When Tent Caterpillars Arrive, Be Safe & Sane

Posted on May 20, 2013 by Ann Lovejoy
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Don’t Burn Down The House

For the past few years, I’ve been seeing an occasional baggy web that indicates the resurgence of tent caterpillars. It’s been quite a while since their last true infestation, which was a memorable one. Personally, I find the sound of caterpillar droppings falling to the ground to be particularly creepy. This year, the tent caterpillars are definitely back in force.

By late April, I noticed a few trees and shrubs holding small white tents full of these pesky creatures. In areas where the infestation was light last year, this years’ crop looks bigger than over. Where there were no caterpillars, the first few webs are just beginning to show up on susceptible trees and shrubs.

Watch And Wait?

Before leaping into action, it’s worth asking ourselves whether tent caterpillars are really so bad? After all, they have been part of the natural cycle of events for millennia. If an infestation of tent caterpillars isn’t very close to your home or deck and isn’t bothering your garden or orchard plants, the recommendation from forestry scientists at WSU is simply to leave them alone.

Why? By thinning the canopy of the forest, tent caterpillars allow young conifers to stretch more quickly toward the sun. Those revolting caterpillar droppings help fertilize the understory of the woodlands. Hmm. However, when tent caterpillars are wreaking havoc in the garden, it is very hard to sit back and let them defoliate your favorite roses or fruit trees. Fortunately, there are a number of safe, sane and effective ways to cope with a revolting caterpillar infestation.

No Flames, Please

These do NOT include using flame weeders. In the past, a surprising number of enterprising folk managed to set their homes on fire because they were trying to kill tent caterpillars with flame weeders. Really, no. No flames, please. You don’t have to simply be passive, though; as soon as you spot either white tents or baby caterpillars, you can take action. Start by stripping off any webs you can reach and bag or burn them. Some folks like to prune off affected branches, but this can be disfiguring to the tree or shrub and depletes the plant’s resources as badly as the caterpillars will.

Spraying toxic caterpillar pesticides only works when you spray the caterpillars, not the webs, which are waterproof and impermeable to toxins. Instead, if there are many unreachable webs in your garden, your best option is to spray the foliage near the webs with Bt or Bacillus thuringiensis. Bt is a naturally occurring bacteria that makes a great pest control. The form of Bt used on caterpillars interrupts their normal digestion and maturation processes. When they eat leaves sprayed with Bt, they stop eating and die.

How Long, Oh Lord?

This process can take a couple of days, though affected caterpillars stop feeding fairly quickly after taking in the Bt. It works fastest on small caterpillars and takes longer with husky big guys. You should see definite results (such as a lack of moving caterpillars) within 2-3 days of spraying.

Like most botanical pesticides, Bt doesn’t last very long, so you may need to spray several times if you have a bad infestation. This may be especially true this year, as fluctuating spring temperatures cause caterpillars to hatch out in flushes. To control an outbreak effectively, timing is critical. Watch your plants, and notice when the caterpillars emerge from the webs. Until they do, nothing is going to kill them, however deadly. Once the babies emerge and begin to feed, you can start your spray program.

Be Mindful Of The Bees

Choose a calm, windless day and a time when bees and other pollinators are not present (early morning or late afternoon). Spray only the trees and shrubs that are hosting emerged and feeding caterpillars. Usually, spraying Bt every 2 or 3 days for a week will take care of even a severe caterpillar attack.

Carefully targeted and timed Bt use minimizes or eliminates accidental non-target caterpillar kill. Because Bt dissipates so quickly, it won’t persist to be a problem for the later-appearing caterpillars of Painted Ladies and other handsome butterflies. Take time to examine your caterpillars to see if they really are tent caterpillars. Tent caterpillars are about 2 inches long, dark brown and very fuzzy, with a white stripe down their back and linear or blobby red or blue side markings. If your caterpillars look like this and are emerging from baggy tents, you can be very sure about your identification.

Take A Good Look At That Face

Before spraying with Bt, examine the caterpillars for signs of parasitic wasps. Typically, the tiny wasps lay a single egg on each caterpillar’s head, though an egg may appear anywhere on the body. The white eggs are about the size of a pinhead. Dotted caterpillars are already doomed.

If you find plenty of white-dotted tent caterpillars, you may decide to do nothing to the caterpillars that are not eating your garden favorites. Tolerating a little damage will encourage the parasitic wasps, which are an excellent natural control. If the caterpillars are feeding on precious plants, you may want to spray Bt anyway, or do some hand picking. However, instead of squishing them, consider tossing tiny caterpillars into an area of weeds or long grass, so they remain available to their natural parasites.

If You Do Nothing

If you do nothing, the caterpillars will pupate, then emerge as moths. In a month or so, you will notice rusty reddish-brown moths/fluttering frantically around outdoor lights at night. The moths will soon lay their eggs for next year’s generation of tent caterpillars. You can strip these egg sacs off very easily when they are fresh or any time during the year. You may also release tiny trichogramma wasps that parasitize the eggs.

Tent caterpillars are most likely to be found on fruit trees, from Indian plum and wild cherry to apples, pears and peaches. They also enjoy alders, cascara, and birch trees. You will need a trombone sprayer (and good water pressure) to reach tents that are high up in large trees. In high population years, the caterpillars can pretty well defoliate these trees. Healthy trees are rarely killed, but trees that are already struggling can be pushed over the edge by a bad attack. Evaluating where the caterpillars are and how many there are can help you decide your course of action.

Oldies Are Not Goodies

If you use Bt, check the label on the bottle to be sure you have a fresh solution. Usually, the shelf life is a year or two for unopened bottles and about 3 months for opened bottles. Wettable powders may be good for two years if unopened. Any Bt lying around in the garage since the last tent caterpillar infestation is most probably no good, especially if it has frozen and thawed. Start fresh for best results!

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Planting Trees For Tomorrow

Posted on May 15, 2013 by Ann Lovejoy
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A Gift To The Garden Is A Gift To The Planet

One of my favorite places to relax is in a little sunporch off my bedroom. The glass roof echoes rain sounds delightfully and the big glass sliders offer an uninterrupted view of trees and sky. Years ago, people could see the water of Fletcher Bay from this room. Now, I can get a glimpse of the water in winter, when the alders and maples shed their leaves. Even then, the cedars and firs encircle me with trees that frame a skyful of clouds.

I don’t miss the water view, really. Sure, it would be nice to see the sparkling bay, but I’ve always felt that trees are in themselves a view well worth cherishing. If I were an artist, I’d make enormous paintings of treetops and clouds reflecting every mood and season. They could hang in cities where it’s hard to see the sky and where trees are rare and mostly tame or dispirited.

Plant A Tree

Since I’m not a painter, I find great satisfaction in planting as many trees as I can. I am so lucky to be able to plant public spaces, from the local library grounds to local schools and churches. I was thrilled  this past year to get the chance to plant a new public park near the ferry terminal. I was given a list of a dozen interested people who wanted to help, but none of them responded to calls or emails about meetings. That turned out to be awesome, since it meant I could do whatever I wanted.

That park has two beds, one of about 5,000 square feet that’s near the street, and another of about 10,000 square feet that backs onto a ravine. The first bed is more formal, holding a sheet of a low-growing, evergreen, shrubby honeysuckle called Lonicera pileata Royal Carpet. There are only three trees in that bed; two Mount Fuji cherries, which will mature into low, wide-skirted beauties that will float like clouds over the mass of green, and a lovely Japanese maple called Acer palmatum Katsura, which colors gorgeously in spring and fall. Each is given enough room to develop into a striking specimen with fully developed form and character.

Wild Things

The L-shaped larger bed is called the Wild Garden, since it flows into the natural environment on the backsides of the L. Here, we installed dozens of trees, clustering native shadbush (Amelanchier) and wild cherries into thickets, as they grow in the wild, and spacing a few specimen maples where they have space to shine. These trees are layered down from the towering skyline of bigleaf maples to the retaining wall with massed shrubs. At the back are groups of ocean spray, Indian plum, sumac and elderberry, along with Garryas, colorful twiggy dogwoods, and buxom Mahonias. Lacing through them are 300 evergreen huckleberries to knit the clusters into a whole.

Here, most of the trees are woven into a living tapestry rather than free standing. In a few seasons, this dense planting will scoop like the sides of a bowl, flowing downward from the surrounding mature treetops to the wide walkways where passersby stroll. The front stretches of the Wild Garden are tamed into sweeps of low-growing barberries and spireas, which so far have not been eaten by the ever-present deer.

Bring It All Home

Not everyone has such a majestic setting to play with, of course, but almost any of us can find space for a tree or two. If your available space is small, look for charming compact trees, some of which can live contended in a container or tree box for decades. If you have room to paint on a bolder scale, plant trees for every season, considering fall color as much as spring bloom, summer fruit, and winter silhouette.

Worried about the environment? Plant a tree. Even a small tree is a gift to the world, exchanging carbon dioxide for oxygen every day its whole life long. The Arbor Day Foundation says, “a mature leafy tree produces as much oxygen in a season as 10 people inhale in a year.”  A recent New York Times article claimed that “one acre of trees annually consumes the amount of carbon dioxide equivalent to that produced by driving an average car for 26,000 miles.” Naturally, the amount of either substance being consumed or created will vary depending on each tree’s size, kind, and state of health. Still, it’s an impressive contribution to the wellbeing of the world.

Plant With An Eye To The Future

While few of us have an acre of land to devote to trees, every tree we plant is a gift to the earth and all its critters. Sadly, many trees fail to reach their full life span because they are planted in inappropriate places. Trees placed too close to buildings, trees planted under power lines, trees set smack by a sidewalk or roadway are largely doomed to die long before their natural lifespan is reached.

When you think about planting a tree, consider both the tree’s ultimate size and the available space. Stand where you want to put your tree and look up. If the airspace is already full of branches, think again. This is especially important when planting a potentially majestic tree like a chestnut, a parrotia, or a katsura. All need a space the size of a house if they are to reach their full growth.

Pick The Right Tree

For many folks this means planting trees that mature at 12-20 feet instead of 100 footers. That’s not bad news, since there are dozens of excellent choices. Those who have a huge empty lot or meadow to fill can dream even bigger. True, a tree planted today won’t achieve grandeur for at least a few decades. However, planting trees is as much about tomorrow as it is about instant gratification.

I was recently sent a stunning set of pictures of “tree tunnels” from around the world. In one scene, ancient yews line a narrow country lane in Ireland. In another, stately sycamores flank a roadway in France. Still a third showed a road vanishing into a vista of flaming maples in New England.

Tunnels Of Leafy Love

Clearly, such plantings require one to own significant amounts of land, but how glorious a sight might be created if a whole neighborhood agreed to plant the same tree in each sidewalk strip. Years ago, friends in Victoria, BC took me for a ride in their Cadillac convertible. At one point they told me to shut my eyes and lean my head back. I opened my eyes to an endless mass of cherry blossom. Trees planted back in the 1950‘s now meet across the wide street, making a perfect arc of bloom in spring.

On another trip, I visited a hazelnut farm in Oregon, where the trees formed seemingly endless arches running across rolling hills. That scene was all the more enchanting because grape hyacinths had naturalized throughout the orchard in an unbroken carpet of blue.  There’s something majestic about such scenes, something that creates a sense of awe and wonder. As John Muir, the Scottish naturalist who founded the Sierra club once wrote, “Everyone needs beauty as well as bread, places to play and pray, where nature heals and gives strength to body and soul alike.”

Look With New Eyes

Lack room for a full-out tree tunnel? Look around, look up, and see where a tree or two might make themselves at home. Even modest properties can host arboreal marvels on a smaller scale. If not a fabulous specimen, why not plant an allee of beeches, or birches, or laburnum, or lilacs? Dream into it, research the possibilities, and plant a gift for the garden and the world.

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The Aftermath Of Spring

Posted on May 8, 2013 by Ann Lovejoy
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Dealing With Bulb Foliage

Spring bulb displays are so bold and beautiful that it’s tempting to pack the beds and borders with them. However, most are not especially good mixers, wanting a lengthy period of ripening and summer drought to restore their bloom power. Foliage ripening can be an issue, since some spring bloomers produce masses of leaves that topple in damp heaps over neighboring perennials once the bulb flowers have faded.

Aging bulb foliage can be unsightly indeed as it passes through various unattractive color changes on the way to brown crispness. It’s tempting at the homeliest point to cut the leaves off, but to do so seriously weakens the bulbs. After a few seasons of such premature treatment, bulbs will rebloom sparsely if at all.

Feed and Fold

One good way to handle all this is to feed bulbs just as they come into bloom. Because the soil is chilly at that point, chemical fertilizers won’t help, but a blend of feather, soy or cottonseed meal and kelp meal will nurture your bulbs as they bloom and fade over the next few months. I also renew their blanket of mulch with several inches of either aged compost or well rotted dairy manure.

When the bulb foliage starts to collapse, you can gently fold it earthward. Once it changes from green to yellow, the foliage is no longer feeding the mother bulb. Now you can tucking it discretely under the mulch and let it decay in peace without becoming an eyesore.

Moving Bulbs In The Green

I am often asked when it’s best to divide or transplant bulbs. Spring bulbs are best moved ‘in the green’, which means after the flowers have faded but while the foliage is still robust and green. Start with the earliest bloomers such as snow crocus and snow drops, which are typically ready to divide by late March. In time, of course, many early bulbs will spread themselves into enormous carpets, as long as their foliage is not removed too soon. However, if you don’t want to wait decades to see this charming sight, you can speed the process up considerably.

Dig up a crowded clump and gently separate the bulbs. Replant them in little colonies, including some larger bulbs as well as tiny seedlings in each new group. Every little cluster will expand each season, and you can facilitate their spread by dividing them every 3-5 years. Add some of the bulb food described above to each new group, mulch them well with compost and your early bulbs will spread with alacrity.

Make A Tapestry Meadow

If you want to introduce snowdrops, crocus, or daffodils into a lawn or meadow, you can cut 3-sided flaps of turf and set the bulbs beneath them. Set the bulbs in groups of 5-10, firm them into the exposed soil, then gently tamp down the grass flaps. This works best with dry bulbs, and is most successful when done in autumn, just as the rains arrive.

To avoid squirrel theft, use varieties of Crocus tommasinianus. Tommies, as the Brits fondly call them, come in soft shades of lavender, purple, and rose madder and bloom in early spring. By nature, they are prolific little critters, spreading by seed and bulblet in any decent soil. At the Bainbridge Public Library, the Friday Tidies put in 500 tommies about 10 years ago. The seed got into our compost, and now every bed we mulch with it produces sheets of lovely crocus from February into March.

Timing The Treatments

In my garden, dozens of daffodils are still blooming bravely in early May, but that’s because I planted them very late indeed. Last week’s heat wave brought temperatures into the 80’s, after a long, slow spring, and many plants went into shock (people too). My bulbs are in shade for much of the day and thus escaped the crisping some plants experienced. Many of the later blooming bulbs are definitely distressed looking now and they will be divided and moved this week.

Among them are snowflakes (Leucojum), larger, taller and later to bloom than snowdrops (Galanthus). They are often confused, since both have white petals tipped or touched with green. However,  where snowdrops have a long outer skirt and a shorter inner skirt of 3 petals each, snowflakes have 6 petals all the same length. They also bloom on 12-16-inch stems, where most snowdrops remain under 6 inches.

Time To Trim

Snowflakes make great masses of foliage, as do grape hyacinths. Unlike more delicate bulbs, these will both rebloom even if their foliage gets trimmed a bit on the early side. In any case, once the leaves have fully browned off and turn brittle, they can be removed and composted.

Potted bulbs that were enjoyed indoors are not always good repeaters when transplanted into the garden. However, if fed with the bulb mix described above and planted well away from any summer irrigation, they usually recover in a season or two. Some, like hyacinths, may persist for decades, slowly increasing by offsets and building into generous clumps.

Time To Hide

The slowly maturing stalks of later blooming tulips can look awful amongst the rising tide of summery perennials. These can be gently persuaded to lie down, then covered with mulch. If you never get around to removing the elderly stems and leaves, it won’t matter a bit. If you prefer, you can also trim them a bit at a time, removing the soft, pale bits and leaving anything still firm and green. This works for lilies as well, which can be similarly weakened by precipitate removal of browning stems and leaves.

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Keeping Blueberries Happy In Containers

Posted on May 2, 2013 by Ann Lovejoy
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Sunshine and Slightly Acid Soil

In a recent entry, I mentioned that, because of my resident deer herd, I grow my blueberries in containers. This sparked several good questions, so I thought I’d provide a bit more detail for those of you who want to try it. However, if you want a lot of fruit and have plenty of room, I’d suggest growing highbush blueberries. These big, strapping creatures can top 8 feet in height, and thrive in full sun. Their roots are shallow and wide-spreading, so they appreciate good garden soil, well amended with compost.

To keep the humus level high, renew blueberry bed mulch each spring and fall. Add any combination of aged manure, mature compost, rotted leaves, and well rotted sawdust or finely ground bark to improve soil and help smother weeds. Compost is especially valuable, since it strengthens and sweetens fruit flavor and provides most of the nourishment these sturdy plants need.

Just Enough, Never Too Much

Give blueberries full sun and good air circulation, as well as a dedicated bed free of root competition from nearby trees. Blueberries thrive near water but don’t tolerate waterlogged soil. They grow best in open-textured, well-drained loam, with plenty of humus (organic matter). They prefer acid soils with a pH between 4.5 and 5.5, which fortunately is quite typical throughout the maritime Northwest.

While consistent moisture is important to blueberry production, excess fertilizer and water dilutes that subtle, tart-sweet flavor. If you use irrigation, make sure it delivers two inches of water a week to new shrubs, and 1 inch a week to established bushes. Don’t overfeed, but use a combination of compost mulch and a slow-release organic fertilizer to enjoy the fullest-flavored fruit. Fertilizers that will mildly increase soil acidity include cottonseed meal, feather meal, and fertilizer blends made for rhododendrons and azaleas.

A Blueberry Edible Hedge

Blueberries can be planted as close as 3 feet apart to form solid hedgerows, which also makes them slightly easier to net so birds can’t capture the entire crop. You can also space them 6-8 feet apart as free-standing individual specimens. If planted in rows, allow  about 8 feet between the rows, especially if you use a large mower to keep a grassy path well shorn (though better paths could be made from wood chips or shavings).

If you’ve got ample space, consider growing Chandler, a tall (5-7 feet) shrub that produces huge, plump berries with great flavor. Blueray (4-6 feet) is an old-time blueberry with excellent vigor and fine flavor. Highbush blueberries bear up to eight quarts of fruit a year. For a long and productive season, grow some early, mid- and late fruiters. If you plan to make pies and freeze extra berries, plant three or more bushes per person, otherwise two each should do.

Light Pruning Makes For Stronger Plants

Blueberry shrubs need little pruning beyond the removal of dead, broken, or weak stems. In spring, trim off any aging, unproductive branches, making room for sturdy new branches to develop. In late winter, trim back productive branches by 25% to encourage new fruit bearing shoots to form.

Where space is limited or deer are rampant, grow your blueberries in containers. Mine are on a deck almost 20 feet above the ground, and so far, no deer has managed to reach them. Compact blueberry varieties will be happiest in large containers filled with slightly acidic, moisture-retentive soil.

Potting Soil For Acid Lovers

Since bagged potting mixes are pH neutral, I blend my own slightly acid garden soil with aged dairy manure and compost. You can also use Booster Blend, a mix produced by Seattle’s Cedar Grove, which combines compost with composted dairy manure.

As I have probably made abundantly clear in previous posts, I never use peat, which is destructively strip-mined and devoid of nutritional value. Dairy manure is an excellent replacement, especially from dairies that don’t use Bovine Growth Hormone or routine doses of antibiotics and steroids. My favorite source for pit-washed dairy manure is Moo Doo For You (see below), but most Agricultural Extension services offer manure Hotlines for sourcing local manures.

Unlike peat, aged dairy manure makes an excellent soil amendment and top dressing. So does coir fiber, a byproduct of the coconut industry. Wiry and tough, yet fine textured, coir breaks down slowly, providing soil nutrients and improving soil texture for several years (or more).

Big Pot, Big Harvest

Give blueberries large containers to accommodate their  wide, questing roots. Plant new blueberries in pots that hold at least 5 gallons. After two years, pot them up into half-barrels, where they can remain indefinitely. To keep them happy, topdress with aged compost each spring and fall, and feed moderately from spring through late summer as outlined below.

Good container candidates include Tophat, the smallest blueberry bush, and Northsky, which tastes like wild berries. Northblue and Northcountry are both 2-footers that thrive in containers for many years. If the container is large enough (think half-barrel), so will my favorite, Sunshine Blue, an evergreen blueberry with silvery blue foliage that looks lovely all year round.

Those in Western Washington can get beautiful aged, dairy manure from:

Moo Doo For You
Mark Vukich
(206) 271-6490
(253) 939-0627

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