Pest management

Controlling various pests in the garden railway
The sign says it all-the never-ending task of gardening.
Don Parker
Spotted (or prostrate) spurge (Euphorbia maculata), growing in the tracks, is one of the problem weeds on the author's Rustin and Decrepit.
Don Parker
Pete Moss is having a run-in with one of the local wildlife pests in Decrepit.
Don Parker
A harpoon trap to control moles, in set position with harpoons poised over a mole tunnel.
Don Parker
When it comes to outsmarting the peskier side of Mother Nature, it's best to have a plan. Otherwise, as attacks by garden pests continue and our frustration level rises, we might overreact and cause more harm than good. In the horticultural world, this plan is called IPM, for Integrated Pest Management (or, in the vernacular, don't mess it up if it ain't broke). In the line of "pests" we might include weeds, plant diseases, insects, and wildlife.


Any plant growing where you don't want it can be considered a weed. However, for our purposes, let's just consider the usual invasive crowd of garden thugs. The first line of defense is physical. To keep grass and other creeping growers out of target areas, use a barrier-plastic lawn edging or other impediments. For weeds that blow in as seeds, getting physical means good, old fashion weeding. Weed after a rain, when plants are easier to pull out of the damp soil; weed when plants are small (when their roots aren't so deep and they haven't yet gone to seed); weed regularly for short periods of time-don't try to do the whole garden at one time and don't wait until it becomes a Herculean task.

The second level of defense is taking advantage of plant competition (aiding desirable plants vs. weeds). Good plant culture-including proper soil preparation, choosing the right plant for the site, proper planting and spacing, correct fertilizing and watering, and 2-3" of organic mulch-will give our desirable plants a head start and competitive edge over the weeds.

The third weapon in our armamentarium is chemical controls, to be relied upon only if the above two defenses are not effective. Here are some of the more common ones.

Pre-emergent controls prevent seeds from germinating or growing after sprouting. One of the more familiar pre-emergents is trifluralin (available to homeowners as Preen). To be effective, this agent must be incorporated into the soil (cultivated into the soil and watered to dissolve) and must be applied before weed seeds begin germinating. (In USDA Hardiness Zone 5, this is mid-March into April to control summer annuals, and late August through September to control cool-weather-germinating annuals; perennial weed seeds will be controlled both times). Corn gluten, an organic agent that is a moderately effective pre-emergent weed controller, is a by-product of the animal-feed industry. It is available as WOW (Without Weeds, sold by Gardens Alive) or Safe 'N Simple (made by Blue Seal Feeds and found at some garden-supply or farm stores). It is a good source of nitrogen for plants, containing about 10% nitrogen by weight. It also must be watered into the soil to be effective.

Post-emergent chemical controls are either selective or non-selective. Examples of selective controls include Fusilade II (fluazifop-p-butyl), which kills most grasses and spares most broad-leaved plants, and compounds containing 2,4-D such as Weed-B-Gon, which kills most broad-leaved plants and spares grass. The prime directive here is "always read and heed the label." When it comes to chemicals, there's not much room for backtracking once you've applied them to plants. Non-selective chemicals are toxic to all plants, although to varying degrees. Of several compounds available to the general public, glyphosate (Roundup) has a better safety-to-toxicity ratio. Glyphosate is quickly broken down in the soil and is only effective when absorbed directly by growing plants. It should be applied when temperatures are over 60° F, plants are actively growing, and rain is not expected for 24 hours. Spray when winds are calm and/or use a piece of cardboard to protect desirable plants. Some plants can be relatively resistant to glyphosate, requiring repeated applications. These include mature, larger plants, or those with extensive root systems.

Plant diseases

Plants are susceptible to bacterial, viral, and fungal diseases, just as other life forms are. The problems these pests cause to plants are harder to recognize and diagnose, making appropriate treatment choices more difficult. Prevention is by far the best medicine in this case. Good cultural practices are the foundation of disease control. In addition to those mentioned above, we should add good air circulation through plants to prevent moisture-loving fungi from attacking. Overhead water only in the morning to allow the foliage to dry during the day. Space plants to avoid overcrowding.

Some new data show that compost is a potent disease preventer: micro-organisms in compost out-compete or inhibit soil pathogens (microscopic thugs), and some composts induce systemic resistance to disease in plants. Use homemade compost or composted leaves from community sources to amend the soil and spread on the surface as a mulch. If you find a favorite plant that looks sickly, it's best to take a sample of plant material to your county agriculture extension agent for diagnosis. Trying one ineffective spray after another only worsens the chance the plant will survive.


Insects often come to mind first when we think of pests, but insects are more likely to be beneficial than harmful. There are many more insects on our side than the few thugs that give the rest a bad name. Establish in your mind a pest threshold-how much damage can you tolerate? Does the damage appear only on close inspection? Does it threaten the vigor or survival of the plant? Are there only a few insects visible? Are you willing to watch for a while to see if the damage progresses?

Choose your weapons wisely. The best offense is, again, a good defense. Cultural practices that produce strong, healthy plants will go a long way in keeping up good pest resistance. When damaging bugs are detected, the first choice is mechanical control: pick off pests, wash them away with a stream of water, and use barriers (such as diatomaceous earth against slugs). There is nothing as satisfying as knocking a Japanese beetle into a can of water with a little dish soap on the surface.

The next class of weapon is biological: predatory insects, such as lady beetles to attack aphids; microbes, such as milky spore against Japanese beetles; and BT (Bacillus thuringiensis) against many caterpillars. These are selective in their attack and will not harm beneficials. Non-selective agents include chemicals made from botanical sources, such as pyrethrum, rotenone, and neem oil. The first two are contact agents, killing insects when sprayed directly on them (found in many household and garden insect sprays). These are toxic to most insects and should be used carefully, targeting the offending pests and guarding the beneficial ones. Neem oil, sprayed on foliage, controls chewing insects when they ingest it. For those of you who hate spiders, I must inform you that spiders are the primary predator of insects: i.e., one of the good guys. I'll even put up with spider webs in my tunnels (and on the front of my locomotives) knowing these vigilantes are on patrol.

Synthetic insecticides vary in toxicity-choose the least toxic first. Insecticidal soaps (Safer Soap, and others) are effective against soft-bodied pests, such as aphids, mites, and soft scale. Horticultural oils suffocate over-wintering pests on dormant plants when temperatures are over 40° F. These are less toxic and have minimal environmental side effects. Most other synthetic insecticides and fungicides are rapidly acting and more effective in the short term and are longer lasting than botanical chemical agents. The need is to balance the wanted pest control against the potential toxicity and residual harmful environmental effects. Always read the label for directions and warnings.


I won't deal with larger forms of wildlife pests (deer, rabbits, groundhogs, etc.). The mammal many garden railroaders complain about is the mole. Moles feed on grubs and earthworms. If Japanese beetles are prevalent in your garden, then plenty of their larvae will be in your lawn-and, probably, moles enjoying them. Many advertised mole controls are pretty useless. Included among these are the "sonic" mole deterrent (a mechanical vibrator stuck into the ground), castor-oil drench, and smoke "bombs." Poison pellets may work but are too hazardous for most households with children and pets around. The recommended and most effective means of removing this offending critter is a killing trap-either a harpoon trap or a choker trap. These are not for the squeamish. But if you have had your track raised, your buildings pushed cockeyed, or your small plants heaved out of the ground enough times, you tend to lose any mercy for these furry invaders.

Mail order sources

Gardens Alive
5100 Schenley Place
Lawrenceburg IN 47025


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