Tough Winter on Euonymus - Burned Leaves

This winter has been exceptionally tough on Euonymus foliage. I haven't seen a variety that was unscathed. Not to worry, winter burn and brown leaves will not be left on the shrubs for long.

Sections of this Euonymus, trained as a climber, has burned foliage dotted about.

This is a grouping of Sarcoxie Euonymus. Usually, its dark leafy green foliage is an attraction to plant as an evergreen hedge. Not this winter. Winter burn has caused the majority of leaves to fall off already, leaving this sample quite bare.

Euonymus are rather resilient shrubs and trailers. They will recover given time and adequate conditions. I'm actually quite pleased to see this damage happen. That may sound strange. As a gardener, I see Euonymus scale quite prevalent in the GTA and I believe it's because of our more recent, gentle winters. Scale insects nestle in and fixate tightly on remaining interior foliage and stems over winter and don't die off in large numbers due to protected warmer winter months. Now, I smile in gratitude - for more of these insects will have died off this winter, because of the harsher conditions.

This is Coloratus Euonymus - the ground cover variety. Even with adequate snow coverage, it too has signs of winter burn.

Healthy, soft buds are key to knowing the Euonymus will bounce back. Be sure to water your Euonymus in case we have a dry spring. Watering the plant will ensure the buds stay hydrated and will emerge as leaves during the growing season. In May, buds will unfurl to new leaves and the older burned leaves will eventually fall off. You can aid the process by shaking the bushes, or raking out the worst of the ground cover variety.

If Euonymus is grown as a climber and there's very little growth beneath, simply shake off dead foliage. If it is stubborn to fall off, then prune back to older buds.

Here, you can see healthy buds remain. Not to worry. They will refoliate the plant.

Once the leaves fall off the bush, examine the leaves on their underside. If you see white, flaky residue, it may be scale. Rake as many of the leaves as you can from beneath. It's likely they (not all do) have some overwintering eggs of Euonymus scale insects. Do NOT compost. Remove the leaves from your garden. Add compost or some triple mix to the soil below and be sure to water the plants if we have a dry spring. I caution adding synthetic fertilizers at this point, since scale insects favour stressed plants and love added nutrients. There are only so many healthy leaves to go around. You don't want scale to over-power the plant. For control of this insect, check out my post on Euonymus Scale.

If the leaves are remaining on a ground cover type, or you don't have patience to wait, you can cut back the stems on top, to reveal the green leaves that were protected beneath.Once the buds unfurl to new leaves, the plant should bounce back by June.

Cupped Boxwood Leaves - Boxwood psyllids

Have you ever seen boxwood leaves cupped and curled like this?

These leaves have curled because of a sap sucking insect called, psyllids. Boxwood pysllids (Psylla buxi) sort of resemble aphids as nymphs - with size and colour. There's usually one generation a year and control is best with an insecticidal soap application in late spring (May in Ontario). Treat when the new growth of leaves fully open. Psyllids don't kill boxwood, but will distort and affect the foliage - aesthetically ruining the glossy look to this broadleaf evergreen. 

In these photos, you can see remnants of their past presence. Their feeding has cupped the foliage right over the bud tips. Causing the tip of the stems to wither and dry up.

You can also see remnants of their excrement - a white residue.

When psyllids nymphs are high in number, you may see their white, waxy excretion before the leaves curl. Usually at the tip of the branch stem. As they feed, the boxwood leaves respond by cupping - sheltering them, where you don't see the nymphs at all. Psyllids usually feed on young, new growth that is tender. Hence the reason the leaves curl so easily.

Their white frass (poop) is quite fluffy and insulates them as they feed toward the bud union of the leaf.

Psyllids have flat bodies, with large eyes. I wish my camera could take a better photo, but you get the idea on how small they are compared to my fingers.

Psyllids lay orange eggs between the bud scales. As the leaves emerge from the buds, the eggs mature and hatch into nymphs - then the feeding begins. Nymphs become a flying winged adults (which look like miniature cicadas) in June and reproduce, laying the eggs near the terminal buds for next years cycle.

I've found you can reduce psyllid numbers drastically with just water. A high pressure spray dislodges many of them and reduces the adult population. Just be aware, adults may be blown off and fly back. So the spray of water needs to be repeated and quite high in pressure.

Not a huge problem, but easily treated.

Above are photos of other notable boxwood characteristics that have confused folks often. These are boxwood flowers (left) and last years seed husks. I've had folks ask me if the right photo is a disease. ;)  

The Dead of Winter - Part Two

Part two: More plants that offer interest in the dead of winter...continuation of Part One.

Corylus avellana 'Contorta' - Corkscrew Hazel 
 My photo does not do this Hazel justice. The zig-zag and twisted stems are just so visually interesting, you can't help but gaze at it's growth habit. Once mature, the shrub will bear catkins and give more visual interests in winter.

Hydrangea anomala petioliaris - Climbing Hydrangea
Like its shrub counterparts, this vine holds its flower heads over winter, and they stand away from the walls it adheres to. The snow sits and adds real texture to your wall or fence.

Euonymus fortunei 'coloratus' - Wintercreeper Euonymus
This is one of my favourite ground covers. I picked it for its fall colouration that lasts throughout the winter. Unlike english ivy and pachysandra, this ground cover brings colour to the ground in the dead of winter. 

Anemone x hybrida - Snow Drop Anemone
When maturing overwinter, these seed heads open and release their fluff. This fluff catches your eye, and also provides bedding for birds nests in the spring. Quite lovely seeing this in the garden. Great paired with Rudbeckia seed heads.

Cornus sericea - Red Osier Dogwood
Every garden should have this as a background plant. Pruning and thinning of branches gives a great resource to empty winter containers. The bright red stems just add great accents to the container and to the landscape.

Yucca filamentosa - Adams Needle Yucca
A tropical feel poking through snow. I love yuccas. They need to be thinned out every few years, but there's nothing more beautiful, then to see green, healthy and rigid stems still remaining when everything like it goes brown and dormant. 

More to come...