spring pests

Best Practices for controlling pests

The Best Practices approach, sometimes called Integrated Pest Management (IPM) is an environmentally sensitive approach to dealing with garden pests. This approach uses the scientific understanding of pests and diseases to determine if a problem requires treatment, and if so, how to proceed in the safest effective way while taking into account the specific sensitivities of the site.

Some factors to consider when choosing a solution to your pest problem:

  • What is the safety of the applicator?
  • What is the solution's impact on people and pets (safety and other factors)?
  • Is there a potential for runoff and what are the consequences for groundwater?
  • Does the solution pose a threat to beneficial insects?
  • What is the persistence in the environment (how long does it stick around)?
  • What is the best timing of the treatment to mitigate the above factors?

Steps to Best Practices for Pest Control

Our best practice definitions provide you with clear steps for finding the best way to solve garden problems. Best practices are assured when these steps are applied in each situation:

  1. Identify the weed, pest or disease
  2. Monitor pest numbers, spread of weeds, or extent of disease damage.
  3. Decide what Threshold of infestation requires action. Can the damage be tolerated? Is it really an issue that requires treatment?
  4. Could Prevention eliminate the need for future treatment (appropriate plant selection, cultural controls)?
  5. Control the problem using the safest effective biological, cultural, mechanical/physical and chemical tools.

It should be noted that Best Practices is not Synthetic vs. Organic. If control is warranted then it is a matter of choosing the right tool to achieve an acceptable result that will minimize harm to humans, wildlife and the environment.

Biological control would consist of natural enemies: predators, parasites, pathogens, competitors (ladybugs, beneficial nematodes or bacillus strains, etc.).

Cultural controls would be practices that prevent of slow the spread of the problem (crop rotation, pruning, watering methods, etc.).

Mechanical and physical methods would include traps for pests, bird netting, row covers, mulching, and removing pests by hand.

Chemical control would be the safest effective pesticides, fungicides or herbicides.

For an in-depth explanation of these steps please see our brochure Best Practices for Integrated Pest Management.

Our staff is happy to help identify the correct Best Practices approach for you. Just bring a picture or leaf sample in to our information desk, we will take it from there.

Who's bugging you?

black spot on roses

There's some good bugs out there!

Many insects, fungi, and bacteria can benefit your garden in one way or another. Beneficials come in many shapes and sizes and each help your garden in their own way, including controlling pests and pollinating plants.

Creating a suitable habitat in your garden will attract beneficials, helping you to have a sustainable garden and support native wildlife. When relying on beneficials as a form of pest control you must be patient and tolerant of a few pests in your garden, and some damage to your plants. Without a few pests around your beneficials won’t have anything to eat!

Download our brochures on beneficials:

black spot on roses
  1. Proper Identification: Black spots with fringed margins that cannot be rubbed off the leaf.
  2. Monitor and Assess the Amount of Damage: How widespread the disease is will determine which route you should follow. Is it on just a few leaves? Has it spread to at least half the plant? If it is just a handful of leaves then removing them is probably the best course of action.
  3. Threshold: Since Black spot is quite common here even if you are diligent the threshold should realistically allow for a few bad leaves. If large numbers of leaves (a third or more) are affected Black spot can cause large-scale leaf drop. This stresses the plant which can invite other problems to take hold.
  4. Prevention: Choosing disease resistant varieties can greatly reduce problems associated with rose care. Good hygiene is critical. Disease spores can overwinter on branches and dead plant material, so start by removing fallen leaves and dead canes. Good air flow also discourages fungal problems. Well-fed plants are better fortified to fend off pests and disease. Dormant sprays can also be invaluable for disease-prone varieties.
  5. Use a Combination of Biological, Cultural, Mechanical/Physical and Chemical Tools to Treat: The mechanical approach would be the physical removal of affected leaves as well as cleaning up any fallen leaf debris. This alone may be enough to prevent further infection. Cultural practices would include minimizing any overhead watering since splashing water from an infected plant can spread spores to healthy leaves. If disease pressures remain low to moderate, safer sprays like neem and bacillus subtilis can be used in cooler weather. Sulfur can be effective in temperatures from 60-85 degrees. More severe infections may require treatment with copper or synthetic fungicides like Immunox. Note: applications of any remedy should take into account flower time and the presence of bees and other beneficial insects.

As you can see, there is a basic formula one can follow when trying to figure out the proper approach to the various problems we face in our gardens. Starting with right plant/right place will go a long way to ensuring success. The old adage “an ounce of prevention is worth a pound of cure” is very applicable here. Remember that gardening is a lifelong learning experience. Have fun and enjoy the process.

For more information on Best Practices:

Print out our brochure Best Practices for Integrated Pest Management brochure.


There are over 4000 species of Aphids. They come in many shapes, sizes, textures and colors. These soft-bodied insects usually occur on new shoots, crowns, and undersides of leaves. The aphid life-cycle includes eggs, nymphs and adults. They can be winged or wingless. Nymphs and adults insert a needle-like structure (stylet) into the plant and suck out plant sap.

Symptoms of aphid damage include curled leaves, yellowish spots, and glossy leaves due to the presence of sticky honeydew (aphid excrement). A “weeping” tree that drips a sticky substance commonly has an aphid infestation. Black sooty mold (due to a fungus) may develop on leaves that have sticky honeydew on them. The presence of this mold may reduce photosynthesis, make the plant unattractive, and possibly reduce flowering and yield.

  1. Proper Identification: Aphids are tiny and come in many colors including green, black and white.
  2. Monitor and Assess the Population and Amount of Damage: A scenario where one plant is heavily infested and the rest are clean might be treated differently than one where all the plants have a few aphids.
  3. Threshold: We know aphids reproduce rapidly and that the edibility of food crops like Brussels sprouts can be compromised quickly. The example of one heavily infested plant probably meets the threshold for some sort of action. A light infestation on all the plants might also require action. Or you may continue monitoring the situation while waiting for nearby ladybugs to solve the problem for you. Or if you’ll be harvesting in a day or two simply rinse them off.
  4. Prevention: Treat nearby outbreaks before they spread to your garden. Row covers make an effective physical barrier. If only one plant is infested row covers may still be able to isolate the other plants.
  5. Use a Combination of Biological, Cultural, Mechanical/Physical and Chemical Tools to Treat: There are many safer options for treating aphids. In the scenario where all plants have a light infestation, hosing them off with a strong stream of water can be effective (mechanical). Introducing predators like ladybugs can control the population (biological). If sprays are needed then various oils (cottonseed, paraffin, neem, etc.) or soaps can be quite effective. In the scenario of the heavily infested plant, if it’s already badly damaged you may simply remove it (physical), or treat it using any of the above methods. There are stronger products available to kill aphids, but in these examples (a small, easily treated food crop) none of these products works any more effectively and some would be less safe to apply.

Controlling Aphids


The brown marmorated stink bug spends the winter in a protected area (such as inside the warmth of your home) and then emerges and becomes active in early spring. Mating follows and eggs are laid on the underside of host plants through early fall.

Stink bug damage in many cases can be hard to see. For example, stink bugs have been observed feeding heavily on snapdragon plants, seeming to prefer the seed pods with no damage to the flower itself.

Download our brochure for solutions to controlling Stink Bugs

spider mites

Spider Mites

Mites are 8-legged arachnids, the most common being the “spider” mite. They are a tiny 1/20th to 1/60th of an inch long and look like moving dots in red, yellow, green, or brown. Because of their tiny size they can be very difficult to spot. Try shaking a damaged leaf over a sheet of white paper. If tiny specks appear and move, there’s a good bet it’s spider mites. Spider-like webbing on plants is another sign of their presence. Mites can travel from plant to plant on the wind and overwinter in several stages of development.

Mites pierce into plants to feed on their sap. This activity weakens the plant and creates discolored spots, streaking or scarring on leaves, as well as causes them to turn a yellow-bronze or curl. This damage can lead to leaf drop and may eventually kill the plant. As mites reproduce very quickly a few can rapidly lead to a serious infestation.

Download our brochure for solutions to controlling Spider Mites


Cut worms are starting to appear this month as the soil temps rise. The main way to decide if you have cutworm or slug damage is if the plants are mowed down like someone stomped through your garden at night, it’s probably cutworm.

Go out at night with a flashlight to check as most of the damage is nocturnal. Beneficial Nematodes can help with the problem although soil temp is restrictive. Above 49°F is optimal. Another natural spray would be anything that contains Spinosad which is a bacteria originally discovered in the soil of an abandoned rum distillery.

Eliminating Cutworms

slug damage

Slugs and snails come in a variety of colors and sizes. Slugs are cigar shaped and sticky/slimy if touched. Snails are much like slugs with spiral shells. Both can severely damage plants. They like damp places and usually feed at night, preferring tender new growth and seedlings. Even though these pests are ground dwellers, they will climb plants and can cause damage well above the ground.

Both pests eat holes out of leaves creating a tattered appearance. They will crawl into the tightest of spaces to chew away at roots and succulent bulbs. Often the damage can go on for weeks before it is noticed. When temperatures warm in late winter eggs hatch and damage accelerates. They are particularly fond of hostas, lettuce, and other tender greens as well as low fruit like strawberries.

If your garden is small, remove slugs by hand. Hunting them by flashlight after sundown can be an entertaining activity, for you and your neighbors. If you get slug slime on your hands, wash it off using white vinegar and warm water.

  • Beer: You can trap slugs and snails by placing beer (any brand will do, they’re not picky) in shallow pans or plastic food containers (such as yogurt or margarine tubs). Cut a few entrance holes around the rim, then fill halfway with beer, put the lid on top to keep out rain, and bury the trap so the entrances are at ground level. Place several containers throughout the garden near damaged plants. Beer is effective for about 3 days before it loses attractiveness to slugs and snails.
  • Natural Predators: Encourage slug/snail predators such as beetles, chickens, and ducks.
  • Barriers: Diatomaceous earth, crushed egg shells, and copper tape can make effective barriers. If damage is severe bait can be extremely effective.
  • Iron phosphate is the active ingredient in products like Sluggo. It is not attractive to wildlife, pets, or children and it breaks down into iron and phosphorous which enrich your soil. It is OMRI listed so is safe for organic gardening.
  • Metaldehyde, available in many forms and brands (such as Corry’s, Deadline, and Ortho) is highly effective but dangerous around pets, wildlife, and water sources.

Regardless of method/product used, ALWAYS read and follow package instructions.

Controlling Slugs


Powdery Mildew is fungus that appears on leaves and stems as white to grayish, talcum powder-like spots that grow larger and denser as the disease progresses. Unlike most fungi, powdery mildew spores do not need water for germination and are most severe in warm, dry climates. Summer’s warm days and cool nights create favorable humidity needs for spore growth as do shady areas.

The spores are spread by the wind and can overwinter on plants and plant debris. Powdery mildews are host specific (i.e. – the mildew on roses is different from the one affecting grapes) – they cannot survive without the proper host plant. Circumstances influencing the disease's severity include the variety of the host plant, age and condition of the plant, and weather conditions during the growing season.

Powdery mildew is usually more unattractive than it is serious, though left unchecked it can reduce vegetable and fruit yields and affect their flavor. Leaves may also turn yellow before dying and falling off. Although plants can be weakened by an infection, they usually do not die.

Some of the vegetable crops affected by powdery mildew include artichoke, beans, beets, carrot, cucumber, eggplant, lettuce, melon, parsnip, peas, peppers, pumpkin, radicchio, radishes, squash, tomatillo, tomatoes, and turnips. The growing tips of fruit trees may also develop the disease. Many ornamentals, such as lilacs, zinnias, and roses can also get infected. Succulent tissue is most susceptible to infection.

Download our brochure for solutions to controlling Powdery Mildew


Impatiens Downy Mildew is a deadly fungal disease which thrives in moist, humid conditions. It specifically infects Impatiens walleriana and hybrids, bedding Impatiens (6 pack style), Rosebud Impatiens, Butterfly and Fusion Impatiens. Early signs include:

  • Light green yellowing or stippling of leaves
  • Leaf edges curl down
  • Faint gray streaks on upper leaf surface
  • White cotton-­like patches on undersides of leaves

Diligence is an important part of dealing with pest and disease problems in your garden. The sooner the better, but realize that a completely sterile environment is not only impossible but unhealthy as well in that you need to encourage a balance.

Download our brochure for solutions to controlling Impatiens Downy Mildew


Mosquitoes have caused, and continue to cause, devastating epidemics that significantly affect people’s health and well-being. West Nile Virus and encephalitis are serious mosquito-borne threats in the U.S.

Female mosquitoes must get a blood meal in order to lay eggs. By taking the blood meal she may infect her host with diseases such as encephalitis, yellow fever and malaria. World-wide malaria is still the most important infectious disease. While we are lucky here in Oregon that malaria is no longer a threat, less than a hundred years ago malaria was common in the US, and with global warming it will likely return.

Like all flies, mosquitoes go through four stages in their lifecycles: egg, larva, pupa, and adult or imago. The first three stages—egg, larva, and pupa—are largely aquatic. Mosquito adults are small, delicate, two-winged flies. At first you might mistake them for the widely distributed, nonbiting midges. However, female mosquitoes differ from similar insects because of their long, slender proboscis, a tubular feeding organ adapted for piercing skin and sucking blood.

Male mosquitoes also have a proboscis, but they use them only for sucking plant juices and other sources of sugar rather than blood. Mosquito larvae, or wigglers, usually are black or brown and occur in stagnant or nearly still water in surface pools, tree holes, or man-made containers such as abandoned tires.

Download our brochure for solutions to controlling Mosquitoes

hover fly
A Beneficial: Hover Fly