Tag: gardening

Does My Elm Have Dutch Elm Disease?

A fungus called Ophiostoma ulmi that was introduced to the U.S. in the early 1930’s causes Dutch Elm Disease (DED). The American elm (Ulmus americana) is highly vulnerable and the disease has killed hundreds of thousands of elms across North America. All native elms are susceptible, as are European elms. However, the Asiatic elms, (U. parvifoli) and Siberian elm (U. pumila) are highly resistant to the disease.

The DED fungus is spread by two insect vectors: the native elm bark beetle (Hylurgopinus rufipes) and the European elm bark beetle (Scolytus multistriatus). The fungus is transported on the beetles from infected trees to healthy trees as they feed on twigs and upper branches. The beetles lay their eggs in the bark and wood of stressed trees along with elm firewood with the bark left on. Developing larvae form channels just under the bark and the fungus grows through the galleries until it reaches the tree’s water conducting cells, or xylem. Chemicals manufactured by the tree during its effort to fight the disease plug up the xylem, causing the tree to wilt.  In the Midwest, beetles typically have two generations per year.

DED is also transmitted through root grafts. A root graft happens when the roots of two trees intermingle and touch. Root grafts between trees are especially widespread in cramped urban street trees. Driveways and sidewalks are usually not effective in blocking root grafts, however, the disease usually does not spread in this manner beneath roads because road foundations are much deeper.

DIAGNOSIS:

elm branch showing the effects of dutch elm disease

During the early summer is when effected trees are the easiest to identify. Leaves on the upper branches will curl and turn a gray-green or yellow and finally, crunchy brown. This symptom is called “flagging”, although a flag alone is not complete assurance that the tree has DED. Another symptom is brown streaks in the sapwood beneath the bark of affected branches, which is the blocked xylem. However, only laboratory isolation and identification can positively confirm that the tree has DED. Check with your local extension or State University, usually they will perform this test for a nominal fee. Most arborists find these two symptoms are enough evidence to treat or remove an elm.

There are two other diseases that may look like DED, Elm Yellows and Bacterial Leaf Scorch. Below is a symptom checker:

Dutch Elm Disease Bacterial Leaf Scorch Elm Yellows
Caused by fungus Caused by bacteria Caused by phytoplasma
Affects individual branches first. Affects lower crown nearest root graft. Damage initially observed on single branches, and spreads to entire crown; oldest leaves affected first. Affects the entire crown at the same time.
Leaves wilt and turn yellow, then brown. Leaves brown along margin, with a yellow halo. Leaves turn yellow and may drop prematurely.
Symptoms often observed in early summer, however, could be anytime during the season. Symptoms appear in summer and early fall. Symptoms visible from July to September.
Brown streaking in sapwood. No discoloration in sapwood. No discoloration in sapwood.
No discoloration in inner bark. No discoloration of inner bark. Tan discoloration of inner bark.
No wintergreen odor. No wintergreen odor. Wintergreen odor in inner bark.

 

MANAGEMENT:

Elm tree with dutch elm disease

  • Branches infected with DED should be removed the same year the infection started. All infected branches should be pruned at least 5 feet, preferably 10 feet, below the last sign of streaking in the sapwood. Dip pruners often (best after each cut) in a solution of 10% bleach to prevent spreading the disease. Be sure to remove infected branches before the disease has moved into the main stem of the tree.
  • Trees with many branches infected with DED should be removed. There is no cure. The best thing to do to stop the spread of the disease is to promptly remove the tree.
  • Wood from DED infected elm trees need to be buried, burned, debarked, or chipped. When chipping and composting, temperatures must attain at least 120F. Cut logs from diseased trees should not be stored for firewood unless it has been debarked and there is no evidence of beetles.
  • Neighboring elm roots need to be severed with a vibratory plow or trencher before the infected tree is removed in order to prevent the movement through root graphs.
  • Choose cultivars that are resistant to Dutch elm disease. ‘Frontier’, ‘Homestead’, and ‘Valley Forge’ are a few that are offered in my area, but there are many more.
  • Healthy elms can be treated with a preventative fungicide injection to protect trees from infection by beetle feeding. Although, fungicide injections are not effective in averting infection through root grafts. Injections can only be done by a trained arborist and depending on the chosen fungicide, must be repeated on a 1-3 year cycle.
  • The consensus on treating the beetles with insecticide is not to. Contact insecticides require repeated applications during the growing season that may kill beneficial or harmless insects. Sanitation is by far the best way to control beetle populations.

Sadly, this is a prime example of what happens when we plant a monoculture of trees. Diversity is where it’s at!!

© The Naturarian

Salvias – Sage

These are very versatile plants. Members of the mint family, thus the interesting square stems. These have a long blooming time of May through October in shades of purple and pink. Salvia love sun and are fairly drought tolerant after about a year of establishment. The do like drained soils, so no wet sites. Mints tend to be deer resistant, for those who share their space with these guys. If cut back after flowering, a second flush of blooms will follow. Sweet!

salvia plant called sage

From Left to Right:

‘Marcus’ – short, compact plant with deep purple flowers ‘Sensation Rose’ – very short, dark rose florets with dark stems ‘Eveline’ – tall type with large, light pink florets, ‘Blue Hill’ – clear, lilac blue

salvia plant

From left to Right:

‘East Friesland’ – Stiff, upright wands of purple ‘May Night’ – Freer-form purple ‘Caradonna’ – Tall, stiff, darkest purple stems that stay showy even after blooming.

© The Naturarian

How to Get Rid of Euonymus Scale

euonymus scale

Edward L. Manigault, Clemson University Donated Collection, Bugwood.org – See more at: http://www.forestryimages.org/browse/detail.cfm?imgnum=1225115#sthash.fE97Hbiu.dpuf
Edwar

Euonymus scale (Unaspis euonymi) is a pest that is around all year, especially on groundcover euonymus. Treatment should be done when the crawlers emerge, which is around the early part of June, although it may be a bit later this year. Male adult scales are white, and females are dark brown and are shaped like an oyster shell. Euonymus scale overwinters as a mated (pregnant) female on the plant stems. Eggs develop beneath the scale and hatch during late spring.

Hatch times coincide with the blooming of:

  • Chionanthus virginicus – White Fringe Tree
  • Crataegus crusgalli –  Cockspur Hawthorn
  • Cornus alternifolia – Alternateleaf Dogwood
  • Syringa vilrosa – Lilac
  • Catalpa speciosa

Management: Pesticides won’t help until the crawlers emerge, but if the population is heavy now, prune out the infested branches to reduce the number of scales. Then, when it is time to use an insecticide it will be more effective. Since there has been a lot of winter damage on ground cover euonymus, pruning will be required to remove the dead branches and take care of two problems at the same time.

Horticulture soap* or oil will work to kill the crawlers.

*Please remember that you can’t make horticulture soap out of today’s dish soaps. Yes, back in the day, when soap was manufactured out of fats, it could be done. However, now they are all detergents, lacking the fat factor necessary to kill the insect.

© The Naturarian

Summer Annual Pots

shade annuals in pot
Summer Annual Container

If you’re looking for sensational summer color, look no further! Summer pots are the way to go. Not only are they full of pizzazz, the color is often right in your face, literally, especially if your favorite container is on a pedestal.

You don’t need to remember a bunch of annual names. The only thing you need remember for a well-presented display is: Thriller, Filler & Spiller! The Thriller is that one large plant that is generally in the center and taller than the rest. Filler are those mid-range sized plants, often of ‘fatter or fuller’ stature. Spiller is just that, plants that hang over the edge of the pot.

Here’s where your imagination needs to run free through the flowers. In many of the containers below, the photos are of the plants after there has been a bit of growth put on them. You can also get instant height from a trellised plant such as a mandevilla, jasmine or other vine.

Another tip ~ Flowering can be increased if the plants are kept on the drier side. This takes a bit of skill, as you don’t want them to dry-out, but keep them on the brink of drying. Why?!? Because. Think of it this way. If you’re kept all fat and happy without doing anything, why not just enjoy the hand-outs? (can you say ‘vegetative growth’? Haha!) Just like some of the folks living off us tax-payers, yet they have nicer stuff than me. =-( However, if you need to work for everything you’re getting, you fight to survive and multiplying is surviving in a plants eyes. Thus, more blooms = more seeds. Boom.

 

Contact us to get on the schedule!

© The Naturarian

Why Bulbs Aren’t Happy Looking Up Annuals Butts…

orange tulipsI was asked by a client the other day if we could plant her annual flowers right over her tulips, with the intent to allow the bulbs to ‘multiply’. I had to pass on bad news. Bulbs and annuals don’t play nicey-nice together. At least not with the selection we have here in the Midwest…

  • Bulbs should be planted at the correct depth for the bulb. If a bulb is planted too deep, to make room for the annual above, it may not grow.
  • Tulip foliage must be allowed to die-back naturally and will make an annual display look a bit messy until the foliage has died back and been removed. If you must prune the leaves back, there’s very little chance you’ll see tulips next Spring.
  • Bulbs, tulips in particular, do not multiply*, rather they disintegrate over time in the ground unless removed after the foliage has died back naturally, are stored properly and replanted in the fall. (Side note: Tulips give 3 years of service, in my opinion.)
  • Annuals planted over bulbs will remove all the nutrients from the surrounding soil leaving the bulb starved.
  • Bulbs need dry conditions, if annuals are planted above bulbs they will rot from the added water annual flowers require.

*Daffodils do multiply, however all the rest of the conditions would not be good for daffodil bulbs either.

 

© The Naturarian

Are My Plants on Crack? Powdery Mildew on Plants

mildew grape leaf.JPG
On grape leaf – Credit: David B. Langston

There are many species of fungus that cause powdery mildew on plants. Most only infect the leaf surface or stems and do not attack the leaf tissue of the host plant. Powdery mildew is not usually a serious problem, but to avoid severe damage to plants, quick control methods need to be taken.

Symptoms of powdery mildew:

Powdery mildews are observed in late spring and early summer as a white or gray powdery growth on leaves, stems, flowers, and fruit. As the fungus developments, buds fail to open, leaves can become distorted, turn yellow, brown or become chlorotic, or may drop prematurely. Fruits may develop blemishes or abort early.

white mildew on peony leaves
Powdery mildew on peony

Powdery mildew grows predominantly on leaf surfaces and does not require water to infect the plant. Powdery mildew fungi overwinter in tiny black bodies called fungal threads, which can be found in leaf litter, twigs, and dormant buds. In Spring, the fungal threads produce spores that start the cycle, especially during periods of high humidity when days are warm and nights are cool, ideal temperatures range between 60F to 80F. Vulnerable plants are most susceptible while new shoots and leaves are expanding. Fungus is host specific, meaning the powdery mildew on phlox does not infect crabapples.

 

How to manage the mildew!

Cultural

Many powdery mildews, especially those that attack woody plants, are more unsightly than destructive. Good sanitation is highly important to reduce infections the next season. Powdery mildews can hibernate through the winter on dead and living plant tissue.

  • Be proactive and purchase disease resistant plants.
  • Space the plants properly, in-well drained soils where plants receive good air circulation.
  • Dispose of diseased leaves as soon as they drop.
  • Do not compost or use as mulch.
  • Always avoid working among plants with wet foliage. Stay inside on rainy days!

Chemical

Since most powdery mildew symptoms occur late in the growing season, it is usually not considered serious enough to justify chemical control. However, some plants may warrant protection and successful chemical control requires applying a fungicide properly and at the right time. Fungicides are a prophylactic, meaning it has to be sprayed on the plant before the infection occurs. Depending on what species or part of the plant (leaves, flower or fruit) you are trying to protect, spray times may be different.

One of my favorite, efficient fungicides to use is the Bordeaux mixture. In the early 19th century, many of the European grape vines were infected with blight caused by the aphid Phylloxera vastatrix (argued to have come from American grapes), but also mildew and other diseases caused by fungi.

In 1885, botany professor Pierre-Marie-Alexis Millardet of the University of Bordeaux studied powdery mildew in the vineyards of the Bordeaux region. He noticed the vines sprayed with copper and lime to keep nibblers away along the roads showed no signs of the disease. To this day, his solution is widely used in vineyards.

© The Naturarian

Epic Fail in My Landscape

dead shrubsIn 2017, I designed and installed a whole new front foundation bed. It took almost a year for me to even design it, as I wanted to find the most obscure plants for my garden. No ordinary plants for me!!

I noticed a new plant being offered at a few nurseries of mine called First Editions® Amber Jubilee® Ninebark or it’s original name, Physocarpus opulifolius ‘Jefam’. Basically, Monrovia bought the rights to ‘Jefam’ and changed it’s name to patent it.

Common Ninebark’s are native here, so I didn’t question the hardiness of this shrub. I thought it’s orange leaves in this variety would be a wonderful addition to my landscape.

Sadly, this spring they barely leafed out. All five shrubs are toast. At $45 a pop at wholesale, that was a hit to my pocketbook. Hubby will be doing me the pleasure of removing them. I’ve decided large perennials would be a better choice for this location. We will be painting the house next spring and they will be safe underground opposed to these shrubs next to the house. The replacement cost is five times lower, also.

So, what happened here!?!

Well. Here are a few thoughts that ran through my mind:

  • They were planted at the correct depth, mulched and watered correctly.
  • They were planted in the correct exposure, 6 hours of sun.
  • There wasn’t an herbicide accident or outside force that took them out.
  • No animal damage.
  • Yes, sometimes things just die.

As a horticulturist, I do take this personally. I don’t understand how something can just die on my watch! I do know there are forces in nature that we as humans can’t understand yet. I get it.

The thing I did find interesting is that these plants started being advertised by Monrovia in 2014. I’m not sure how long the original ‘Jefam’ had been around. In 2017, nurseries were full of them. This year, they aren’t listed in any of the inventories. This tells me that the plant wasn’t popular or didn’t over-winter well at the nurseries. If a nursery can’t keep a plant alive, who could?

In the end, I figured my story would make non-professional gardeners feel better. Things do die in the landscape, even under the watchful eye of an educated horticulturist.

PS – I wrote this post before I ripped them out of the landscape and didn’t want to do a whole rewrite…

There is another possibility/reason they croaked. Their root systems were very week and undeveloped, a nursery management issue. Nurseries sell by pot size and actual size. Most likely the nursery had many orders for these and sold them sooner than they should have from a recent upsize in pot. Immature plants with under-developed root systems survive just fine under drip irrigation and climate control. Once out in the real world (like kids after college), they don’t realize how tough the real world is. These ripped out of the ground with little effort, as the rootball was only he size of a softball. It should have been the size of a basketball, at least.

© The Naturarian

Help With Volutella Blight on Pachysandra

pachysandra ground cover with blight diseasePachysandra terminalis is a beautiful, lush, evergreen ground cover for a semi-shady spot. One of the most common problems with pachysandra is a fungal infection called, Volutella Blight. Generally, pachysandra has very few issues when well cared for. However, when other situations stress the plant out, opportunistic pests can take over.

Volutella Blight has a fungal ring associated with the damaged lesions. Winter damage has an even-toned brown to the damage.

How to not stress out your pachysandra:

    • Plant it in a partial shade or shade area. Not in the sun.
    • Do not overwater, water in the morning and use drip irrigation, not overhead.
    • Be sure to do a fall cleanup to remove any fallen leaves or plant debris from the bed to improve air circulation and reduce moisture levels. Blow lightly with blower.
    • It is also helpful to periodically thin the planting to prevent dense growth and increase air circulation. Use leaf mulch, not woody chips.

blight on pachysandrapachysandra with winter injury

Blight on the left / Winter damage on the right

Fungicides such as mancozeb and maneb can be used to protect remaining plants and the new growth of any pachysandra that have been cut back. These treatments can help deter infection but will not cure infected plants. You would need to spray at 7 to 14 day intervals from spring until early summer. Generally this time would coincide with the blooming of serviceberries (Amelancheir) and Redbuds (Cercis canadensis).

© The Naturarian

Ring Around the Lawn – Fairy Rings

fairy ring fungus in lawn a ring of darker colored grassFairy Ring fungi are in the soil to break down old tree stumps, roots, logs and other larger pieces of organic material in the soil below the lawn. The uniform outward growth of the fungus results in the development of rings. Once the material is exhausted, the fairy ring will disappear. This may take many years. Several fairy rings may appear close together, especially in lawns that were previously wooded areas.

When these fungi digest the organic material, they expel nitrogen. This is why the grass looks seemingly happy in the fairy ring. However, sometimes the opposite effect can happen, which depletes soil nutrients and produces toxic levels of hydrogen cyanide.

Fairy ring with mushrooms bloomingApproximately 50 species of fungi in the Basidiomycetes family are known to cause fairy rings in turf; however, there are only three outcomes:

  • Variety A: The most inconspicuous type of fairy ring. The dark ring of grass is absent. Only parts of the ring will show fruiting bodies (mushrooms) at different times of the year, mostly during wet springs.
    • Remove the mushrooms to help retard the spread in the area. Don’t over-water.
  • Variety B: It’s the dark green rings, with or without mushrooms, which identify these varieties of fairy rings. At worst, this type of ring can appear unsightly with its lush growth, accompanied with mushrooms.
    • Remove any mushrooms and use a balanced fertilizer to green up the rest of the lawn so the ring is not as obvious.
  • Variety C: This variety of fairy ring is the most destructive and damaging as it produces a ring of dead grass. The dead area can contain fruiting bodies. If a soil profile is pulled from the dead area, white thread-like structures called mycelia will be visible in the soil. Mycelium is hydrophobic. Because of this property, it causes water to move away from the circle, thus drying out the grass.

There are really no fast cures for fairy rings that aren’t extreme. Digging up the area to remove the organic matter the fungi is feeding on, along with all of the adjacent soil is one method. It’s been said that fairy rings do not cross. Some have said that digging up soil from one fairy ring and exchanging it for another has worked. Spraying fungicides are ineffective and a waste of money.

It is best to just be proactive in how you maintain the lawn. Do not over-water or over-fertilize, and be sure to aerate in the spring.

dancing fairiesThere’s another theory about how fairy rings are created…

Fairies create the circles by dancing within them.

Some cultures believe these circles to be dangerous to humans. Those violating fairy perimeters become invisible to those outside and may be unable leave the circle. The fairies then force the intruder to dance till exhausted, dead or in the throes of madness.

The only safe way to investigate a fairy ring is to run around it nine times. Doing this permits the runner to hear the fairies dancing underground. This must be done under a full moon and in the direction the sun travels.

Other cultures still believe in fairy activity and that fairy rings are omens of good fortune. Some legends see fairy circles as places of fertility and fortune. The Welsh believe that mountain sheep eating the grass from a fairy ring flourish and crops sown around tend to grow better. European folklore believe fairy rings are gateways into elfin kingdoms.

© The Naturarian