic, phloem systemic, and vapor redistribution.

image shows pesticide movement within plant tissues
Figure 1. Translaminar relocation

Read more about this in the article on Sprayers101.com: https://sprayers101.com/redistribution/. While you’re there, explore the many other posts covering everything from sprayer optimization and nozzles to maintenance. Also featured on the page is Airblast101, a comprehensive handbook on the principles of air blast spraying.

Right: Brent Warneke (right) and Brian Hill (left) with the Intelligent Sprayer used for research at the North Willamette Research and Extension Center

Brent Warneke and Brian Hill with the ISS sprayer

Welcome to the Nackley Lab

We’re just getting started with our content, and we’re excited to share our work on nursery and ornamental production. Here are some things you can expect coming your way:

  • Soils and substrates for plant production
  • Irrigation and Nutrient Management
  • Strategies for managing pests
  • Climate-Ready planting
  • Greenhouse Management

We are proud to partner with many of the local growers, students and other extension partners in the Pacific Northwest. Stay tuned to learn about our team and the work we’re currently involved with!