Can we improve our soil and manage insect pests with techniques that slow and maybe even ultimately reverse the human damage to natural resources? Practices that started innocently enough to improve and simplify food production have turned into a huge problem. Science has proven that tilling the soil not only adds carbon dioxide to the atmosphere, it kills valuable soil organisms.
Chemical pesticides are also bad news for soil organisms. Yes, insects and other pests can devastate food crops and other plants. But relying on Integrated Pest Management (IPM), championed by scientists at University of California and other research institutions, can help eliminate hungry insects. Chemical herbicides and pesticides can kill as many as 120 beneficial organisms, including microorganisms that keep soil healthy.
Chemical pesticides are a haphazard solution at best. Even if the pesticide takes out the target pest, 90 percent of the application lands on the surrounding area.
We need to embrace organic methods of insect and weed control. That's what IPM is all about. Instead of reaching for the pesticide, practitioners of IPM consider the environmental factors that affect the pest and its ability to thrive. With this information, we can create conditions that are unfavorable for the pest. IPM uses strategy, not just brute force, and is an ecologically sound way to deal with insect and plant pests.
To understand IPM, a military analogy might help. Your first task is reconnaissance. Once you have properly identified the enemy, you need to determine their numbers and evaluate the damage they are causing. Then you can deploy a strategic combination of biological, cultural, mechanical and chemical weapons, starting with the tools that do the least environmental harm. IPM almost always relies on a multi-pronged approach, not a single method.
One example of biological control is the use of natural enemies. In addition to ladybugs, beneficial insects include soldier beetles, lacewings, minute pirate bugs and assassin bugs.
Cultural controls aim to keep pests from becoming established. This can be as simple as adjusting irrigation. Too much water can encourage root disease and weeds; too little can weaken plants and lower their disease resistance.
Mechanical and physical controls kill a pest directly, or block them and make it hard for them to invade. Using hardware cloth as a gopher barrier is a common mechanical control. Rodent traps are another example.
In IPM, chemical control is a last-ditch effort. When they must use pesticides, practitioners of IPM select and apply them in a way that minimizes possible harm to people, non-target organisms and the environment.
While one of the goals of IPM is to reduce the use of chemicals, there are times when applying a chemical is the wisest strategy. In that case, careful timing and the proper application rate are critical to minimizing the impact on non-target species and the environment. For a more complete description of IPM tools, see ipm.ucanr.edu
Using chemical fertilizer does nothing to improve your soil. Plants fed with these products are like weight lifters pumped on steroids. When you stop fertilizing, you will probably have some mediocre to sickly- looking plants.
Plants grown in healthy soil sustain themselves. On a molecular level, the nitrogen, phosphorus and potassium in chemical fertilizers are identical to the same nutrients in natural fertilizers. But that ignores the role of healthy soil in nurturing plants.
We get healthy soil by applying compost, whose organic elements nurture soil microorganisms. With chemical fertilizers, we short-circuit the natural processes that nature has used for millennia. Instead of feeding plants, we need to feed the soil. Nature will take over from there.
This YouTube video [https://www.youtube.com/watch?v=JqA8DqBtRuo] shows how composted soil is the best nourishment plants can have. This experiment showed the root systems of borage plants fertilized in different ways. The control plant was grown with no fertilizer and had a root system that looked pretty good. A plant fed synthetic fertilizer had almost no root system at all. A third plant, fed with an organic product, had roots similar to the plant grown without fertilizer. The fourth plant, grown in compost-amended soil, was the lucky winner. Its roots formed an impressively large, healthy-looking mass. That's what nature intended.
Pollinator Workshop: UC Master Gardeners of Napa County will present a workshop on “Planting for Pollinators” on Sunday, May 22, from 1 pm to 3 pm, at Yountville Event Center, 6516 Washington Street, Yountville. Learn how to create and maintain a year-round habitat for pollinators of all sizes in your garden. Online registration or telephone the Parks & Recreation Department at 707-944-8712.
Grey Water Workshop: UC Master Gardeners of Napa County will present a hands-on workshop on grey water use in the garden on Saturday, May 28, from 11 a.m. to 1 p.m. at Las Flores Learning Garden, 4300 Linda Vista Avenue, Napa. Workshop includes a refresher on irrigation and a talk on firewise landscaping. Bring gloves and wear gardening attire. Space is limited. Register at http://ucanr.edu/2022LFLGMayGreyWaterIrrigation
Got Garden Questions? Contact our Help Desk. The team is working remotely so please submit your questions through our diagnosis form, sending any photos to mastergardeners@countyofnapa.org or leave a detailed message at 707- 253-4143. A Master Gardener will get back to you by phone or email. For more information visit https://napamg.ucanr.edu or find us on Facebook or Instagram, UC Master Gardeners of Napa County.