Archive for Garden Pests – Page 2

Birch Trees Going Going Gone

Birch trees going going gone

Another 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.

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.    Fast forward to today.  Boy was she right!!  It seems to me as I look back over these past years that the birches in the subdivisions died first.  Many developers, builders and home owners picked the Himalayan White Birch also called Jacquemontii, for its crisp white bark and over planted them.   In 2009 I was working with landscape design clients in a Vancouver neighborhood.  They had already had 2 birch trees removed and we made a replacement plan for the third as part of the Landscape Design in a Day.  Their neighborhood had already removed over 200 birches.  Their developer had used them extensively.  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.  Over time however the bronze borer changed its preferences and became attracted to the available and over planted Himalayan or White Birch.  It makes sense from an evolution perspective; why not change to fit the food that is available?  Smart bug!!!

Fixed up close view

Himalayan White Birch used to repel 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 with my clients so I am in every conceivable neighborhood.  The Bronze Birch Borer is now in North Portland to SE Portland, not just the suburbs.

These days when I have a client who has a healthy looking birch I give them the current research and bad news.  From what I have read there isn’t a whole lot of good news.   I often include in their design a potential replacement tree for when, not if, their tree is devastated by the Birch Bronze Borer.  It’s shocking and pretty sad for them to hear that they will probably witness the demise of their tree especially when it looks just fine.

th2_betula_heritage_3

Heritage River Birch in winter.

If you have a birch tree that is thriving consider starting to irrigate it if you haven’t already. You might start by deep watering it every two weeks. Under no circumstances should you water your tree every day – that is not helpful  (see my watering tips blog).   There are chemical protections that you can apply to your tree before it becomes infected that will typically keep it from getting the borer.  General Tree Service is one company who provides this  service.    Sometimes the tree can be saved  if you can catch the infestation at the very beginning but you will need to apply the pesticide every year.  Another important issue to think about it this:  The product is a systemic pesticide.  Many people refuse to use any systemic pesticide because some can kill honey bees.  Birch trees are wind pollinated not bee pollinated and so the systemic should not theoretically affect honeybees.   If you have flowering plants of any kind under or near the birch those plants will uptake the pesticide and that can harm bees.  This protection for your birch is contrary to protecting bees.  I guess you could take out your hostas or other flowering plants and put in sword ferns.  In short, if you love your tree, start taking care of it.  The first trees that died seem to me to have been neglected trees in full sun and in areas where there were too many birch trees so the borers could move from one tree to the next door neighbors tree.

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

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

What to look for:  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 but remember last years horrid, hot and nasty summer?  There were trees who seemed to get the borer early and by the end of the summer, the trees were gone.   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 hole, a sort of reddish liquid which looks as bad as it sounds………Is my tree bleeding?  So this is not a happy blog but there are some great trees to consider for replacement.

th2_cercidiphyllum_japonicum

Katsura tree with beautiful fall color.

New resistant varieties;   I am hesitant to trust that new resistant white barked birch varieties will stay resistant since the Jacquemontii/Himalayan did not stay resistant.  When I have a client who loves birch trees 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 and since it is not related to birch I am not worried about Borers.  I know that the trees I place in a home landscape may be removed for capricious reasons by the next homeowners but selecting trees that have the best chance of becoming mature old specimens in their neighborhood is my chance to contribute not only to my clients well being but for my city and region.  Keeping up to date up on the best trees to use and keeping my selection diverse will make the best urban forest for the future.

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.

White birch trees that have been planted in part shade, in good soil that drains well and that get irrigation may continue to survive.  Another bit of advice from Kym Pokorny’s article is to mulch over the shallow roots of your birch tree.  This provides some protection from heat and also from physically damaging the surface roots.  I’ve been told by an arborist in the past not to put more than 2 inches of mulch over  roots.  The best person to ask about these fine points of tree care is an ISA Certified Arborist.

Katsura 'Red Fox' has unique red foliage.

Katsura ‘Red Fox’ has unique red foliage.

I came across a lovely 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 doesn’t seem to be infected.  Some birch trees that are individuals, seed propagated instead of cutting, may have some unique genetic protection and so we can only hope that some of these individual trees will remain to grace our landscapes and homes.

 

 

 

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.

Treatment for Blackberry and Ivy – How To Get Rid Of It

Garden Tips for getting rid of Plant Invaders

The best time of year to treat blackberries and English ivy is coming right up…..so prepare now!

Blackberry Fruit

How can anything so sweet, be so evil?

Plan to treat invasive blackberry in September and early October. The reason for the specific timing is this: only in the fall will the plants pull an herbicide to the roots, thereby killing the entire plant. The rest of the year treatments are only partially effective. For greener garden practices that use less chemicals treat the plants only in the fall, and water your bad old blackberries well prior to treatment. In fact you could even fertilize them and pamper them for about two weeks…….and then treat the with an herbicide.

My long time client Pat Tangeman  is clearing a large area of her property . She bulldozed last winter and got rid of a decades old blackberry wilderness that had an extensive root system with many large stumps. However, even a bulldozer didn’t kill all the blackberries! Many came back this spring so she called me to problem shoot and design a planting plan for the area.

The result:
This fall she will treat her remaining blackberries and will allow the herbicide to trans-locate to the roots to truly kill the plant. Then she will have the remainder of large roots dug out. Once this is done she can plant the new garden we designed together. Victory over the blackberry!
Another client in the Dunthorpe area is having her English ivy treated by professionals the first of September. She is utilizing the same techniques by doing the pre-watering and pampering herself. Once the invasive plants are dead we will be ready to place her new garden plants from her garden planting plan.

Not sure still when would be a good time? Need a professional hands on approach to help get you started? There are still a few appointments for Garden Coaching open in September and October. Winter is also a great time for making plans so you can have what you want instead of taking your precious time to care for a layout and plants you don’t like.

Attack of the Root Weevils

Or Why you should care about root weevils,  and what to do about them once you do

Close Up Picture of the Root Weevil

I have noticed that most established shade gardens have visible leaf damage  from adult root weevils (see photo showing leaf notching). It is ugly, but it doesn’t kill your plant. The serious problem is caused by their larvae who eat the roots of your plants during the late fall and winter. It is very difficult to kill the larvae because they live underground nestled into the roots of your plants to be close to their chosen food source. Think of them as tiny, tiny zombies! Rooooooooooooooootttttssssssssssssss………..

So how do you know if you have a root weevil problem? Here is what I recommend:

Its the damage done to the roots that we worry about. We must control the adult weevil before she lays her eggs.

Its the damage done to the roots that we worry about. We must control the adult weevil before she lays her eggs.

Check your indicator shrubs for notching! These are Hydrangea, Red Twig Dogwood, Azalea, and Rhododendrons. Many perennials will also show the notched leaves such as Hostas and Coral Bells (Heuchera).  If you have only a few notches, you don’t have to do anything or you could treat once a year as a preventative measure.  If you have more than a few notches, we need to talk but you can also check out my blog for all the gory details of killing root weevils.  It is tricky to do.

Don’t bring them into your garden………Here is a timely tip, be very picky about buying plants on discount, or at fundraisers!  Look for notching on the leaves, and don’t buy any plant that has notching, or is near plants with notching. That means there are probably eggs in the potting soil that will hatch in your garden. You don’t want to introduce them into your garden.

Now the important part. How do you get rid of them?

The easy answer is, in the long term, the harsher one. The chemical products out there are either harmful to you or harmful to the bees which we need to keep our gardens productive and beautiful. Using chemicals to get rid of root weevils is definitively not the way to go.

I purchase living nemotodes that are specifically listed for root weevil. Properly applied, they will swim through your soil, enter the body of the root weevil larvae, and lay their eggs. The nemotode hatchlings will eat the larvae. Initially you will do this in both September /early October and the following May which are the ideal nemotode vs. larvae times!

The two  most important things ares that the soil must be warmed up and moist and you must apply the nemotodes must be applied at dusk, never in direct sunlight.   If we are having a cool May you may want to wait until June or call me and ask. In September you want to be sure your soil is well watered prior to the treatment of nemotodes, and then water well for two weeks following the treatment. This will eliminate some of the root weevil problem for 2013. You will have to repeat the biannual treatments for a few years to get the weevils properly controlled, and then continue with a once a year preventative treatment cycle (still in September OR May).

The good news is that it is really easy to do!
1) Take a 5 gallon bucket and fill it up with water.
2. Treat the water with a product called pondzyme (people use it to protect their fish from the additives in our water). I use 1 and ¼ teaspoons of Pondzyme to 5 gallons of water.
3) Add the nemotodes to the water.
4. Using a plastic pitcher I then water the nemotodes into the soil where I see leaf notching.
It is very little effort for a dramatic and healthy result.   Good gardening!

Resources:
Living nemotodes for root weevil larvae can be purchased now through September at: Portland Nursery
http://www.portlandnursery.com/
Farmington Gardens
http://www.farmingtongardens.com/
Cornell Farms
http://www.cornellfarms.com/
and other higher end garden centers.
Tranquilty Ponds has 3 locations and they sell an 8 oz bottle of Pondzyme for $26.00.  Remember you need the pondzyme to protect your nemotode warriors from chemicals in our water so don’t skip this step.  It is very concentrated so it should last you a very long time.    http://portlandpondsupplies.com/