Mulch selection makes a difference
Several years of drought have killed over a million trees in California since 2010. Most of those trees died in 2016, and more are doomed. Many local trees are not as healthy as they could be due to drought, bark beetle infestation, and disease. These trees have more dead leaves and twigs, making them susceptible to fire. Rather than allowing fire to race through your landscape, create spaces that slow or stop those flames.
California state law (PRC 4291) requires that all rural homes have a 100-foot defensible space. This space helps keep you, your family and our heroic firefighters safe. While suburban homes have different laws, fire safety is still critical and fire-safe gardening just makes good sense.
Defensible space is made up of two zones. Zone 1 is a 30-foot perimeter around any structures. Keeping Zone 1 fire safe means removing all dead vegetation from the ground, roofs and rain gutters, pruning tree branches at least 10 feet away from buildings, moving patio furniture away from trees and shrubs, and moving wood piles and other flammables into Zone 2.
Zone 2 extends 100 feet from your home. To keep Zone 2 fire safe, mow grasses to 4 inches or lower, rake up dead vegetation, and create spaces between trees and shrubs. This means removing any tree branches that are 6 feet from the ground or less, and pruning trees to be 10 to 30 feet apart, depending on the slope. Because shrubs can flame upward, they should be placed or pruned so they are three to six times their height from any trees, depending on the slope.
Mulch can add fuel to a fire, or slow its spread. The most dangerous mulches include shredded rubber or western red cedar, gorilla hair, and pine needles. Pine bark nuggets, Tahoe chips and other plant biomass from tree chipping operations create a moderate risk. Composted wood chip mulch does not create a significant fire risk.
There are no truly fire-resistant plants. Keep your home safe by planting low-growing, high-moisture plants closest to your home. When deciding where to install plants, imagine your home in the bottom of a shallow bowl. Plants should get taller, further from buildings. This helps draw fire away, rather than closer. Despite their name, evergreens are far more flammable than hardwoods.
If fire risk is especially high, remove shrubs and vines that touch your home (plant new ones later), and rake mulch at least 5 feet away from all structures.
Create a fire safety plan. Seriously. It takes 20 minutes and could save your life.
Above all else, in case of fire, get out and stay out. Everything else is temporary.
by UC Master Gardener Kate Russell
This article first appeared in the August 16, 2018 issue of the South Valley Magazine.
Garden threats turned opportunities
Take a walk with new eyes: Most people walk through their garden with specific chores in mind. Those mental notes are handy for getting things done, but sometimes they can interfere with our ability to see the bigger picture. Try to see what works and what doesn't at the seasonal level, rather than noticing which plants need watering or weeding right now. Walking through your garden with these new eyes will help you identify three strengths and three threats within the landscape.
Three threats: Gardens and landscapes are not the tranquil sanctuaries they appear to be — they are battlegrounds. Plants, insects, pathogens, microbes, and many more are constantly battling one another for limited resources. Which three things cause the most trouble for your landscape? Is it slugs and snails? Aphids? Compacted soil? Is the soil too alkaline? By identifying the three biggest problems faced in your garden or landscape, you can focus your efforts specifically on them. Very often, correcting the biggest problems in a landscape improves overall plant health enough that they can handle the smaller problems on their own — and you can relax in the shade!
Three strengths: Every garden has its strengths. It doesn't matter what your garden's strengths are, but you cannot take advantage of them until they have been identified. Walk through your landscape and ask yourself which plants cause you the least amount of trouble. Which areas seem to have less pest or disease problems?
What types of weeds seem to turn up consistently? These conditions and plants can be used as indicators of what works best in your garden. After you pull weeds, ask yourself why those particular species are so successful in your yard. If most of those weeds have deep taproots (dandelions, mallow, prickly lettuce), try growing mustard, carrots, fennel, beets, and other root crops. Spreading weeds (wood sorrel, bindweed, spurge) can indicate the perfect location for mint or oregano. Use the natural characteristics of your garden's strengths and put them to work for you.
Identifying your landscape's strengths and weaknesses can help you stop fighting an uphill battle. Noticing what works in your landscape allows you to put effort where it will be most effective. This will help keep your plants healthier and give you more time to enjoy your summer.
by UC Master Gardener Kate Russell
Photo: Spotted spurge seedling. UC, by C. Elmore
This article first appeared in the July 15, 2017 issue of the South Valley Magazine.
If you have citrus trees, you likely have citrus mealybugs
Citrus mealybug description
All mealybugs are soft, flat, oval-shaped critters with segmented bodies. The mealybugs that attack Morgan Hill citrus are covered with a white wax that also creates spines (filaments) around the outer edge and the back end of the bug. Unless you use a hand lens you probably won't notice individuals, but mealybugs colonize areas creating white, fuzzy egg clusters that are easy to spot.
Mealybug lifecycle
When mealybug eggs hatch the crawlers are pale yellow with red eyes, and distinct antennae. Crawlers are not born with their protective wax coating. They begin to excrete it soon after hatching. They are called crawlers because they crawl to a feeding site, where they will continue to develop (and damage fruit) for a month or two.
Citrus mealybug damage
Each female mealybug can lay hundreds of eggs, and there are usually two or three generations a year, so infestations can become a problem. As sapsuckers, citrus mealybugs pierce fruit, leaves, and young stems to get at the sap. They also feed on tender, new growth. As they feed mealybugs leave behind a trail of honeydew that attracts ants and creates the perfect growth medium for sooty mold. Citrus mealybug feeding near fruit stems also leads to fruit drop. This feeding also reduces fruit quality. Trees fail to thrive and are prone to infestation by disease and other pests. In addition to oranges, lemons, limes, and grapefruit, citrus mealybugs also have a taste for ornamental plants, such as tulips, coleus, cyclamen, begonias, and dahlias.
How to control citrus mealybugs
The first step to controlling citrus mealybugs is to monitor your trees, especially in spring and fall, for signs of ant trails, sooty mold, and egg clusters. Since ants will protect and farm the aphids for their honeydew, apply sticky barriers to tree trunks to block ants from protecting the aphids against natural predators. Those natural predators are your trees' best defense against citrus mealybugs. Lady beetles, lacewings and hoverflies will devour these pests so avoid using broad-spectrum pesticides. For extreme infestations, you can buy an introduced predator called the mealybug destroyer (Cryptolaemus montrouzieri). Insecticides are not recommended. Diatomaceous earth and insecticidal soaps can also be used.
Mealybugs prefer dusty conditions so hosing trees off can make them less appealing to citrus mealybugs.
by UC Master Gardener Kate Russell
This article first appeared in the March 23, 2018 issue of the South Valley Magazine.
Cabbage aphids wreak havoc in the garden
Cabbage aphids (Brevicoryne brassicae) can wipe out a cabbage crop before it ever gets started. Native to Europe, this pest of cole crops is now found throughout the United States.
Like other aphids, cabbage aphids are small, teardrop-shaped, sap-sucking pests that can reproduce at an alarming rate. While soft-bodied cabbage aphids are actually grayish-green, they look powdery blue to grayish-white because of a waxy covering. Cabbage aphids are not difficult to see because they live in dense colonies that can cover stems, new leaves, and entire plants practically overnight. In our moderate climate, these pests produce live offspring year-round.
Aphid defense
Cabbage aphids have an amazing defense mechanism. They produce an enzyme in their head and throat muscles which gets combined with defensive chemicals (glucosinolates) from their host plants to create an explosive chemical reaction. This reaction produces mustard oil. Unfortunately, this “walking mustard oil bomb” defense is particularly effective against ladybug larva.
Vulnerable plants
Cabbage aphids feed on the youngest, most tender parts of new cabbage, broccoli, Brussels sprouts, kale, and cauliflower. These pests also eat the innermost parts of cabbage and Brussels sprouts heads. Large colonies can stunt or even kill young plants. Heavy aphid feeding causes leaves to curl up, providing the pests with a protective cover.
Aphid controls
Prevention is key to cabbage aphid control. Row covers are an excellent way to protect young crops while they are getting established. Once aphids are seen you can often use a strong spray from the garden hose to dislodge them. If that doesn't work, insecticidal soaps can provide some control. Since some insecticidal soaps may be phytotoxic (meaning sunlight causes them to burn the plant), it is a good idea to apply them on a foggy day, especially for cabbage and Brussels sprouts.
Another way to make life more difficult for cabbage aphids is to remove any weeds in the mustard family from your property. Cabbage aphids hide out in the mustard and then return to your garden plants. Pesticides can be used as a last-ditch effort, but aphids are developing resistance to these chemicals—a potentially dangerous spiral.
Another problem with using pesticides against cabbage aphids is that those same chemicals also kill beneficial, predatory insects, such as lady beetles, parasitic wasps and syrphid flies (hoverflies). These helpful insects are natural predators of caterpillars, imported cabbage worms, diamondback moths, loopers and armyworms, which can cause other problems for your cole crops.
Monitor your plants every couple of days and be on the lookout for cabbage aphids!
by UC Master Gardener Kate Russell
Photo: South Valley Magazine
This article first appeared in the February 9, 2018 issue of the South Valley Magazine.
Chicory is commonly used as a coffee substitute
Chicory is a woody perennial that comes in many different varieties, depending on the cultivar used: roots (var. sativum) and leaves (var. foliosum) are the most common. Chicory, occurring naturally, can indicate compacted soil. Luckily, its deep taproot help breaks up that compacted soil, plus it's drought tolerant!
Chicory as food
Chicory is a highly versatile plant. Its slightly bitter leaves are used in salads, the buds can be blanched, and the taproots are frequently roasted and ground up as a coffee substitute. You can reduce the bitterness by changing the cooking water two or three times. Roots are harvested before flowering stems emerge. These roots can be cooked and eaten the same as carrots or parsnips, ground into flour for bread, or used as a coffee substitute. Plus, chicory contains twice as much of the cancer-fighting, heart-healthy polyphenols found in spinach.
Chicory description
A member of the daisy family (Asteraceae), chicory (Cichorium intybus) is one of those large, gregarious groups that may surprise you. For example, curly endive, Belgian endive, and radicchio are all types of chicory. Lettuce and dandelions are close cousins, while chicory's distant cousins include sunflowers, artichokes, and yarrow. Also known as cornflower, bachelor's buttons, coffeeweed, blue daisy, and wild endive, chicory's flowers are composite, and leaves are normally toothed or lobed. Plants grow 10 to 40 inches tall. Flowers appear July through October.
How to grow chicory
In our planting zone (9b), chicory is a cool season crop that can be started in January and February for an early summer crop, and again in July or August for an early winter crop. This gives the seeds time to get started before the weather turns too hot or too cold. Summer's heat causes chicory to bolt, but a light frost actually adds just a touch of sweetness. Seeds should be planted 1/4 inch deep and thinned to 12 inches apart. Avoid overhead watering, as the leaves are prone to rotting.
Chicory pests and diseases
Despite its rugged nature, there are some pests and diseases that can impact chicory. Bacterial soft rot, damping off disease, fusarium wilt, white mold, anthracnose, and downy mildews are all diseases that attack chicory. Aphids, cabbage loopers, beetles, leaf miners, thrips, and slugs and snails may feed on your chicory plants.
Chicory grows like a weed. Once established, you can pretty much ignore it until you decide to harvest whatever part you have a hankering for. And, hey, even the flowers are edible!
by UC Master Gardener Kate Russell
Photo: South Valley Magazine
This article first appeared in the December 17, 2017 issue of South Valley Magazine.
