Category Archives: Plant Health

Climate-Ready Landscape Plant FIELD DAY

UC Davis Plant Trial Field Day 2020
Photos: UC Davis Plant Trial Field Day 2020 cr: Karrie Reid

Who should attend: Professionals from landscape, horticulture, nursery and related fields; OSU Master Gardeners; garden writers; academics/educators

When: September 14th 2022; 10am – 2pm (Arrive when convenient; ratings take about 60 min)

Where:                  OSU’s North Willamette Research & Extension Center

15210 NE Miley Rd, Aurora, OR 97002

What’s involved: Evaluating aesthetic qualities of selected landscape plants (about 60 minutes).

Photos: UC Davis Plant Trial Field Day 2020 Credit: Karrie Reid
Photos: UC Davis Plant Trial Field Day 2020 Credit: Karrie Reid

About this Event

The ever-changing climate iputs pressure on the industry to develop more sustainable plants. As part of a six-university study, OSU seeks to improve urban water-use efficiency by evaluating landscape plant performance on three irrigation treatments corresponding to the Water Use Classification of Landscape Species (WUCOLS): High, Moderate, and Low categories of water need. The plants are irrigated regularly during their first summer after planting. Treatments are imposed during the second growing season where researchers collect growth and quality ratings.

The Field Day allows landscape, nursery, and horticultural industry professionals and educators the opportunity to see new plants in their 2nd year and share your opinions and preferences by rating a representative sample of the plants in the field undergoing irrigation treatments. One plant from each of the 3 water levels, for 15 different species (some released to the public and some not yet) will be surveyed. Along with this field of 360 plants, you will be able to get a sneak peek at the next year’s field, currently in an establishment phase.

Important Details: The fields are packed dirt/uneven mulch, sturdy comfortable shoes, sunscreen and/or a hat are suggested. At the trial site, you will be provided a ratings sheet, clipboard, pen, and given general instructions when you arrive. It is a self-guided tour among our 720 landscape plants. Lots to look at but only a small sub set to evaluate. Hot Coffee and cold water will be provided. We value your feedback and hope to see you there!

For questions contact:

Brian Hill

(562) 841-1522

brian.hill@oregonstate.edu

2022 Field Day Tour and Open House

August 23, 2022

Nackley Lab nursery production open house takes place August 23. 2023 from 11am – 2pm

Our event will be a part of the great Nursery related activities happening around the Willamette Valley as part of the Oregon Association of Nurseries Farwest Show, which will also feature Dr. Nackley, and Brian Hill, M.S. and many others from Oregon State and beyond.

The Nackley lab open house will feature research on our four themes: Irrigation science, pest management, plant health, and plant trials.

Free to all, no registration required.

Parking: follow signs to south side of the Cravo North Willamette Research and Extension Center and then follow signs walk 5 mins (west) to Nackley Lab Welcome Center.


Masks are welcome, not required, per University policy

The tour route will travel through fields with uneven terrain. Farm cart transport (e.g. gators) can be available for those who request assistance.

Schedule of Events


Field Tour
11 :00 -11:15 Station 1. Welcome, overview of the program and biostimulant research on Shade-Trees
11:15 – 11:30 Station 2. Plant-based irrigation scheduling: pressure bomb and infra-red thermography
11:30 – 11:45 Station 3. ET-based irrigation scheduling and Flatheaded borer research
11:45 – 12:00 Station 4. Cover cropping and Heat-stress prevention
12:00 – 12:15 Station 5. Boxwood blight control
12:15 – 12:30 Station 6. LiDAR “smart” air-blast sprayer and drone demonstration

12:30 – 1:00 Station 1. Open chat with research team, refreshments and grilled sides.

Open House
1:00 – 2:00 Self guided tour. Researchers will be at each of the six stations to answer questions. Sprayer demos will take place at station 6 every 15 mins.

Plant Health: When Do Shade Trees Do What They Do?

Brian Hill

A Phenology Study is underway at NWREC!

The pretty flowers of spring, shade providing leaves of summer, and fire like colors of fall help us know when the seasons are changing. We use calendars to plan everything in our lives. Nature does the same but not in the same way.

Progression of seasonal changes in shade tree crown and color
Shade tree seasonal progression from spring (top left) to fall (bottom right).

What causes trees to change?

We can all remember early spring weather that was warm and dry as well as those years when we hoped our 4th of July BBQ would not get rained out. These weather differences from year to year influence events in nature that are crucial for species to survive. Plants and insects go dormant over the cold winter and begin growing in the spring and do it without a single calendar. They use day length and temperature to schedule their life events. The day length in the Willamette valley changes from 8 hours and 46 minutes in winter to 15 hours and 36 minutes in summer. These changes are predictable because they are cause by the tilt of the Earth, which doesn’t change. Our calendars align with these dates (winter solstice and summer solstice).Temperature, however, is unpredictable because there are a vast number of factors that influence it.

What changes are we monitoring?

A large part of the nursery industry in Oregon is dedicated to growing shade trees. Best management practices require monitoring for signs of event changes throughout the tree’s life cycle. This is known as Phenology, defined as the study of cyclic and seasonal natural phenomena, especially in relation to climate and plant and animal life. The Nackley Lab has a small in ground tree nursery that we use for experiments. For the past 3 years we have been conducting a Phenology Study where we have tracked the dates our tree events happened.

Monitored events in our Phenology study

  1. Bud Break: Date when the protective scale coating is shed from the bud exposing the tender new growth shoot
  2. First leaf: Date the first leaves are completely unfolded on at least 3 branches
  3. All Leaves Unfolded: Date when 90% of buds have reached first leaf
  4. First Flower: Date the first flowers are opened and stamens are visible on at least 3 branches.
  5. Full Flower: Date when half or more of the flowers are fully open
  6. First Ripe Fruit: date when the first fruits become fully ripe or seeds drop naturally
  7. Full Fruiting: Date when half or more branches have fully ripe fruit or have dropped seeds
  8. 50% Color: Date when half or more of the branches have leaves that have started to change color
  9. 50% Leaf Fall: Date when half or more of the leaves have fallen off the tree
image shows the phenology stages of flowering trees
Phenological stages of flowering trees from bud break (top left) to full flower (bottom right).

How can this information be useful?

As we collect data in year 3 (2022) of this study we are excited for how this data may be used in the future. Temperature data can be used to make degree day models which are based on heat units. The number of heat units per day are added together in a running total. This information is much better at predicting events in nature when compared to calendars. When growing shade trees in a production nursery setting, defending the crop from disease and predators is essential. Spraying a tree with a fungicide at bud break keeps them growing healthy. Spraying pesticides at first flower protects trees from insect attacks. By creating degree day models, growers can predict when to apply chemical protection for trees, eliminating double applications caused by calendar reliance.

Growers know the uncertainty caused by a changing climate impacts tree growth events. It’s hard not to trust the calendar dates which we plan everything else in our lives by. Future projects include modeling the events recorded over the last 3 years, and seeing how they align with degree day accumulation. The end goal is to use what we’ve learned to help keep the labor and pesticide costs down for the local nurseries while the produce the beautiful tree’s we all depend on.

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.

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