Learn to Grow: Integrated Approaches for Managing Garden Pests, pt. 2

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We are continuing on our IPM journey this week with a discussion of mechanical and biological controls for home landscapes. If you missed last week’s discussion, be sure to visit the links at the end of this article to learn more about integrated pest management and cultural control options.

Mechanical Controls for Pest Management

Mechanical control is the simple act of physically removing the problem from your landscape with the use of tools such as mowers, shovels, or your own two hands. If you have limited mobility, there are many ergonomically designed tools available that will help make weed removal very easy. Mechanical control is certainly more labor intensive than using herbicides; however, repeatedly hand-pulling weeds will often stress them to the point that they will no longer grow, or will get out-competed by other desirable plants.

For weed control in landscape beds, cardboard is an excellent, low-cost option you can put down before you mulch an area. It also has the added benefit of being compostable and can be laid each time you re-mulch landscape or vegetable beds. I do get questions about landscape fabrics and I would recommend avoiding those if at all possible for long-term weed control. A main drawback for fabrics or plastic mulches is that they only block annual weed seeds already present in the soil; they do a poor job at controlling perennial weeds and, assuming you add some type of mulch or compost over the fabric, new annual weed seeds will have a perfect environment on which to grow in just a year’s time.

Bark mulch

Bark mulch like this shredded cedar mulch is a great, low-cost solution for weed suppression.

A better option is to apply a 2-3 inch layer of mulch, which, in addition to cardboard, provides an excellent, biodegradable weed control option each year. Coarse bark mulches are well-suited for weed control and, fun fact, hardwood mulches can help adjust soil pH slowly over time, which can be immensely helpful as we deal with our acidic mountain soils.

Destruction of old plant materials is a great form of mechanical control in vegetable or annual beds. By destroying left over plant materials, you will reduce the amount of habitat that pest insects like to lay their eggs in. Tillage can be a great form of control for soil-dwelling insects like Japanese beetle grubs, as well as weed seeds. Exposing these pests to the soil surface will provide a bounty of food for many songbirds and other beneficial insects. Remember too that cultural practices like crop rotation or cover crops can be used in conjunction with your mechanical controls and will provide even better control over weeds and insect pests.

Biological Controls

Your yard is alive and teeming with an abundance of beneficial insects, many of which are predators or parasites of insect pests, and all of which rely on nectar and pollen as a part of their diet. Providing a diversity of plants that flower at different times of the year is a great way to ensure that you have a sustainable population of beneficial insects each year. Insects like insidious flower bugs, big-eyed bugs, assassin bugs, and tiger beetles are just several of the beneficial insects you might find patrolling your garden throughout the season.

Carolina tiger beetle

This Carolina tiger beetle can be found in any NC yard, hunting down and devouring unsuspecting insect pests.

When selecting plants for pollinators, consider ones like cardinal flower, goldenrod, coneflower, joe-pye weed, crimson clover, and bee balm. These plants provide attractive additions to the landscape, but also serve as a year-round habitat for beneficial insects. Thinking about what you want, doing some research ahead of time, and selecting plants more purposefully will give you a leg up in managing pests. Remember that you will have a greater population of beneficial insects if you choose perennial plants and plant in areas that receive little disturbance over time.

Tying it together

So far, we have discussed cultural, mechanical, and biological control options for pest management in home landscapes. By now, you can start to envision the type of system whereby you are using a variety of options to become more proactive about pest management. Next time, I will cover chemical controls, including organic and traditional options for pest management.

Learn More!

To learn more about IPM, visit the Haywood County website, where you can post your questions via the ‘Ask an Expert’ link or contact the N.C. Cooperative Extension of Haywood County office. For more information on home gardening in general, visit the Extension Gardener website.