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We would like to think that a garden is composed of magnificent plants in a pleasing arrangement, perhaps complemented by stone or brick, wood and water -- the way they are in photographs in coffee table books. But they are not. Real gardens are composed of plants, of course, but also insects, viruses, mice, deer, and woodchucks. As beautiful as a plant may be, something would like to eat it, infect it, or curl its leaves up for shelter. Far from gentle Edens, gardens are small jungles, with battles happening everywhere, just out of sight. We see the results: chewed leaves, keeled-over tender transplants, stunted growth, gnawed stems, and trunks with neat patterns of holes.
But it's not all one-sided. Plants have their defenses, and every predator faces enemies. It is fair, or at least even-handed, in the larger scheme of nature, but to the gardener it sometimes feels like a very personal attack. Somehow it's all a little less overwhelming when you realize that every gardener faces a similar cast of characters.
Spruce Spider Mites
When the needles on your spruce are flecked with a yellow-tan color or completely turning brown, your spruce is being attacked by spruce spider mites. Whether to treat them in spring or summer can be confusing.
Mites are usually associated with hot and dry conditions, but some, including southern red mites (which attack holly, azalea, and rhododendron) and spruce spider mites (which attack spruce, hemlock, pine, and arborvitae), are active in cool seasons.
Spruce spider mites feed on older needles and reproduce during spring and fall. They take the summer off. If left untreated, they can cause serious injury.
Rayanne Lehman, an entomologist at the Pennsylvania Agriculture Department in Harrisburg, says that mite eggs spend the winter at the base of needles and on the bark of branches. Eggs can be controlled from late winter until the time the buds break by using a dormant-season dilution (this will be listed on the label) of a horticultural oil spray whenever the temperature is above 50 degrees. Thorough coverage is necessary because the oil works by smothering.
After bud break in the spring, take a spraying break. Very young foliage should not be sprayed. Use a summer dilution if more spraying is needed later in the season.
If you have a Colorado blue spruce, be aware that it is sensitive to dormant oil and may lose its blue-green color for two years while new needles grow.
Mite populations should be checked every two weeks during spring and fall by rapping three times on four branches spaced evenly around the tree to drop mites onto white paper. Watch for what look like dark, crawling pepper grains; if you see ten, take action. But also keep an eye out for fast-moving, light tan mites -- predators that feed on the spruce spider mites. If the predator population rises and the spruce spider mite population decreases, treatment may not be necessary.
Destructive Woodpeckers?
Woodpeckers are beautiful birds, but hearing one hard at work in your yard or seeing the resulting holes is not one of the joys of nature; it is a cause for concern.
Woodpeckers and their cousins, the sapsuckers, drum on trees, posts, and sometimes houses for three reasons: food, shelter, and conversation. Sometimes they are busy for all three of these reasons. A male might be looking for a mate and warning other woodpeckers that this is his territory -- sort of like that loud guy at the other end of the bar.
Following the age-old truth that if you're good at something, you should do it often, woodpeckers use their drilling skills to make cavities in trees rather than living in nests. Digging a big hole isn't much different from digging a small one; it just takes longer. The nice thing about nests is that they are built quietly.
Mostly, though, woodpeckers drill to eat, looking for insects that are living under the bark or in the wood. Sapsuckers are a bit more sophisticated. They drill a horizontal row of holes, which fill with sap. The sweet sap attracts insects, which become tangled in the stickiness and are then easy prey for the sapsucker.
Try to note which tree your woodpeckers are concentrating on for food or shelter. Nature doesn't make any dummies; woodpeckers pick on stressed trees that are infested with insects or have some other problem. It is unlikely that a woodpecker could kill a tree, since the holes it makes do not girdle the trunk, which would completely sever the vascular channels for water and food. Any tree with that much interest for a woodpecker is already in trouble for other reasons.
Take the drumming as an alarm, and try to alleviate the problem. It isn't the woodpecker's fault, but the messenger is traditionally blamed for the message. In this case, the message is being delivered loud and clear.
Beetle Identification
Asian beetles, which have caused so much damage already in Brooklyn, are in danger of spreading throughout the New York area and beyond. But one bug that frequently causes alarm among homeowners is 3/4 of an inch long and brown with a zigzag white stripe on its back. Seen them? Relax.
Most likely it's a western conifer seed bug, which likes to come indoors for the winter, moving from nearby needled evergreens. In the spring, it heads back out to feed on developing seeds and early flowers, creating a little excitement as it buzzes around trying to find an exit. It is just a nuisance.
Asian long-horned beetles, on the other hand, cause a great deal of harm. This recently discovered beetle kills trees. The key identifying characteristics are their black and white antennae, which can be more than twice the length of this 11/2-inch beetle itself, and the black body with white spots.
If you suspect you have found an Asian long-horned beetle, immediately contact the New York State Department of Agriculture and Markets at (516) 288-1751 or (800) 554-4501, ext. 72087. If you live outside of New York, contact your state's Agriculture Department. It's a good idea to be on the lookout because so far, this insect has no natural enemies in the United States.
Tent Caterpillars
April not only brings spring; it also brings the tent-like cocoons that house the larvae of eastern tent caterpillars.
Among tree defoliators, only the gypsy moth can rival the eastern tent caterpillar. Although they prefer apple, crabapple, and wild cherry, eastern tent caterpillars also attack other popular deciduous trees, including ash, birch, maple, willow, oak, cherry, peach, and plum.
As the cocoons get larger and more obvious, and more ominous, gardeners begin striking back, but not always in the best ways. Burning them or dropping them into kerosene is a common method of control, but there are better approaches. Tent caterpillars can be controlled at several stages. Before they emerge in April, remove the distinctive egg masses, which are 3/4 inch long and appear varnished black, encircling smaller twigs. After emergence, they gather at the branch crotches and begin to create their protective tents.
On rainy, cool days the caterpillars stay inside, so those are the best days for pulling the tents, occupants and all, into a bucket of soapy water, eliminating the problem of disposing of the contaminated kerosene. If you prefer, you can open the webs on inclement days and spray Bacillus thuringiensis (Bt), which attacks and kills young caterpillars. On days that they are out feeding, a drenching spray of insecticidal soap can provide acceptable control.
Summer Spraying
Using horticultural oil can be frustrating when the insects return after just a few weeks. Caution with chemicals is always appropriate, but the new fine horticultural oils can be applied more than once without burning the leaves on your shrubs.
As long as you follow label directions and use the summer dilution rate, 1 percent or 2 percent, rather than the dormant rate of 3 percent or 4 percent, your shrubs should not have a problem. Since horticultural oil kills by smothering and does not have any residual effect once it dries, you have to spray when the insects are in an active stage of life. That may mean two or three times during the season, but recent studies at the University of Maryland have shown little or no damage from up to four sprayings with the newer, highly refined oils.
Many people believe that applying oil in full sun risks damaging the leaves, but the opposite is true. Applying it on cloudy or humid days lengthens the time it takes the oil to dry, preventing leaf transpiration -- the leaf's ability to transport nutrients -- and increasing the possibility of damage.
Sap-Sucking Squirrels
Squirrels are always a little nuts, but occasionally they seem to go overboard. For no apparent reason, oaks are attacked, with dozens or hundreds of branch tips chewed off and tossed on the ground. But, as always, nature has a reason.
Tree sap is very nutritious, but the trees prefer to keep it inside, where it belongs. Hungry squirrels simply chew off a few inches of the terminal end of branches, suck the sap that oozes out, and drop the remaining twig. Sort of like piling empty crab legs on the plate.
Mark McDonnell, the director of the University of Connecticut Bartlett Arboretum in Stamford, says this is primarily an urban phenomenon, probably due to squirrel population density and the limited spring food supply. In addition to oaks, maples are often on the menu. It is unlikely that permanent damage will result. Think of it as a very efficient pruning job.
One, Two, Three, Twitch!
Bugs can be downright entertaining, if you forget that they sometimes damage your plants. Pine trees attract an especially interesting pest. In groups of twenty or thirty scattered around the tree, green caterpillars with white heads suddenly quit chomping away at the needles and, as if they were part of a single organism, twitch. The whole tree seems to be moving, which is cute, until you remember that they don't belong in your trees.
From the time they hatch in mid-April and May, until they molt in June or July, the larvae of the European pine sawfly hang out together, eating the older needles on many species of pine, especially Scotch, mugho, and Swiss mountain. Unlike many spring insects that feed on tender new growth, sawflies eat older growth, and have finished by the time new needles expand, resulting in trees with bushy new growth on otherwise bare branches. Sawflies cannot kill a tree, but they can weaken it.
The 3/4-inch-long larvae can be identified by their black heads, green body stripes, and eight pairs of yellow-green prolegs attached to the abdomen. The twitching is the giveaway. When they are disturbed, the group reacts together, turning both ends up and holding on in the middle, looking for all the world like a well-rehearsed conga line.
Sawflies can be controlled by several methods, depending on your gardening philosophy. Hanging out in large groups may improve the individual's chances when it comes to most predators, but it makes it easier for gardeners to pick them off branches and drown them in soapy water. Spraying with insecticidal soap is effective; read the label for dilution rates and directions. Chemical insecticides can also be used, but Bacillus thuringiensis (Bt), the natural gardener's favorite, is not effective because the larvae are not true caterpillars.
Garden Buddies
Many gardeners want to take advantage of bugs that eat other bugs, and use one to protect their garden against another. Ladybugs in particular have a reputation for eating aphids in great numbers. One problem that holds many gardeners back is that the hired guns brought in for the job may not stay forever.
If we had the ability to see the take-no-prisoners warfare that goes on in our gardens, we would realize they are hardly little patches of Eden. That there are any leaves left at all by September reminds us that the bugs that eat also get eaten.
The various insects, bacteria, and fungi that dine on plants' enemies are grouped together under the term "beneficials," although they sure don't do it with any thought of helping the gardener out.
Whether bringing in mercenaries or encouraging home-grown critters, the principles are the same: try to create an environment where they can thrive. Michael Raupp, the chairman of the entomology department at the University of Maryland in College Park, says that two simple steps will turn any garden into a place ladybugs, lacewings, spiders, or big-eyed bugs would be pleased to call home.
First, quit dousing everything in sight with broad-spectrum insecticides. Spot treat instead, applying the right product (especially the less toxic horticultural oils and insecticidal soaps) only on badly infested plants. If damage is minimal, avoid spraying. One-size-fits-all insecticides kill good bugs as well as bad. Spraying everything eliminates hiding places where beneficials can wait out the storm, perhaps finding someone else to eat in the meantime.
Second, increase the diversity of plants. At one stage in their life cycle, beneficials may eat your aphids, but at another stage they may need nectar or pollen. Biodiversity provides the good guys with a change of diet as prey populations decline.
Introducing beneficials into greenhouses has been successful, but there have not been enough controlled studies done outdoors to really know. But Raupp suggests you go ahead and buy the ladybugs. If they don't come back next year, at least you will avoid chemicals this year. Besides, even if they aren't in your garden, they're somewhere nearby, dining on the bad guys.
For a free copy of "Suppliers of Beneficial Organisms of North America," write to the California Environmental Protection Agency, Department of Pesticide Regulation, Environmental Monitoring and Pest Management, 1020 N Street, Room 161, Sacramento, CA 95814-5624.
Besieged Hemlock
Hemlocks with little clumps of white dots along their branches are hemlocks in trouble. Occasionally misdiagnosed as a fungus, these dots are really a particular insect's eggs. Indiscriminate spraying, no matter what with, won't do the job fully. Sometimes the white spots return just a couple of weeks later; sometimes they don't seem to go away at all. As always with gardening, it pays to know what you are dealing with and to have an effective plan for attacking the problem.
Hemlock wooly adelgid is a voracious pest that can kill hemlocks in a few years if it is not treated. Those white dots area protective waxy substance the insect uses to protect itself and its eggs. If you were thorough in your spraying, the eggs and insects are most likely dead, but the waxy mass can persist for months.
There are two generations each year, so even though you should spray all parts of the tree with horticultural oil or insecticidal soap as soon as you see them, get into a regular schedule of spraying once sometime between April and late June and again in September to catch both generations when they are most vulnerable. Household soaps are lye based, and can damage young growth. Be sure to use insecticidal soap, which is fatty-acid based instead.
Maple Galls
Icicles on your sugar maple's leaves? Little green projections that eventually turn reddish occasionally show up, sticking straight up from the leaf surface. Some years there are more than others, but, few or many, they are so peculiar that they worry tree owners. Inevitably, gardeners are afraid that these are a sign of imminent danger.
These growths are not a disease or harmful. They are maple spindle galls, the equivalent of a condo with a restaurant on the ground floor. Several species of microscopic four-legged creatures called eriophyid mites feed on the leaf tissue. At the same time they inject into the leaf a growth-regulating substance. This chemical causes the leaf to grow the galls, making a home for the mite. Spindle galls may be as much as 1/2 inch long and are very thin, like misshapen pencil leads. They stand straight up and turn from green to red to black over the season. Other shapes of galls, such as beadlike swellings or flat, felty patches, are caused by other species of gall mites on other kinds of maples, like silver, red, or Norway.
Mites that entomologists call special females begin the process. After the mite spends the winter under bark scales on the trunk or branch, it settles down on a nearby leaf and begins to feed. Once the gall is complete, the mite stays inside and may produce several generations over the summer.
By late summer, with the young mites refusing to move out and the summer's mess piling up, a new generation of special females leaves through an opening on the lower surface and looks for some peace and quiet under a bark scale. Once the rest of the mites discover that there's no one to cook and clean, they desert the galls and die. The galls become dark brown or black, looking like a summer rental on Labor Day.
Spittlebugs
Walk into the garden on a sunny morning and you might notice the sun shining off a white, frothy glob of something along the stems of some of your plants. Gone within a few days, it then returns.
When your garden looks as if someone has been drooling on the plants, spittlebug, a sucking insect, has announced its presence.
During the immature stage of the spittlebug's life, it feeds on plant sap and produces a frothy white mass along the stem or where the leaves join the stem. The spittlebug coats and surrounds itself with a drop of fluid made from undigested plant sap and a binding material produced by its abdominal glands.
The foam, which comes from mixing in air, much as an immature human does with a glass of milk and a straw, serves two purposes. It keeps the tender insect moist, and it provides protection by hiding a small insect in a large disguise. The coating makes the bugs hard to wash away, or even know exactly where they are or how many there are, since the frothy masses can run together.
Spittlebugs usually cause little real damage, except on pines and other conifers, where severe infestations can be trouble.
Using Nematodes
Few insects arouse our ire quicker than Japanese beetles. Gardening catalogs, especially "organic friendly" catalogs, promote nematodes as a natural control product for Japanese beetles. Biology at that specific a level isn't part of our schooling, so it is normal to wonder just how a tiny wormlike creature can catch, let alone eat, a flying beetle.
I'm tempted to say the early worm catches the...
Nematodes, tiny roundworms in the genera Steinernema and Heterorhabditis, are no more than 1/20 of an inch long, but they are truly big-game hunters. Some species actively hunt for prey; others wait around to jump on a favorite pest as it passes by. The nematode enters its host through a body opening and releases bacteria with which it has a symbiotic relationship. The bacteria multiply and poison the host within two or three days.
Nematodes are used to control lawn pests during their larval stages, among them chafers, armyworms, and cutworms; various beetles; the borers that attack peach and dogwood trees; and the black vine weevils that attack rhododendron.
Although they may sound like the perfect gardening assistant, nematodes can be cranky. For one thing, they are fussy eaters, so you have to match the nematode to the pest. Knowing what pest you have is the key to buying and applying the right nematode at the right time. Some nematodes stay near the surface; others burrow down about 4 inches deep.
Because they live in the film of water between soil particles, nematodes will die if the soil gets too dry. They prefer soil temperatures of at least 75 degrees and are very sensitive to ultraviolet light.
To treat lawn problems, including Japanese beetle larvae, mix the nematodes with water according to the instructions, and apply them late or early in the day, when temperatures, drying winds, and light are reduced. Make sure that you put down at least 3/4 inch water just before or after applying the nematodes so they can move through the soil.
If it sounds as if you have to be prepared to treat nematodes with the same care you would any other household pet, you do. They'll be out there after your garden and lawn pests just as long as you are willing to see to their needs.
Sources for nematodes include The bug Store, 113 West Argonne Avenue, Kirkwood, MO 63122, (800) 455-2847, catalog; and Gardens Alive, 5100 Schenley Place, Lawrenceburg, IN 47025, (812) 537-8650, catalog.
Privet Problems
Old privet hedges can become quite a sight. Sparsely leaved branches and older dead or dying branches can turn the hedge into a pathetic sight. Sometimes it's a matter of poor maintenance -- usually incorrect pruning. When that isn't the reason, it's time to look elsewhere.
My suspicion is that the hedge is being attacked by white prunicola scale, a small insect that also feeds on lilacs and ornamental cherries and plums. During mid-July, the insect is in its egg stage. Look carefully at the stems and branches, and you should see crusty, dirty gray-brown patches. The eggs provide protection, but when the insects hatch into the crawler stage, from late July to mid-August, they are vulnerable. Spraying them with horticultural oil (follow the label instructions carefully) should help.
Privet is most commonly sold in bundles of bare-root plants early in the spring. Ask your garden center to call you when they arrive.
Sticky Attack
Out wandering among your birch trees one morning, you discover a neat row of holes nearly girdling the trees. Small boys with swords? A coded message from the great beyond? No, it's those woodpecker relatives, sapsuckers.
Your birches are a busy place. The yellow-bellied sapsucker uses them not only for food but also for communicating with other birds in the surrounding area. But the sapsuckers aren't killing the trees, because those neat little rows of holes they drill, sometimes horizontal and sometimes vertical, do not cut off much of the supply of nutrients and water flowing up and down the tree's vascular system. When they rap for communication, they hold their beaks in a way that doesn't injure the tree. The cause of the decline may be birch borer or another problem, but the sapsucker's interest is just coincidence.
Sapsuckers especially like birch and apple trees, but they use more than 275 species of trees, shrubs, and even vines as a place to obtain a one-stop balanced diet. When they find a tree to their liking, they may return to it year after year. Unlike their woodpecker cousins, sapsuckers are not attracted to stressed trees and are not looking for insects under the bark. They simply find the soft inner bark and the sap nutritious, and when the holes fill, the sap attracts and traps insects. When the bird returns after doing whatever it is that birds do between meals, there is a bonus of a little extra protein.
It is possible to discourage the attack, depending on the size of the tree and your climbing ability. Sapsuckers are migratory birds, and they make their tree choices when they arrive, from late March through April. Individual trees can be covered with light plastic netting, although that is usually done only for commercial fruit and nut trees. The visual effect of a tall birch covered in net, swaying mysteriously in the evening breeze, may be somewhat disconcerting. Besides, the birds are beautiful and the damage isn't serious, so why not just relax and get out your binoculars?
Cicada Killers
August brings not just the height of summer but also an insect with a peculiar habit that can be very annoying. Using its large, powerful jaws it digs holes all about, especially in the dirt-filled spaces between patio stones and driveway paving blocks. They never, or almost never, attack people, but they can be destructive in their own way, causing a mess.
They are big, they are ugly, and they are threatening, but mostly they are harmless. These 1 1/4-inch wasps, called cicada killers, give their young a good start in life by burying a paralyzed cicada with each egg. The wasps are easily identifiable by their yellow abdominal markings, rust-colored head and thorax, and amber-yellow wings. Females can sting but normally have to be provoked. Males do not sting, but, as usual, are aggressive and territorial.
These wasps prefer bare soil, sandy areas, or lawns where they dig deep burrows 3 or 4 feet long, leaving small antechambers along the way for eggs. When the eggs hatch, the larvae feed on the cicada, spin a cocoon, and overwinter. The adults emerge in July and August, and repeat the cycle, annoying home owners and golfers (sand traps are a common nesting area).
Since they are around for only a month or so, live and let live is the best policy. If they have really outworn their welcome, a layer of metal window screening buried an inch or two below the surface between the rocks will discourage them, but they may just find another spot nearby.
Squirrel Invasion
For wildlife, squirrels are pretty entertaining. While these clowns are welcomed into the garden by many people, others resent their habit of digging up plants. Old gardener's recipes for keeping them away include sprinkling crushed pepper or mothballs around or in prized potted plants. Apparently squirrels don't read the old recipes, which rarely work for long. If they are driving you crazy, try to put yourself in their place to understand the problem.
The most likely explanation for a squirrel invasion is that either they are using your pots as a larder for burying nuts or they think they have. Squirrels are tough, stubborn, and smart, although they don't always remember where they put things.
Mothballs don't work, and you would have to put an awful lot of pepper down before any self-respecting squirrel would find it offensive. There is a possible home remedy, although it may be worse than the problem. A test by Paul Curtis of the Department of Natural Resources at Cornell University, in Ithaca, New York, showed that woodchucks stayed out of a cabbage patch when a strand of rope surrounding the garden was strung every 3 feet with cloth strips that were sprayed once a month with bobcat urine, hanging down around nose height.
It has to be a leap of faith, but since squirrels and woodchucks are both rodents, and both are the bane of gardeners, maybe it would also work on squirrels. Bobcat, fox, and other predator urine is rather pungent, and a terrace may be too close to an open window or a neighbor, but when gardeners fight squirrels or woodchucks, grasping at straws is an old tradition.
Bobcat urine is available from M&M Fur Company, Box 15, Bridgewater, SD 57319, (605) 729-2535. Fox urine is available from Turkey Creek Furs, 841 West 11th Street, Crete, NE 68333, (402) 826-2516.
Cicada Reminders
By midsummer of 1996, trees in the New York area and other places looked like they were under attack. Branch tips all over the trees were filled with browning leaves and every tree seemed to be dying. Thoughts of mysterious diseases occurred to passers-by, but then the destruction stopped.
The damage was done, but expect to see it again in 2013, the next time the seventeen-year cicadas are due to emerge in the Northeast. Fortunately, the damage is not fatal.
After spending their lives quietly underground, the nymphs emerged from the ground this summer, climbed into trees, and became adults. The males sang while the females deposited eggs in slits they made in the branch tips, where the wood was fresh and soft enough for them to cut into. This kills the branch tips. After a month or so, the eggs hatch, and the larvae drop to the ground and dig in for a new seventeen-year cycle. (They probably stay buried so long because they are embarrassed by the mess their mothers made.)
The Good Earthworm
Are you a friend of earthworms? Do you ever wonder whether they are doing someone, somewhere some good?
Earthworms help decompose plant material, improve the structure of the soil, and make nutrients more easily available to plants. Their tunnels, which may extend 3 to 4 feet down, improve drainage and help the movement of oxygen and carbon dioxide in the root zone. This soil aeration accelerates microbial action, which speeds the breakdown of pesticides.
By all means, stand up for earthworms.
Euonymus Scale
Scruffy, white scales on euonymus twigs and stems are a sign of trouble. The insect that forms the scales is susceptible to treatment with horticultural oil, but sometimes it seems as if the treatment doesn't work.
Euonymus scale is a miserable insect because it is both dangerous (to euonymus, pachysandra, ivy, and others) and well protected inside its hard cover. Since heavy infestations can kill euonymus, especially when repeated over several years, it is important to watch for the signs of scale: yellowing leaves that drop off, twigs that die back, and the tell-tale white or brown scale covers on stems and along leaf veins; or better yet, plant resistant varieties.
Scale insects should be treated with horticultural oil in early to mid-April, while they are waking up from overwintering inside their armor; in early June, while they are in the crawler stage; and in mid-July, when the season's second generation is out crawling. Use the oil only at these times, when the insect is vulnerable. Horticultural oil kills by smothering and has no residual effect.
It is difficult to tell when scale insects are really dead. No tiny bodies pile up at the base of the shrub, and the scale cover remains stubbornly attached long after the insect inside is history. Rub a scale or two with your thumbnail two weeks after spraying. If no liquid squeezes out, the insect inside has died and dried up.
A Crocus Mice Won't Eat
When a mouse is hungry during the winter, it looks undeground for a favorite treat -- crocus.
Mice seem to love all crocus except Crocus tommasinianus.
Other crocus can be protected using a method found successful by Joe Eck and Wayne Winterrowd of North Hill Garden Design Associates in Readsboro, Vermont.
Fill an old plastic nursery container (2-gallon size or larger) with an equal mix of compost and sand until only 6 inches remains. Place the crocus corms so that they are only a corm-width apart, and finish filling with the mixture to the top of the container. Fold hardware cloth (a stiff wire mesh) tightly around the rim. Dig a hole deep enough so that the container is 2 inches below the surrounding soil level. Place the container in the hole; then fill it with soil until level. The crocus will come up through the wire mesh and will be protected against marauders. Winterrowd and Eck have found that planting crocus this deep slows their multiplication, so they do not have to be reset as frequently.
If you don't like the crocus where they are, it is easy to lift the can and replant it without disturbing the corms. It's also easy to create larger drifts by planting several containers in an area. If you don't want to go to the effort of planting in containers, try planting bulbs that mice, chipmunks, squirrels, and voles don't like: allium, Anemone blanda, chionodoxa, daffodils, fritillaria, leucojum, puschkinia, scilla, snowdrops, Spanish bluebells, and winter aconites. When planting these smaller bulbs, don't skimp on numbers, and plant them as soon as you can. Planting depth differs for many of these bulbs, so be sure to check the package.
Sad Glads
Gladiolas are an old-fashioned favorite in cottage gardens, but they can have problems. One common set of symptoms you may see are stems that turn brown, leaaves tinged with silver, and a lack of flowering.
Those glads are showing all the classic signs of thrips, one of their most serious pests. Thrips are tiny insects (the adult females are about 1/16 inch long), and they hide themselves inside the flower bud and leaf sheaths, where insecticides can't get to them. Thrips are very selective about their hosts, so it is unlikely that they came from somewhere else in the garden. If you bought new corms last year, they are probably the culprits.
Thrips can be beaten at their own game. They overwinter under the scales of the corms, so when you dig them up to bring them inside for winter storage, you are also protecting the thrips.
You have two options, each with an excellent chance of solving the problem. You can store the corms between 35 and 40 degrees (but don't freeze them) for at least four months during the winter. This is fine for the corms but kills the thrips. Or before planting in the spring, you can soak the corms for ten minutes in water at 115 degrees, which also kills thrips.
In research done at the University of Florida Agricultural Research and Education Center in Bradenton, soaking the corms reduced the number of flower spikes. But since uncontrolled thrips will eventually infest all of your gladioli and kill them, that may be a small price to pay.
A Tale About Scale
Privet hedges may protect your privacy, but sometimes they need their own protection. Dead or dying branches with white patches, especially near the base, often look like they are infected with a fungus.
It's not a fungus; it's white prunicola scale (Pseudaulacaspis prunicola). Privet, lilacs, and ornamental plums and cherries are the reluctant hosts for this insect.
White prunicola scale prefers the trunks and larger branches, not the tender new growth. Once it finds a branch it likes, it stays put. The soft-bodied insect would be an easy target for predators, but each produces a hard scale for protection. Within this cover, it simply sits there and sucks the juice out of the plant. It's a boring life but an effective survival strategy.
What you're seeing are huge numbers of bright white covers of maturing males, which eventually molt to a winged stage and fly off to find a mate. The females' covers are less obvious; they're larger and rounder but more subtle -- sort of a mousy gray. As with at least one other species I can think of, the females stay home, and the males get to travel.
There are three generations ea look like they are infected with a fungus.
It's not a fungus; it's white prunicola scale (Pseudaulacaspis prunicola). Privet, lilacs, and ornamental plums and cherries are the reluctant hosts for this insect.
White prunicola scale prefers the trunks and larger branches, not the tender new growth. Once it finds a branch it likes, it stays put. The soft-bodied insect would be an easy target for predators, but each produces a hard scale for protection. Within this cover, it simply sits there and sucks the juice out of the plant. It's a boring life but an effective survival strategy.
What you're seeing are huge numbers of bright white covers of maturing males, which eventually molt to a winged stage and fly off to find a mate. The females' covers are less obvious; they're larger and rounder but more subtle -- sort of a mousy gray. As with at least one other species I can think of, the females stay home, and the males get to travel.
There are three generations each year. The females that overwinter on the branches lay eggs in the spring. When those insects mature, they mate and lay eggs in midsummer, giving birth to the second generation. Those young insects mate and lay eggs in late summer.
The key to their control is to get at them when they are most vulnerable: the females before the eggs hatch and the young insects during their crawler stage, after they leave the mother's cover and strike out on their own, but before they can produce their own protective scales.
September is a prime time for controlling them by spraying with horticultural oil (following the label instructions for summer dilution rate or growing season rate).
Fall Webworm
Recently I have been seeing ailanthus trees with what appear to be gauzy bags full of worms. Any leaf unfortunate enough to be inside the bag has been eaten down to the quick. Week by week the bags enlarge, engulfing more and more leaves, and appear to threaten the tree itself.
Common tiger moths lay their eggs in late summer on the undersides of leaves of more than a hundred species of trees, especially trees that are along roadsides or in other open locations. The larvae, aptly named fall webworms, spin webs enclosing both themselves and their food supply, the leaves. The larvae go through several stages of their life cycle within the webs, leaving only when they are ready to pupate into adults. They leave by crawling down the trunk or by the more dramatic route of lowering themselves down a single strand of web, like bungee jumping on a small scale.
Webworm infestations may be ugly but aren't dangerous, and there is no need to treat the problem. Unlike tent caterpillars, which emerge in the spring and can weaken a tree by defoliation, fall webworm emerges when the leaves have just about finished food production and are getting ready to drop anyway. Webworm populations fluctuate for a variety of reasons and you may see more in some years, but they balance out over the long haul.
Sowbugs
Moving houseplants back inside after a long summer out of doors usually means lifting pots and finding a zillion little armadillo-like bugs underneath. Between watching them run away or curl up into a little ball, you have to wonder what they have been up to under there.
Sowbugs, or pillbugs, are commonly found in the moist shelter under pots, but they have no interest in eating your houseplants because their jaws are too weak. Their under-pot diet consists of molds, fungi, blue-green algae, and any decaying matter -- stuff that you don't particularly want under your pots anyway.
By the way, sowbugs are not insects; they are crustaceans, with eleven pairs of legs, and are distantly related to lobsters.
Hemlock Wooly Adelgid
Insects and diseases are usually pretty specific about which plant species they attack. A neighborhood hemlock is infested with something that looks like a wooly aphid, and they appear to migrate into your yard, settling on some of your shrubs. The issue is whether or not to take action.
Your dogwoods and hydrangea are in no danger, but your neighborhood's hemlocks are in a life-and-death struggle. Hemlock wooly adelgid (not an aphid) is very host specific, attacking only hemlocks.
Mark McClure, chief scientist at the Connecticut Agricultural Experiment Station in Windsor, says he does not know of any insect pest that would attack both hemlocks and dogwoods or hydrangea. The adelgid excretes a waxy mass with the appearance of cotton or wool fluff, about the size of a tightly wound cotton swab, as a way of both protecting and raising the humidity level around itself and its eggs. This material is dry and light, and can be dislodged, letting wind or animals carry it about, with some of it coming to rest in your garden.
The hemlock wooly adelgid is voracious in large populations. Left untreated, healthy hemlocks will be killed in four to six years, and trees in poor condition can die in just one or two.
Hemlock adelgid can be treated with horticultural oil or insecticidal soap any time the weather remains above freezing, usually between April and late October. Since there are two generations each year, McClure recommends a thorough drenching of all parts of the tree in April and then in late June, or in the fall and again in mid-May.
At War with Voles
Voles. They tunnel in your garden and gnaw at the roots of vegetables and foundation plants alike. Probably among the cures that haven't worked for you is placing mousetraps baited with apples, peanut butter, and even small pieces of Juicy Fruit gum in their holes. Now that many gardeners are trying to keep to organic principles, it would be nice to have a simple way to deal with these voracious pests.
Not that you really care what kind of voles you have, but if you are seeing their runs -- the surface mounding that is a result of tunneling -- you have meadow voles. Pine voles, which tunnel deeper and attack roots, are harder to catch, but for trapping either kind, apples, cunning, and patience are the keys. Paul Curtis, extension wildlife specialist at Cornell University, said home remedies don't work, nor do the grain-based poisons on the market because voles don't like grain as much as they like nearly everything else in your garden.
Two traps will work. Harpoon-style traps are buried upside down over a section of the tunnel that you first flatten. When the vole tries to clear the tunnel, he springs the trap. Mousetrap-style traps are baited with food and left near exit holes. Apples are Curtis's favorite bait, but voles are easily frightened, so the trap should be made cozy by protecting it with a tent made of a folded piece of a roofing shingle. (Leave enough room overhead for the trap to spring.) An upside-down shoe box with a 1 1/2-inch hole on each side and a rock for a weight will also work and has the added benefit of keeping most other animals out.
Voles prefer mulched plants, so clearing down to bare ground may discourage them from eating specific plants. And don't confuse voles with moles. Voles eat plants and have typical rodent front teeth like squirrels, short tails, and tiny ears. Moles eat insects, their teeth are sharply pointed, and they have enlarged claws on heavy front paws, perfect for digging.
Under certain circumstances shotguns are considered organic, but I'm not so sure about Juicy Fruit.
Saying Goodbye to Gnats
Water a ficus tree and sometimes a small cloud of tiny brown bugs takes off from the soil and hovers around until the flood of water goes down, whereupon they simply disappear. It's as if they were patiently waiting to keep their feet from getting wet. Whether you are good with houseplants or not, this sort of thing can be disconcerting.
That little cloud of bugs is most likely fungus gnats. It should bring the pride associated with ownership of a miniature ecosystem, but many people prefer to own plants without the associated wildlife. The weak flying adults are slender, long-legged, with long antennae, clear wings, and dark brown or black bodies, about 1/8 inch long. Altogether it is a very stylish pest, and one that does little damage.
Over a three-week life cycle, eggs become larvae, which form pupae, then adults. Adult fungus gnats get around, usually coming into the house on other plants or through windows. They lay eggs in the rich, damp soils that are inevitably home to decaying plant material and microscopic communities of algae and fungi. The larvae dine on these entrees and occasionally on the fine root hairs of the plant.
To see if fungus gnats are the problem, place the cut side of a raw potato on the soil for 3 to 4 days. When you pick it up, if larvae are present, you will see them on the soil under the potato, or see their tunnels in it. Unless the population is large, they are simply a nuisance. Repotting in sterile soil and not keeping the soil too wet -- and keeping the house a bit cool -- can help. High infestations can be controlled during the larval stage with the product Knock-Out Gnats, a strain of Bacillus thuringiensis (Bt), bacteria that produce a substance that is toxic when ingested by the larvae. Since pupae and adults are not affected, more than one application is necessary. As with any other control product, read the label and don't be tempted to improvise on the instructions. It is available from Gardens Alive, 5100 Schenley Place, Lawrenceburg, IN 47025, (812) 537-8650.
Adult populations can be monitored, and reduced, with Sticky Traps, yellow 3- by 5-inch cards covered with a sticky material and laid horizontally across the pot. Yellow seems to attract gnats. The traps are available through Gardens Alive and Gardener's Supply Company, 128 Intervale Road, Burlington, VT 05401, (802) 863-1700.
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