Archive for April, 2016

Today is Arbor Day!

Celebrate! Plant a tree!

Show someone close to your heart that you really care about them by planting a tree in their honor or in memory of a loved one. One day it will grow to be a majestic tribute to that very special person!

A majestic oak silhouetted against the winter sky

Here are a few tips for planting trees.


Below is a post that I wrote on Arbor Day in 2012.

I thought I would share it today in honor of Arbor Day 2016!


Today is National Arbor Day!

Our new woodland garden replaces our front lawn!

Our new woodland garden replaces our front lawn! We planted a little pink dogwood, hosta, and several azaleas. Now it just needs some mulch.

It’s always the last Friday in April although some states recognize a different State Arbor Day that corresponds better with planting times in their state. Since Arbor Day was founded in 1872, it has been customary to plant a tree in observance of the holiday and on that first Arbor Day, it is estimated that about one million trees were planted.

As you celebrate Arbor Day this year, keep in mind that as important as it is to plant new trees, it is equally important to care for and protect the trees that are already growing in your landscape.

Damage to mature trees due to insects and diseases (many introduced from other countries) can be devastating to your landscape as well as the surrounding areas and adjoining forests. Diseases such as the Chestnut blight and Dutch elm disease and exotic insects like the emerald ash borer and the Asian long-horned beetle have killed tens of millions of trees across the U.S.

Chestnut blight canker on the stems of a young American Chestnut. Photo by Eric Jones

Chestnut blight canker on the stem of a young American Chestnut.
Photo by Eric Jones

The chestnut blight, caused by a fungus (Cryphonectria parasitica), was introduced to North America from Asia in the early 1900’s either on infected lumber or through diseased trees. Within 40 years of its introduction, virtually all the chestnut trees in North America were wiped out. Although mature American chestnut trees have disappeared from our forests, small trees often grow from stump sprouts since the blight doesn’t kill the roots. Unfortunately, these small trees rarely grow to reproductive age before they are attacked and killed by the fungus. Such a sad ending for these once majestic trees which often reached 200 feet tall and 14 feet across! There is no cure for this disease but much work has been done to genetically engineer a disease resistant American chestnut using genetic material from a few stump sprouts that managed to produce seeds and a bit of DNA (as little as 3%) from Asian species that show resistance to the blight. The American Chestnut Foundation is at the forefront of this research with a mission …

…to restore the American chestnut tree to our eastern woodlands to benefit our environment, our wildlife, and our society. The American Chestnut Foundation is restoring a species – and in the process, creating a template for restoration of other tree and plant species.”

How’s that for a great Arbor Day message!

Woolly adelgids on the branch of a young hemlock.

Woolly adelgids on the branch of a young hemlock. Photo by Eric Jones

Another pest that is doing its best to wipe out whole a species of trees is the hemlock woolly adelgid (Adelges tsugae). This past Sunday on a wonderful but rainy walk in the George Washington National Forest, Eric and I saw evidence of this destructive pest on a young hemlock. The hemlock woolly adelgid was also an accidental introduction from Asia and is devastating populations of eastern hemlock (Tsuga canadensis) and Carolina hemlock (Tsuga caroliniana) throughout eastern North America. The insect damages the trees by feeding at the base of the needles causing them to desiccate and eventually drop off. Heavy infestations have been known to kill trees in as little as four years but healthy trees can sometimes survive an attack for a longer period of time. Luckily, there are products that the homeowner can use to help control hemlock woolly adelgids but sadly in our hemlock forests, these pests are causing the destruction of large numbers of these beautiful trees. Read more about the woolly adelgid.

As they have with the American chestnut, researchers have developed an adelgid-resistant hybrid by crossing the Carolina hemlock with an Asian hemlock which is resistant. While this is great progress – it does nothing to save the trees that are already infected!

Seen these hanging around?

Seen these hanging around? These purple structures are Emerald Ash Borer traps used to evaluate populations of the pest.

Another group of insects that causes widespread damage to established trees is the wood-boring insects including the emerald ash borer, the Asian long-horned beetle (both introduced from Asia), and a wide variety of the bark beetles.

The emerald ash borer, first reported in Michigan in 2002, has already killed millions of ash trees and is a potential threat to all the ash trees in North America.

The Asian long-horned beetle is one of the most destructive of the wood borers because it is not selective and attacks a wide variety of hardwood trees.

Bark beetles, like the spruce beetle, the mountain pine beetle, and the southern pine beetle, have killed millions of conifers in North American forests especially during severe outbreaks.

Bark beetles attacked this weakened pine and contributed to its death.

Bark beetles attacked this weakened pine and contributed to its death.

I remember when we were in Alaska several years ago seeing where the spruce beetle had killed entire forests of Sitka Spruce. Although bark beetles generally attack trees that are weak, dying, or already dead, the species listed above are particularly destructive because they will attack live, seemingly healthy trees.

For the homeowner, there are products that can be used to help control some of these pests. Horticultural oils can help control the woolly adelgid if they are sprayed at the correct times.

Some systemic insecticides may help control adelgids, emerald ash borers, Asian long-horned beetles, and pine borers. Bayer Advanced 12 Month Tree & Shrub Protect & Feed II and Bonide Annual Tree & Shrub Insect Control are products that can be mixed and poured at the base of the tree according to the label directions. These products are not available in all states. Always read and follow the label directions when using any pesticides. Read more about borers.

On this Arbor Day, The Nature Conservancy reminds us of some important tips to help protect our trees.

  • Keep your trees healthy and vigorous! Many destructive insect pests and diseases are attracted to trees that are stressed due to poor nutrition, drought conditions, and mechanical injury such as lawn mower or weed whacker nicks in the trunk.
  • When purchasing trees, purchase certified, pest-free nursery stock.
  • To avoid inadvertently spreading invasive pests or diseases, NEVER transport firewood when you travel, always obtain it locally!

So make a pledge this Arbor Day to pay attention to your existing trees and strive to keep them strong and healthy!

… and plant a tree!

Until next time – Happy Gardening!

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Freeze damage on quince flowers

Well it’s happened once again!

The foliage on some of the daylilies was damaged

The foliage on some of the
daylilies was damaged

Unseasonably warm temperatures in March have pushed spring along in the mid-Atlantic states; only to have below freezing temperatures the first week of April provide a wake-up call that warm weather is not here to stay just yet.

Frost and freeze damage to tender new growth is evident throughout the Viette gardens and we are definitely not alone in seeing plant damage from this sudden cold snap.

The following was posted on our discussion board yesterday morning:

I live in Hollywood, MD (southern MD) and this past weekend we had freezing temps and my hydrangea leaves were damaged. I have 5 plants total, 3 chest-high and two others a little taller. They were looking wonderful with the leaves coming in nicely. They are 5-7 years old. This is the first time I have seen damage like this at the beginning of the season. They are calling for freezing temps again Sat. night. I am planning on buying and putting plant sheets on them to prevent further damage but I am wondering if it is too late. I am so disappointed. I was so looking forward to their blooms this summer. Anyone have experience with this with any tips or what I should expect as far as blooms, leaves coming back?

The dogwood flowers froze and turned brown.

The dogwood flowers froze
and turned brown.

I have had experience with this!

I even wrote a blog post about it at the time. The same thing happened in the spring of 2012 after a very warm March. In early April of that year the temperatures plummeted – just like this year. There was major damage to many shrubs (including my lacecap hydrangeas) and perennials that had broken dormancy earlier than normal due to the unusually warm March temperatures. The dogwood flowers were beginning to open and they got zapped as did the tender new growth on the boxwoods and on a few young native hollies growing in the woods.

New holly leaves turned black but tougher older leaves were fine

New holly leaves turned black but
tougher older leaves were fine

The new growth on the boxwood was severely damaged

New growth on the boxwood
was severely damaged

Boxwood and hollies can be trimmed back to remove any damaged foliage. As for the lacecap hydrangea, it’s best to wait and see. You don’t want to risk cutting off flower buds that might still be alive! Fortunately for me, I did not cut my damaged hydrangeas back that spring and they eventually recovered with lush new growth and they bloomed beautifully in the early summer – much to my surprise and delight!


This peony bud was zapped and some of the foliage was damaged a bit.

This peony bud was zapped and
some of the foliage was damaged.

This year it may be different, although it is too early to tell how extensive the damage may be. Walking around the gardens just now, it didn’t seem too bad. Some of the daylily foliage was nipped and a few of the peony buds froze but all-in-all, it wasn’t as bad as I had feared. That may change after this weekend, though.

Most of the hosta in the gardens are covered now so I wasn’t able to see if they had been damaged. They were covered before the worst of the cold.

Hosta covered in the gardens

Hosta covered in the gardens

At least most of the herbaceous perennials like daylilies and hosta can be trimmed to remove damaged foliage and they will respond with a flush of new growth. The cold damage will not usually affect the flowering of these summer blooming perennials.

Shrubs that bloom on new wood, such as butterfly bushes (Buddleia), Caryopteris, crape myrtle, and some hydrangea, can be pruned later in the spring to remove any damaged foliage or branches without affecting their flowering. In fact, we recommend waiting until the danger of cold weather has passed before doing any pruning on these shrubs.

As I walked around, I also noticed that many of the blossoms on the quince and the early blooming crabapple varieties had turned brown from the freeze.

Quince flowers were killed but the tougher foliage was not hurt.

Quince flowers were killed but
the tougher foliage was not hurt.

The pink quince flowers just melted out.

Most of flowers on the
pink quince turned brown.

It’s really too bad because they were just beginning to get really pretty!

The crabapple flowers and the tender new foliage were damaged

Crabapple flowers and the tender
new leaves were damaged

The buds that haven’t opened yet seem mostly sound.

That’s good news for the rest of the spring bloom but …

This cold snap is not over yet!

The nighttime temperatures are forecast to remain in the low 30’s for the rest of the week and by early Sunday morning they may drop into the upper teens in some of the colder areas. Brrrrrrr!

Hopefully the forecast is wrong but don’t count on it! Be sure to protect your plants tonight and keep them covered through Sunday morning.

Maybe this will be the last of the cold weather. Time will tell …

Until Next time – THINK SPRING!

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