First Published 1/22/2004
Killing Zinnias

It’s a funny thing. When people find out that I grow plants for a living, they suddenly feel compelled to confess their predilection to killing plants…and I think I know why. My guess is that they simply want reassurance that they are, in fact, still morally sound. I sure hope so, because when it comes to killing plants, I’m the master.

Plant Perfidy

To be honest, I’ve lost count of the number of plants I’ve killed over the years. Since childhood, I’ve frozen, underwatered, overwatered and burned plants, to name just a few of the injustices I’ve committed. It wasn’t because I was being malicious; I love plants. It’s just that to learn what really makes them tick, you’ve got to push them to their limits.

Death to Zinnias

Which brings me to zinnias; I’ve somehow managed to destroy more than my share of them over the past several years. My history with zinnias has not been one of casual neglect; in fact, I’ve given them the best environmental conditions and treatments in the greenhouse, hoping that they’ll reward me with excellent growth. And yet, despite all my efforts, inevitably a consistent percentage of the plants topple over here, there and everywhere, until eventually I’m faced with a checkerboard pattern of living and dead zinnias. I was starting to feel some self-doubt, until I recently received my copy of Hort Technology. This publication, which is essentially a compilation of the latest horticultural research, had one particular report that caught my eye. It was about disease resistance of the top fifty-seven zinnia cultivars, and I instantly felt vindicated by a statement of one of the researchers: “…disease problems are so prevalent that many greenhouse growers will not produce zinnias.” So at least I’m not alone.

This by no means implies that you can’t successfully grow zinnias in your backyard. It’s just that in the typically warmer, more humid greenhouse environment, zinnias are particularly vulnerable to powdery mildew, alternaria blight, and bacterial leaf and flower spot. But if zinnia seed is sown directly into the garden, they grow rapidly and fare quite well in our sunny, fairly dry climate. If you want to grow zinnias, simply sowing straight into the garden in June, when air and soil temperatures are reasonably warm, is the best strategy.

Decompose in Peace

Here’s my response to people who feel compelled to confess their propensity for killing plants: don’t worry about it. Gardening isn’t about creating the perfect display of plants, unmarred by the ugly realities of life. Gardening means embracing the natural world, and involving yourself in the life cycle of the plants you love. Yes, it can be painful to lose a patch of zinnias or a treasured maple tree, but instead of giving in to despair, use the experience to your advantage. Try to learn something from each fallen plant, and in time the sensory rewards of your garden will exceed the costs, both economically and emotionally.

That’s the beauty of growing plants. You grow them, you kill them, and you learn something new. With a little bit of adventurous spirit, the journey can be just as rewarding as the destination.

First Published 1/8/2004
Mealybugs

Mealybugs look innocent enough. In fact, one could argue that they’re kind of cute, with their white, fuzzy coating. But mealybugs, despite their benign appearance, are a particularly insidious insect pest. If you’re not careful, a single mealybug-infested plant can act as a base for the bugs to spread throughout the home and make a meal of one plant after another.

The Citrus Mealybug

There are several species of mealybug, but the citrus mealybug is probably the worst of them. Although it gets its name from its appetite for citrus trees, this particular mealybug attacks a whopping twenty-six different plant families. Furthermore, a single female citrus mealybug can lay 300-600 eggs.

Although mealybugs originate in tropical regions and don’t survive outdoors in our climate, they are quite adept at hitching a ride on plants brought into the home. Once they’ve found a warm, safe harbour, they can spread, slowly but steadily, using any touching branches as bridges to cross from one plant to another.

Feeding Time

Mealybugs tend to congregate in large numbers where the plant stem branches off into a leaf. From these vantage points, mealybugs stab their mouths into the plant tissues and begin drawing out sap. Mealybug feeding weakens plants, and causes leaves to become yellow and distorted.

Mealybugs also excrete a sticky liquid called honeydew that not only looks bad but also provides a nice home for a fungus called black sooty mold. The mold doesn’t directly attack the plant, but it cuts down on the amount of light the plant receives, and it makes the plant look dirty.

Paradise Lost

Once mealybugs get established, getting rid of them is difficult. There are very few pesticides that are effective on mealybugs, and many applications are necessary to achieve reasonable control. Besides, spraying large tropicals in the home is neither practical nor prudent. I know of one person who has employed a more natural, but extremely expensive solution. She has a large solarium attached to her home, filled with dozens of huge, beautiful tropical plants. But after inadvertently introducing a mealybug-infested plant into the solarium, her tropical paradise was quickly overrun. After having attempted an extensive but fruitless spray program, she turned to biological controls. She ordered a type of ladybeetle called Cryptolamus montrouzieri, commonly called the mealybug destroyer, from a company in B.C.. The adult beetle is 0.5 cm long and shaped like a ladybug, with a black body and a reddish head. (The larva looks like some sort of monstrous alien, with waxy white appendages poking out of its body.) Cryptolamus are quite effective at destroying mealybugs, but a thorough understanding of Cryptolamus idiosyncrasies-and deep pockets-are needed. In this case, it took several months and an incredible $5,000 worth of mealybug destroyers to complete the task!

Fortunately, there are cheaper control options if you have mealybugs on just one or two plants. Dip a Q-tip in rubbing alcohol and dab each bug, ensuring that you keep the alcohol off the leaves. Malathion insecticide can be mixed in with the alcohol to increase the killing power, but you must follow the safety instructions on the pesticide label.

During the summer, you can take the plants onto the back patio and gently hose the mealybugs off the plants. I’ve done this to some large, infested cacti, with excellent results.

Finally, if you do notice a mealybug infestation, make sure your plants are segregated. Placing plants far apart will hamper the mealybugs’ efforts to spread from one plant to another.

The Only Sure Method

The best strategy for keeping your tropicals mealybug-free is exclusion. Don’t ever bring mealybugs into your home! A five dollar tropical that requires ten dollars’ worth of pesticides is seldom a good deal.