Monitor for Signs of Trouble

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A monitoring tool box might include a good bug book, a hand lens, and specimen jars.Click To Enlarge

A monitoring tool box might include a good bug book, a hand lens, and specimen jars.

Photo: Scott Phillips

by Helga Olkowski
April 1997
from issue #8

If you want to lose weight, chances are you will combine several strategies like exercising more, eating a low-fat diet, and drinking a lot of water to achieve your goal. You’ll also monitor your weight regularly to see how you are
doing. You might use a bathroom scale, that pair of pants that is too tight around the waist, or your image in the mirror to detect those pounds slipping off. Likewise, if you want to reduce pest problems in your garden, follow the same approach by combining a number of strategies and then monitoring regularly to see what’s happening.

Be consistent and write things down. Monitoring means regular observation. Professional pest management specialists monitoring a landscape usually check it at least once a week during the growing season. Then, if a problem does show up, they might check it more frequently. If any kind of control strategy is implemented, they will monitor both before and after to see the results.

Most gardeners already monitor their gardens in an informal way, but often by the time they notice a problem, it may be too late to manage it in a non-toxic manner. Also, human memory and our busy lives being what they are, it is often difficult to remember the exact conditions observed at a previous time. So, the key to effective monitoring of anything, whether it be your weight or garden pests, is writing down what you see.

A simple and effective way to record your observations when monitoring is to keep a garden log. The log might be combined with other gardening notes, such as when you planted early lettuce and whether a particular tomato variety was productive and tasty. Or, if you had some especially nasty pest problems last year, consider a little notebook just for pest management records.

One form a garden record might take is a sketch showing the positions of garden plants in a map layout. Perhaps you made such a map when you planned out your vegetable plot initially. Be sure all of the plants are labeled, then make copies of the map, staple them together, and you have an ideal form on which to jot down your observations. Be sure to date each page as you fill it out. Write your observations in a color that contrasts with the background map.

Simple tools of the trade. Many insects are tiny, so a hand lens is a great tool to have with you in the garden. Also, you may wish to stuff a pocket with some containers to hold collected specimens. Prepare a few empty pill bottles by pasting on a fresh label and making a tight cotton-ball stopper for each. Don’t use the air-tight cap that comes with the bottle because any specimen you put inside will mold from the moisture. A plastic bag or two might also come in handy for larger samples of leaves or plant pieces that are showing symptoms of disease. Blow up the bag and close it tightly with a knot so air surrounds the sample.

Learning to read the clues.
At times, it’s hard to tell what’s important and what isn’t in the garden. In general, it’s safe to say you are looking for creatures, large and small, that are out there on or around your plants. Also look for plants that seem to be doing poorly and have noticeable changes in the color or texture of their foliage. If you are a beginner, you may want to jot down everything that strikes you as unusual, whether it’s leaves wilting, weed germination, or unidentified worms in the soil.

Sometimes you see damage without knowing what caused it. But by careful observation you will learn to spot the clues. Slime trails mean slugs and snails, and pin size, round holes are probably flea beetles. Thrips rasp off the surface cells of the leaves making them pale and slightly shiny. Cutworms sever very young seedlings at the base, leaving the tops lying nearby, and caterpillars and weevils often eat semi-circles in leaf edges.

Now and then, you can guess the type of pest problem from the frass, or insect manure, left behind. For instance, thrips leave tiny brown spots on leaf surfaces, plant insects like lygus bugs leave smallish brown spots, but tomato hornworms leave relatively large fecal deposits. Eventually, as you become attuned to the wildlife in your garden and keep notes you can refer to later on, you will become adept at linking plant damage with the critter responsible.

Putting a name to a face.
You may come across an unfamiliar insect and wonder if it is a plant eater or a beneficial insect that eats plant eaters. This is when you whip out your prepared, cotton-stoppered pill bottle. On the label, write the date and plant from which you collected the insect. Specimens you want to kill quickly and save can be put in the freezer overnight.

Once you have your specimen, how can you identify it? Luckily, there are a number of good illustrated books to help you. Your library is another good source. Knowledgeable folks at the local garden club, plant nursery, community college, or cooperative extension office can help you decide what kind of an insect you have, even if they cannot put a species name to it. If you are lucky enough to have a master gardener program in your area, stop by the office with pill bottle in hand for help.

Quantifying what you see. If you think trouble is brewing, make an effort to quantify what you see. Often, quick action, like hand-picking insects, will prevent extensive damage. Drop the undesirables into a wide-mouthed jar half-filled with water and strong detergent. Count how many bugs you pick, either per plant, per yard or row, or per branch or leaf, and write it down. Then, if you have the same problem the following week, you will know if it’s getting better or worse.

The fun of monitoring begins when you go back to look the second, third, and fourth times. Now you have records that enable you to make comparisons with earlier conditions. You can begin to correlate the numbers of pests you see with the damage they cause. But don’t panic prematurely. A lot of plant-eating insects in the garden means a lot of their natural enemies will come around, too. So, there is no need to control anything unless you think the damage will become truly intolerable.

If you wait, the predators and parasites of the pests may suppress them. Then you will have observed a great process at work—natural control.

Finding out what works. By monitoring regularly you will be able to determine just how many pests it takes before action is required. And, since you’ll be watching what’s happening, you can catch the pests before their numbers build up. If you decide to take action, by spraying with insecticidal soap for instance, make counts before and after so you will know if the treatment worked or not. Ideally, a good monitoring program helps you figure out the least toxic approach to reducing pest damage in your garden.

Good insect guides

Take one of these books into the garden with you. They all contain excellent color photos and information on insect habitat, life cycles, and feeding habits.

National Audubon Society Field Guide to North American Insects and Spiders
by Lorus and Margery Milne

Rodale’s Color Handbook of Garden Insects
by Anna Carr

Simon & Schuster’s Guide to Insects
by Dr. Ross H. Arnett, Jr., and Dr. Richard L. Jacques, Jr.


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