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Keep garden pests to a minimum with daily foliage checks and integrated pest management


Tomato hornworm is one of those pests which a home vegetable gardener is likely to encounter and can easily be hand-picked as one option in an integrated pest management strategy.

June may be the busiest month of the gardening season, not just for gardeners but also for the insects, mites, and some four-legged critters which thrive by feasting on plants. Many of these, of course, are just part of the natural landscape where their numbers and damage are kept in balance by other creatures which prey upon them.

Unfortunately that balance is often upset when the pests are non-native and become invasive. Such is the case with the spongy moth caterpillars now engaged in consuming the foliage of so many plants in both natural and managed landscapes. While the amount of harm to these plants varies, there will be some permanent damage to plants, especially younger specimens and those which suffered repeated defoliation. The good news is that, eventually, even these pests will be brought under control, not so much by human interactions but by naturally occurring fungi and viruses.

Of course, it will take some patience before this balance occurs. However, for those of us who depend on fruit and vegetable gardens to provide much of our food and find solace in the ornamental gardens around our homes, patience may not be a virtue. The productivity and survival of those plants does often require some pest and disease control. It doesn’t necessarily mean rushing off to the nearest garden center and buying pesticides. Rather, it is best to employ a long-range strategy that will reduce the impact of pests and diseases and be healthier for us and the environment. This strategy is referred to as integrated pest management or IPM.

To begin with, make it a daily routine to check plants for any signs of abnormality. It may be sudden wilting or discoloration of stems, browning or spotting on foliage, or holes chewed in plant leaves. And don’t forget to look on the undersides of plant leaves, a favored location for aphids. Some plants are more likely to have such problems than others. These are referred to as key plants and should be given more frequent attention. Likewise, there are key problems, that is, pests that are most likely to occur, e.g. Japanese beetles on roses, cabbage worms on cabbage and related crops, tomato hornworm and early blight on tomatoes. So, always be alert to these.

Once a problem is identified, consider the options for control. That could be something as simple as hand-picking the pest or pruning off a diseased plant part. In the long run, replacing a disease susceptible plant or variety with a resistant one is an option. For example, there are varieties of tomatoes resistant to early blight and other diseases. For those growing garden phlox (Phlox paniculata), powdery mildew had been a common concern. Now with varieties such as ‘David’, that concern has faded.

Of course, there are times when application of a pesticide is necessary. Fortunately, there are many options when considering those materials. Give priority to biorational pesticides. These are typically products that are natural rather than synthetic, are target specific, break down rapidly, and have much less risk to human health than synthetic pesticides.

IPM is much more complex than could be covered in a brief column such as this, but it does deserve further exploration by all gardeners. Fortunately, there is plenty of information available online or at the local library.

When not battling pest and disease issues, focus on these tasks:

  • Pick peas daily and early in the morning. Their sugar content is highest then. Peas are ripe for picking when the pods are round. Those pods which appear lumpy are overly mature and the peas will not be as tasty.
  • Rely on the “Days to harvest” information on packets of radish seed as a guide to determine when to harvest radishes. However, that time interval may vary a bit depending upon weather and soil conditions but at least it is a starting point. Pull up a radish or two as a sample to see if they are large enough for the entire crop to be harvested. Ideally, a succession of small plantings should be made to ensure a long season of harvests.
  • Place a box or small crate, such as those in which clementines are sold, over a mouse trap set on the vegetable garden to capture voles. I set up several of these especially around potatoes, sweet potatoes, and vine crops sprawling on the soil, all of which are favorite targets for hungry voles. Half-gnawed spuds and melons are not very appetizing to humans.
  • Don’t let up on weed control in the vegetable garden. Weeds compete with vegetable plants for soil nutrients and are often initial hosts for insect pests.
  • Cut off the scapes (flower stems) on garlic before they curl, but don’t discard them. The scapes can be used in many recipes. The young scapes are great for use in stir fry, soups and stew, as well as pesto. Older scapes — those which have curled — are a bit tougher but may still be used to make soup stock.
  • Set your mower to a cutting height of no fewer than 3 inches. There will be less stress on the grass plants should the weather turn very dry. Also, the tall grass helps shade out many weeds. Of course, if you work at a golf course and have to mow the greens, it’s best to ignore that advice.

Garden Journal columnist Ron Kujawski began gardening at an early age on his family's onion farm in upstate New York. Although now retired, he spent most of his career teaching at the UMass Extension Service.

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