The Hampton Gardener: Buggin’ Out

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The emergency call came in just two weeks after I had last seen Louis and he was frantic, in a panic.

It’s not like I hadn’t warned him and tried to tell him what the signs were, but Louis hadn’t listened to me back in September when I first mentioned that he, like many of us, would at some point become victims.

It wasn’t all his fault, of course, but if a cure was possible, it was all on his shoulders.

He had mealybugs on a beautiful 8-foot palm in a 20-inch pot that he brought into his house last summer. It was infested and his panic centered on not knowing what in the world to do about it.

“Andrew, you know a few weeks ago you told me to start checking the plants in the house? Well, guess what? I was looking at the undersides of that beautiful palm in the dining room and all of a sudden I noted this cottony stuff on my fingers and then I saw it under most of the fronds. What’s going on, what am I going to do?”

Without having to ask any more questions I knew he had mealybugs and because it was late November and in the mid-30s outside he was in deep trouble. Had he examined the plant in July or even August he would have noticed the thin white filaments that the adults spin and then cover themselves with as a protection from predators to hide their young and, yes, insecticides. Back then, had he told me that he’d only found a single crawler, we could have set up a simple spray of soaps or oils that would have solved the problem or at least made it manageable. But now, with the plant indoors, spraying it and getting the tops and undersides of the foliage treated was going to be a challenge. Years ago we could have put poisons in the soil that would have made the whole plant toxic and killed the bugs. Back then, we could have put a large plastic bag over the plant and put in a vaporizing pest strip that would have killed the bugs in just days. But like the toxic soil treatment, these solutions are no longer options. And that’s actually good.

But let’s go back six months to when Louis bought this plant. These mealybugs didn’t fly in. They don’t have wings. They didn’t crawl in. In a lifetime they may move all of 20 feet. And they didn’t cross over from another plant because there were no other plants in the room. Louis bought the mealy bugs. When he bought the plant the young suckers were there. They may have been tiny, the size of a pin head or slightly larger, or they may have been bigger and just hanging out in the frond sheathes, but they were there and he should have looked for them, as should you. Whoever sold him the plant should also have been more careful as they obviously didn’t do a good inspection. Nor did the person doing the phytosanitary inspection in the state where the plants were grown, probably Florida. These inspections are required by law before plants are shipped across state lines and the grower must provide proof of the inspection to the receiving vendor.

Everyone was a fault, but Louis had to solve the problem or trash the plant.

If he wanted to save the plant, he had only one choice. On a day when it was close to 50 degrees outside he’d need to get the plant out and spray it or get it into a shower stall or tub where spraying could be done without getting the spray out of the enclosure. He had a choice of a specialty horticultural oil or insecticidal soap, but he’d need a sprayer. Louis told me he had one of those sprayers that many of us might use to mist a plant that holds about 8 ounces, but I told him to forget that. At the very least he’d need something like a Chapin sprayer (they have a small, 48-ounce pressurized sprayer, but a gallon sprayer builds up more pressure and is more versatile) so that the sprays would penetrate the cracks and crevices as well as cover both sides of the foliage. These treatments have no residual effects (they kill only on contact), which is what makes them so safe for us and our pets, but if they don’t come into contact with and cover the insects and cover their bodies they are useless.

And once sprayed, the plant would have to dry a bit before being taken indoors again.

But that’s not the end of it.

If the spraying is done correctly, many, if not most of the exposed mealybugs will be killed, but not all of them. It’s the remaining few that are dangerous because it would only be a matter of time before new ones would hatch, mate and reinfest the plant. It might be two months later, or six months later, but without follow up spraying, reinfestation is guaranteed.

So, my recommendation is three sprays 10 days apart. You can stretch it a bit or even shorten the timing to take advantage of the weather outdoors, but one spraying just won’t do it. And even after three sprays, on a plant that you know has been infected, I’d do protective sprays again in the spring and again in the fall.

Now, I had to temper my criticism because three weeks earlier I was hit as well, but with scale. As I’ve noted before, I had scale several years ago on a ficus that I’d picked up at a home improvement store. Luckily, it was during the summer and I was able to get the plant outside and do the oil spray regime. By fall, the Ficus was scale free to the point where I felt safe to bring it indoors for the winter. Now, four years and one larger pot later, it steals what little bit of sun I have during the winter in my small dining room, but it’s scale free.

This time though I was moving a large orchid to a place where it would get more light and humidity when my fingers stuck to the undersides of the leaves. I knew right away what that meant. It was honeydew, the sugary excrement that insects exude after they digest the plant proteins. Sure enough, on the underside of the leaves were mature scales. It was a no-brainer for me though. I had rescued the plants more than a year ago after they were used for a party and I’d gotten them to reflower twice. Not having the energy and time to treat the orchid with oil then treat it two more times and monitor it for months, it met an untimely demise.

You have to make choices in life.

But again, the story of the scale had started more than a year ago. The scale was obviously present when the orchid was purchased because, like the mealybugs, the scale doesn’t fly and doesn’t really crawl from plant to plant unless the plants are in physical contact. So it was there all this time slowly reproducing and finally exploding in numbers late last summer when it was warm and humid.

The lessons from these tales are numerous. First, when buying plants, inspect them carefully. Mealy bugs and scale are great hiders and all it takes is one or two under a leaf, at a leaf axil (joint) or under a leaf sheath and in a few months that one or two will become dozens. The cold of winter, even indoors, will slow them down, but come spring and summer they’ll reproduce like crazy. And if discovered at home at the wrong time of the year, control may be nearly impossible. Second, inspect your plants on a regular basis. Look for mealybugs, scale, spider mites, aphids on the shoot system and fungus gnats, which congregate at the soil. Mealybugs and scale are the most difficult to control. Spider mites are the quickest to kill a plant such as a gardenia, hibiscus or miniature rose, but if you give these plants regular sprays of water paying particular attention the undersides of the leaves, you’ll seriously disrupt or end their fun. Aphids are easy to control with pyrethrin-based sprays that are safe for you and pets, but should not be used anywhere around fish or fish tanks.

Here’s my advice. You should inspect your plants weekly. Look at both the top and undersides of the leaves, but also look in the cracks and crevices where young scale and mealy bugs begin their feeding. If you ever touch the foliage and it feels sticky, that’s a sign of honeydew. If you ever see a black mold growing on the foliage, that’s a sign of a mold that’s growing on the honeydew. The presence of honeydew on the foliage is a pretty good indicator that some insect has been feeding there or on foliage above. Look for aphids on the plant growing tips and on flowers. Fungus gnats will always congregate on the soil and their larvae can be seen wriggling about the soil surface. Spider mites are a bit more difficult as you need at least a 10x to 20x hand lens to spot them or their spherical eggs on the undersides of leaves of plants like hibiscus, citrus, gardenias and even dracaenas. If you see the webbing or discoloration (often referred to as stippling) they cause as they suck the life out of foliage, it’s probably too late. Whatever you do, don’t drag a spider mite infested plant through the house as they will catch the slightest wisp of wind and be transported to another plant. Just put a plastic bag over the plant, seal it and get it out of the house.

Never let your plants touch each other as this kind of contact allows the most immobile of insects the opportunity to travel and infect the neighboring plant. Always inspect and, if you can, isolate new plants that you bring into the house. At this time of the year, this means really checking out poinsettias carefully. In this case you are looking for any signs of white fly, which you’ll spot on the undersides of the leaves. This was once a major problem, but most of the plants that are sold now are pretty clean, but check. Be proactive, inspect and do it regularly and know what to do for control if you should find any of the noted critters. Not every insecticide can be used on every plant for every bug. Read the label and, of course, keep growing.

Andrew Messinger has been a professional horticulturist for more than 30 years. He divides his time between homes and gardens in Southampton, Westchester and the Catskills. E-mail him at: Andrew@hamptongardener.com. The Hampton Gardener is a registered trademark.

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