The Complete Guide to Landscape Design, Renovation, and Maintenance
by Cass Turnbull

PESTS AND DISEASES
The "eekstomp syndrome" is what our local Extension Agent, Sharon Collman, calls it. The homeowner sees a black beetle on the sidewalk--EEK, they STOMP it dead. Those black beetles are valuable predators in your yard: they eat the bugs that eat your plants. People hate bugs. They assume that all bugs are bad bugs. People think that if they get a powerful enough spray--one that gets everything--they can put an end to what they think are invading insect hoards. They fear that, if they don't do something, the bugs will proceed unchecked to decimate everything in the yard.

Predator/Prey Relationships
The truth is that the vast majority of insects and other critters in the yard are doing minimal harm and many others are doing a lot of good. Another little-appreciated fact is that nature, even in your backyard, is, for the most part, self-correcting. The miniature world of bugs is an entire ecosystem. Some bugs reproduce fast and eat a lot--like rabbits in the world of bigger animals--and other bugs are predators--the wolves. When you have an outbreak of plant-eating insects, they reproduce much faster than their predators. It takes awhile for the predator population to catch up. For example, aphids may become quite numerous before the wolves (ladybugs and lacewings) reach numbers sufficient to destroy their population. Refer to the accompanying graph of typical prey-predator population cycle. Usually the homeowner panics just as the predators really start to get going. Pesticides often wipe out the predators as well. This leaves an open field for the prey, the aphids "bunnies" (some of whom always escape or hatch later or fly in from next door), now totally unchecked, to reproduce like crazy. You will get a rebound, a population explosion. And then you will have to spray again, and again, and again.

The adage to remember here--and it works in all nature--is, "If you kill the predators, you inherit their work." There are lots of predators in your yard. Some are nice looking and easily recognized, like birds and ladybugs. Others look just as icky as all those other bugs--spiders, wasps and flies, beetles and the impressively grotesque praying mantis, whose name is a double entendre.

Other natural checks on pest populations include their own collection of yet tinier parasites and diseases. A good example of this is the tent caterpillar. It doesn't taste good enough for most birds to eat, but a very specific fly likes to lay its eggs on their bodies. The larva from these eggs eat the guts of the caterpillars. Incredibly gross! You can see it for yourself. Find some tent caterpillars and look for the distinctive white dot or dots--those are the eggs. A dotted caterpillar is a doomed caterpillar.

"Great bugs have lesser bugs
Upon their backs to bite 'em
And they in turn have lesser bugs
And so ad infinitum."

People will panic. They should know that most healthy plants can withstand a fair amount of damage. A healthy broadleaf tree can even be totally defoliated for a year by tent caterpillars or whatever, and return just fine. One-fourth of total leaf surface damaged is considered the rule of thumb for human intervention in an ornamental landscape, though.

Watching Nature at Work
At the time this book is being written, my area has entered the second year of tent caterpillars. Last year they were so severe that entire groves of alder trees stood with branches as barren as in winter, but in mid-June. It was then that I realized I was seeing "natural selection" in progress. The trees that would actually die would be the ones that were already weakened. For whatever reason, the defoliation would simply polish them off. The fittest would survive. Nature was thinning the alder grove, just as the farmer thins the row of young carrots, leaving the most promising ones. This year, the nests or tents were fewer and in the city just simply failed to produce vast quantities of adult caterpillars. Nature, not chemicals, checked their progress. (There is evidence discovered by Drs. David Rhodes and A.B. Adams that the plants change chemically and become less tasty.)

Pesticides are often non-selective. They kill both the predators and the prey alike. This results in an unchecked population explosion of unwanted pests. Your yard has become chemically dependent.

Mankind is becoming increasingly skillful at eliminating species of plants and animals. We are best at destroying birds, but we do well with mammals and reptiles, too. However, try as we may, we have never been able intentionally to eliminate a single pest species of insect using chemicals. The common reliance on large quantities of pesticides has, however, had the alarming result of selecting for pesticide-immune bugs! Malaria, a disease carried by a certain type of mosquito, was all but beaten by the use of DDT to destroy the bug. Because of the insect's rapid rate of reproduction, however, we now have breeds that are not affected by the commonly used pesticide. Farmers are finding out these hard facts about "controlling nature" now, too. Some continue to cover spray and hope that chemical scientists will be able to invent new weapons as fast as the insects can mutate. More and more farmers are selecting pest and disease-resistant plant varieties, while encouraging natural predators and parasites, and becoming tolerant of low levels of damage. These are looking like wiser and wiser alternatives. They are wise choices for you, too.

Host Specific Pests
Something which is not commonly known is that most pests and diseases have only a few favorite plants, and many plants have specific pests that especially like them. I know, for example, that if you have a birch tree, you have, or will soon have, aphids and honeydew. If you have a native or eastern dogwood, it is likely to have a fungal disease that scorches leaf tips, called Anthracnose. Your weeping cherry probably has blossom brown rot and your rhododendron has root weevils munching little notches in the leaves; your blue spruce has spruce aphids that are causing all the inside needles to brown and fall off in the summer, long after the aphid itself is gone. Your deciduous azaleas and Oregon grape have something that looks like powder on them (powdery mildew), and in addition, your old deciduous azalea has a grayish lichen on the branches and stems, which isn't actually hurting the plant at all, it just lives on the plant.

Other organisms can even be "symbiotic," which means they actually help their hosts. A common, thread-like type of fungus called "micchorizae" lives in association with the roots of some trees and plants. It takes nutrients from the roots but in return it helps the roots absorb water and elements from the soil.

Ninety percent of the bugs in your yard do no significant damage to your plants. Many are beneficial insects like this praying mantis.

Knowing that most pests are fairly "host specific" (they like only one or two kinds of plants) may keep you from panicking and spraying your whole yard for fear that what your dogwood has is going to spread. It will also help you to diagnose your plant's problem. Accurate diagnosis and good timing are keys to effective treatment.

The numbers and types of pests that want to lunch on your trees and shrubs are vast. They can be divided into several large categories which determine what you can spray to stop them. There is no one chemical that gets them all. There are the so-called "broad-spectrum" pesticides that get whole sub-groups of insects. However, they often get the beneficial insects as well. Reliance on broad spectrum pesticides will also hasten the day that the bugs become resistant to them. Horticulturists now advocate using as narrow and focused a product as you can get in order to reduce the impact on the rest of the environment as much as possible.

Disease Categories--Pest Diagnosis
General categories of insects and diseases are as follows:

Plant disease organisms:
- Fungus and bacteria (including root rots)
- Virus--little chemical cure available

Insects and mites:
- Chewing insects: caterpillars, beetles and sawflies, for example
- Piercing-sucking insects (such as aphids and scales)
- Mites

You must find out what you have in order to treat it. The insecticide you used to kill a caterpillar, won't work on a fungus disease. And chemicals will not kill a virus. Many insecticides used to kill caterpillars on your tree will, if they get on the clover flowers in your grass, poison foraging honey bees, which will take it back to the hive and kill all their buddies and larval bees, too.

For caterpillars you may be better off to use Bt. Bt is short for Bacillus thurigiensis, a naturally occurring disease that kills just caterpillars. It is the active ingredient in several brands of sprays.

Bee kill is a big problem. Bees are the gardener's friend. We must have them to pollinate our fruits and vegetables. Environmental precautions are listed on the label. Once again, the label on any container of pesticide is a legal document--it must be read and the instructions followed. It will tell you if it can kill bees or poison the fish in the water. It also lists the exact plants and bugs or diseases the chemical will get.

You must take the time to sit down with your magnifying glass and read and understand it ALL. Then, FOLLOW THE DIRECTIONS. If it cautions you to avoid spraying plants in bloom, then AVOID SPRAYING PLANTS IN BLOOM.

Timing
Just to make matters more complicated, it is a simple fact that proper timing is crucial to good pest control. Not only must you diagnose your pest, you need to know the vulnerable point in its life cycle. The window of spray opportunity for some species of scale is, for example, only a couple of weeks in the spring when they are in their crawler phase.

Cover Sprays
Seem pretty complicated? Well, it is. I guess this is why people resort to general sprays. Some chemical spray companies provide cover spray service to homeowners by coming four to six times a year and blasting everything in sight with a barrage of different chemicals. Because this kills all the beneficial organisms as well, the homeowner is locked in to the pesticide treadmill. When weaning chemically-dependent yards from cover sprays, one often experiences a small explosion of pests because the beneficial organisms are absent--sometimes confirming in the mind of the homeowner the need for spraying.

I suggest people avoid becoming chemically dependent on cover sprays. Just say NO! Not only are we pouring gallons of poisons into the environment (see tales of horror in the chapter on weeds) that do God-knows-what to beneficial insects, birds, pets, people, and the ground water, it's also a terrible waste of money and chemicals. Often they spray for pests that are long since departed, or because of poor timing, their sprays miss the target. It hastens the day when the pests develop resistances to the sprays and then we will be in even worse trouble. It is as if you treated your own health by having a doctor come by four times a year and give you massive doses of penicillin, pain killer, and radiation therapy, just in case, whether or not you had anything wrong. Well, that's one way to do it.

Itegrated Pest Management
To manage your garden, I recommend following the principles of IPM, which stands for Integrated Pest Management. It is a decision-making approach that looks at the problem from several integrated methods, based on the pest, its stage of development, and the site.

Foremost among these is preventive maintenance by keeping healthy plants and a healthy ecosystem. As John Davey, the father of modern arboriculture, said eight decades ago, "Good health defies disease!" It's true. Bugs and diseases pick on unhealthy plants. The sap or pitch in a healthy tree will actually blast off and drown an insect that pierces its skin. Unhealthy plants can least withstand even moderate damage.

In an earlier chapter I described moving some azaleas farther apart. When I did so, I added dried manure and organic matter to improve the soil. Previously they had been perpetually eaten and tortured by root weevils. Now there is only the occasional munch mark. If you follow the advice of previous chapters (good soil, eliminate weeds, cut out dead wood, rake up leaves if they are diseased, not too much or too little water or fertilizer, right plants, right place) you won't have so many disease and insect problems.

If there is really a need for chemical intervention (and that's a big IF) use the least toxic and most pest specific chemical.

When a broad-spectrum pesticide is chosen, aim it at the target pest and affected plant only. If it can harm bees, don't use it when the plant (or underlying clover) is in bloom. Don't spray everything else in the yard "just in case." Try alternative methods of control. Dormant oils can be used in the winter to smother egg masses. Oils are just that--oil--and some kinds are used to smother scale crawlers, aphid eggs, and mites, too. Timing, again, is very important. A whole line of insecticidal "soaps" is becoming more widely used--either alone or mixed with reduced concentrations of chemical pesticides. Davey Tree Expert Company is leading the way with accurate research in this program of soap-chemical pest control. The soaps are especially useful in controlling soft-bodied insects such as aphids and scale in the crawler stage.

Many diseases are aggravated by gardening practices. Watering at night places water on leaves during the cool time so leaves don't dry off. Wet leaves during warm (60 to 70 degrees) temperatures are ideal for some fungus diseases such as powdery mildew, rose black spot, and some vegetable diseases. Early morning watering allows leaves to dry fast.

Proper diagnosis of the disease or insect problem will help you avoid over-reacting. Find out whether you are dealing with "cancer" or just the "common cold." If you find phythopthora, a very contagious and devastating root rot, you have good cause to consider chemical treatment. If it's just a spit bug, ignore it. Tolerance is the watchword.

When you feel you have to, spot spray with chemicals, use the right ones, follow directions, and pay attention to timing.

Cooperative Extension Services
Here again, the Cooperative Extension Service of your state's land grant college is a valuable resource. Many states or counties have Master Gardener programs as well. You can take a piece of affected plant and/or the bug into a plant clinic and the volunteer will help you diagnose it. Be advised that a weak plant may attract several insects or diseases and, if you are lucky, the predators of those pests. Don't assume that the first bug you see is the one responsible for the damage. The Cooperative Extension Service also has inexpensive bulletins describing common pests and their cures. Some may have taped phone messages, such as my county "Dial-Extension." The really nice thing about the Cooperative Extension Service is its staff of specialists who are well-versed on the specific pest or soil problems and plant requirements of your own area. Their information is given on research-based facts not gardener mythology, and the price is always right.

Other Tips For Pest Problems
It may also be useful to know that your garden is a little more prone to pests and diseases when it's new, before the web of checks and balances has developed and your plants get older and tougher.

The problem with using garden pesticides responsibly is that you are apt to have a headache from reading all that fine print on the labels. Having to know the names and life cycles of many pests can be a daunting assignment. Keeping a healthy yard and only treating the few persistent, predictable, serious and unavoidable problems may make it seem less overwhelming. It certainly makes better sense than trying to eliminate all pests.

In my area, the only plants for which I sometimes recommend homeowners seek chemical help (after following good cultural practice) are cherries, for brown rot; fruit trees--especially, for scab; roses, for black spot; dogwoods, for anthracnose; and blue spruce. Your area will have its own predictable problems list.

Root weevil populations in azaleas, rhododendrons, primroses, fuchsias, pieris, salal, bergenia, sometimes get out of hand and may occasionally need spraying with appropriate chemicals. Chronic chewing and shredding of leaves year after year, however, indicates a cultural problem, like poor drainage or insufficient water or susceptible species. Lists of resistant species are available through Extension Agents and nurseries. Know that you will always have some damage. The plants can take it--if you can.

Moles
Mole populations occasionally expand beyond acceptable proportions. The population may "crash" naturally, or you may choose to intervene. Moles, by the way, do not eat plants. They are carnivorous. They eat worms and the like. Mice that use mole tunnels eat plants. Usually people want to get rid of moles because they are just sort of tearing up the place. (The irrational actions of some in response to mole hills may be where the phrase "making mountains out of molehills" came from.)

Mole remedies number in the scores. Most problems that have 101 solutions, have none that work reliably. Mole cures that don't work include pouring various nasty liquids down the hole, gassing them with exhaust from your car, windmills and whirlygigs that rattle and blow in the wind (the vibration is supposed to chase them off), cat hair in the hole, various plants that they presumably hate, laxatives, and, my favorite, chewing gum. The only proven cure for getting rid of moles is the scissor trap. Correct placement in a major underground arterial runway is necessary. Sometimes one needs to modify the trap to catch the smaller species. Information on trapping is also available from your Cooperative Extension Service.

Bees, Yellow Jackets, Wasps
Bees, yellow jackets, and wasps are not created equal. Bumble bees, for example, are extremely slow moving and docile. These are the big fat almost furry-looking ones. Black and yellow or orange. They always make me smile--I think of them as the teddy bears of the insect world. You'll have a hard time getting a bumble bee to sting you. You'll have to step on it in your bare feet, probably, or dig around a nest in the compost pile and insult its mother. Honey bees, a little sleeker, honey to brown in color, are smarter and a little touchier. Generally speaking, if you don't bother them as they go about their business collecting nectar and pollinating, they won't bother you.

Meat-eaters, like yellow jackets and bald-faced (white faced) hornets are more likely to nail you if you get too close to their nests. The bald-faced hornets are especially hot headed. Their white bald heads are quite distinctive. If they feel threatened, they will chase you down, drill you with their stinger, and send their pals after you, too. And they hurt! When I'm weeding and I look up to find a paper wasps' nest two feet from me in some shrub, my heart skips a beat. But only if a yellow jacket or hornet nest is actually too close to human habitation do I bother dealing with it. Places like the children's play area or your front porch. After all, these insects are predators and serve useful functions in the garden. I just avoid working around the nests. Bald-faced hornets will not scavenge in picnic areas. However, a major problem with the common yellow jackets is they pester at picnics, around garbage cans, and at the edge of water sources. Yellow jacket nests may need to be eliminated for this reason. I'm allergic to yellow jackets and carry pills with me for when I get stung, usually once a year, but I'm in the business, as they say. The average person won't get stung for years and doesn't need to worry unduly.

Working as a Master Gardener, I once had a woman ask for a chemical to kill aphids. I suggested she just put up with them on her maple tree. But no, she insisted. She had just had her tree radically topped so she could spray it all over to kill the aphids, because they created honeydew, and someone told her if you have honeydew, you will have yellow jackets. And, well, her husband was allergic to their stings. People have unreasonable expectations for controlling the natural environment. You might as well stop driving because you might die in a traffic accident. The rational answer is, use good sense, and be reasonably cautious as you go about your business.

For that nest just outside your door, several products will give you good control. Spray cans of hornet killer will shoot up to fifteen feet, will even freeze them in mid flight and totally wipe out the nest when you soak it. You will want to use it at first morning light or late at night when the hornets are all quietly at home, asleep, not during the day when they are buzzing around defending their territory.

Slugs
Last on the list of common pests in this area is SLUGS, omnipresent SLUGS. I've only had to spray a few times in my yard to keep a couple of diseases in check, but I always bait for slugs. You can help keep slug populations down by destroying their hiding places and places they lay their tiny, pearl-like eggs (which look like Osmocote). These places are the dark and moist nooks and crannies. Eliminate piles of leaves and debris, and areas of weeds. "Organic" methods of control include hunting at night, either stabbing them with trowel or tossing them in a pail of soapy water. Ick! Other people place saucers or pans of beer (seriously!) on the ground. Do not sink the saucer to ground level or you will get the good beetle predators as well. The slugs come from miles around to climb in, get drunk, die blissfully and dissolve. Still, too gross for this gardener. I use bait. Slug bait is made of methaldehyde, usually on an apple pumice or bran base. It's very attractive to slugs and very deadly. Unfortunately, some may attract and poison birds and dogs, too. Therefore, you will have to hide the bait, under boards or some other way. Some people place bait in a plastic container with lid, like cottage cheese containers. They cut a hole in sides or lid to allow slugs entry and to keep it off soil and away from birds, kids, etc. This also keeps the bait dry. Stores sell small brown bait umbrellas that look sort of like mushrooms, too. You can push one of those over your pile of bait to hide it from the dogs, protect it from the rain, moist soil, and sprinklers, which destroy its effectiveness after a few days. I sometimes use Go-West meal, which you sprinkle lightly around--the idea being that it's not in a big enough quantity to cause harm. It claims to have moderate effect in controlling root weevils as well.

IPM Spray Services
The smarter companies in the pest-control business are now moving toward programs utilizing several or all the principles of Integrated Pest Management. Instead of coming home to a yard full of shrubs dripping in chemical pesticides, you come home to a pest-monitor report hung on your doorknob. It means that you are paying someone for what they know, to regularly check your trees and shrubs, assessing the pest and disease situation. They can spot early warning signs, when intervention is most successful. Most homeowners call up and ask for help when the damage has maxed-out and the pest may even be gone. If you get a really good company they will recommend chemical controls for only the most serious problems, not every little bug that takes a nibble. Many companies offer a full care program for your yard, including proper pruning and fertilizing. It would seem that the concept of preventive medicine through good health is an idea that is catching on--for people, for the urban environment, and for the planet as a whole.

SUMMARY
To summarize intelligent pest management:
(1) Good health discourages pest and disease problems. Good soil, water, pruning, garden hygiene (weeding and raking leaves).
(2) Be tolerant of a certain amount of damage because it allows enough food sources (bugs) to keep the predators alive, which will, in turn, help check the population of the pest. Just remember, some caterpillars turn into pretty butterflies or moths that become bird food. Think about it, you may care to share your plants.
(3) Use disease resistant plants and correct placement. Right plant, right place.
(4) Correct diagnosis. Find out what it is, if it's really a problem, when and how to control it.
(5) Try mechanical and cultural controls.
(6) When using chemical controls:
a. read the LABEL--ALL OF IT.
b. right timing.
c. spot spray.

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