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Archive for May, 2014

Botrytis infected peony stem and bud

An ugly name for and ugly disease!

Botrytis or gray mold is a fungal disease that attacks many perennials but especially peonies – the “aristocrat” of the spring perennial garden!

A peony bud and stem infected with botrytis

A peony bud and stem infected
with botrytis

Anyone who grows peonies eagerly anticipates the appearance of their glorious blooms in mid to late May. Sometimes we are bitterly disappointed when our peony stems suddenly begin to turn brown, wilt, and flop over.

It is especially upsetting when this occurs after the flower buds have developed and are beginning to swell on the stems. We can hardly wait for them to open and reveal their beautiful flowers – but then … Ugh!

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Botrytis at the base of this peony leaf

Botrytis at the base of this peony leaf

Botrytis blight often rears its ugly head in the garden after late spring freezes or during periods of cool, rainy weather. It can be especially damaging to plants when wet, humid conditions persist over several days.

Botrytis (Botrytis paeoniae) is probably the most common disease of herbaceous peonies. It typically first appears as brown or black patches on the bases of the young leaves and stems when they emerge in the spring. The stems and leaves wilt rather quickly and fall over.

This peony bud would have produced a beautiful flower!

This peony bud would have produced
a beautiful flower!

A gray mold which produces and disseminates a tremendous number of spores eventually develops in these areas. These botrytis spores are carried by the wind and also by insects to the leaves and flower buds of other nearby peonies where they grow and cause leaf blight and bud rot. Often, this is when the damage becomes most noticeable. The very tiny flower buds turn black and fail to develop further while larger buds and the stems just below them turn brown and quickly droop over. Unfortunately, under favorable conditions, botrytis can quickly spread through your peony beds unless steps are taken to control it.

What can you do?

Botrytis spores beginning to cover this diseased bud.

Botrytis spores beginning to
cover this diseased bud.

If you notice botrytis on the buds, leaves, or stems of your peonies, carefully remove the infected plant tissue, place it in a bag and discard it in your trash – do not put it in your compost pile! Never prune infected stems and foliage while the plant is wet or you risk spreading the disease to other healthy plants.

Botrytis overwinters in dead leaves and other plant tissue so it is important to remove all plant debris from the garden in the fall. Cut peony foliage to the ground in September or October, bag it up, and put it in the trash. Rake up dropped leaves and remove them from the garden.

Again, do not compost any of this plant debris.

Leaf blight caused by botrytis often develops after the blooming period.

Leaf blight caused by botrytis often
develops after the blooming period.

In the spring, just as the shoots begin to come up, spray the shoots and the surrounding soil with a mixture of Bonide Mancozeb (with Zinc) and Immunox according to the label directions. Then begin a spray program, spraying first with Mancozeb, copper fungicide, or Bonide Fung-onil and then 10 days later spray with Immunox or one of the other fungicides that you didn’t use for the first spray. Repeat this every 10 days until they flower.

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In our gardens, botrytis wasn’t too bad this year. However, I have had a few calls about the sudden death of peony buds or the lack of bud development all together. If you don’t see signs of botrytis, the following are a few other reasons why peonies might fail to bloom:

  1. A late spring frost or freeze might kill the buds. We had some very cold nighttime temperatures this spring. It dropped into the mid 20’s several times in the middle of April and we even had frost in mid May this year.
  2. Peonies may be planted in too much shade. Sometimes, as your landscape matures, full sun gardens can become more and more shaded. Peonies will bloom in bright shade but the bloom will begin to decline in deeper shade.
  3. Too much nitrogen will hinder flower development. Your grass loves lots of nitrogen; peonies, not so much. Nitrogen promotes lush green growth – just what you want for your lawn but not your perennials. Foliage comes at the expense of flowers. Be very careful to keep your high nitrogen lawn fertilizer out of your perennial beds if you want a nice show of flowers! Choose an organic fertilizer like one of the Espoma “tones” or another fertilizer that is lower in nitrogen.
  4. Bare root peony showing the two types of "eyes".

    Bare root peony showing
    the “eyes”.

    Your peony may be getting too old. As your peonies get age, flowering may slow down. To rejuvenate your peonies and make them bloom well again, dig and divide them in September or October when the foliage begins to turn brown. Here are some tips.

  5. Peonies are planted too deeply. Plant your peonies so the eyes are no deeper than 2″ below the soil surface. If they are planted deeper than this, they may not bloom.

Our peonies were pretty spectacular this year! I hope yours were, too!

Peony 'Gay Paree' blooms in the Viette gardens. It is one of Andre's favorites.

Peony ‘Gay Paree’ blooms in the Viette gardens. It is one of Andre’s favorites.

If you don’t have any planted in your garden, maybe it’s time to find a sunny spot for one or two! Check out our list!

Until next time – Happy Gardening!

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Dead buds along a hydrangea stem.

It was a long, cold winter Charlie Brown!

I think we became a bit spoiled with the unusually warm winter temperatures we have experienced over the past few years. Not to say that the winters had been balmy, but we hadn’t had a good “old-fashioned” cold winter for a while.

This winter had some really cold nights; the temperature dropped below zero quite a few times here in the Shenandoah Valley and the wind made it feel even colder. Below zero wind chill readings kept kids home from school on many occasions. I’m not sure why – we had to go to school no matter what the temperature was outside! And we had to walk a long way to the bus stop!

Anyway, it WAS a cold one to be sure.

We are now beginning to become aware of some of the winter kill that occurred over this very frigid winter. Plants that normally breeze through the winter unscathed got hammered by the deep freeze. Consequently, we have had many calls and e-mails this spring addressing this general problem.

I live in zone 6 in VA and am waiting for my 7 year old Hydrangea macrophylla bush to leaf out on the old wood. It’s about 4 feet tall and leaves have sprouted from the base of the shrub but no leafing action has come out of the branches. Do you think I should wait a few more weeks to see if leaves will come out like it did last year or should I assume that it’s winter damage from our long winter and just prune it to the ground?”

My lacecap hydrangeas were sprouting nice new growth from the rootstock but the tops were dead.

My lacecap hydrangeas were sprouting nice new growth
from the roots but the tops were dead.

The lacecap hydrangeas in my own garden are in the same shape. This was a very tough winter for many trees and shrubs. Buddleia, crape myrtle, Leyland cypress, boxwood, azalea, gardenias, and many others are showing varying degrees of cold damage.

Dead terminal bud.

Dead terminal bud.

Buds all along the stems were dead as well.

Buds all along the stems were dead.

The buds were freeze dried!

The buds were freeze dried!

In many cases, the above ground portions of hydrangea and Buddleia were killed during the winter. When I checked the buds along the stems of my lacecap hydrangea, they were all dead as a doornail. Nice and crispy! Same with my Buddleia – all above ground stems were dead.

Luckily, many of these plants will still have live, healthy roots. Like the gardener above, all my hydrangeas have lovely green growth coming up from the roots. My Buddleia are also sprouting new stems from the base.

The only option for these shrubs (including also boxwood, yew, azalea, rhododendron, and gardenia) is to cut the dead stems back to green wood. In my case, I will be cutting my lacecaps all the way back to the ground. They will still grow into an attractive shrub this summer but I know I won’t have flowers on them this year. Hydrangea macrophylla, which includes the lacecaps, blooms on old wood and unfortunately, all my old wood is dead.

Buddleia cut back to the ground is beginning to sprout new growth at the base.

Buddleia cut back to the ground is beginning to
sprout new growth at the base.

Happily, Buddleia blooms on new wood so there should be plenty of flowers for the butterflies and hummingbirds on my butterfly bushes this summer.

Crape myrtles and Leyland cypress were also hit hard by this cold, cold winter, especially at the northern edges of their hardiness range. As evidenced by the many questions we have received this spring, trees that normally have little or no winter kill are showing a lot of damage this year.

Crape myrtle cut back to live wood after a hard winter.

Crape myrtle ‘Hopi’ cut back to live
wood after a hard winter.

The solution for crape myrtles is pretty simple; just cut them back to healthy, green wood once they begin to grow again and you can easily tell what is live and what is dead. They will respond with a flush of new, vigorous stems. Since these trees bloom on new wood, you should still get some beautiful flowers this summer.

Be sure to feed them with Espoma Plant-tone or Holly-tone after pruning if you haven’t fed them yet this spring.

Leyland cypress with winter damaged branches are more of a problem. These trees produce new growth from buds at the tips of the branches and also from buds that are randomly located along the stems. You can’t just chop off the damaged portions and have it reliably break out in new growth. The best option for these shrubs is to feed the foliage with a liquid fertilizer and ground feed with Espoma Holly-tone (10 lbs per 100 sq feet of root surface). Often if the damage isn’t too severe, the tree will put on new grown and the damaged tips will drop off. Some pruning may be necessary but if whole branches were killed, you may unfortunately end up with a permanently disfigured tree.

A monarch butterfly visits Buddleia 'White Profusion'

A monarch butterfly visits
Buddleia ‘White Profusion’

Look on the bright side
consider this a great opportunity to rejuvenate some of your trees and shrubs. They will flourish with lush new growth and your summer flowering trees and shrubs may even bloom better this summer.

Next spring, your spring flowering shrubs should produce flowers on a beautiful new, but shorter plant! However, be forewarned that it may take up to two years before you see a full, bountiful bloom.

If you aren’t able to save your tree or shrub because it is too damaged or even completely dead, consider the loss an opportunity to try an exciting new variety!

Until next time – Happy Gardening!

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Gray treefrog

Well, spring is finally here to stay – I hope!

Pink Lady's Slipper

Pink Lady’s Slipper
Photo taken by Eric Jones

In fact, lately it seems that we have skipped spring and gone right into summer! It’s been downright hot out there the last few days!

It sure has been a roller coaster ride of high and low temps this season! Spring was very late this year and, with the exception of the redbuds, the flower show of blooming trees seemed to be less than spectacular. Eric is currently teaching his Field Botany May Term course for Mary Baldwin College and he comes in most days disappointed with the slow progression of spring and the lack of blooming wildflowers. They finally saw some Pink Lady’s Slippers on Friday.

Oak catkins

Oak catkins

Just two weeks ago, tiny oak leaves began to pop out and now they have expanded to nearly full size. The pollen-filled catkins are hanging down from the branches and every outdoor surface is beginning to be covered with oak pollen. The pine pollen won’t be far behind – I have just noticed that the male cones are beginning to develop on our big pines. Pollen season is upon us!

For several weeks, we have been hearing the trill of the treefrogs in the evening. This is always a sign that spring is near.

Male Spring Peeper calling (Hyla crucifer), North America.

Male Spring Peeper

The spring peepers are one of the first treefrog species to emerge and begin singing. You can often hear them in early March. They were late this year and I just heard from my family in Vermont that they are now singing in earnest up there. The sound of their trilling can be deafening on a still night!

“Spring is here,” they seem to say!

Male gray treefrog with throat pouch expanded.

Male gray treefrog with throat pouch expanded. Very pale against the pole.

One warm morning last week as Eric and I were having coffee on the deck, Eric noticed a pale gray blob wedged beside the pole that holds our wind speed indicator. When I went closer to investigate, I discovered it was a treefrog which Eric later identified as a gray treefrog (Hyla versicolor). He was a cute little guy and was doing his best to blend in with the pole. Eric was able to get some good pics.

Gray treefrogs are common throughout the eastern US. They are large treefrogs with grayish skin that is surprisingly dry and warty for a frog. They aren’t quite as warty as a toad but more so than the typical frog.

Gray treefrogs are able to change their skin color to some degree in order to blend in with their background; sort of like a chameleon only the change isn’t quite as dramatic. He was very pale when he was up against the white pole but when he moved away from that light background, he slowly became a bit darker. It was very interesting.

Notice how his color darkened a bit when he moved away from the white pole.

Notice how his color darkened a bit
when he moved away from the white pole.

One of the distinguishing traits of treefrogs is the large discs at the tips of their toes. These toepads allow them to climb up vertical surfaces like our deck post. Apparently, gray treefrogs have particularly large toepads but we couldn’t see his toes very well – he kept them curled up under his body most of the time.

Treefrogs typically vocalize/sing at night but this guy started singing a little bit while he was on the deck – perhaps he was just confused! It was interesting to see his throat pouch balloon out each time he called. The males are the only ones that sing. They sing to attract the female frogs.

Gray treefrog calling. They usually call at night to attract females

Gray treefrog calling. They usually sing at night to attract females.

Frogs and toads are wonderful “friends” to have in the garden because they prey on many of the pests that are destructive to both our ornamental and vegetable plants. They eat insect pests like beetles (including cucumber beetles), crickets and grasshoppers, ants, earwigs, and cutworms.

Gray treefrogs have a distinctive light patch below their eye.

Gray treefrogs have a distinctive
light patch below their eye.

Like I said – great friends to have in your garden!

Toads are especially nice to have around because they LOVE slugs and even snails. Many gardeners put “toad houses” in their gardens just to encourage these warty friends to live amongst their plants. And contrary to popular belief – you can’t get warts from handling toads!

We were happy to find this little visitor on our deck. I hope he sticks around to feast on some of the bugs that get in our deck lettuce every year. I bet those nasty green aphids would be easy (and tasty) pickings for a treefrog!

Until next time – Happy Gardening!

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