When: Oct 4, 2023 12:00 PM Pacific Time (US and Canada)
Topic: Crop Pollination in Hydroonic Systems
Hydroponic production systems can be used to produce high value specialty crops year round. However, many of these crops would typically require bee pollination in open-field situations. This webinar will cover the basics of greenhouse crop pollination, including how best to manage environmental conditions and purchase/place bee hives for optimal success.
This webinar is one of a four-part series of hydroponics webinars, hosted each Wednesday, from noon-1pm: October 4, 11, 18, and 25.
This webinar is free, but requires advance registration. The webinar will be recorded, and made available after the event, to all who have registered.
Gail Langellotto is Professor of Horticulture at Oregon State University (OSU), where she coordinates the Urban Agriculture Certificate Program. An entomologist by training, she studies pollinators in urban systems. She is a collaborator on the OSU hydroponics team and a joint University of Oregon, Washington State University, and OSU building integrated agriculture project.
Nursery science researchers have embarked on a journey to harness the principles of soil hydraulics to reshape container production practices. In the past couple of years, Dr. Chris Criscione and Dr. Jeb Fields and others released a series of articles that showed that stratifying pine bark can serve as a substitute for peat-based media in floriculture and bark-based woody plant production. Through layering premium floriculture media over cost-effective pine bark within containers, they reduced reliance on peat. In their study focused on Petunia hybrid ‘Supertunia Honey’, the stratified substrates yielded crops of comparable size and quality, along with enhanced root productivity. Their work also showed superior performance of bark:coir substrates in a stratified setup, even when subjected to reduced irrigation when producing Loropetalum chinense ‘Ruby’ liners. Positive microbial communities in stratified systems further aided in mitigating water stress. Furthermore, Red Drift® rose plants grown in stratified substrates exhibited equal or superior crop growth despite receiving less controlled-release fertilizer. This suggests potential for reducing fertilizer and irrigation rates while upholding crop quality, offering a sustainable avenue for containerized crops. This blog post aims to shed light on stratified substrates and also provide insights into ongoing projects at the Nackley Lab that are delving into this innovative frontier of nursery science.
Soil hydraulics delves into the intricate world of water movement within soils—how water traverses the soil matrix, its distribution, and its intricate interactions with soil particles and structure. It’s a field dedicated to understanding the physics governing water’s journey through soils, and this knowledge carries significance for agriculture, environmental science, hydrology, and civil engineering. Soil hydraulics guides irrigation strategies, shapes drainage designs, and fuels sustainable land management practices.
Central to soil hydraulics is the concept of matric potential, a critical factor in irrigation management and plant-available water. Matric potential captures the degree to which soil particles retain water due to molecular attractions—it’s essentially the “stickiness” of water to soil particles. When soil isn’t completely saturated, minuscule air-filled spaces exist between particles. Water molecules adhere to these particles, creating capillary forces that coax water upwards. The strength of the bond between water and soil particles determines the matric potential, effectively influencing water availability to plants.
Two other essential players in the realm of soil hydraulics are soil texture and structure. Envision soil as an intricate mosaic, with particles coming together to form aggregates, shaping distinct pathways and chambers. This arrangement, referred to as soil structure, creates macropores— akin to express highways—through which water can flow rapidly. At the same time, micropores, reminiscent of narrow alleyways, gently retain water against gravity’s pull, acting as reservoirs for plant roots during dry spells. Additionally, soil structure influences permeability, determining how efficiently water infiltrates and the risk of surface runoff.
Soil texture, on the other hand, hinges on the proportions of sand, silt, and clay particles in the soil. Each particle type comes with distinct traits that shape water dynamics. Coarser-textured soils with more sand have ample space between particles, allowing water to move quickly with less retention. Finer-textured soils, rich in silt and clay, boast smaller gaps between particles, leading to slower water movement and higher water-holding capacity.
However, when soil is confined to pots or containers, it undergoes transformations in its natural structure due to various container-related factors. The restricted space of a pot, contrasting with the expanse of natural soil, can lead to the erosion of soil structure. Aggregates—clusters of particles forming pores and pathways—can deteriorate over time due to limited expansion room. This confined space often results in compaction, where soil particles compress closely, reducing essential air-filled pores needed for root growth and water movement. The watering practices specific to potted plants can contribute further by compacting soil particles as water occupies gaps. The absence of natural soil organisms and plant roots within containers hampers the maintenance of soil structure. Repeated disturbances, like transplanting or repotting, can exacerbate these structural changes. To counter these effects, selecting appropriate potting mixes that retain structure, incorporating organic matter for improved aeration and water retention, and being mindful of compaction during planting and watering are recommended.
Traditionally, the nursery field has focused on creating homogeneous potting mixes that maintain structure while offering suitable hydraulic properties. Classic blends often comprise bark, coir, peat, perlite, vermiculite, and pumice. However, a recent shift in focus has led scientists to explore how layering media can simulate natural soil hydraulics—an approach known as stratified substrates.
Stratified substrates involve arranging potting media of varying textures in layers within a single container. This structured layering entails placing coarser-textured substrates at the bottom and finer-textured ones on top, mimicking natural soil layers. This technique aims to influence water movement, nutrient distribution, and hydraulic behavior within the confined environment of a container. By borrowing from the stratification seen in the ground, stratified substrates strive to optimize resource efficiency, plant growth, and root development in controlled settings like potted plants.
Some may draw parallels between stratified substrates and the practice of placing rocks or gravel at the bottom of larger plant pots. While both concepts involve layering materials, there are distinctions. The practice of adding gravel or rocks to enhance drainage in larger pots shares a kinship with stratified substrates. However, it doesn’t replicate the comprehensive layering dynamics seen in stratified substrates. Adding gravel mainly addresses drainage concerns without fully incorporating the layered hydraulic principles inherent to stratified substrates.
Dr. Chris Criscione, in collaboration with the Dr. Jeb Fields group at Louisiana State University, has been at the forefront of investigating stratified substrates in containerized plant growth. Their research delves into how layering different potting media textures can enhance water retention, nutrient availability, and overall plant performance. The studies highlight promising outcomes, such as heightened root productivity, improved growth, and enhanced quality under stratified conditions compared to conventional substrates. This technique holds potential for bolstering sustainable crop cultivation within controlled environments.
Nevertheless, it’s crucial to acknowledge that findings from studies conducted in one geographic region—such as the Southeastern USA—may not seamlessly extrapolate to other areas with distinct climates and environmental conditions, like the Pacific Northwest. Climate, temperature, humidity, and other factors can significantly influence plant growth and water dynamics. Given this variation, research in regions like the Pacific Northwest, such as Oregon, is crucial. The unique environmental factors there, including cooler temperatures and higher rainfall, can impact water movement, nutrient availability, and plant response to stratified substrates. Bark-based substrates, common in some areas, may behave differently in terms of water retention and drainage in regions with distinct soil compositions. To address this, the Nackley Lab initiated a collaboration with Dr. Fields and others in 2022, planning to explore the impacts and benefits of stratifying substrates in Nursery production. The first stratified substrate experiment was launched in 2023 at Oregon State University North Willamette Research and Extension Center (NWREC), aiming to reduce resource demand and provide insights into the effectiveness of stratified substrates in that context, contributing to more informed decision-making for nursery production and horticulture practices in the region.
The Gravel Pad update you’ve been waiting for, and more!
There’s so much going on in the season of plenty around NWREC! Enjoy this virtual tour of a few projects around the nursery.
Dalyn has been continuing her work with mini-lysimeters that control irrigation in shade trees – these tiny scales weigh the potted plants and use the change in weight as they dry to determine when to turn on the water. The lysimeters are gathering data on plant weight along with an on-site weather station to better understand the relationship between heat and irrigation in gravel pad production. Read more about this project here.
The Willamette Valley has had a few HOT summers in a row, even though lately this one has been pretty mild. Nevertheless, we haven’t given up on finding solutions for heat mitigation – including growing ornamentals under drought conditions to see which are the most “climate-ready” to meet changing needs. We’ll be asking the public to evaluate those plants in the upcoming Climate-Ready Field Day, come along and see how the plants are progressing (click the link above for more info).
In addition, we’re evaluating different means of mitigating the heat and the resultant high rates of evapotranspiration (basically ways to reduce plant sweat), from misting the young plants to covering tissues with kaolin, introducing fungicides that may be beneficial in managing water loss, using white pots instead of the traditional black, and even growth inhibitors – it’s been a pretty amazing feat to monitor the effects as you can see- check out this monitoring station!
A small project growing marigolds for festivals and holidays – like Dia de los Muertos – is also underway. Growing the marigolds has certainly brightened up the Nursery Zone at NWREC, and we’ve progressed into evaluating passive means to dry the flowers, saving energy and resources while preserving the gorgeous summer color.
There’s even more in the works – stay tuned for information about fall workshops and PACE courses created specifically for nursery and greenhouse production for topics covering drone sprays, integrated pest management, and more.
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!
At the Western Region International Plant Propagators Society (IPPS), the Pacific Northwest Insect Management Conference (PNWIMC), and the Orchard Pest and Disease Management Conference (OPDMC) last month, we presented cutting-edge research and advancements in our field. Our presentations at the Western Region IPPS and PNWIMC focused on the latest developments in sensor-controlled irrigation, and flatheaded borer management, respectively.
At the Orchard Pest and Disease Management Conference, we discussed the latest techniques in IPM for managing powdery mildew with biological fungicides applied by our laser-guided Intelligent Sprayer system. Through our presentations at these conferences, we aim to advance the knowledge and understanding of plant health in our field and to promote collaboration among professionals. By sharing our research and engaging in discussions with our peers, we strive to advance the science of horticultural production to support the growth and success of the horticulture in the Pacific Northwest region.
At NWREC, we have been working on our new hydroponic greenhouse project. However, since October we have encountered construction challenges in connecting the natural gas heaters, which has impacted the growth of crops such as lettuce, tomatoes, and cucumbers. As a result, lettuce growth has been slow and plagued by Botrytis, and warmer-growing crops like tomatoes and cucumbers have fared even worse. We are working to resolve the permitting issues with the heaters as soon as possible and look forward to updating you on the progress of the greenhouse project in the coming year.
Recently our own Brent Warneke wrote another great article for Sprayers 101 covering the Intelligent Sprayer System – check it out here: https://sprayers101.com/airblast-sensors/
Want a preview? Here’s a synopsis:
Air-blast sprayers are versatile, reliable, and can be modified to fit numerous types of crops, all of which are reasons for their continued popularity. Yet despite their popularity, air-blast sprayers have long had a reputation for inefficient application characteristics. Sensor controlled spray systems reduce labor costs and pesticide waste. Recently, they are receiving renewed interest as their reliability has improved and more options have become available. There are two main types of sensor sprayers:
+ On/off sensor sprayers + Crop adapting sprayers
Sensor types Infrared sensors: The inability to resolve characteristics of plant structure makes IR sensors suited to less complex applications such as triggering the sprayer on and off at a plant. Additionally, these systems can be used for herbicide sprayers where the sensors are aimed at the trunks of trees/vines and turn off the sprayer as they pass the trunk or to target it for the purpose of sucker sprays.
Ultrasonic sensors: using multiple sensors, it’s possible to collect canopy volume data with similar accuracy to taking manual measurements. These are typically used on canopy sprayers with around 3 sensors per side of the sprayer.
Laser sensors (LiDAR): Provides the most accurate measurements of plant structure (mm resolution). Only one sensor needed for accurate measurement.
Plant fluorescence sensors: These have a spatial resolution between ultrasonic sensors and LiDAR sensors. Most commonly used on “weed-seeing” herbicide sprayers but also on canopy sprayers. All sensor sprayers must have a speed sensor to synch the sprayer ground speed to the sensor system.
Spraying with sensor sprayers Insect pest and disease control with sensor controlled sprayers has been widely shown to be similar to that of standard sprayers. Control can be achieved on those crops with spray volume savings from 20-70% depending on the sensor system used and crop spray volume savings are higher in crops with more variability labor savings, less pesticide release into the environment, tractor wear, and driver fatigue are also reduced as the sprayer is in operation for less time.
Sensor sprayers can result in 20% to over 90% less spray drift. Autonomous sensor sprayers companies are currently developing and selling autonomous sprayer units that drive themselves and can be integrated with sensors.
For the past few years we’ve limited gatherings on the farm due to COVID-19 restrictions. In the summer of 2022, however, we were finally able to welcome the public back for Nursery Program Field Days. We’d like to take this opportunity to boast about a few of our highlights from the last several months.
For the first time, the Nackley Nursery Production team was an official stop on the Oregon Association of Nurseries Farwest Innovative Production Grower Tour. Our portion of the tour at NWREC showcased sensor-controlled irrigation, heat-stress mitigation techniques, LiDAR smart-sprayer systems, and practices that can reduce boxwood blight spread, and methods of scouting and monitoring insects in nurseries and greenhouses. These projects offer a wide range of savings for growers.: up to 80% improvement in irrigation efficiency, up to 70% reduction in sprayed pesticides, and a significant reduction in boxwood blight infection.
The second big event was an open house for our Climate Ready Landscape Plant trial, the largest coordinated landscape plant irrigation trial in the Western US. Plant professionals from around the region came to rate plants and discuss how we, as a society, are going to maintain healthy landscapes while faced with increasing extreme weather.
Ongoing projects that will continue this year include, research by our graduate student Sadie Keller, who is investigating Oak and Maple drought tolerance. This summer, Sadie shared her preliminary findings with scientists at the American Society for Horticultural Science, in Chicago.
In addition, Dr. Melissa Scherr continues our research on the Pacific Flatheaded beetle, with the anticipation of a grower event hosted at NWREC discussing current research on Flathead Borer biology and control this coming April – 2023.
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.
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.
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
Bud Break: Date when the protective scale coating is shed from the bud exposing the tender new growth shoot
First leaf: Date the first leaves are completely unfolded on at least 3 branches
All Leaves Unfolded: Date when 90% of buds have reached first leaf
First Flower: Date the first flowers are opened and stamens are visible on at least 3 branches.
Full Flower: Date when half or more of the flowers are fully open
First Ripe Fruit: date when the first fruits become fully ripe or seeds drop naturally
Full Fruiting: Date when half or more branches have fully ripe fruit or have dropped seeds
50% Color: Date when half or more of the branches have leaves that have started to change color
50% Leaf Fall: Date when half or more of the leaves have fallen off the tree
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.