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Privet, Chufa, Mealy Bug & Knotweed

Privet affected by a leaf roller; where to obtain Yellow Nutsedge (Chufa) for eating; more on identifying a giant of a plant shown here; and mealy bug on Wisteria should be easy to control.
by Art Drysdale
by Art Drysdale


Art Drysdale, a life-long resident of Toronto and a horticulturist well known all across Canada, is now a resident of Parksville, British Columbia on Vancouver Island, just north of Nanaimo. He has reno-vated an old home and has a new garden there. His radio gardening vignettes are heard in south-western Ontario over radio station Easy 101 FM out of Tillsonburg at 2 PM weekdays.

Art also has his own website at

June 22, 2008

Above, two shots of Yellow Nutsedge (Cyperus esculentus); the plant itself and the tubers which are edible; and a shot of Greg DeGreef’s mystery plant growing in Edmonton that turns out to be Giant Knotweed (Polygonum sachalinense). Below two shots of the wicked mealy bug on tropical plants (author photos).

Maxine from somewhere in Western Canada (a generally mild area, because privet doesn’t grow in the colder climes!) asked this question of Donna Dawson, back on June 13: “Hope you can help me or one of your subscribers. Our Privet Hedge (Ligustrum) is being attacked by a very, very small greenish, yellow almost translucent bug. Does not look quite like an aphid. Our local gardener told me it is a leaf miner. I looked it up on Internet and I am still not sure if that is what it is. Leaf miner strips the leaf and turns it brown. I do not have any brown and the leaf is not eaten or stripped as yet but the leaves are so tightly curled, somewhat like a small cigar. When you unroll the leaf there are two to three small, a little bigger than a spider mite bugs. Our weather has been cool and wet. Please help me identify what I am dealing with.”

My response to Maxine was that from her description it was definitely not a leaf miner that was at work. Leaf miners work between the upper and lower epidermis of leaves and in the early stages you can usually see a tiny wiggly line which the insect leaves as it eats while moving through the leaf. Later at least a part or the entire leaf turns brown and dies. What I believe Maxine has is a leaf roller--in the case of privet, it can often be caused by the privet aphid (Myzus ligustri). It is fairly easily controlled with any insecticide. My preference would be Wilson Sevin, still generally available.

Just the day before, Antonio Escudé wrote with this fun question: “Hola Arturo! I am looking for seeds/plants and some pointers on how to grow this weed. My family is from Spain and we've been having the hankering for these delicious tubers lately.”

The chufa Antonio refers to, I believe, is also known as Yellow Nutsedge (Cyperus esculentus). It grows in most soil types and over a wide range that includes much of southern Ontario. It can be grown from seed, or from the tubers produced in the soil, which can also be eaten as suggested by Antonio.

It is a perennial, and in wet soils is considered a bad weed that is difficult to control because it resists herbicides. The seed seems a little difficult to come by, for two reasons. First, likely because it is considered a weed, it would appear suppliers are not able to ship it to Canada, and second, most suppliers sell only large quantities, such as ten pound bags! I did find a nursery in Ontario (from whence I presume you are writing). It is Acorus Restoration, #722, 6th Concession Road, Walsingham, ON N0E 1X0; Phone: 519-586-2603, or check . Walsingham is just south of Tillsonburg, and they are slightly west of Hwy. 59. They sell a 10 cm pot with a single plant for $3.50.

Last week I reported that Greg DeGreef of Edmonton wrote to Donna Dawson with an unusual plant for ID: “Can you tell me what this plant in the attached photo is? This is a large grove in front of a friend's house, he gave me a couple of root pieces and it is doing very well in front of my house. It is perennial and I was told it was bamboo, but my research so far tells me that most bamboo has pointed leaves. The shoots are purple in colour.”

My response was as follows: “As Donna has said, it certainly does not look like a bamboo; besides, how many of them are hardy in Alberta. My immediate guess would be Japanese knotweed (Polygonum cuspidatum). The distinguishing feature would be the tiny white flowers displayed during the summer. If it is not Japanese knotweed, I would still think it is a Polygonum, just not sure which one. Do check the flowers when it blooms, and let us know. By the way, the USDA says it is a noxious weed over much of the U.S. and Canada except (in Canada) it is not known in Alberta and Saskatchewan. But as to hardiness, it is known in Alaska, so it should be hardy there.”

New this week, just a day later Greg wrote back after doing his own research: “Thanks so much for taking the time to look at my mystery plant. You have given me a good enough start that I can now say that this plant is giant knotweed (Polygonum sachalinense). The determining details were the very large leaf size, 30 - 40 cm, and the 3 meter plus height. Now I have to worry that this invader may be damaging my house, at least I can eat the shoots to slow them down!”

I have once again placed Greg’s photo with this item here.

Finally this week, Debra Macfarlane of Salt Lake City Colorado wrote to Donna with an unusual happening, at least for us, and apparently for her as well: “I have a mealy bug infestation on a mature Wisteria plant. They are on the stalk not the leaves. Everything I have read indicates this is unusual. Have you heard of this? Should I use a systemic? Should I spray first? Will it spread to the rest of the yard? The climate is just now becoming hot here in Salt Lake. We have had some rain and a lot of cold weather. This doesn’t add up either. Thank you so much for your response.”

Yes, certainly here in Canada where Wisteria can be grown, having mealy bug on them is unusual. But then the how and why of insects spreading is a major science.

There is a good chance they will spread, but mealy bug is easily controlled with almost any insecticide. Anything you happen to have should do the trick. Apply it to soak the infestation well, two or three times in a four-week period.

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