Common Houseplant Pests: Part 4 Mealy Bugs (Update)

I continue to get messages and comments regarding my mealy bugs on jade plants post. It's a sad reality, but a common ground for those of us who love our houseplants and want to save them.

Here is an update of my previous post regarding that sad jade plant that we rescued.

After spraying with water, dabbing with alcohol and repotting; the jade plant is starting to really bounce back. It's been over a year since any mealy bugs have been seen. It was a labour of love. Staking it now - we are trying to regain a balanced growth habit. I just wish we had more light to get tighter stem growth.

No more distorted leaves and white flakey bits in the leaf axils. All clean.

Interesting enough, 3 months ago, a huge jade plant was gifted to us and on close inspection, it too was covered in mealy bug.

I didn't even take a picture of the before, as it went straight into the bathtub and got a spray down. I wasn't going to allow mealy to take over the house. This plant was worse. However, while trying to spray the plant down, the tightness of growth habit didn't allow for a thorough job. Instead, the power washer was used on a softer spray setting and all the nooks and crannies were blasted.

 This is the result. After a thorough blast, a heavy prune (to thin out and expose the inside of the plant) and the removal of nearly all the top portion of soil - it's starting to come back.

 All the pruned lesions are showing new buds and growth.

As you can see, some of the spray from the power washer made damaging holes. No worries. Once more leaves emerge, I will pinch this leaf off.

With healthy new leaves and tons of new growth - within a year, this jade plant will begin to look as good as when it was gifted to us.

Who needs chemicals?

Viburnum Beetle - Pyrrhalta viburni

Ok, this has to be the worst sight to a gardener:

Nothing breaks your heart more than coming across this sort of devastation too late in the season.

The Viburnum Leaf Beetle. There's only a handful of Viburnums this beetle doesn't eat (link here).  Unfortunately, when I first had a look at this Arrowood Viburnum in early June, it was too late. 3 weeks ago, I gave it a major prune anyway.

I had to cut the shrub down hard as a preventative. Had I done this in early April, I could of averted this ugly scene below:

Brand new, succulent growth that the adults are now feeding upon. However, the bulk of stem growth that is left has been drastically reduced, which in turn will reduce egg laying sites after mating.

A relative new-comer to North America, (originates from Europe and Asia) these leaf eating beetles are by far the most frustrating.

The adults poke and lay their eggs in the tender, new growth shoots. Here on the previous year's growth, you can see the exit holes from the egg laying piercings. 

The beetles have (in this photo above) placed their egg piercings just above a leaf node. Close to possible leaves when they hatch in spring. Smart, eh?

When the eggs are laid, there are abrasions on the stems that are not as noticeable as these. Especially, when the stems begin to harden off and go brown in the autumn. Sometimes, the tissue around the pierced holes go grey and discoloured instead of the normal brown healthy colour. Above, you can see how they look on new stem growth. In relation to my had, they are so tiny, but probably 10 or so eggs are laid in each pierced lesion.

This time of the year, the adults feed voraciously and mate. Soon to lay eggs and pierce holes in the tender stems, starting the process all over again. 

I removed as many adults by hand and squished them. Yuck. It is easier to remove the adults rather than the larvae.

Life Cycle and Treatment: It's hard to believe this little beetle could be so damaging.

In early May, eggs hatch and larvae push through their winter home and devour new leaves emerging.  They feed on the undersides of the leaves. Going unnoticed until the damage is done. In June, they crawl down to the base and sometimes fall to the ground to pupate. I've read: cleaning up fallen debris and leaves help to remove pupating sites and reduce their chance to become adults. But, I still saw adults emerging from below after doing so.

Now that I have removed as many adults as I could see, I will keep my eye on the remaining foliage to see if I see more of the lace pattern on the leaves from their feeding sites.

In October, when the leaves drop, I will reexamine the stems for egg laying sites and cut away more growth to prevent the eggs from hatching next spring.

You can use dormant oil treatments before bud-break in spring, but it will only marginally reduce larvae numbers and not kill them all off entirely.

One note: you can use some contact sprays during the larvae stage, but sooooo many beneficial insects feed off the larvae. Direct spray contact will kill them too.

Pruning and a watchful eye will save what's left, better than any chemical.

Clematis Wilt - Phoma clematidina

Clematis are some of the most beautiful flowering vines available to the avid gardener. However, several cultivars are prone to clematis wilt.

This newly transplanted clematis (moved this past spring) has shown signs of the wilt disease.

Rather a young plant, we waited for the flower buds to unfurl, but with the heavy rains we've had and humidity, the buds never got large enough to flower.

On closer inspection, the flowers were wilted and lost some colour.

The stem bearing the flowers at the base had the typical Clematis Wilt brown leaves.

Clematis wilt a few years ago was known as Ascochyta clematidina, but now it is classified under Phoma clematidina. A fungus which in wet weather, multiply by spores, creating blotchy lesions and eventually browning of leaves - making the plant wilt.

Even though the leaves at the tip of the stem are green, the base leaves are all like this.

The best route of action, is to cut back (as far back to the ground level) any stems and leaves that are infected. Do not compost the remnants. Destroy or remove. Re-situate the plant, if it is prone to dampness (frequent foliage contact with water).

Cut right back to ground level. No sense in letting any remaining leaves to infect other healthy ones.

This clematis was planted in a fair bit of clay soil. Adding compost and humus rich soil will help boost it back to health.

Clematis generally like to have "cold feet" which is a term used to describe cooler roots. Help clematis by shading the base of the plant. Planting the clematis slightly deeper than it is in the pot is wise. Make sure the roots are deep enough to keep cool. Planting a perennial or placing a rock over the root system is also beneficial.

While recovering, it's best not to let the remaining foliage get overly wet. You can't help the rain, but any additional waterings should avoid the foliage getting wet.

This is the stem in question. Discarding it, I have cut it in half. The wilt began at the base, slowly working its way to the tip. A sad shame, but thankfully, the wilt didn't spread to the other stems.

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.

Common Houseplant Pests Part 3 - Scale

Here's an Agave plant. Notice anything?

Take a closer look!

Brown fleck in red circle.

Here it is on a Yucca plant. And it's not damage or part of the plant.

What I've taking photos of are tiny insects called scale. Here they are feeding both on an Agave and Yucca leaves. There are several species of scale. Scale are sap sucking, flat discs - moving ever so slow, and multiplying under the radar. These insects go undetected until their numbers are high, unless you know what to look for.

I hate using chemicals. I avoid using them as much as possible. Unfortunately, with this practice, patience and perseverance are key and constant monitoring over a period of time is necessary to get rid of them.

This agave plant is young.  It's newly emerging leaves are also targeted by scale more so than then older leaves. The tender tissue of new leaves are more delectable for the scale to feed on. Easier for their mouth parts to tap into.

You may wonder where they come from. Sometimes they go unnoticed when you make the plant purchase or receive one as gifts. Scale eggs are laid in the "crotches" and crevasses of the base of the leaves. Adult lay them in protected areas. Once they hatch, juvenile in-star scale insects emerge. They migrate above their nested area and begin feeding. More often than not, you find greater numbers of scale insects towards the protected areas within the core of the plant. I consider them to be "lice" of the plant world. Real bother and difficult to get rid of.

Ever notice shiny, sticky leaves on your house plants and wonder, where did that come from? With scale and other sap sucking insects, you can detect their numbers by their excrement. They "poop" out honey-dew, the sappy remnants of their diet and it rains down on the foliage below. This poop is quite sticky and it makes the foliage shiny.

Be vigilant, by either gently scraping off the scale with your finger nails, or using a cloth or cotton swab (dampened by rubbing alcohol). If you find scale numbers too high to combat them individually, you can take a water bottle sprayer, and mix 1 part dish detergent, 1 part rubbing alcohol to 10 parts water. Agitate the spray mixture thoroughly. Spray the plant liberally, until all leaves, crevasses and crotches are soaked. After an hour or so, once the spray mixture has dried, take a dampened cloth with rubbing alcohol and wipe off the dead scale. This is important, as adult scale can have young eggs or newly hatched in-star scale marauding under their shells.  Repeat as necessary.  If you have a large house plant, and find it most difficult to spray, reduce it's size by pruning the plant. Less foliage means less chance for the insect to feed from. Reducing the bulk of the plant will eradicate many more insects than just spraying alone. If it cannot be pruned, wait to treat the plant until you can bring it outdoors. Treat then outside, where space and temperatures are more favourable.

In one experience, I had to repeat this process 4 times before I got rid of the insect for good.

Diligence pays off. It also becomes a learning process and a great tool in learning how the scale life-cycles persist. When it comes to plants, I'll give it my all to rid them of this pest.

Keep a close eye on your plants and it'll pay off.

This particular scale I've found on Yuccas, Dracaenas, Agave, Bromeliads and Sanseverias.