By Angelo Randaci, Earth’s Ally Master Gardener and Horticulture Expert
Summer harvest is around the corner, do not let bugs feast on your blooms and veggies before you do!
Although most insects that inhabit our garden do no harm to our plants, the ones that do can cause a significant amount of damage. It is during the summer months that garden pests are most active, so be prepared to initiate both protection and control when needed.
Choosing insect control methods should involve a combination of cultural and mechanical techniques along with minimal risk pest control products that are both safe and effective for pest prevention. Cultural practices include good sanitation, removing infested plant material, proper watering, fertilizing, and choosing pest resistant plants whenever possible. Mechanical methods could be as simple as using a spray of water to knock off aphids or hand-picking to remove unwanted caterpillars. Insect control products that may harm birds, aquatic organisms, pollinators, pets, and people should be avoided. Instead, use a reliable, organic product suitable for use in all your garden areas.
Identifying the most annoying bugs that inhabit your plants is crucial in deciding on a control measure or even if one is needed. Keep a sharp eye out for the insects listed below. They are the most common pests found both indoors and out.
Identifying Garden Pests
Whiteflies – Whitefly infestations are prevalent during hot dry summers and on plants suffering from stress, especially water stress. Both adult and immature whiteflies feed on plants by sucking the sap from the foliage. Damage occurs as yellowing of leaves that eventually shrivel and drop prematurely. They can transmit viruses from diseased to healthy plants through their feeding.
Aphids – Aphid populations rise along with warm weather. They live on plants, especially on new plant growth and buds. Damage occurs as misshapen, curling, stunted, or yellowing leaves. Their numbers multiply rapidly and they will infest both indoor and outdoor plants.
Scales – Scale insects are common pests of trees, shrubs, and other plants. The adults appear as little circular bumps in various colors (depending on the species) on stems and branches of plant hosts. Damaged plants appear withered and sickly. Leaves may turn yellow and drop prematurely. Because the adults are protected from insecticides by their hard coverings, control should be focused on the immature scales (crawlers) before they develop their protective covering.
Mealybugs – Mealybugs infest all plant parts, roots, stems, twigs, leaves, flowers and fruit. Damaged plants may develop yellow leaves as well as premature leaf drop. Deformation is caused by the mealybugs injecting toxins into the plants while feeding. Most common places to look for them are undersides of leaves, stems, branches and in crevices between leaves and stems.
Sooty mold fungus - is caused by sap sucking insects such as whiteflies, aphids, mealybugs, and scale. The mold grows from a sweet, sticky substance secreted by the plant-sucking insects called honeydew. This appears as a grimy, black soot on the branches and leaves. While sooty mold does not infect the plants, it can indirectly damage the plant by coating the leaves to the point where photosynthesis is affected. Control this fungus by controlling the insect causing the damage.
Spider mites – Spider mite populations increase during midsummer dry spells and on stressed plants. Look out for feeding marks that appear as light dusting on the upper leaf surface. Spider mites on plants inhabit the undersides of the leaves, but the damage is noticeable on the upper leaf surfaces. As feeding continues, leaves take on a dull appearance. When infestations are severe, webbing is visible on the plants. Mites are very small but can be seen with a hand lens.
Thrips – Thrips are extremely active when temperatures are warm, feeding in large groups on many host plants including assorted garden vegetables and flowers. Damage from thrips includes streaks, silvery speckling, and small white patches.
Looking for more info? Read more about identifying common garden pests on the Earth’s Ally blog.
9 Essential Tips for Managing Pests
- Purchase a hand lens. Plant pests are often difficult to identify with the naked eye. A simple hand lens will help you identify garden pests and make informed decisions. Choose one that delivers at least 10x magnification.
- Practice vigilance in looking for any plant problems. Early detection of pests is essential. Insect pests, such as whiteflies, are often brought into the garden through infested plants from a greenhouse or nursery. Inspect all new purchases and keep them isolated from your other plants until you can give them a clean bill of health. Thrips, whiteflies, and aphids can transmit diseases as they travel from one plant to another. Protecting your organic garden is important and using an Insect Control that leaves no harmful residues will keep your plants in good health.
- Identify the pest before taking any action to make sure you are not harming the beneficial insects. If you identify beneficial insects on your plants, they are probably eating the bad ones. Control may not be necessary. If you are unsure of the identity of an insect, collect it in a jar and take it to a local nursery or County Extension office for identification or purchase an insect field guide to help identify the insect.
- Yellow sticky traps are an inexpensive method used to monitor pest populations. Sticky traps are simply a yellow paper coated with an adhesive. Insects are attracted to the yellow color and stick to the adhesive on the paper. Sticky traps will attract aphids, leaf-miners, whiteflies, fungus gnats, moths, thrips, and other flying insects. They are used in greenhouses, gardens, orchards and indoors for houseplants to monitor pest populations.
- Ask yourself, “Is control necessary?” If only a few leaves are damaged, you may not need any control. Keep a sharp eye on the plant to see if control will be necessary in the future. When pests are visibly present, a control like Earth’s Ally Insect Control is beneficial to keep on hand for a quick knockdown on soft-bodied insects.
- Grow plants that repel insect pests. Lavender, chrysanthemums, nasturtiums, marigolds, and petunias are just a few plants known to discourage a variety of insects. Plant these along with pest resistant herbs such as rosemary, thyme, basil, mint, and lavender to help repel unwanted pests.
- Keep your plants healthy. Develop a good quality soil for your plants to thrive. Keep them watered and fertilized to avoid plant stress. Healthy plants are more likely to survive insect pests.
- Create a habitat to lure beneficial insects that will attack your garden pests. Annuals like alyssum, cosmos, zinnias, sunflowers, and marigolds planted in harmony with perennial flowers and herbs such as yarrow, lavender, mint, fennel, angelica, and tansy will attract numerous beneficials. Dill, parsley, cilantro, celery, and carrots are biennials. Leave a few in the ground. They will flower the second season. They provide attractive food sources for a variety of beneficials and are colorful in the garden. Leave some in your vegetable garden to attract the pollinators to your veggies as well.
- Identify your caterpillars and provide host plants. If you want to have beautiful butterflies in your garden you must first have caterpillars. While you don’t want tomato hornworms eating your tomato plants or cabbage loopers eating your cabbage, you do want to welcome other species such as monarchs and tiger swallowtails to your garden. Consult a field guide to identify caterpillars, adults, and their preferred food. Some butterflies have specific larval food preferences (host plants). A prime example is the monarch butterfly. Adults only lay eggs on members of the milkweed family. Plant milkweeds such as Asclepias Curassavica which will not only flower all summer for you but will encourage monarch butterflies to your garden for both larval food and nectar for the adults. Designate a portion of your yard for caterpillars if you have the space or incorporate larval host plants into your garden design.
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