Thorny problems: what is wrong with my weeping willow?

Euphorbia mellifera

For several years we were really pleased with the success of our Euphorbia mellifera, which grew to 6ft at the corner of our terrace. The two cold winters of 2011 and 2012 took their toll and we thought for a while it would die. However, fed and rained on, it seemed to rally last summer, but it has never grown back to its original magnificent height. Is there anything we can do?

Marie Colby, via email

Euphorbia mellifera is the loftiest of the evergreen/shrubby euphorbias, but as you have said, it does take a bit of a hammering during prolonged cold spells, “wilting” alarmingly when frosted – although not generally killed. For those who don’t know this lovely and impressive plant, I should mention that the additional buzz you get by giving it the large amount of space that it needs – looking best, I think, all on its own with the shelter of a sunny wall behind it – is the strong honey scent of its numerous and huge late-spring/early-summer flowers.

Sadly, this euphorbia, like others of its tribe, tends to burn itself out and thus has a relatively short life, and it sounds to me as if yours might have had its best years. I’m presuming that last summer it made a lot of new growth from close to ground level, some of which will be rather skinny and lax. If I were you I would remove quite a lot of this since it won’t flower anyway and also cut one or two much-branched older stems. Take care not to let the white sap get on your skin, since it is known to be an irritant. Thus pared down, your plant may look and behave better this year than last, and you have another season in which to search the garden for its seedlings, since there are bound to be some around. Pot up one or two in readiness for the inevitable day when you will have to dig this plant out and start again.

Mother’s Day hydrangeas

My children gave me a blue flowering hydrangea on Mother’s Day. The wee card included says it is an indoor plant. Is this true? Will I not be able to plant it outside? If I do, would it need to come back in next winter? The flowers kept collapsing/wilting, so I put it in a basin of water. I now see the card says to keep it moist, but I should avoid overwatering “at all times”. Oh, dear!

Mary Arkless, Aberdeen

I hope this response doesn’t come too late to save this glorious but quite possibly ill-starred hydrangea, definitely an outdoor plant. I have, in my time, seen numerous casualties of this sort: wizened little scrappits in plastic pots of desiccated multipurpose compost reluctantly abandoned after many a dinner party/birthday/Mother’s Day, et cetera. I have even on occasion seen several horticultural relics stacked outside the back doors of particularly popular/sociable people, whose non-gardening guests/relations assume that they would prefer to be given something with roots on, rather than just a bunch of tulips. (Wrong, very wrong: posh flowers are always gratefully received – so many of us can’t bear to pick the ones that we grow in our gardens… but sorry, I digress).

The problem with what I rather dismissively call “florist’s” hydrangeas is that they have been elaborately forced into blooming at the wrong time, all emphasis put on flower rather than root development. Their physiological clocks are therefore all at sixes and sevens, and the considerable effort and patience needed to get them back in the right time zone is quite reasonably considered by most of us to be a horticultural challenge too far. What you should do with these exotic things is, as the label suggests, keep their roots just moist while they bloom. In due course, remove the faded flowers, cutting back the stems to a pair of leaves.

After this the plants have to be kept just ticking over, somewhere light and really cool – they hate centrally heated conditions – until mid-May or thereabouts. They can be potted on into a larger pot of something suitable (50/50 loam-based John Innes No 3 and multipurpose compost) and put outside in a fairly shady place for the hottest part of the summer while they recover their composure, growing leafy and even hopefully making a few new stems. Regular watering is important. You can get them into the ground in the autumn and they will have every chance of winter survival and may even flower a little the following summer. The next spring (my goodness, this is beginning to sound like a real marathon… it is, but I have done myself, it so I know it works) they can be properly pruned and thenceforth should go onwards and upwards. Remember that since your flowers were originally blue, you should treat the plant with Hydrangea Colourant (from Vitax) to keep them that way.

Alternatively, bin the poor thing and have a kind but firm word with your children.

A weedy driveway

James and Sarah (by email, no surname) want to know whether they can restore a worn weed-infested driveway in their garden by simply topping it up with a thick layer of new gravel or, they ask, should they weed it first.

The mere idea of weeding a drive by hand is enough to make grown men (and women) weep, so I suggest that these two use a weedkiller. Some of the weeds are likely to be tough-rooted perennials, such as dandelions, and would be virtually impossible to dig out of compacted ground anyway. Pathclear 3 is specially formulated to see off annual and perennial weeds on paths and driveways, and has an additional magic ingredient that also stops seed germination for several weeks, if not months. It has to be used with care, of course, as it can adversely affect plants with shallow, underlying roots: I once used Pathclear on a bricked area that had become intolerably weedy between its cracks, and gave a serious headache to an adjacent matt of osteospermum whose roots had wandered in under the bricks in search of water. It revived eventually, but was hideous for weeks. If you don’t like the idea of using such a powerful weedkiller, then go ahead and top up the layer of gravel, and just spritz any tough perennial fighters individually with glyphosate as they appear (it will probably be those dandelions, I have to say.)

Weeping Willow Tree Problems

Are you concerned about the problems you are facing with your weeping willow? Keep reading to know how to care for these trees, about the different problems associated with it, and their remedies.

Weeping willows (Salix sepulcralis) are graceful trees that have been mentioned in literature many times. These trees look extremely beautiful and stand out nicely in any landscape design, which is why they are so popular as ornamental trees. These are also one of the fastest growing trees that provide excellent shade. After the initial years of the tree’s growth, very less maintenance is required for it. But, in the initial years, one needs to take great care of the young tree to prevent any problems associated with it.

Pest infestation is one of the most common problems with this tree. The pests that usually attack weeping willows are scales, borers, aphids, caterpillars, and gypsy moths. Let us look at the problems and diseases faced by these trees.

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Diseases

  • Tree appears dead when planted near drainage:
    Never plant a weeping willow near drainage ditches or sewage lines, as the roots of this tree grow deep and can break these lines, causing damage for the surrounding area and the tree itself in the process. However, if you observe your tree shedding its leaves and looking almost dead, and know that it was planted near a drainage ditch, scrap off a little piece of the bark and check if it is green. If you find that it is green about 6 inches below the surface, that means the tree is alive. If you find it brown, it means that the tree is dead. If the tree is alive, replant it elsewhere; but if it is dead, get rid of it.
  • Old tree with rot:
    Rot is a sort of bacterial or fungal infection. In this disease, the roots of the tree at the base of the trunk can be seen to be turnind red. The average life span of the weeping willow is almost 30 years. If the tree is over 30 years and has got rot disease, better get rid of it as it might fall down and damage the surroundings.
  • Brown spots on the leaves and shoots:
    This is a disease called marssonina canker or black canker. In this disease, dark brown spots appear on the leaves, and white lesion with black rings can be seen on the twigs and stems. Trim out the infected branches and treat the tree with fungicides or bactericides. If this still doesn’t work, get rid of the infected tree to protect the rest of your garden.
  • Olive-green infection on leaves and stems:
    This is a disease called willow scab, and it occurs mostly during the growing season of the tree, which is usually April and May. It causes olive green colored infection on the underside of the leaves that is more prominent at the veins. To protect the tree, prune out the diseased branches and treat it with a good fungicide. Sometimes, willow scab and black canker affect the tree together, and this disease is called willow blight.
  • Round bulges 1-3 inches in size:
    These could be cysts formed due to eggs laid by insects. These cysts are harmless, however, cut open a bulge to check what it contains.

Other Problems

There are many other problems that affect weeping willow trees. Some problems can be fixed, some problems can be avoided, while some have no other solution other than the removal of the tree. Here are some more problems that might affect this tree:

  • Wilting or browning of the tree due to severe drought conditions.
  • Physical damage due to any accident might result into premature loss of the tree.
  • If the tree is standing in a watery-logged region for long, it can create anaerobic conditions, which results into the decaying and dying of the tree.
  • Extremely cold weather might cause vertical cracks in the trunk, which might invite various diseases, like cancer or rot.

One can always prevent these hazards by taking good care and maintaining a healthy weeping willow.

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Is my newly planted weeping willow in shock?

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Weeping willow only has half its leaves

Hello;
Unfortunately, we are receiving numerous calls about willows with similar symptoms as yours. It is most likely, and appears to be from the pictures, a fungal canker disease. Willows are susceptible to canker diseases, but are typically not infected unless they are under stress. Most likely, the tree was infected during the heat/drought stress in 2012. Our 3 weeks of temperatures hitting 100 degrees F was a major stress. It can take a few years for the disease to progress far enough for die back to occur. In the meantime, the tree appears fine. That, coupled with the extreme cold last winter and extremes in temperatures this past winter all lead to this issue. I wish I could give you a “cure” but there is not one. If there is still enough live tissue (branches with leaves) to try and save the tree, you could prune out the dead branches, maintain adequate moisture around the tree and place a 4 to 6 foot diameter ring of wood chip mulch,about three inches deep, around the trunk and hope for the best. If the tree dies and needs replacement, keep in mind that while willows are a beautiful tree, they are not a quality tree due to weak wood and canker issues. Consider a higher quality tree such as a red, bur or white oak; miyabe or Norway maple, etc. etc. etc. Thank-you for using eXtension. Let me know if you have additional questions.

The post and video I did about the pruning of a Weeping Pussy Willow has been surprisingly popular, to myself anyway, so I decided it was time to share everything I know about caring for this small weeping tree. My client up in the San Francisco Bay Area ordered the 1 you see here from Wayside Gardens about 15 years ago which I planted and then maintained. It’s not a plant commonly sold in those parts so I was very curious to see how it would do.

Although there were quite a few Pussy Willows growing around the pond on my childhood farm in New England, I didn’t even know there was a weeping variety. Many times gardening is experimentation and I love weeping plants so I said “why not give it a go” – you know what I mean?

The above photo is before pruning in spring of 2012; this pic shows it right after.

In short, the Weeping Pussy Willow tree of which I speak has been lovingly nicknamed “Cousin Itt” and is doing just fine. It has grown in width more than in height and turns into a massively foliated blob if not pruned a few times a year in our temperate coastal California climate. These plants are tough and are actually pretty easy to maintain. And yes, when now left unpruned, Itt turns into the leafy version of the amusing character from the Addams Family.

Here I am with a soon to defoliate Cousin It:

Here’s everything I’ve learned about caring for a Weeping Pussy Willow tree, whose botanic name is Salix caprea pendula:

Exposure

The Weeping Pussy Willow prefers full sun but will do fine in part sun as long as it’s afternoon sun. The 1 that you see here is planted in a very sunny spot but it’s right on the California coast so mornings can be foggy. Not enough sun equals poor flowering & a reduced growth rate.

Water

These plants like regular water & look much better if given an ample amount. The regular Pussy Willow (bush form) grows just fine alongside ponds & doesn’t mind having its feet moist. Cousin Itt is on drip & is located at a part of the garden where the water flows down a hill & collects in this spot. Despite our California drought, Itt keeps on keepin’ on!

Growing Zone

In accordance with the USDA Plant Hardiness Map, the Weeping Pussy Willow is recommended to be grown in zones 4-8. Zone 4 goes down to -24 degrees F. By the way, the 1 that you see here grows in zone 9b – 10a so sometimes you can push it a bit, depending on the plant & the low/high temperatures.

I planted Cousin Itt in spring but fall is fine too, just as long as it has time to settle in before a frost.

Here’s Cousin Itt in early December 2015 as the leaves start to change color.

Soil

Simply put, the Weeping Pussy Willow isn’t fussy about soil but prefers it slightly on the acidic side. You can amend the soil with leaf mold, coco coir &/or a good local compost – the plant will love you.

Feeding

I’ve never fertilized Cousin Itt but threw lots of leaf mold & coco coir into the hole upon planting. This garden gets a 2″ top dressing of a local, organic compost (over 10 cubic yards of it!) every 2 years which the Weeping Pussy Willow thoroughly enjoys.

Pruning

I love to prune & giving Cousin Itt a haircut is a creative challenge I actually enjoy. The best time to prune this plant is in the spring after it flowers. Because the 1 you see here grows in a temperate climate, it has to be pruned 3 times a year to keep it “de-blobbed”. I had to rescue it in 2011 from a really bad pruning job (a serious hack I tell you!) & because these weepers grow so vigorously & are so tough, it bounced back to its former self within a year or so.

I gave the Weeping Pussy Willow a year or 2 to get going before I pruned it. Here’s how I go about pruning this plant now that’s it’s older & more established:

1) I remove all the sprouts coming off the trunk

2) Remove the branches & ones that cross over other branches

3) Thin out main branches to open the plant up

4) Remove some of the smaller branches which are growing upwards. If you don’t want it to grow any taller, than remove all branches growing up. This plant is slowly getting taller because I leave some.

5) Remove some of the branches which grow laterally off the main branches. This branching tends to occur on the bottom half of the branches.

6) In all of the previous steps, be sure to take the branches you’re pruning off all the way back to a main branch. Otherwise, you’ll gets more lateral growth then you want.

7) I prune the branches up off the ground. Even though this causes lateral branching, I don’t want it smothering all the poor unsuspecting plants below.

Flowering

These harbingers of spring are not only loved for their weeping form but also for their flowers. Pussy willows have catkins which are actually inflorescences of many tiny flowers. The grey furry “pussies” (no dirty minds here please, we’re taking plant parts!) are what we love to cut on long branches & put in a vase in spring; or for us, it’s like winter. The masses of tiny yellow flowers will later emerge from those furry nodes.

Here are 2 reasons that your Weeping Pussy Willow may not be flowering:

1) Not enough sun OR

2) A late frost strikes after the catkins have started to appear & wipes out the flowering.

You can see a few of the catkins emerging here.

Size

Cousin Itt is already over 7′ tall. The width is about the same. I believe they max out at 8-10′ but I’ll let you know in a few years!

Important To Know

1st to know: This plant is grafted (I show the graft in the video & also below). A Weeping Pussy Willow is grafted on top of of regular Pussy Willow trunk. So, never completely cut below the graft because the plant will revert to bush form.

2nd: The Weeping Pussy Willow is deciduous so don’t worry when it starts to loose its leaves.

Never prune off below the graft (the bulbous, swollen part the arrow is pointing to) unless of course you’d rather have a Pussy Willow bush rather than a Weeping Pussy Willow Tree .

Weeping Pussy Willow trees are easy as pie if you don’t mind doing a bit of pruning every now and then. This 1 grows in a windy valley just 7 blocks away from the Pacific Ocean and blew completely over when it was about 7 or 8 years old. A few days later we uprighted it and added a bigger stake. It has a bit of a lean today but it’s so full it’s hard to notice. Cousin Itt is slightly off but very resilient I tell you!

Happy Gardening,

Weeping Willow Tree Diseases and the Ways We Can Tackle Them

Weeping willow tree diseases may be of many types and if left untreated, they might rip this elegant tree off its beauty. Know about these diseases and how to manage them.

Mostly found in the Northern hemisphere, the weeping willow tree is among the most popular deciduous tree types which people choose to add to the beauty of their landscape. Scientifically known as the Salix Babylinoca, the weeping willow tree is one of the fast growing shade trees. It can attain a height of about 10 ft in just about a year with proper care and maintenance.

Ponds, streams and lakes are the common areas where the Weeping Willow tree mostly grows. It can also adapt to different types of soil. It is drought-tolerant to some extent, and prefers moist and cool conditions.

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A weeping willow tree is characterized by its rounded, drooping branches which are again accompanied by lush green foliage and long, thin leaves. Depending upon the type of the tree, the leaves wear colors of light yellow-green shade to an eye-catching blue color, in the fall. Fall is the time when the trees shed their leaves and during summers, the weeping willow is ideal for its use as a shade.

Diseases that Commonly Affect the Weeping Willow Tree

# A weeping willow tree is mostly affected by root rot which has its ill effects on the roots of the tree and eventually leads to its decline. This disease is often a result of over-watering. Excess watering deprives the roots of air required for the plant’s survival thus, causing them to decay and eventually death of the plant.

# Willow trees are also vulnerable to develop crown gall, a bacterial disease of plants (especially of pome, stone fruits, grapes and roses which forms excrescences on the stem near the ground). It is responsible to form galls near the soil line, and farther up the plant. Galls are abnormal swelling of plant tissue caused by insects, microorganisms or injury. This disease may also cause the tree to contract secondary diseases that attack the tree through the decaying galls.

# Weeping willow fungus diseases known as scabs attack the freshly sprouted leaves and cause the formation of blackish or reddish-brown blotches which infect the leaf stocks and cause them to wither and fall off. If left untreated, the scabs can infect the twigs and branches of the tree. You may also notice black cankers (caused by a fungus Physalospora miyabeana) in the form of grayish or pale brown depressions. Whitish gray lesions with black borders appear on the twigs and stems. A combination of black canker and willow scab is known as willow blight. Due to these two tree diseases, defoliation occurs year after year, and eventually the tree dies.

# Many types of fungi cause leaf spots, and the powdery mildew gives the appearance of a white coating on the leaves of the Weeping Willow. At times yellow spots can also be detected on the lower sides of the leaves, which are caused due to rust. In severe cases, defoliation is common. The leaves may also carry harmless black, raised spots known as tar spot.

How To Care for a Weeping Willow Tree

# For countering crown gall, you should get rid of the infected plants, and do not replant in the same area until after two years.

# For countering willow scabs and black canker in Weeping Willow trees, prune out infected branches and use resistant species.

# Regular fertilization and raking up the fallen diseased leaves are essential to keep away all kinds of fungi from affecting the Weeping Willow.

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# Common weeping willow pests are the gypsy moth, caterpillars, scales, aphids, and borers. In order to get rid of such pests, you can go for insecticides or natural weeping willow pest control. Before deciding on any such pest control, seek proper advice from the dealer or someone who is well acquainted in this field.

# Planting your weeping willow tree in loose, healthy soil is important. Before placing the tree, ensure that the hole which you dig in is twice the size of the root ball. After placing the tree do not leave the roots exposed; cover them well with soil. Thereafter, using a sprinkler or a hose allow the tree to soak well in water. Take a note that the plantation of the tree must be done about six weeks before the first frost of the season, to allow the tree to get adjusted to its new environment.

# In places where there is extreme heat, the potted weeping willow tree must be placed in a well-shaded area. As it grows older it will start getting used to such a temperature. In the summer months, the tree must receive water during extended dry spells. If the leaves are drooping then it may indicate under or over-watering. So, keep a check on the watering. Crisp, healthy looking leaves show that the tree is receiving adequate amount of water.

# In the first year, keep weeds and grass away from the tree and keep the use of fertilizer to a small amount. Prune a matured weeping willow tree regularly, as it helps in the healthy growth of the tree the following year.

Good soil, proper feeding and adequate watering keeps the Weeping Willow healthy, and helps it to maintain its prosperity. If all these factors are well looked after, then you should not be concerned, even if your tree looks dead in the winter months. In the fall, the tree would shed its leaves and the trunk will turn brown, indicating that the tree is going into a dormant state. It’s a natural process which all deciduous trees go through.

Keep a close eye on the common diseases that could affect your tree, and wait for the spring when you can enjoy seeing it flourishing with health and beauty.

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Weeping, Weeping Willow

Interesting. Take a look at these common disease problems on the east coast of the Atlantic (from http://edis.ifas.ufl.edu/st576)

-Root rot can occasionally infect root systems and cause decline.

-Crown gall causes galls to form near the soil line or farther up the plant. Take out infected plants and do not replant in the same area for at least two years.

-Willow scab attacks and kills young leaves within a very short time. The fungus enters twigs, kills back the young shoots and causes cankers. Olive green spore masses can be seen along the veins on the undersides of leaves. Another fungus, Physalospora miyabeana, attacks willow and the two fungi in combination cause willow blight. Prune out infected branches and use resistant species.

-Black canker causes dark brown spots on the leaves. Whitish gray lesions with black borders appear on the twigs and stems. Prune out infected branches and use resistant species. Weeping willow appears to be resistant.

-Many fungi cause cankers on willow and infected branches are pruned out. If the trunk is infected and girdled, the tree will die. Keep trees healthy by regular fertilization.

-Many fungi cause leaf spots but are not serious enough to warrant preventive sprays. Rake up the fallen diseased leaves in the fall.

-Powdery mildew causes a white coating on the leaves. The disease is usually not serious.

-Rust causes yellow spots on the lower surfaces of leaves and, if severe, defoliation. Rake up and destroy leaves from diseased trees.

-Tar spot causes black, raised spots on leaves. The spots are harmless. Rake up and dispose of fallen leaves from diseased trees at the end of the growing season.

I’m wondering about the first one since you don’t see any visible signs above ground. Our Agricultural College has a plant disease diagnosis service, perhaps you can find a similar situation near where you live to see if that’s what’s going on. The general decline and sporadic leaf dieback can point to a systemic issue like that, but do check out the leaves closely for the other symptoms – investigate on leaves that are transitioning from green and healthy to brown and dead.

Best of luck and thanks for using the Ask an Expert feature.

Hakuro-nishiki Dappled Willow

The beautiful foliage is best set off against a dark background. For a striking display, plant beside or in front of deep purple foliage plants such as a ‘Black Lace’ elderberry or Purple Smokebush. Japanese willow is an excellent choice for a specimen plant in a large open space or near a water feature, hedge, screen, or windbreak. They will thrive in low areas that are generally more moist. Dappled willow will also do a very nice job of erosion control on slopes and banks. When sheared frequently to maintain size, the bush can be well used as a bed or border plant, or as a foundation planting. ‘Hakuro Nishiki’ will also do well in a very large container, as will other dwarf willow shrubs.

The very large tree form species willows have not been recommended for home landscaping due to their invasive, water seeking roots and weak wood. The root systems, which are excellent at seeking out moisture, can be particularly damaging to septic systems. The root systems of the dappled willow and dwarf shrubs, although well developed at maturity, do not compare to the size of a full size willow tree. The tree form ‘Hakuro-nishiki’ has been grafted to the trunk of another willow variety, and therefore will have a larger, more extensive root system than the shrub. Although there is little information available regarding damaging roots from the trunks used for grafting, these grafted tree forms were developed specifically for use in small home landscapes. It is highly doubtful that a trunk would ever be used from one of the very large willow trees that can be so damaging to septic tanks. Willow roots in general grow very fast, just like the willow plant. They can grow several feet per year and will usually spread equal to their height (a mature ‘Hakuro Nishiki’ may reach about 10 feet). In general, willow roots are invasive and can exceed the width of the tree’s branches as much as 3 to 4 times. But again, that refers to the large tree form willow. If you have a septic system and are concerned, why stress? Plant your grafted tree in a very large container, or at least at a great distance from the tank and pipes.

All willows, the Dappled Willow shrubs and grafted trees included, are susceptible to disease problems which include blight, crown gall, fungus, root rot, cankers, rust, Willow Scab, leaf spot and powdery mildew. May also be afflicted with insects including aphids, scale, borers, lace bugs, beetles and caterpillars. If your willow has been affected by insect or disease, or winter injury, remove all affected branches. You may severely prune out all damage, leaving very little healthy plant if necessary. The problem may be overcome by the complete removal of afflicted branches. Thinning out a third of the oldest branches to the ground every year or two may reduce problems, as older wood is more susceptible to disease and pests.

The family of willow is susceptible to a long list of insects and disease but they are not necessarily particularly damaging much less fatal to the plant. A few of those may specifically be common for the Dappled Willow.

  • Anthracnose diseases are fungi the can cause defoliation (leaf drop) to several types of trees, including the willow. The damage usually occurs after cool wet periods during bud break. A single attack will generally not be harmful, but yearly infections will definitely reduce growth and may contribute to the demise of the tree.

  • Rust causes small brown powdery areas of fungus on leaves and stems.

  • Aphids leave a sticky sap on the leaves, which can then be afflicted with a black sooty mold. A serious infestation will leave the plant vulnerable to other pests and disease. The aphids are usually small fat green insects, about 2mm long, but may also be black, yellow, pink, or brown.

  • Caterpillars eat the leaves, quickly leaving an unsightly plant.

  • Leaf beetles strip the tissue of leaves, leaving leaf veins exposed. There are various beetles that attack willows (and poplars). They are small, ‘metallic’ blue, brown or brassy and about 4-5mm long.

  • Sawflies larvae eat leaves, causing extensive damage. The adult is up to 10mm long with 2 pair of wings and dark bodies and legs. They may look like flying ants.

Dappled willow can be propagated from softwood or semi hardwood cuttings. To produce new plants, just plant 8” cuttings of stem without leaves into consistently moist soil in a small pot or nursery bed, they will generally root easily. When the roots become visible through the drainage hole in the pot they are ready to plant in the ground. Willows root fairly quickly, and cuttings potted in October should be ready the following spring. Full grown dappled willows also transplants quite successfully. A large plant should be cut back to about 12” in very early spring or late Autumn, then moved to a new planting hole.

Salix integra ‘Hakuro-nishiki’ Dappled Willow is hardy in zones 4-9. However particularly cold winters in zones 4 may cause loss of much of its variegation the following season. Shearing and fertilization will help to regain the colorful foliage. Since the dappled willow is hardy up to zone 4, you should not need to do anything special to winterize your dappled willow. Do follow standard practices to winterize shrubs and trees in cold climates: Water regularly and thoroughly in autumn to allow the plant to take in as much water as it needs, it will naturally decrease water intake as freezing weather approaches. And do NOT fertilize after about mid august. Fertilizing will encourage new growth, which may be damaged by freezing temperatures.

When you do prune your dappled willow, take some of those beautiful branches inside for a fresh arrangement. They are quite lovely in a bunch on there own, but also are great as filler and to add height in a vase with other cut flowers and branches. Put a few dappled willow branches in a vase with delphinium or lupines for a striking arrangement.

That should cover the more general questions about the ‘Hakuro-nishiki’ . Some questions are more specific to variable conditions that may affect growth.

My dappled willow seems dry even though I water, the leaves are drying up.

Most likely it IS dry. Dappled willows need consistently moist soil without being wet. Depending on soil conditions and weather, you may need to water weekly. Do not water lightly and frequently. Give it a good soaking, weekly if your soil is not moisture retentive or sandy, and if it is hot and dry. Every 4 or 5 days if the conditions are severe, less often if the conditions are less severe, but try not to let the soil dry out.

Can I overwater my dappled willow? What are the symptoms?

Symptoms of over watering generally begin with yellowing leaves. If the wet conditions persist, the leaves will begin to drop. Unfortunately, the symptoms of overwater, drought stress, and root rot fungus can be very similar. They all typically begin with yellowing leaves, then leaf drop, and eventually limb dieback. Poke into the soil, and if it feels moist, stop watering until the soil begins to dry quite deep. Then water generously, but do not water again until the soil begins to dry. If your willow begins to improve, over watering was likely the problem. If it has not improved, wait as long as you can stand it for improvement. Often the best thing for a sick plant is to do as little as possible. If the condition worsens, the problem could be one of the many diseases that afflict willows. Take a few close up, clear pictures, and a few freshly cut branches to a good local nursery to see if they can diagnose the problem. One last possibility, did you fertilize in the spring? Dappled willows do best with a generous dose of general purpose fertilizer in spring. Yellowing leaves, usually with no other symptoms, can be a lack of fertilizer.

Will pruning keep the roots on my ‘Hakuro-nishiki’ small?

Not substantially, I know the standard rule of thumb is that the root spread will generally be at least as large as the branches spread, and for large willow trees the root spread is much greater, but keeping top growth small will not affect the root system much. I expect that if you keep a 10 foot shrub pruned to a consistent 2 feet, the root growth will somewhat retard just because the plant does not need so much root. If you are concerned about the notorious willow roots tapping into septic tanks and water lines, see above.

When should I plant a Japanese Willow?

The best time to plant is early spring or autumn when the weather is relatively cool so the plant and soil do not dry out too easily. Planting anything can cause some stress, so try not to add to it by planting on a hot, dry, or windy day. Most shrubs and trees can be planted anytime, even midsummer, with proper care. But those that don’t tolerate the long hot summers even after established will struggle. If it is already summer, wait until fall or spring to make it easier on the plant, AND you!

Can I transplant my dappled willow?

Yes, they tolerate transplanting quite well. Take note of when best to plant in the previous question. If your shrub is already quite large, reducing the size will make it easier to manage.

My variegated willow is reverting to all green – the foliage on a few branches is completely green. Is there anything I can do?

Many of the plants with variegated foliage can begin to revert, particularly the variegated Norway Maple. In the case of a dappled willow, there are several thinks you can do to reduce the occurrence. First, the colorful variegation is most prominent on new growth – frequent pruning will encourage new growth. Next, best color is achieved in full sun. Unless you live in a hot zone with long dry summers, do plant in full sun. And, fertilizing will also encourage good color. Be sure to fertilize generously each spring with a general purpose fertilizer. If your soil is extremely poor you may want to fertilize again 6-8 weeks later. And finally, prune out branches that have all green foliage. The all green limbs always grow the most vigorously, and if allowed to continue will overtake the variegated limbs.

Are the dappled willows susceptible to disease?

School of Integrative Plant Science

Leaf-sucking insects, such as the potato leaf hopper (Empoasca fabae), and stem-sucking insects, such as the giant willow aphid (Tuberolachnus salignus)and the black willow aphid (Pterocomma salicis), can also debilitate fast-growing willows. Potato leaf hoppers extract plant sap directly from the leaf veins and simultaneously inject a toxin that causes injury to the plant. The dual effect of feeding and toxin causes a complex of symptoms known as “hopperburn”. Leaf curling is the most obvious symptom and is usually accompanied by reduced growth. Salix viminalis and S. viminalis hybrids are highly susceptible to potato leafhopper and more resistant varieties often display leaf curl with minor growth reduction.

Leaf Sawfly larvae

Willow sawfly (Nematus ventralis) is also a common, periodic pest on willows and poplars in North America, Europe, South American and Australia. Sawfly larvae look like caterpillars, but are actually a non-stinging member of the wasp family. The larvae feed on young tender leaves leaving only the midrib of each leaf. Occasional dramatic defoliation events can strip an entire plant. While this could be debilitating to a young plant, it is not usually a major problem for mature plants.
Other minor pests include stem borers such as the willow stem sawfly (Janus abbreviates) that lays its eggs in willow stems. As the larvae develop, they tunnel down and eventually bore out of the stem. The net effect is death of the individual stem above the exit of the larvae.

For more information on these pests, please visit our pest fact sheets or contact Larry Smart or Greg Loeb

Diseases

In collaboration with George Hudler’s lab, we have begun to identify microbes that cause disease on willow in the United States. Shawn Kenaley has collected and begun analyzing samples of diseased leaves and stems, and we have been surveying for disease symptoms in replicated trials across the Northeast since 2005.

Leaf rust

Rust is one of the most damaging diseases of shrub willow. The majority of rusts that infect willow have been identified as Melampsora epitea and M. paradoxa. Rust appears as small (1-2 mm), orange or brown, slightly raised pustules of teliospores on the surface of the leaf. They usually complete a complex sexual life cycle that involves an alternate host, such as larch, fir, or saxifrages. Rust populations multiply through infection and repeated re-infection of the leaf during the summer finally producing teliospores that overwinter on the dead infected leaves in the litter. With the onset of severe infections, rust defoliates the plant prematurely and reduces yield significantly. Moist, cool summers and mild, temperate winters are ideal environmental conditions for Melampsora growth. Such conditions are often found in Northern Ireland, England and Sweden where rust has proven to be a major problem in willow plantations. Furthermore, rust infections can predispose a plant to infection by secondary pathogens, which may lead to further reductions in yield or premature death. Species used in bioenergy plantations that display particular susceptibility to rust include S. burjatica and S. viminalis in Europe and S. eriocephala in North America.

Resistance to willow rust is under strong genetic control, therefore selection and breeding programs in Europe and the United States emphasize rust resistance as the primary management for this disease. In Northern Ireland, planting shrub willow in mixed-culture stands has effectively reduced inocula and has proven to be an effective method of non-fungicide control of rust disease. The physical barrier provided by resistant varieties limits the movement of the inocula and slows the buildup, often delaying the onset of disease. This strategy has successfully slowed the spread of disease and reduced the impact of rust overall on willow plantations.

Willow scab, caused by the fungus Venturia saliciperda affects Salix species throughout Europe and the eastern United States. The scab appears as small olive-brown masses on infected leaves, petioles, and/or twigs following wet weather (April-August). In plantations, willow scab causes only slight damage to current season’s shoots and leaves. However, when heavy infections repeatedly occur over a period of years, the disease can reduce growth and vigor, resulting in twig or branch dieback and predisposing the plants to insects, other pathogens, and drought stress. Willow scab is widespread throughout New England and New York State. The disease also occurs in Pennsylvania, New Jersey, North Carolina, and Washington State. Most species of indigenous and naturalized Salix species are susceptible and several willow species used in bioenergy production, S. eriocephala, S. purpurea, S. miyabeana, and hybrid-progeny of S. purpurea and S. miyabeana are confirmed hosts.

Black canker of willow is caused by the fungus Glomerella miyabeana (Glomerellaceae). In North America and Europe, the black canker pathogen is consistently associated with the willow scab fungus and together they combine to produce a serious disease of willow known as “willow blight”. In the late spring and early summer (April-June) brown to black lesions appear on leaves and twigs affected previously by the willow scab fungus. Infected leaves usually shrivel and die as the fungus grows rapidly from the leaf blade to the petiole, then into the twig forming a canker. Cankers may remain localized at the point of infection or expand and encircle the twig. In willow plantations of New York State, the occurrence of black canker disease appears to be rare and has only been found affecting hybrids of S. viminalis and S. miyabeana.

Other diseases, such as crown gall disease caused by Agrobacterium tumefaciens, anthracnose tip blight caused by Colletotrichum spp., and cankers caused by Dothiorella spp., Botryosphaeria dothidea, Cytospora spp.,and Leucostoma spp. have not had broad impact on bioenergy plantation yield, but may reduce cutting yield in nursery plantations. These slow-growing diseases localized to the upper portions of stems are regularly removed by harvest on a short rotation. As long as stem canker or tip dieback diseases do not penetrate into the stool, they typically have only a minor impact, since buds just below the affected area will rapidly break dormancy and emerge to continue growing.

Next: Cropping Systems

Willow Tree Bark Is Falling Off: How To Treat Peeling Willow Bark

Willow trees (Salix spp.) are fast-growing beauties that make attractive, graceful ornamentals in a big backyard. In the wild, willows often grow by lakes, rivers or other bodies of water. Although willows are not sickly trees, a few diseases and pest infestations do attack and cause willow tree problems. If willow tree bark is falling off, you may need to take action.

Common Willow Tree Problems

Willows are not picky trees and most thrive in almost any kind of soil as long as there is adequate sunlight. They grow best in sites with full sun. However, the tree is vulnerable to several diseases and pests, including a few that cause willow tree bark peeling.

A few of the most serious willow tree problems do not cause peeling willow bark. These include infestation by gypsy moth caterpillars, willow leaf beetles and bagworms that will defoliate the tree.

The worst willow diseases include:

  • Crown gall, which causes stunting and dieback
  • Willow scab, which causes olive green spore masses along the underside of leaves
  • Blank canker, causing dark brown spots on the tree’s leaves.

These are not your tree’s problem if your willow tree bark is falling off.

Reasons for Peeling Bark on Willows

Peeling willow bark can be caused by insects. If your willow tree bark is falling off, it could be a sign of borer insects. Both poplar and willow borers can tunnel through the inner layer of the willow bark. This causes peeling bark on willows.

Your best bet if your willow tree has borers is to clip out all diseased branches. Then you can spray the willow tree with permethrin to kill borers.

Another possible reason for willow tree bark peeling is too much sun. Willows most often get sunscald in winter when sun reflects off bright snow. The sunlight heats the tree bark, causing the tree cells to become active. But as soon as the temperatures plunge, the cells freeze and rupture.

If your willows have yellow or red patches on the tree trunk, this may be the result of sunscald. Those spots can also crack and peel as time passes.

The tree will heal from sunscald, but you can protect your wills by acting before winter. Paint the trunks with diluted, white paint in early winter to prevent sunscald.

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