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 http://www.ipm.ucdavis.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.
- Author: Jane Callier UC Master Gardener
Heal the earth by healing the soil? Are we really able to slow global warming by manipulating dirt? Humans have been stripping mother earth of her verdant, life-supporting cloak for a long time, but the damage has shot up to a critical stage in recent years.
Earth has been stripped so bare that ecological systems are out of balance, resulting in, among other things, global warming. Extreme weather is causing drought, wildfire and increased difference between land and sea temperatures. Wet areas are becoming wetter and dry areas are drier. We need to help mother earth regain her cloak. Soil is the fabric.
One teaspoon of healthy soil contains millions of microscopic organisms. This life is in the first two inches of soil, the topsoil. Over time, large amounts of carbon have been released into the air by tilling the soil, a seemingly harmless practice.
Scientists now know that soil structure is a complex system of relationships among microorganisms. Tilling destroys this network, rendering soil largely lifeless.
Ironically, the natural process of plant photosynthesis, the focus of tilling the soil in the first place, draws carbon out of the atmosphere. A time-lapse video of earth's atmosphere shows large amounts of carbon are released early in spring when tilling occurs and before plants start to grow. The situation improves as plants grow, drawing a significant amount of carbon out of the atmosphere. As plants decline in fall and winter months, atmospheric carbon again increases.
One way to alleviate the huge carbon release would be to not till the soil. Growing plants in more places year-round would also increase the microbial life in the soil.
Turning soil disrupts the food web, the elaborate structure of interconnected soil organisms. Once broken, this food web has to rebuild and that takes time.
Organic material provides food for soil organisms. Imagine earthworms as giants, with the remaining soil organisms diminishing in size from tiny insects and nematodes to microscopic bacteria and fungi. Decaying plants and animals feed these soil organisms, releasing nutrients as they break down and form humus.
Even one application of compost helps decrease the carbon level in earth's atmosphere and creates nutrient-rich humus. Humus is important to healthy soil. It improves the water-holding capacity that enables the population of soil organisms to grow. These soil organisms create a network that acts as glue, improving soil structure.
Compost greatly benefits plant growth and helps soil retain water so you need to irrigate less often. Compost also helps fight off plant disease and insects. By composting, you keep trash out of the landfill, helping to reduce methane gas.
Eliminating tilling and rotating crops improves yield, especially in dry climates like ours. Other benefits include soil, water and nutrient retention along with fewer weeds. When you till the soil, weed seeds are exposed to air and light and may germinate. With every shovelful, you bring more weed seeds to the surface.
Instead of turning the soil, cut plants off at the ground. Chop up leaves and stems, leaving them in place to compost. Add a layer of weed-free compost on top to make the soil friable and feed soil organisms.
Nature has been performing a continuous cycle of growing and returning material to the soil for thousands of years. Organic material like compost increases life in earth's over-tilled and compacted soil. Other ways you can add organic material to the soil are by using a mulching mower, letting fallen leaves decompose in place, and implementing the chop-and-drop system as you groom your garden.
Nature doesn't aspire to an immaculately groomed look. We should return organic material to the earth. We need to train ourselves to enjoy gardens with a more natural appearance.
Managing your soil using these methods is key to maintaining healthy aggregated soil. Regenerating the soil is a natural, inexpensive way to reduce greenhouse gasses. The solution is right under our feet.
Put the practice of no-till gardening to work in your own garden. Avoid disturbing the soil. Keep soil covered with mulch. Keep plants growing through the year to feed the soil. And diversify plant material through crop rotation. For a more in-depth look at these ideas, watch “Soil is the Solution: Healing the Earth One Yard at a Time,” a recorded workshop of UC Master Gardeners of Napa County presentation.
Composting Workshop: Napa County Master Gardeners will host a workshop on “Home Composting: Worm & Rapid/Hot” on Saturday, May 21, from 10 am to 11:30 am, at Napa Valley College Upper Valley Campus, 1088 College Avenue, St. Helena. Learn about rapid (hot) composting and worm composting, why to do it and how to build a pile or bin. If you complete the workshop, you can purchase a backyard compost bin for $20 or to get a worm bin kit. Register here.
Planting Workshop: UC Master Gardeners of Napa County and Ole Health present a workshop on planting peppers, eggplant and basil on Saturday, May 21, from 10 am to noon, at Ole Health, 300 Hartle Court, Napa. Class size is limited; please register through Ole Health: https://www.olehealth.org/our-services/community-outreach- resources
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.
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.
- Author: Penny Pawl, UC Master Gardener of Napa County
The first time I saw soldier fly larvae in my worm bin I did not know what they were other than maggots. I picked them out with a long tweezer and dropped them on the ground. My intention was to kill them when I was done. However, when I looked between my feet, a blue-belly lizard was down there eating them. Since then, I have learned that soldier flies are considered delicious by chickens, lizards, fish and other creatures.
One time I collected the larvae and put them in a bottle to see what would hatch. Out came a creature looking much like a black wasp. By then I knew that these insects were great composters. I had been away for two weeks, and when I returned and checked my compost bins, the bin with the soldier fly larvae was down a foot or more. At that point, I knew these were good guys.
Later I read that researchers at an East Coast university were testing the larvae's ability to compost cow manure. On another occasion I saw them returning to a worm bin to lay their eggs.
Over the years I have had some interesting creatures live in my compost bins alongside my worms. I've seen a couple of small snakes, small toads of all kinds (I thought they were catching fruit flies) and lizards, to name a few. When I learned that soldier flies were high in protein, I wondered if that's why all those other critters were in my bins. They were eating these precious composters.
I didn't initially suspect that. I thought the snakes were after the tiny toads. I found a snake one day with a toad in its mouth and removed it. The toad loved that; the snake was not so happy.
Recently I heard about Hermetia Protein, a company in Sonoma County that gathers restaurant waste daily and composts it with soldier flies. This aroused my curiosity and led me to do some research. I have not seen soldier flies in my bins for a few years and wondered why.
Soldier flies are native to the Western Hemisphere. The fly itself lives about a week. It does not sting or eat any food during this time but it does drink water. The larval stage is usually quite long and is the main life of this insect. It goes through six stages as a larva. They are voracious eaters: a thousand larvae eat over two pounds of food a day. They will eat almost any kitchen garbage except eggshells (which worms love), weeds, paper and cardboard.
If you decide to try soldier flies in your compost bins, don't let their numbers get too big and crowd out the worms, sow bugs and other creatures. They like warmer weather but the pupae will survive in cool weather. While they don't like a wet bin, they do like it damp. So you may need to add water from time to time. Make sure your container has drainage holes.
You can buy soldier flies online. Some are sold dried, for people who own pet lizards, toads, goldfish and chickens. Others are sold live so you can raise more for your pets or put them in your compost bin. There are bins made for raising them and YouTube videos on how to set up a bin. On KQED's YouTube channel, you can watch a video about a farm raising the larvae for resale. They have a special breeding room and play music for them. Then they collect the tiny eggs. Each female lays around 500.
Universities around the country are studying these creatures for various purposes, including recycling, and there are projects to raise soldier flies worldwide.
Food Growing Forum: Join Napa County Master Gardeners for a forum on growing squash and what else to do in the May edible garden on Sunday, May 8, from 3 pm to 4 pm, via Zoom. Register to receive the Zoom link: https://ucanr.edu/2022FoodForumMay
Guided Tree Walk: Join Napa County Master Gardeners for a free guided tree walk in Napa's Fuller Park on Tuesday, May 10, from 10 am to noon. Meet at the corner of Jefferson and Oak Streets. Space is limited to 12 and registration is required at https://surveys.ucanr.edu/survey.cfm?surveynumber=36856
Composting Workshop: Napa County Master Gardeners will host a workshop on “Home Composting: Worm & Rapid/Hot” on Saturday, May 21, from 10 am to 11:30 am, at Napa Valley College Upper Valley Campus, 1088 College Avenue, St. Helena. Learn about rapid (hot) composting and worm composting, why to do it and how to build a pile or bin. If you complete the workshop, you can purchase a backyard compost bin for $20 or to get a worm bin kit. Register here.
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.
Cucumbers are an easy summer vegetable to grow in Napa County gardens. I'm sure of that, because last summer I participated in the Napa County Master Gardeners' field test of three different varieties, and we had more cucumbers than we could eat for a couple of months.
We decided to try three types of cucumbers. One was the heirloom variety ‘Lemon', another was a middle-Eastern type called ‘Beit Alpha' and the third was a newer hybrid called ‘Tsuyataro'. Lemon is a prolific small heirloom. Beit Alpha is a smaller cucumber, best harvested at 5 to 6 inches, and Tsuyataro is more typical of longer, slender cucumbers and should be harvested at 8 to 9 inches.
Cucumbers are botanically Cucumis sativus, part of the same plant family that includes squash, pumpkins, gourds and melons. All of these are warm-weather vegetables, requiring soil warmer than 65°F and nights above 55°F. Generally, Napa County weather is suitable beginning in May.
Nine Master Gardeners planted seeds in early May. Some planted directly in the soil, while others started their seeds in small pots to transplant later. All seedlings were supposed to be planted in sunny locations and fertilized at planting time was recommended. We hoped each participant would have two plants of each type to compare.
Opinions differed about how to space them. One source said to plant hills of 4 to 5 seeds, eventually thinning to two plants, but the source didn't mention how far apart the hills should be. Another source suggested planting seeds in rows and thinning to one plant every 6 inches. Yet a third source said to space plants a foot apart.
While not all trial participants reported their spacing, I can tell you that in my garden beds I put the six plants, two of each kind, a foot apart near a short trellis made of fencing material. The six plants covered the trellis easily and produced close to the reported average yield. The space they took up was roughly three feet by three feet (three plants spaced evenly on each side of the tentlike trellis).
Once seeds sprouted, they grew quickly. Because they are vining plants, they can be grown on low trellises to keep fruit off the ground. Cucumbers are small enough that they will hang without falling off. They tend to be straighter and will take up less space if given support.
By late July, all three varieties were starting to produce harvestable cucumbers, and they continued to produce into October. The harvest peaked in August and September. Because the plants produce over several weeks, you don't need to plant a second crop for an extended harvest.
How productive were they? Five growers reported an average of 18 pounds of Tsuyataro cucumbers (from two plants) over the harvest period. Six growers averaged 21 pounds of Lemon cucumbers, and six averaged 17 pounds of the Beit Alphas. If you grew two or three varieties, as several of us did, that is a lot of cucumbers. Participants ate them raw, made salads, pickled them and gave them away. I expect a good number found their way to the food bank.
A few growers reported problems. Some lost plants while they were still quite small, without being sure what had eaten them. Others reported that their plants were not very productive but speculated that they weren't getting enough sun due to partly shaded locations. Late in the season, even successful growers reported misshapen and seedier fruits. No one reported insect infestations or other pests once the plants were growing well.
There were no reports of bitter cucumbers, but some were seedy, especially the Lemon variety. The solution is to harvest cucumbers when they are young. Because Lemon cucumbers are small, they take more prep time in the kitchen than other types. Some trial participants didn't care for the Lemon cucumbers but others were surprised to find that they liked them if harvested young, before they got large or turned yellow.
Four growers chose the Beit Alpha variety as their favorite. The remaining votes were split between Tsuyataro and Lemon. However, all of us will grow cucumbers again this summer. Their abundant yield repaid the relatively little effort to plant them and the limited space they required.
Library Talk: Join Napa County Master Gardeners and the Napa Library for a free talk on “Soil is the Solution: Healing the Earth One Yard at a Time” on Thursday, May 5, from 7 pm to 8 pm, via Zoom. Register to receive the Zoom link at http://ucanr.edu/2022MaySoilSolutionLibaryTalk.
Food Growing Forum: Join Napa County Master Gardeners for a forum on growing squash and what else to do in the May edible garden on Sunday, May 8, from 3 pm to 4 pm, via Zoom. Register to receive the Zoom link: https://ucanr.edu/2022FoodForumMay
Guided Tree Walk: Join Napa County Master Gardeners for a free guided tree walk in Napa's Fuller Park on Tuesday, May 10, from 10 am to noon. Meet at the corner of Jefferson and Oak Streets. Space is limited to 12 and registration is required at https://surveys.ucanr.edu/survey.cfm?surveynumber=36856
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.
Here's a word to add to your garden vocabulary: Euphorbia. This is not to be confused with euphoria. How did a plant family get such a curious botanical name?
The family is named for Euphorbos, a Greek physician who lived more than two thousand years ago. He wrote about a succulent plant, similar to Euphorbia, that he believed was a potent laxative.
All Euphorbia have one thing in common: a white milky sap that is caustic, an irritant to humans, dogs, and cats. The causticity varies among species. In Roman times, the sap was used to treat a variety of illnesses. It is caustic enough to keep deer and cattle from grazing on plants in this family.
The Euphorbia family contains more than 2,000 different plants, including perennials, annuals, biannuals, and many succulents. The common name for some of them is spurge. Poinsettia (Euphorbia pulcherrima) is a member of the family. I once saw a hedge of poinsettia in Southern California blooming in summer. The flowers were much smaller than the potted poinsettia we see in nurseries at Christmas.
Euphorbia flowers are unusual in being either male or female. They don't have all the parts they need for reproduction and rely on bees, other insects, and bats to help them create seed. In contrast, tomato blossoms have both male and female parts and will self-pollinate with help from wind, bees, or deliberate agitation. As I walk by my blooming tomatoes, I give them a good shake.
Milkweed (Asclepias species), the host plant for monarch caterpillars, also produces white sap but is not a Euphorbia. Even so, its sap can be painful.
Castor bean (Ricinus communis) is a member of the Euphorbia family. Originally from Africa, the plant is now cultivated in many places for its oil, which is used in a variety of products. The seed pod contains sap, but the seed, the source of the oil, does not.
The castor bean plant is thought to deter moles. These small creatures tunnel through the soil looking for worms and other food. Their tunnels divert water from plants and can wreak havoc in the landscape, so an effective deterrent would be welcome. My war with moles has been going on for some time and so far, they are winning.
You may be surprised to know that you are driving around on a member of the Euphorbia family. The rubber tree (Hevea brasiliensis) is a Euphorbia. Automobile tires are made from natural latex, the tree's milky sap. This plant originates in South America but is now grown in many tropical countries. Workers cut the bark and collect the latex, which is used in the manufacture of everything from rubber tires to rubber gloves.
Some Euphorbia are weeds but many are desirable landscape plants. Most are drought tolerant. During my research, I discovered Euphorbia marginata ‘Early Snow,' which has variegated leaves and interesting white flowers. I intend to plant it and deepen my connection to this amazing family.
Workshop: Join the UC Master Gardeners of Napa County for a hands-on workshop on “Garden Pest Management” on Saturday, April 30, from 11 a.m. to 1 p.m., at Las Flores Community Center, 4300 Linda Vista Avenue, Napa. Bring gloves and wear gardening attire. Event will be canceled in the event of rain. Registration required or register at
Library Talk: Join Napa County Master Gardeners and the Napa Library for a free talk on “Soil is the Solution: Healing the Earth One Yard at a Time” on Thursday, May 5, from 7 pm to 8 pm, via Zoom. Register to receive the Zoom link at http://ucanr.edu/2022MaySoilSolutionLibaryTalk.
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.
