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Safely Manage Insect Pests In The Garden

Jun 30, 2020 ● By Melinda Myers

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We plant and tend our garden hoping to enjoy a bountiful harvest and beautiful blooms. But despite proper planning and planting, insects can move in and wreak havoc on the garden. Yet we can manage problem pests without harming the pollinators that are so important. Monitor the garden throughout the summer to watch the plants grow, making periodic harvests and discovering insect pests while the populations are small and much easier to manage.

Assess the care the plants need to thrive. Make sure to water thoroughly and only when needed. Consider mulching the soil with shredded leaves, evergreen needles or other organic material to conserve moisture, moderate soil temperature, suppress weeds and improve the soil as they decompose.

Only fertilize if needed. Over-fertilization, especially with high nitrogen and fast-release products, can stimulate lush, succulent growth that is more susceptible to insect damage. Let the plants, not the fertilizer label, be our guide. Pale plants and those not performing as expected may need a nutrient boost. Consider a low-nitrogen, slow-release fertilizer that won’t stimulate lush, succulent growth or damage the plants when the weather is hot and dry.

Tolerate a bit of damage and wait for the songbirds and beneficial insects, like lady beetles and green lacewings, to manage the pests, or consider using an eco-friendly control product. Organic Materials Review Institute (OMRI)-certified Summit Year-Round Spray Oil can be applied to garden plants during the growing season to manage insects such as aphids, mites, adelgids, scale, leafhoppers and whiteflies. Horticultural oils have been used for many years because they are low-risk and effective against a variety of pests. They kill insects by blocking the air holes through which they breathe. This makes them effective against all stages of the insect’s development, from egg through adult.

The oil must contact the insect to be effective. If a beneficial insect lands on a treated plant, it will not be injured. Avoid treating plants when bees and other beneficial insects are present, so as to not accidentally spray them with the oil.

YRSO horticulture oil can also help reduce the incidence and spread of aphid-transmitted viruses. It interferes with insect feeding, which helps reduce the transmission of the virus by the insect.

Lightweight horticulture oils have a minimal waiting period between the last application and harvest. Always check the label before using any product, whether organic, natural or synthetic. There is valuable information on the label, including application rates and directions to obtain the best results.

Horticulture oils can also help in managing powdery mildew on plants like bee balm, phlox, peonies and cucumbers. Some can be applied when plants are dormant to smother and kill overwintering mites and aphids, as well as egg masses of pests like the gypsy moth.

Melinda Myers has written more than 20 gardening books, including Small Space Gardening. She is a columnist and contributing editor for Birds & Blooms. For more information, visit