Archive for Garden Pests – Page 2

Natural, Dog Friendly Slug & Snail Control In Your Portland Landscape

California Brown Snail in Portland, OR

Slugs and snails do a lot of damage in Portland gardens.

Slugs and Snails in your Portland Landscape

My history with slugs in the garden

I was never thrilled with my options for dealing with slugs and snails. In the 80’s we had the typical little gray French slugs and snails in our gardens and they were pesty enough.   I had often just hand picked them and kept the numbers down. Then in the 90’s we started seeing California Brown Snail and they added significantly to the total damage. It was too much for me to manage organically. The beer bait didn’t work for my garden on a city sidewalk in NW Portland’s Nob Hill District. Dogs would drink the beer which is NOT good for them and the traps looked tacky too. Using the snails for escargot doesn’t work as a pest management practice since the typical serving is six 1 ½” snails per person. My family would never go for Escargot anyway. They are not adventurous diners.

Slug Bait Problems

NW Native banana slug does not damage living leaves

The banana slugs only eat leaves that are decaying or broken. They also pollinate native spring flowering plants on the forest floor. I did not like leading them to slaughter.

I started using the “pet safe” iron phosphate slug bait. It was an easy method to cut down the population compared to beer baiting or hand picking them. The problem with slug bait is that it does not discriminate. It would lure innocent NW native banana slugs to their death along with the real culprits that did the damage to my plants.

Another problem with slug bait is it doesn’t protect your plants immediately. Slug bait lures the slugs to the bait but does not kill them right away. They have time to do a lot of damage before they sicken, stop feeding and then die.

Worms die from iron poisoning

The major issue is the iron phosphate remains in the slug’s body and breaks down and ends up in the soil. This iron residue left behind in the soil created a toxic environment for worms, the creatures who keep our soil healthy.

I didn’t notice it myself until I got raised beds in my community garden. I noticed a steady decline in the population of worms in my beds.

Copper wire around vegetable bed deters slugs

Daizzie inspecting the copper wire which keeps slugs out of my veggies by producing electric shock.

There is an inert ingredient in the pet safe slug bait that combines with an active ingredient to kill earthworms. They die from iron poisoning. The combination was also causing harm to wildlife and to small domestic animals so it was time for me to make a big change.

Slug Bait Alternative-Natural Slug Control

Ann Lovejoy is a trusted resource and treasure for Pacific NW gardeners. She is the one that made the connection between the iron phosphate “pet safe” slug bait and the harm it was doing.   Read more about how slug bait kills worms. 

She made several suggestions for what to use instead of slug bait. My favorite is using liquid caffeinated coffee sprayed onto plants as a repellent. I tested it this past fall to great success. I was able to protect my kale crop from slugs. I purposely sprayed coffee on only half the plants as a test. The plants I did not spray were missing half their foliage. The plants I sprayed had no holes or missing foliage. I sprayed at least once a week during the fall rains. Ann says a direct spray of coffee will kill the slugs but I could not tell if this was a success. I sprayed the coffee directly on slugs but when I came back the next day the sprayed slugs were no where to be seen. They may have crawled off and quietly expired but I was not sure. Maybe my coffee wasn’t strong enough. I will do more testing now that the soil has warmed up enough for new slugs and snails to hatch. I’ll post again and share what strength of coffee it takes for an obvious demise.

I can’t wait to share this with my landscape design clients. Many clients have pets. The fact that pet safe slug bait is toxic needs to be shared.

Scrubbing dog friendly copper wire slug deterent.

Scrub copper wire with wire brush – slugs can cross the wire if it’s oxidized or dirty.

Use Copper Wire for Raised Beds and Containers

Another option to deal with slugs in raised beds is to line the edge of the bed with copper. I used a copper ground wire but you can use sticky copper tape available at most garden centers and it will last maybe one garden season if you are lucky. It is easy to buy and apply to your raised beds, pottery and containers.

Slug or Snail?

What’s the difference between slugs and snails? Slugs and snails are pretty much the same animals according to Robin Rosetta, Associate Professor at OSU. Over time slugs evolved out of a hard shell so they could move through cramped spaces and allow them to get down into the soil to find food and protection. Apparently, there is still sort of a shell under their hump like mantle. Snails still have a shell and so are restricted to above ground activities. They use their shells to survive inclement weather and are protected from some enemies and predators.

For more information on dog friendly landscaping, contact us!

Bad News about Slug Bait and Winter Garden Care Tips

Winter is just around the corner here in Portland.   Here are 5 timely tips to help you care for your landscape right now.

Slugs Last chance to knock out slugs! Control your slug population now in late fall.  They lay thousands of eggs that will hatch in spring.  I’ve got bad news about using the so called pet safe slug baits. New science says it kills your earthworms and can sicken your pets and other animals.  Control your slugs with beer traps or even better an instant coffee spray.  Yup coffee! Fill a spray bottle with strong instant coffee or any coffee except de-caf.  Spray the leaves of plants they prefer and any slugs or snails you see.

I grow lots of winter greens here in NW Portland so I’ve been out there spraying down the leaves of my beautiful Dinosaur Kale plants to protect them now.  Spraying coffee once a week in fall and early winter makes a big difference in the spring hatch of slugs.   Read more about why slug bait harms worms.

Portland garden tips include coffee

Its the caffeine that kills slugs or snails. Instant coffee works well.

Mulch.  If you only do one thing to improve your soil and care for your plants, mulching is the biggie.  Schedule your winter mulch application for the last week of November to mid-December or hire someone to blow in your mulch.  Companies such as Bark Blowers will blow in mulch including the newer “living” mulch products that I prefer.  One company that provides mulch inoculated with beneficial bacteria is Natures Needs, a product called  Recology Compost.  McFarlane Bark, Mt Scott Fuel and Grimms Fuel supply basic mulch products.   Did you mulch just 2 inches deep?  Great!  Now go and unbury the crowns of your plants so they don’t die from rot during our wet winter. Burying plants with mulch might be a good practice in Vermont or Montana but not here.

Iron gate design with snow

Landscape Design in a Day client’s custom gate. Photo by Lori Aveling

Protect your plants from winter temperatures

The best cold protection for plants in the winter isn’t something that naturally occurs to most people.  Over watering and over fertilizing done in summer can cause plants to not go dormant.  When cold weather comes, they are not prepared.  Read more: Protecting Plants from Winter Cold Starts in Summer 

Pruning knowledge  There are many plants that should not be cut back in the fall and winter.  There are many perennials and grasses that can be cut back to create a more attractive winter landscape. This is a case by case basis which drives new gardeners crazy. Consider consulting with your garden designer who can teach you what to do to your plants and when.  It feels good when you know what to do.

Protect your pottery  The best winter protection for your pottery is proper drainage and location.  Make sure water drains through the pots hole and doesn’t back up.  If water sits in the bottom and it freezes, good bye pot.  I have had Vietnamese high fired pottery outside and intact for over 15 years.  I always put drainage material in the bottom of the pot and a piece of flagstone under the pot or I use those little pottery feet.

If I have expensive pots where they will get east winter wind, the kind of wind that freezes rain to ice on the power line, I would move them into a protected area for winter right now. I hate to even think about that kind of weather but we get our share here in Portland Oregon, especially in January.   Its hard to pay attention to the weather report, and besides who wants to move heavy pots around when its icy cold out?  Not me.

For more information on how we can help you during winter months with your garden design.

Protecting Our Portland Birch Trees from Bronze Birch Borer

Protecting Our Portland Birch Trees from Bronze Birch Borer

 NE Portland birch tree marked for removal by the City of Portland due to bronze birch borer.

Birch trees marked for removal by the City of Portland due to bronze birch borer.

Birch Trees Dying from Bronze Birch Borer

Many developers, builders and home owners picked the Himalayan White Birch (also called Jacquemontii,) for its crisply white bark and over planted them. They even planted them in parking strips with no irrigation, in full hot sun, which is not a good place for a birch. My Vancouver client’s neighborhood had over 200 mature infected trees removed. They had already lost 2 birch trees and I made tree replacement suggestions as part of their Landscape Design in a Day.

Back in the 1980’s the Himalayan White Birch was touted as the new success story because it had been hybridized to repel the Bronze Birch Borer (BBB). At that time I was a student learning about trees at a local community college. The European Weeping White Birch had been decimated by the BBB so everyone was very excited about the new Himalayan White Birch. Over the next 20 years, the bronze borer changed its preferences and became attracted to the over planted Himalayan White Birch. It makes sense from an evolution perspective; why not change to fit the food that is available?  Smart bug!!!

City of Portland has tagged this borer damaged birch tree for removal

30 years ago Himalayan White Birch was used because it repelled Bronze birch borer.

Recently I have noticed the dreaded yellow tape of death tied around birch trees in the city. I create my Landscape Design in a Day drawings on site so I am in every conceivable neighborhood.  The Bronze Birch Borer is now all over Portland and has spread south to Klamath Falls.

Today when I see my client has a birch tree, I give them the current research and it’s mostly bad news. I often include in their design a potential replacement tree for when, not if, their tree is devastated by the Birch Bronze Borer.

River Birch (Betulus Nigra) is a safe replacement tree - Bronze birch borer does not feed on this birch tree.

Heritage River Birch in winter. River Birch (Betulus Nigra) is a safe replacement tree – Bronze birch borer does not feed on this birch tree.

Protecting Your Portland Birch Tree

My research says watering your trees regularly before they are infected is a huge step toward preventing the disease. If you have a birch tree that is thriving or only has minimal borer damage, consider starting to irrigate it ASAP. Start by deep watering it every week to two weeks starting in early summer into mid to late fall.  Don’t let your tree get stressed. (Deep water is a long slow soak with your hose.) Under no circumstances should you water your tree every day – that is not helpful.  (See my watering tips blog).

Pesticide treatments

I’m also reading that more people are using a chemical treatment (which will help your tree) than they were initially. I’m not very happy about that because the treatments will harm bees. They are mostly drenches that are systemics (bad for bees) or injections done by tree services which are also systemic in nature (and so bad for bees). Apparently the timing of the treatment and how it is done can make it less lethal to bees but isn’t this backward of  saving the bees and therefore our food supply? If it were my tree, given my very strong feelings about protecting bees, I would try watering deeply and regularly and not treat the tree with pesticides. If the tree is too far gone I would have it removed, grieve and plant a new tree that is resistant to disease and insects and prefers little summer water.

Weeping Katsura tree has similar texture to Birch

Katsura tree at Lan Su Chinese Garden in Portland, Oregon

In short, if you love your tree, start taking care of it. The first trees that died were neglected, poorly sited and in neighborhoods chock full of white barked birch trees.

Weeping Katsura is my go to birch replacement now since borers have killed so many birches.

Weeping Katsura in one of my clients gardens in Willamette Heights.

Signs of Bronze Birch Borer

The first signs are yellowing foliage in the top of the tree. As the insect infestation continues, small branches and tips die. It moves on into the larger branches. Declining to the point of death usually takes several years. There are other signs of borer; ridges in a lightning pattern and a distinctive D shaped hole in the bark. There can be a kind of stain coming from the holes, a sort of reddish liquid which looks as bad as it sounds.

Cercidiphyllum_japonicum, Katsura tree

Katsura tree with beautiful fall color.

New Resistant Varieties-Maybe

I am hesitant to trust that new resistant white barked birch varieties will stay resistant if we over plant them as we did the Jacquemontii/Himalayan white birch.  I offer the river birch which has a brown peeling  bark and typical birch leaves.  Alternatively my favorite replacement for birch trees is the Katsura tree also called Cercidiphyllum. The Katsura has the graceful shape somewhat reminiscent of a birch tree with heart shaped leaves that flutter in the breeze.  I feel it is a safer choice since it is not related to birch at all but alas no white bark!

Selecting trees that have the best chance to become mature old trees is my way to contribute to my clients and our community. Keeping up to date on the best trees to use and keeping my selection diverse will make the best urban forest for the future.

Kym Pokorny, (now writing for OSU’s Extension Service),  says these are good replacement choices;  ‘Heritage’ river birch (Betula nigra ‘Heritage’) and ‘Whitespire Senior’ gray birch (Betula populifolia ‘Whitespire Senior,’ which has the whitest bark of the replacement tree ideas.  I suspect if we over plant these borer resistant birch trees, the borer will change its tastes to the available food so the best thing to do is plant lots of different trees.

Katsura 'Red Fox' is a smaller tree that is getting used in irrigated parking strips.

Katsura ‘Red Fox’ is a smaller tree that is getting used in irrigated parking strips.

I came across a lovely old white birch tree just the other day in the Buckman neighborhood and gave my new client, who had just purchased the home, some information on how to care for the tree. The tree seems untouched by borer and is situated where it gets some afternoon shade.  He will start to summer irrigate.  Perhaps some birch trees are unique individuals because they were grown from seed and this unique genetic combo may cause them to be unattractive to the BBB. We can only hope that some of these remaining individual trees, if irrigated, will remain to grace our landscapes and homes.  In 2010 Kym Pokorny, my favorite garden writer, warned that our graceful white bark birch trees might become a tree of the past in Portland. Boy was she right!!

 

 

Lace Bug Update

Azalea Lace Bug damageLast year I wrote a blog about a serious new insect problem for landscapes in the Pacific Northwest. It was serious because rhododendrons and azaleas make up a large percentage of the plants in most gardeners landscape. The easy way to control the insect was with a systemic pesticide that harms bees.  Many people were talking about removing all their susceptible plants rather than harm bees.

Here’s my latest report and what you can do to save your plants without killing bees:

Save bees and your azaleas and rhododendrons. How big a problem?
I have visited over thirty client landscapes in the Portland area since February – all the gardens but two had moderate to severe lace bug damage on rhodies and azaleas.  I was already expecting the 2015 lace bug plant damage to be a huge problem for my clients. Robin Rosetta, Associate Professor, Extension Entomologist, OSU says the lace bug hatch is a full month early.  This is very bad news unless you are prepared to start treating your plants now in mid-to-late April and early May.

Lace bug eggs waiting to hatch.  Photo by Robin Rosetta.

Lace bug eggs waiting to hatch. Photo by Robin Rosetta.

Strong blasts of water should be applied to the back of the leaves to damage the wings of the lace bug while it is in its soft nymph stage.  It can be a little difficult to hold your leaves steady to spray the back side, especially if it is a large rhododendron.  Portland Nursery has something called a Bug Blaster Head for your hose.  It’s easier to use and has a safer pressure for your plants’ leaves.  It also has a wand attachment that would make it possible to treat a large rhododendron.

Insecticidal soaps applied to the back of the leaves will also damage the lace bug nymph. These two methods are effective only while the nymph is soft.  Once it turns into an adult, soaps won’t work and water spray will not remove embedded eggs.

Green-Lacewing March Biological

Green-Lacewing March Biological

This may get confusing because the bad bugs that damage your plants are called lace bugs.  I’m about to introduce you to a good bug that eats the bad bug. The good bugs are called green lace wings.  If you don’t want to spray your plants because they are too big, there are too many plants or you want to work toward a long term solution; you need to purchase green lace wing larvae from March Biological  or go to Portland Nursery to order through them.  The green lace wing will eat the newly hatched lace bug and prevent the lace bug population from exploding.  Getting green lace wings in a high population in your garden will help with the next one or two lace bug hatchings that we expect this year.  My friend, Phil Thornburg, from Winterbloom has successfully diminished his damaging lace bug population. It took him a couple of years but he did it by applying green lace wings instead of pesticides.

Plants in full sun seem to be the most damaged from lace bug.
Basically they are stealing the green right out of the plants’ leaves and laying eggs that will hatch in another month adding insult to your already damaged plant.  Remember to water your rhododendron and azaleas regularly this summer –  they will need the extra support.

Question: What does lace bug on my rhododendrons have to do with bee colony collapse disorder?

Rhody Lutea March 2015 treated with bee killing spray

Rhododendron ‘Lutea’ in my client’s garden without any damage.  A rare occurrence.

Answer:  Systemic drenches often contain imidacloprid. It’s popular because it’s easy, the chemical is suppose to be safer for mammals (so humans, rats, bats are pretty safe) but the spray will harm or kill bees or any insects who feed on the plant.  For months afterwards bees take it back to the hive with the pollen so it’s not just harming one bee – it’s harming the colony.

The time to treat your plants without harming the bees is now!

 

Lace Bugs on the Move in Oregon

Azalea lace bug is a new pest that has decided rhododendrons are on the menu as
well as azaleas. This seems like a big problem because azalea lace bug has multiple
hatchings in a season and can do a lot of damage. The old rhododendron lace bug only hatched once a year in the Pacific Northwest.

Azalea Lace Bug damage

Rhododendron leaves showing damage from azalea lace bug

Organic Control Methods

Systemic sprays and insecticides kill bees. It’s very important to use methods that don’t harm beneficial insects.  Since drought and sun stressed plants are more susceptible, one method is to give these plants better care.  Practically speaking, I would say irrigate even your old rhododendron trees that never seem to need  a drop. Water them once a week during hot summer days as a preventative measure. Preventative methods are best.  So far this spring, out of perhaps 60 gardens, I’ve only seen one garden that didn’t have these new pests.  Preventative methods I’m recommending are building up green lace wings in your garden preferably before you have the pest or when you see that you do have it and better watering.

Using green lace wings, a beneficial insect, is another effective way to combat lace bug.  You can purchase green lace wing larvae and apply them near your affected rhododendron, the idea is to build a population of green lace wings in your garden from March Biological in Sherwood, Oregon. Ladybug Indoor Gardens in Medford, Oregon can also be reached at: 541-618-4459541-618-4459.  Please note, green lace wings are pretty, they remind me of Tinker Bell, sort of.  Using the green lace wings does work, as my associate and friend Phil Thornburg, (Winterbloom) can attest.  It took about 3 years but his plants have fully recovered and he has a nice population of the lovely green lace wings in his gardens as a bonus.  Their latin name is Chrysopididae and you can look them up on Wikipedia for more details.

OSU Azalea Lacebug PDF file imageThe chemical sprays I have seen recommended for lace bug are harmful to beneficials such as honeybees.  My recommendations are purchase and apply green lace wings and irrigate azaleas and rhododendrons weekly in the summer.   This will allow us to wait until a honeybee friendly solution to help us protect our plants is found.

Azalea lace bugs are here to stay.

For more details, download the informative Oregon State University flyer.