Tag Archives: Featured

IPM: Early Season Scouting – Where to look when there’s nowhere to look (yet!)

Melissa Scherr

Scouting for insects and areas of potential introduction early in the spring can save headaches long into the season, and it’s relatively simple with just a few inexpensive pieces of equipment. The basic starter toolkit includes just a hand lens or magnifying glass, a sheet of white paper on a clipboard, and some flagging tape to easily mark trouble spots. Easy enough, you say… but what are we looking for with these tools?

hand lens held in hand
A standard hand lens, equipped with a small light
worker wearing head lens examining plant
Head gear equipped with magnification can aid in searching plants for small insects

In General

Beginning early in the season and identifying where problems are most likely to emerge first will allow targeting in regular scouting and monitoring activities. Using online tools like Degree Day models for your county can also help identify when the pests are likely to move into crops based on this year’s weather data, especially when combined with information from previous years’ scouting records.

Where to Sample

When initiating scouting activities, it’s also important to consider the entire landscape of the operation. Though monitoring hotspots and suspected problem areas will help with anticipated infestations, creating sections of manageable scouting areas throughout the operation will help avoid unanticipated outbreaks as well. It’s tempting to stick to the “most affected” areas, but that limits the ability to see the whole picture. Make sure to also examine common entry ways for workers and machinery as these can act as vectors of pests.

Dividing space into equal sections and sub-sampling can save time while making sure all areas within a crop are sampled

For nurseries and greenhouse where plants are in pots for most of the season, it’s important to search not just young plants, but the media and the pots themselves. The media, if not sanitized, should be inspected for overwintering grubs, mites, and other small pests that enjoy cool, wet substrate, like springtails. In pots with plants, search the bottom of the stems where they come into contact with the soil, lightly scraping to disturb any inhabitants and observing activity. For plants that have overwintered in pots, select several representative pots to remove soil up to 12” from the stems to search for grubs like cutworms.

rows of pots with plants
Make sure to search not only the plants and soil, but the edges of the pots as well.

Pots that have overwintered plants or substrate should be checked thoroughly, inspecting under the rims of the pot (for those with a folded over lip), under the pots, and upon removal of the plant and soil if possible, inside the pot. If the entire plant, roots and soil can be gently removed to examine the inside of the pot, also check the roots and substrate for evidence of tunneling around the pot.

What to Sample

Sampling for insects isn’t like any other organisms because insects are small yet highly mobile, yet in their relatively small range can be highly exploitative. For this reason, be prepared to look for more than just insects, but also their products and proof of activities.

Look for:

  • Stressed plants: otherwise healthy-looking plants with branches that appear wilted or weakened; whole plants that appear sick while others are not affected. Search the leaves, stems and plant crevices for evidence of insect presence
wilted plant
Stressed plants are a good indicator of pest presence, especially when stress is limited to one or a few plants initially.
  • Honeydew: sticky sap covering leaves or stems, appearing to have dripped from other surfaces as a result of sap-feeding insect activity on the plant – this sap may also be growing molds or other fungus secondarily
sap on plant leaves
Sap leaked onto surface of leaves from insects feeding above
  • Frass: insect poop. When insects tunnel and feed, they leave behind frass in the form of sawdust-like piles, black or brown flecks, or poop stuck to fine silken webbing in the case of silk-producing insects.
insect poop on leaf
Insect frass is often the same color as the food source, or black flecks
  • Exuviae: the shed skins of insects, lost as the insects grow. Usually seen later in the season, but as some insects emerge from their overwintering stage, they may molt and leave their exuviae on the surface of the soil, on their host plant, or on nearby artificial structures (especially in greenhouses).
leafhopper and shed skin
The shed skin often resembles the insect and can be used to identify the pest

How to Sample in Early Spring

1. Beat Sheet/Tap Sample

A beat sheet is a large square sheet held under foliage while the foliage is vigorously shaken or beaten with a stick. As one can imagine, this is less reasonable for tender young nursery and greenhouse plants. However, it can be easily modified for more effective and less damaging use when scaled down to a plain white sheet of paper on a clipboard as suggested in the aforementioned toolkit. Holding the clipboard under the plant, gently tap the plant with your finger to dislodge any insects that may be attached to the plant – usually anywhere from 30-60 seconds is plenty. Using the hand lens, the insects can then be identified and counted.

using a ruler to tap over a paper
Using a ruler or pencil can create a more consistent sample

2. Aspirator

These are readily available on supply websites, and can be used to gently vacuum small insects off of plants and sheets of paper for identification with a microscope, for freezing/preservation, or simply to remove the pest from the plant.

an aspirator is used to sample insects on lavender
Scouting for insects with an aspirator

3. Berlese Funnel

If activity is observed in plant substrates, this is helpful in identifying the specific insects and arthropods present. A sample of the media is introduced into the funnel with a light/heat source above. As the sample dries and heats, the insects move deeper into the funnel, eventually falling through to the collection cup for easier preservation and identification. A soda bottle and desk lamp are sufficient for a makeshift Berlese funnel.

berlese funnels
Large berlese funnels for large soil samples
desktop lamp and soda bottle works as a makeshift berlese funnel
A desktop lamp and soda bottle works as a makeshift berlese funnel

4. Sticky Cards

A traditional means of monitoring flying pests, use appropriate density according to location (In general, 1 card per 1,000 ft2 is standard). There are a few different types to monitor specific pests: blue cards attract mainly thrips; yellow cards attract multiple species. If you have crawling pests, you can place them on the bench overnight (when crawling insects tend to be the most active. To collect, simple cover with a piece of plastic wrap and observe insects using hand lens or magnifying glass. Things to remember: aphids have a life stage that is wingless, and thus won’t be caught on sticky cards; if natural enemies are released, REMOVE sticky cards as they will also capture these beneficial insects.

blue and yellow sticky cards
Yellow and blue standard sticky cards
yellow sticky card with insects
Sticky cards capture small flying insects when suspended in plant canopies

5. Potato Trap

In western Oregon where there has been a good deal of rainfall through the winter, monitoring fungus gnats is especially pressing in the early spring. Potato slices placed onto the surface of the soil/substrate is an excellent trap for fungus gnat larvae, both to monitor populations and to remove them from the soil.

6. Trap Crops

As it becomes time for pests to invade crops, early placement of trap crops and distract them from cash crops. They can also provide services as sentinel plants to warn of increasing pest populations as the season continues, as well as track phenology. Well known trap plants are:

  • Tomato, eggplant, lantana or marigold for greenhouse whitefly
  • Marigolds, crotons, chrysanthemums, roses, impatiens and ivy geraniums for spider mites.
  • Peppers and fuchsias for aphids.
  • Gerbera, verbena or chrysanthemum for thrips 


Scouting for insects changes with the season, but there are things that can be done early in the year to discourage and stay on top of changing conditions. Good record keeping and persistent monitoring are the keys to success when it comes to keeping pests at bay!

Nursery Knowledge: Plant Hydraulic Physiology – Unlocking Nature’s Water Secrets for Greener Futures

Lloyd Nackley

TL;DR: Plant hydraulics unravels the journey of water within plants, aiding tree health, nursery production, urban forest management, and climate resilience. 🌿🌍

In 2023, we delved into the fascinating world of xylem architecture and how plants move water. In this post, we’ll uncover the secrets of how trees and other woody plants manage water, adapt to challenging conditions, and ultimately contribute to a greener, more sustainable world.

sprinklers watering young trees
Overhead watering in red maple saplings

Real-Life Examples

Understanding plant hydraulic physiology has real-life applications that impact our daily lives. Think about the forests that surround your town or city. These vast woodlands provide us with habitat for wildlife, clean air to breathe and recreational spaces. Knowing how water moves through trees helps us manage and protect these valuable resources. For example, foresters use this knowledge to assess the health of forests and make decisions about when and where to plant new trees. . Additionally, farmers use plant hydraulic physiology in agriculture to develop more resilient crop varieties that can withstand droughts, ensuring a stable food supply. So, the next time you hike in the woods or enjoy a fresh piece of fruit, you’ll know that plant hydraulic physiology plays a crucial role in making it all possible.

Plants water-saving superpowers

Imagine it like this: when the soil dries and the plant begins to get thirsty, it doesn’t just rely on its stem. It has other ways to stay healthy. Think of these ways as a set of superpowers. These superpowers help the plant survive when the soil water is unavailable.

plants in dry soil
Native and naturalized plants are better at managing body water in response to their environment

One of these superpowers is stomatal conductance. It’s like the plant’s ability to open or close tiny valves on its leaves to save water. When water is scarce, it can close these valves to keep as much water as possible. Another superpower is leaf conductivity. This is about how well water moves through the leaves. The plant can control this too. When it’s thirsty, it can slow down the flow of water through its leaves. And then, there’s leaf wilting, which you might have seen before. When a plant wilts, it’s like it’s saying, “I’m really thirsty!” It’s a sign that the plant needs water.

These superpowers don’t all kick in at the same time. First, the plant might adjust its stomatal conductance andits leaf conductivity, before things get serious, and stem conductivity is affected. Scientists have studied these superpowers in different plants. Some scientists have proposed the theory of a plant hydraulic fuse, much like a fuse on a stick of dynamite. The idea behind the plant hydraulic fuse is that plants have a mechanism to prevent catastrophic failure in their water transport system. When faced with extreme water stress, they can cavitate (or burst) segments further from the main stem. Blowing-off the edges to preserve the main trunk. This deliberate disruption helps protect the most vital parts of the plant from experiencing embolisms (blockages) and ensures its survival. They’ve figured out the order in which these superpowers come into action when a plant is thirsty. This information helps us understand how plants deal with water stress.

planted ornamental plants in landscape
Studies help to understand what plant attributes allow for better success in drought conditions

Nursery production and practical applications

For nursery professionals, knowing about these superpowers can be helpful. It’s like having a manual for taking care of plants. By watching for signs of plant water stress, like wilting leaves, or measuring stem conductance, leaf transpiration, and plant water potential, professionals can decide when to water the plants to keep them healthy. In the world of nursery production, where we grow young plants to get them ready for life outside, understanding plant hydraulic physiology can be a real game-changer.

Let’s break it down:

Watering Wisely: Imagine you’re caring for a garden, and you need to water the plants. You could just eyeball it and water them when they look thirsty (like when they start to wilt). But, there’s a smarter way. You can weigh the pots to figure out when they need water based on their weight. It’s like checking the gas tank in your car to know when it’s time for a refill. Even smarter, you can use science to measure how much water the plants need based on how they’re doing on the inside. This way, you don’t have to wait until they’re wilting to know they need water. It’s like having a fitness tracker for your plants!

plants irrigated in a greenhouse
Managing water in a greenhouse is a function of understanding plant physiology while remaining economical

Getting Tough: Plants are like little superheroes. They can learn to handle tough situations, like not having enough water. Just like how training can make athletes stronger, exposing plants to a bit of stress (like less water) in the nursery can help them be more resilient when they’re planted outside.

Finding the Balance: Sometimes, you have to make tough choices when growing plants. If you water them too much, they might get sick. But if you don’t water them enough, they won’t grow well. It’s like finding the right balance between playing in the rain and staying dry.

Environmental impact

Plant hydraulic physiology isn’t just about plants; it’s about our planet’s health too. As we face environmental challenges like climate change, understanding how plants manage water becomes increasingly important. Imagine a world where plants couldn’t adapt to changing water conditions. It could mean more forest fires, reduced crop yields, and even less greenery in our cities. By studying how plants cope with water stress, scientists and conservationists can make informed decisions about preserving ecosystems and mitigating the effects of climate change. This knowledge also guides water-saving practices in agriculture and urban planning, helping us use this precious resource more efficiently and sustainably. So, when we learn about plant hydraulic physiology, we’re not just exploring the inner workings of plants; we’re taking a step towards a healthier planet for everyone.

So, what’s the bottom line? Knowing how water moves in plants can help nursery professionals make smart decisions. It’s like having a playbook for growing strong and healthy plants. And by using science, we can grow better plants while saving water and protecting the environment. It’s a win-win for everyone!

Meet the Team: Joshua Perrault

The Hop from Washington to Oregon

I come from a rural area of the Yakima valley in Washington State. I had the unique privilege of growing up as a part of a family hop farm and was surrounded by agriculture from birth. It may come as no surprise that this led me to pursue a career in agriculture, specifically horticultural plants. Throughout my younger years I spent a lot of my spare time working on my family’s farm and in other agricultural companies around the valley. Once I graduated from high school, I knew that I wanted to further my education, which led me to Washington State University in Pullman, Washington.

fishing from a paddleboard

At WSU I majored in agricultural biotechnology and minored in horticulture. While in Pullman, I also was a part of the Alpha Gamma Rho fraternity which, being a professional as well as social fraternity, connected me with many people from similar backgrounds and with similar interest in agriculture. During my undergrad I was exposed to many subjects, specifically pertaining to plant genetics, molecular biology, and sustainability. I went into my undergrad years with the original intent of going into plant breeding but, throughout my time, my interests did shift. While I still am, and always will be, interested in plant breeding and genetics, I found myself gravitating more to classes involving sustainable production and plant physiology.

During my undergrad, I also held jobs that gave me great experience and helped to shape the direction of my life. While at school, I worked with a professor who was working on technology to improve the sustainability of irrigating wine grapes. This gave me more perspective on how we can, as agriculturists, improve water use and moved my focus closer to sustainable production. I also, starting in 2020, would spend my summers as a lab tech in the tissue culture and genetics lab at Yakima Chief Ranches, a hop breeding and brand management company. This was a young program, and I was presented with many opportunities to assist in the development of protocols and to design experiments of my own. When I graduated from WSU with a B.S. in integrated plant sciences, my experience working with YCR led them to ask if I would oversee the commercial micropropagation of virus and viroid free plants. A request which I gladly accepted.

J Perrault smiles at the camera standing in a greenhouse

I knew when I took the lab management position at YCR, that I wanted to pursue a graduate degree. Because of this, we designed the position as a temporary appointment in which I would essentially create the foundational policies, procedures, and management practices which I could then hand off to those that came after me. This leads me to my search for a graduate program and my decision to go to Oregon State University. I decided to pursue a master’s degree in horticulture with Dr. Lloyd Nackley as my advisor. Having just started, I am still getting my feet under me, but I am very excited to be learning more about the world of nursery production and the physiological responses of plants to stress. Someday I hope to go back to the hop industry and bring new perspectives and ideas with me.