Nematodes are microscopic round worms that live in the soil. There are beneficial nematodes and highly destructive varieties. Most nematodes live in or near plant roots because that’s what they like to eat. Often, they are carried into the garden on shoes and tools.
There are many types of nematodes. The most common Bad Guys are:
There are not many above ground symptoms, so identifying nematode infestations can be difficult. If you notice wilting during the warmest part of the day, even though the plants have enough moisture, lack of vigor, or chlorosis (yellowing leaves), it is time to take a look at the root system.
To examine the root system, gently pull out the plant, breaking up the soil around the roots, and then rinsing the roots off under running water. Then take a close look at the roots. If you see swollen areas, called galls, there may be a nematode problem. These galls are usually small, but they can be as big as one inch in diameter. Roots may also appear deformed or abnormally shortened.
Once nematodes are present, crop rotation and allowing the ground to go fallow for a season are the best treatments. Non-susceptible crop varieties should be planted for 3-5 years to completely starve out a nematode population. Leaving an area unplanted (fallow) for one year will also work, as long as the soil is kept moist enough for nematode eggs to hatch. Once they hatch, there won’t be enough food and they will starve.
Planting resistant varieties is another way to defeat nematodes. Look for tomato varieties with the code VFN on the label.
If you have gophers in your garden, you know it.
Lush, healthy plants suddenly wilt and die, or disappear altogether. When you take a look, the plant falls over and you discover that the entire root system is gone! Reliable irrigation systems suddenly spring leaks for no apparent reason. And your yard is littered with crescent-shaped mounds of fresh dirt, with a plugged hole to one side. Yep, it’s gophers.
These little burrowing rodents also go by the name pocket gopher because they have external cheek pouches, or pockets, which they use to carry food and nesting material.
Being diggers, they have long front claws, powerful front legs, short brown fur and small ears. They also have lips that can close behind their front teeth to keep dirt out of their mouth when they use their teeth for digging! There are five California gopher species, ranging 6-10” long.
Gophers are prolific. They can have up to three litters of 5-6 young each year. Gopher tunnels can cover an area 200 to 2,000 square feet in size and they can dig several tunnels a day. Feeding tunnels are 6-12” below ground, but nesting and storage chambers may be as deep as 6’ underground. Gophers tend to live alone, unless it is a female raising her young. Gophers live approximately 3 years. Young gophers are able to reproduce when they are one year old. If you do the math, a single female gopher can produce over 36 babies in her lifetime!
The first step to controlling gophers is to identify the primary tunnel. To find the primary tunnel, you can buy a gopher probe or use a metal rod. The rod is inserted in the soil around a tunnel opening until a sudden give is felt. Continuing the process, you can follow the tunnel’s path to the gopher’s main route. Traps traps or poison baits can be placed at the tunnel entrance. Be sure that pets and children cannot access the bait. Gas or smoke fumigation of gopher tunnels is not effective; they simply wall off the gas until it dissipates. Professional exterminators can fumigate with aluminum phosphide to eliminate gopher populations.
Raised beds can be protected from subterranean invasions by installing 3/4” wire mesh at ground level. Chickens wire does not work. Valuable ornamentals can also be protected by digging a 2’ trench and installing wire mesh. The mesh should also be 1’ above ground. Unfortunately, this practice can damage roots and gophers can simply dig underneath the wire.
Despite rumors to the contrary (and extensive advertising), ultrasonic devices are not effective. Either is chewing gum. Cats, dogs, owls, snakes, and coyotes love to eat gophers.
Everyone knows what berries are, right?
Sweet, juicy summer favorites commonly include strawberries, blueberries, raspberries, and blackberries. Of course, in the world of botany, you'd be wrong on most counts.
What are berries?
Botanically, berries are the fruit (pericarp) produced by a single ovary. By this definition, the following plants are all berries:
Berries that are not berries
Strawberries and raspberries are not berries. Weird, right? Strawberries are accessory fruits. The flesh of an accessory fruit is not made from the ovary. Instead, it is a protective growth from surrounding tissue. Raspberries and blackberries are aggregate fruits. Aggregate fruits are made from single flowers, but many ovaries that are held together in a cluster. Speaking of clusters, what about grapes? Yep, grapes are, by definition, berries.
Plants that produce berries are called baccate or bacciferous. [I wonder if that name comes from Bacchus, the Roman god of wine.] Most berries are sweet and delicious, but not all of them. Potato flowers produce berries, but don’t eat them - they’re poisonous! Elderberries and mulberries are fine to eat when ripe, but poisonous when unripe. People have been eating berries for as long as we have existed, but we’ve only been cultivating them for a few hundred years, so there’s probably a lot more to learn.
Berry plant basics
Generally speaking, nearly all berries are shallow-rooted plants that prefer southern or western exposure. They do best in loose soil, so you can help berry plants by working a lot of compost into any heavy clay before planting, especially for blueberries. Soil compaction will seriously interfere with berry production. The use of deep-rooted green manure crops, such as hairy vetch, mustard, fava beans, marigolds, or rye before planting will help loosen the soil, add nutrients, and reduce erosion in berry plantings.
Berries do well in raised beds and they prefer soil with a pH of 6.2-6.8 (slightly acidic). My soil tends to be more alkaline, and our water supply is very alkaline, so regular acidification may be necessary.
Over-the-counter pH tests are very useful in this regard, unlike soil tests. I urge you to get your soil tested regularly by a lab.
Berry pests and diseases
While each species has its own particular problems, most berries are susceptible to verticillium wilt and other fungal diseases. Crops should be rotated every 5 years to interrupt the pathogens’ life cycle. Commercial berry growers regularly fumigate with methyl bromide to combat black root rot. Methyl bromide is an ozone-depleting chemical that has been phased out of use in most other countries. You can help harvested berries last 30% longer by storing them in the refrigerator and only washing them just before eating.
People started cultivating strawberries commercially in the late 18th century. The Romans thought its wild cousin had medicinal uses due to the heart-shaped berry. Strawberries require an accumulation of 200-300 hours of temperatures between 32-50 °F to break dormancy. These are called chill hours. Strawberry flowers look hermaphroditic but they function as either male or female. New plants can be propagated using runners. If you want fruit, remove the runners. Like potatoes, strawberries are especially well suited to planting in towers. Powdery mildew, leaf spot, and leaf blight are common diseases, and pests include ants, fruit flies, slugs, moths, thrips, weevils, mites, and aphids.
Did you know that blueberries were not domesticated until 1911? Unlike strawberries, most blueberry varieties need 650-850 chill hours. What this means in warmer areas is that blueberry bushes may not know what to do with themselves after an extremely mild winter, Blueberries love acidic soil. They perform best in soil with a pH of 4.2-4.8. You can acidify soil by adding sulphur. Be sure to follow package directions when adding sulphur. According to researchers at Cornell University, nitrate-based fertilizers can be toxic to blueberries.
Blackberries and raspberries are close cousins. Due to color variations, sometimes the only way to tell the difference is to pick them. If the torus (receptacle stem) stays with the fruit, it’s a raspberry, if it separates from the fruit, it’s a blackberry. Both varieties are called bramble fruits or caneberries, because the fruit is produced on bristly canes each year. First year canes (primocanes) produce palmately compound leaves and no flowers. Second year canes (floricanes) do not get longer. Instead, they produce lateral buds with 3-5 leaflets. At the ends of these lateral buds, fruit is produced on short stems called racemes. These members of the Rubus genus don’t seem to care what type of soil they are in.
The most common problem with Rubus plants is insufficient pollination. You can improve the odds of pollination by installing plants that attract pollinators. Keep in mind, every time the tip of a cane reaches the ground, a new plant will start to grow, so it is important to trellis these berries, unless you want an impenetrable bramble patch! Birds, caterpillars, aphids, weevils and beetles are the biggest pests. Anthracnose cankers can be treated with Bordeaux mixture (lime, water and copper sulfate). Raspberries should not be planted where peppers, eggplants, tomatoes, bulbs or potatoes have been grown. These plants are often hosts for verticillium wilt, which can stay in the soil for many years. Traditional folklore says you should not harvest blackberries after Old Michaelmas Day (October 11th), because the devil has spit on them. Though it sounds funny, the truth behind the fiction is that cooler wet weather can cause certain molds to start growing on the fruit and may make it toxic. Once established, blackberries and raspberries will come back, year after year.
In 2015, I installed three young currant seedlings. They do well in our area and the fruit is delicious, but the summer heat really took a toll. There are three basic varieties of edible currants: blackcurrant, redcurrant, and white currant. They are, along with gooseberries, members of the Ribes genus. Despite the name, these fruits are not related to the dried currants used in baking; those are a type of grape. If you want to grow currant berries, you can’t live in New Hampshire, North Carolina, or West Virginia. If you live in Massachusetts, New Jersey, Rhode Island or Delaware, you’ll need a permit. These bans are in place because Ribes can carry White Pine Blister, an imported Asian rust fungus that has devastated high elevation pine forests. Currants generally prefer cool, well-drained soil, in partial shade or full sun. In our warmer climate, they prefer heavy soil (yay!) and partial shade. They can be grown as either shrubs or trees. Fruit is borne on spurs of 2- and 3-year old wood. Pests include aphids, spider mites, imported currantworms, and currant borers. Currants need a lot of potassium, but they are sensitive to potassium chloride, a common ingredient in fertilizer.
Whether or not it’s technically a berry, you can add these plants to your garden or foodscape for many years of delicious fresh food.
Mulch can be anything placed on top of soil to cover and protect it.
Naked soil is vulnerable to erosion, weed seeds, compaction, and water waste. Mulching provides many benefits:
So, what makes a good mulch?
A good mulch allows air and water to pass through easily, while blocking the sunlight needed by weed seeds for germination. Obviously, gravel fits that description, but do you really want to pick out all those rocks at planting time? Or, what about black plastic landscape cloth - doesn’t that do the same thing, without all the work? No, it doesn’t. Ultimately, the plastic will break down, allowing weeds easy access and adding chemicals to the soil. Instead, take advantage of natural processes and use plant-based mulches. They add nutrients and improve soil structure as they break down and they can often be found for free!
Straw/Hay - Local feed stores will occasionally offer free hay or straw that has gotten wet, making it unsellable. It still makes a great mulch, so long as it is spread while still wet. Wet hay bales have been known to smolder and burn, or even explode. Believe me, I speak from experience.
Compost - Compost that is placed on top of the soil becomes a highly effective, nutrient rich mulch.
Grass clippings - Grass clippings are a nitrogen-rich mulch, which may lead to temporary nutrient fluctuations. Don’t leave them in piles, however, as they will stink to high heaven and may spontaneously combust!
Leaves - Rather then sending deciduous leaves to the land fill every autumn, they can be used as an excellent mulch or added to the compost pile.
Pine needles - If you have a friend with a pine tree, they would probably be very happy to get rid of the needles. Pine needles are excellent mulch because they break down very slowly. Unfortunately, despite popular opinion, green pine needles only slightly alter soil pH and dried needles do not acidify it at all.
Plant trimmings - As you work in the yard, you can create instant mulch with the chop and drop method. Simply chop up whatever you are pruning off where you are and let it fall to the ground the way nature intended.
Chipped and shredded tree trimmings - Most tree trimming companies are happy to give away full or partial truckloads of perfectly good mulch. Just be sure to inspect the material for palm tree pieces before it gets dumped on your driveway! Coarse wood chips make an ideal mulch. They break down slowly, improving soil structure and feeding the soil microorganisms that make plant life possible.
How to apply mulch
Mulch should be applied 2-6” thick, depending on particle size. Smaller pieces fit together more closely, so you don’t need as much as for larger bits. If weeds are a serious problem, or you are eliminating a lawn, it is a good idea to use a really thick layer of wood chips. Be sure to keep mulch several inches away from trunks and stems. If mulch is in constant contact, problems such as crown rot can occur.
As worms, beetles, weather and microorganisms breakdown the mulch, improving the soil, more mulch will need to be added.
Creating and applying compost is one of the very best things a gardener can do for their soil.
Composting is the natural process by which organic materials are broken down, making them available to plants and microorganisms. It is a major component of pedogenesis, or soil creation. Without healthy soil, we begin to lose our food, water and air. Yeah, it’s kind of important.
More benefits of composting include:
One of the nicest things about composting is that bacteria and fungi do most of the work for you! Other organisms, such as worms and insects, also pitch in to help. Now, it is possible to simply dump everything in a pile and wait for nature to takes its course. Eventually, there would probably be a nutrient rich soil amendment, but it might take years. It might also turn into a stinky, rotten mess. Follow these tips for successful composting in a reasonable amount of time.
Selecting a site for composting
Wire bins work well and are highly mobile. You simply move the wire away to flip the pile and pitch the material back in, watering as you go. If you look online or in your local library, there are many DIY compost bin instructions available for free and these simple structures do not require a contractor's license or skill set to build. For me, I find that simple piles work the best. I keep my regular compost pile near my chicken coop, for convenience. Occasionally, I move it to an exhausted bed for a season to supercharge it with nutrients and organic material.
Understand the process: Organic matter + air + water = compost
Organic matter consists of yard and kitchen waste that has been cut into 2” or smaller sized pieces. Smaller pieces compost faster because there is more surface area for decomposers to reach.
Organic matter is considered either “green” or “brown”. Green matter includes cut grass, pulled weeds, kitchen scraps and manure, and it is rich in nitrogen. Brown matter is rich in carbon and includes dried leaves, straw, and shredded newspaper. The ratio of green to brown is a major factor in how long it takes a compost pile to breakdown. “Hot” piles work fastest and use a 30:1 carbon-to-nitrogen ratio, while slower piles can have a 2:1 carbon-to-nitrogen ratio. If material is continually added to a single pile, it will slow the process. A better choice is to have 2 or 3 piles, at various stages of decomposition.
Meat and dairy in the compost pile?
Most recommendations warn against using meat, dairy, and grease in compost piles. Other people have no problems with it. Personally, I use the majority of my kitchen “waste” to make soup stock. The solids are then fed to my chickens. Whatever they don’t eat (along with what they did eat) ends up in the compost pile, bones and all. I have had no problems and my plants seem to appreciate the calcium. Of course, my dogs do a very good job of keeping opossums, rats, and raccoons out of my yard. It's your call. One other method of decomposition that uses fermentation, rather than decomposition does allow you to add meat and bones without difficulty. This method is called bokashi.
Decomposition is an aerobic process, which means it needs air. Air helps breakdown organic matter and those tiny workers need it, too! Air enters a compost pile by turning it every few days. [Read: good exercise]
Water is needed for the same reasons as air: it aids in decomposition and it keeps microorganisms and other decomposers alive. Keep the compost as damp as a wrung out sponge and avoid simply watering the top, as this tends to cause runoff. Watering as the piles are turned works the best. If the pile gets too wet, spread it out and let it dry, or it will rot.
Temperature is another composting factor. As materials break down, especially the green ones, energy is released in the form of heat. If you’ve ever watched a big pile of freshly cut grass, you know exactly what I mean. Under the right conditions, a pile of grass clippings can burst into flames! (And it stinks to high heaven). Ideally, the right conditions will generate temperatures between 122 - 131 degrees Fahrenheit. If temperatures remain above 140 for at least 10 days, weed seeds and pathogens will be killed. If temperatures stay above 160, however, decomposers will die and the process will stop.
Because temperature is a factor, do not expect much out of a compost pile in winter. Material can still be added, or another pile started. In spring, the whole process will begin again. Also, if an area is especially hot or wet, cover the compost pile to maintain desirable moisture levels. Some people take composting very seriously and monitor temperature. I didn’t until I started composting the bedding from my chicken coop.
Animal bedding and manure are reasonably good sources of nitrogen and organic material, but they can make you sick. To be safe, manure must be composted for at least 45 days, 15 of which must be at temperatures between 131°F and 170°F, and turned at least 5 times. Assuming it hasn’t been recontaminated by air-dropped bird poop or other pathogens. Raw manure should never be applied to the soil while plants are growing. If it is, be sure that the manure does not touch the plants. Composted manure and bedding have significantly improved my soil health and helped to reduce compaction. Apparently, all those earthworms and burrowing beetles love the stuff!
When is compost ready?
Compost is called “finished” when it is ready to use. There is simply no way to say how long finishing will take because of the factors already mentioned. Generally, speaking, under reasonably good conditions, a compost pile is ready for use within 45 to 60 days. Finished compost takes up 25-40% of the original occupied space, depending on its ingredients. Compost can be dug into beds before planting, a 2” layer can be applied over lawns as an amendment, or it can be used as mulch or top dressing. I like to add just a little compost to the bottom of potted plants before adding high quality potting soil and my plants seem to like it a lot.
Composting with worms
For those who do not have space for a compost pile, bin, or drum, try composting with worms! This is called vermiculture. Worm bins can compost an amazing amount of yard and kitchen scraps pretty quickly. Did you know that worms can eat their body weight in scraps every single day? Learn how to build worm bins and compost with worms at the UC Agriculture and Natural Resources page about worms.
Remember, composting is easy and it provides a powerful boost to the garden. Start composting today!
A canker is a sunken wound in bark caused by fungal and bacterial diseases. The wound is an open sore filled with dead plant tissue. Okay, so it’s not the prettiest thing we’ve talked about, but it is important to know where cankers come from, how to prevent them, and how to treat them. Your trees will thank you!
Canker causes & identification
Some cankers are obvious and some are not. They are caused by fungal and bacterial microorganisms that infect the cambium layer of trees and shrubs. Cankers are very slow to heal and often do not heal at all. If the wound travels laterally, the sap found in the xylem and phloem cannot move and the branch dies.
Foliage on infected branches often turns yellow or brown and wilts. Cankers can encircle (girdle) and kill limbs or an entire tree. Common canker diseases include: Eutypa dieback, pitch canker, fire blight, Fusarium wilt, chestnut blight, pine blister rust, anthracnose diseases and sudden oak death.
How to prevent cankers
The best prevention method is planting resistant cultivars. Also, installing plants best suited to the local microclimate helps them to be strong enough to fight off pests and disease on their own. Good cultural care, such as proper pruning, watering and feeding will also help prevent disease. Whenever dead or diseased limbs are seen, they should be removed and destroyed right away. Avoid heavy feeding, since that stimulate vulnerable new growth. Sunburn and overwatering can both make plants susceptible to various canker diseases. Many healthy trees have these pathogens present. Trees that are stressed become susceptible to disease.
Once a fungal disease has taken hold, getting rid of it can be difficult. Most fungicide treatments are ineffective against fungal cankers since the pests are safely inside the plants they infect, and the same is true for bacterial cankers. Maintaining healthy plants allows them to fight for themselves.
Bees are closely related to wasps and ants. Their common ancestor was an insect eater. The first bees evolved about 100 million years ago. Bees and flowering plants have coevolved to support each other, which is why bees are such efficient pollinators. There are over 20,000 species of bees worldwide and they are found on every continent except Antarctica.
In San Jose, California, we have hundreds of native bees, with 4 predominant species:
Honeybees are not native to North America; they were imported from Europe.
Most people are familiar with the burning pain caused by a bee’s sting. This venom is produced in two exocrine glands and injected with a stinger when a bee feels threatened. Not all bee species have stingers. Honeybees are the only species that die after stinging.
Bees are distinct from other insects because they have bristles (setae) on their bodies, grooming combs on their forelegs, and many species have pollen baskets on the rear legs. If you are an entomologist (bug geek), you would also know that female bees have a divided 7th dorsal plate, but I’ve never noticed and I don’t think it makes much difference in the garden.
Bees have five eyes. Yep, five. They have two very large, compound eyes that pretty much cover their head, and three small eyes (ocelli), which are used to gauge light intensity. Male antenna have 13 segments, while females have 12. These antenna hold many sense organs that can detect touch, smell, taste, and “hear” by registering air movement. Bees have a long proboscis for drinking nectar; imagine a tubular tongue with suction powers. A bee’s thorax has three segments, each with its own pair of legs. The back two segments also have membranous wings. Many bees are orange and black.
Bees range in size from the tiny (0.08”) stingless species, to the largest (1.54”) leaf cutter species, the giant mason bee (Megachile pluto). Sweat bees (Halictdea) are the most common species in North America, but are often mistaken for wasps. The Arctic bee species, Bombus hyperboreus, actually attacks and enslaves other bees!
Bee-havior (Sorry, I couldn’t resist!)
Most bees lives in colonies, but some bees are solitary. Honeybees, bumblebees and stingless bees live in eusocial colonies that feature a queen, female workers, and male drones. The word eusocial describes a highly organized social construct in which brood is cared for collectively, overlapping generations live together, and labor division that creates castes that are either reproductive or not. Carpenter bees, leaf cutter bees, sweat bees, and mason bees are solitary.
Every female solitary bee is fertile and builds her own nest. These nests can be in hollow twigs, in holes chewed from wood, or in the ground. Some solitary bees share nests, but they do not interact. These collectives are called aggregations. Solitary bees do not produce beeswax or honey, and there are no workers. Solitary bees are prolific pollinators, though they tend to specialize on a single or a few plant species. Some solitaries specialize in collecting floral oils or aromatic compounds! In cases where there is only one pollinator for a specific flower, threatening the existence of one species threatens the other.
There are four species of nocturnal bee. They have enlarged ocelli that are hypersensitive to light, but cannot form images. Most of these are found in high elevation jungles because of the flowers in those regions that bloom only at night.
Bees have many enemies. Birds, such as shrikes, swifts, swallows, jays, and flycatchers catch them flight. Large wasps, called beewolves, frequently dine on bees. Robber flies and dragonflies are also known to eat them. Raccoons, mice, skunks, voles and bears love to eat bees and honey. [Did you know that beekeepers wear white because dark colors make us look too much like bears to the bees?]
Bees are also attacked by parasites, such as varroa mites and tracheal mites, and bacterial infections that cause sacbrood, deformed wing virus, chronic bee paralysis, and black queen cell virus. They can also catch a fungal disease called chalkbrood. Public concern has increased as Colony Collapse Disorder becomes problematic.
People have been collecting honey from beehives for over 17,000 years and raising bees (apiculture) for honey, pollination, beeswax, propolis and royal jelly for nearly 5,000 years. Professional beekeepers have shifted their focus from honey production to contract pollination. For example, California’s almond crop is the world’s largest managed pollination event, attracting a million hives to its orchards each year.
Despite advertising claims, royal jelly collected from queen cells and bee pollen harvested from drones has not been proven to provide health benefits to humans. In fact, royal jelly and bee pollen can cause allergic reactions that lead to fatal anaphylaxis. On the other hand, bee venom acupuncture has been shown effective against some types of arthritis pain and inflammation.
All bees start out as an egg. Newly hatched larvae do not have legs, but they have horns on their head! These whitish grubs have 15 segments, jaws for chewing food, and a gland under the head that secretes a liquid that solidifies into a silk they use to build a cocoon. After encapsulating themselves, they enter a pupal stage where they go through complete metamorphosis and emerge as a winged adult.
Bee gender is determined by whether or not the egg was fertilized. Fertilized eggs are born female and unfertilized eggs are male. Fertile females store sperm in their bodies and “decide” whether to lay male or female eggs. Eggs are laid in cells along with a food supply.
In colonies, workers continually feed the larvae in a process called progressive provisioning. Worker bees also secrete royal jelly from glands in their head. It is used to feed the queen and all larvae, regardless of gender or caste, for the first three days of life. When a new queen is needed, several small larvae are selected and placed in special queen cells, where they are fed copious amounts of royal jelly. This treatment triggers the development of queens.
Social bees communicate with each other by dancing. The figure-8 “waggle dance” communicates the location of food with three pieces of information: sun position, the earth’s magnetic field, and the polarization pattern of the sky. (It boggles my mind, too. Don’t feel bad. You can learn more here.)
Bees as pollinators
All bees are pollinators, which makes them beneficial insects. They fly from flower to flower, collecting pollen and nectar for the hive or their brood. In doing so, they carry pollen grains on hairy legs and in pollen baskets to other flowers. Nectar, which contains mostly sugar, is a fast energy source. Most of the pollen, which provides protein and other nutrients, is fed to baby bees (larvae), but enough is dropped that bees are responsible for pollinating the lion’s share of earth’s flowering plants.
After collecting pollen, nectar, and tree resins, workers return to the hive. Tree resins are converted into propolis, which is used to increase the structural stability of the hive and to prevent pests and diseases from entering. Propolis is also used to mummify dead intruders that are too large to be carried out. Propolis is used by people as a varnish for some stringed instruments. Propolis has been claimed as a skin cure-all. It shows some effectiveness in treating cold sores and other mouth lesions, but all other claims have yet to be proven.
Bees in the garden
As beneficial as bees are, it is important that we, as gardeners, do what we can to help them. In particular:
Armored scale is easy to miss, but infestations can suck the life out of mature trees and shrubs and destroy fruit crops
Description of armored scale
Imagine a tiny, 1/8” dark brown bowl, turned upside down. Underneath this protective cover is a round, squishy insect, with no head or legs visible to the naked eye. Scale insects have a straw like mouthpart that is inserted into bark, fruit, or leaves of citrus and other fruit trees, nut trees, and ornamental trees and shrubs.
Armored scale varieties
Unlike soft scales, armored scales do not produce honeydew. In San Jose, California, we have four varieties of armored scale: oystershell, San Jose, Asian cycad, and euonymus.
Oystershell Scale (Lepidosaphes ulmi)
Oystershell scale has a distinctly elongated shape, unlike the circular shell of most scale insects. Mature specimens can be as large as 2.5 mm long. It favors deciduous trees, such as maple, poplar, dogwood, ash, and willow. This variety lays 20-100 tiny white eggs that can be found under the protective scale shell.
San Jose Scale (Quadraspidiotus perniciosus)
Accidentally imported from Asia in the 1870, San Jose scale attacks apples, pears, and peaches. It is now found throughout North America. This species produce live young, called crawlers. A fertilized female can produce as many as 10 crawlers a day for 6-8 weeks - that’s over 500 offspring per scale!
Asian Cycad Scale (Aulacaspis yasumatsui)
Asian cycad scale was brought to the States from Thailand and China on nursery stock. This pest has a 100% mortality rate for any cycad plant species that it infests. Spray insecticides have not been effective. Cycads are often called “living fossils” because they have been around since before the dinosaurs! While they look similar to palm trees, they are more closely related to pines. The most common cycad species is the Sago Palm.
Euonymus Scale (Unaspis euonymi)
Another Asian import, eponymous scale attacks spindle trees, wintercreeper, Western burning bush, and strawberry-bush across the U.S. They attach themselves to the underside of leaves, causing stippling and chlorosis. Males and females can girdle twigs and branches, causing die-off. Males look like white exclamation marks and females are mottled brown.
Armored scale lifecycle
Scale insects can have up to three generations each year. Male scales are tiny golden winged insects that normally emerge to coincide with apple blossoms. The females emit pheromones that attract the males. Crawlers (nymphs) are bright yellow and they resemble spider mites. They either walk or are blown to a new location where they undergo distinct changes. The first stage (instar) occurs when the nymph secretes a white, waxy covering, known as the white-cap stage. The second instar is called the black-cap stage because a darker scale covering is secreted. If the nymph is male, it will go through two more non-feeding instars before taking flight.
How to control armored scale
San Jose scale is often controlled naturally by several varieties of chalcid wasps and lady beetles. Insecticidal sprays and horticultural oils can be used to reduce infestations. Severely affected limbs should be removed and destroyed. Pesticides can be used effectively, but remember that you are putting poison in your yard.
The best control methods are regular inspections and pruning that improves overall plant health and air flow.
Cucumber mosaic is caused by a virus called Cucumber mosaic cucumovirus (CMV). This disease has the widest global host range of any plant virus.
It is mostly spread by aphids, but this disease can also be carried on shoes and garden tools and on seeds. It is most commonly seen on all cucurbits, except watermelon.
Symptoms of cucumber mosaic
Young infected leaves tend to cup downward. Mature leaves become severely mottled with light and dark green patches. Leaf midribs may become deformed with a zigzag growth. Due to the interference of photosynthesis, growth is stunted and fruits can be deformed with bumps. Cucumber mosaic can cause cucumbers to turn white.
How to control cucumber mosaic
As prevalent as the mosaic virus is, planting resistant varieties is the best control. Once an outbreak occurs, all affected plants should be removed and thrown away. A reflective mulch can be used to repel aphid vectors. Chemical pesticides and insecticides have not been proven effective against cucumber mosaic.
These members of the Evening Primrose family (Onangracea) generally love filtered light and will even thrive in shady areas. They do not perform well in full sun. I hang mine in a basket from a branch in one of my orange trees. It looks pretty when it’s blooming and I don’t even notice it when it’s not.
Fuchsias prefer overhead watering and will need to be watered frequently during our hot summer months. Spider mite and fuchsia gall mite damage can be minimized with insecticidal soap. During flower production, feed a complete fertilizer every few weeks or use delayed release plant food stakes (my personal choice for containerized ornamentals).
In winter, I leave mine alone completely, and every spring it comes back adding a lovely touch of color. The hummingbirds seem to like it, too!
Fertilizer is one of those things that falls under the, “Too much of a good thing is a bad thing” category. All too often, at the first sign of unhealthy plants, people grab a bag of fertilizer before checking for inhospitable soil conditions, unhealthy roots, irrigation problems, nutrient toxicities, and pest or disease infestation.
Different plants have different nutrient needs. Simply dumping a box of 10-10-10 around the garden isn’t a good idea and it’s a waste of money. The chemicals can leach into ground water, burn sensitive new roots, and damage beneficial soil microorganisms. It can also make plants grow faster than they can maintain over the long haul, leaving them weak and vulnerable later in life. Many woody ornamentals never need to be fertilized, even when they are first planted, while containerized plants need regular fertilizing.
N, P & K
Most gardeners are familiar with the three numbers displayed on bags and boxes of fertilizer, but we’ll do a quick review, just to be sure. Those three numbers represent the percentage by weight of nitrogen (N), phosphorus (P) and potassium (K). Think about this for a moment. A 10-pound bag of 10-20-10 fertilizer contains 1 pound nitrogen, 2 pounds phosphorus, 1 pound potassium, and 6 pounds of filler. Yes, filler. If all your plants need is nitrogen, blood meal may be a better choice.
Plants use 16 chemical elements as food. Those elements include oxygen, carbon, and hydrogen, along with 13 mineral nutrients. Those mineral nutrients are broken down this way:
Nitrogen (N) - leaf growth
Phosphorus (P) - root, fruit and flower growth
Potassium (K) - stem and cell growth
Before applying fertilizer, invest in a good soil test. It’s worth it. And it’s a fascinating snapshot of what is really going on in the garden. Now, I don’t mean one of those over-the-counter test tube kits. Those are a waste of money, in my humble opinion. When searching for a soil lab, it is best to pick one near you. The east and west coasts have very different soils (ours is alkaline; theirs is acidic, for one thing). This means that different types of tests are used to analyze soil samples.
I learned some surprising facts about my soil when I sent in a sample. Most important, I learned that my soil already has a ton of everything, except iron. Without iron, the plants weren’t able to absorb the abundance of available nutrients. Adding fertilizer would have been a complete waste of time and money. Instead, because I had the knowledge, I was able to apply a foliar (leaf) spray of iron and my garden plants had access to everything they needed! So, get your soil tested before adding anything.
Types of fertilizer
If you are like me and prefer a more natural approach, use compost instead of fertilizer. Since I raise chickens, composting is even more effective. Chicken poop is high in nitrogen, and practically anyone can raise hens or build compost. Yard and kitchen scraps that would normally end up in landfills can be transformed into nutrient rich compost that that also improves soil structure.
If you decide fertilizer really is necessary: READ THE BAG. Seriously. Federal law requires that specific instructions and useful information are printed on the container and for good reason. Follow directions carefully and wash your hands when you’re done. Technically, there is no chemical difference between nitrogen from compost and nitrogen formulated in a lab. Nitrogen is nitrogen. The difference lies in everything else. What are the fillers? What else is in the compost that plants need? Honestly, there’s a lot we don’t yet understand about how living things interact. I prefer to err on the natural side, just in case.
For a hysterical read about the effects of too much fertilizer, check out Don Mitchell’s Moving/Living/Growing Up Country series.
Earwigs are second only to slugs and snails in crop destruction.
Members of the order Dermaptera, the earwig most commonly found in California is the European earwig (Forficula auricularia). Earwigs were introduced accidentally in the early 1900’s. The word Dermaptera comes from Greek words that mean ‘skin wing’. Contrary to the old wive’s tale that claims earwigs lay their eggs in human ears, which is not true, the name actually comes from the uniquely ear-shaped hindwings, which are rarely used.
Earwigs are easily recognized by their pinchers, or forceps, on the back end. You can tell the gender of an earwig by the shape of these pinchers. Males have curved pinchers, while female pinchers are straight. While they generally don’t bite, they can and will if they get caught in your clothing or hair. Mature earwigs average 3/4” in length.
Protected from sunlight and heat in a dark, moist place during the day, earwigs emerge at night to hunt and feed.
On one hand, earwigs are beneficial insects because they eat aphids, mites and other insects. On the other hand, earwigs are serious pests, especially in the spring. Earwigs can decimate young seedlings in a single night and cause serious damage to soft fruits such as figs, peaches, nectarines and berries. Earwigs can also damage many flowers, including zinnias, marigolds, and dahlias.
It is relatively easy to trap earwigs using a moistened, tightly rolled up newspaper. Earwigs will seek out the cool, damp sanctuary in the predawn and you can simply toss them in a plastic bag and put them in the trash or feed them to your chickens. Another simple trap consists of an empty tunafish can with 1/2” of oil or bacon grease in the bottom. Soy sauce can be added for even better effectiveness. Sink the tins near fences, walls and large shrubs, to ground level. The earwigs will drown themselves.
Earwigs prefer a more moist environment than our normal California summers, so limiting access to moisture is another way to reduce earwig populations. Pesticides are generally ineffective against earwigs.
Next time you see a shiny black bumbler rumbling through the garden, don’t panic. Carpenter Bees generally do not sting.
Female Valley Carpenter Bees (Xylocopa varipuncta) are shiny black, while the males (in the video) are golden and fuzzy. Female carpenter bees only sting when provoked and males do not have stingers. Another interesting bit of carpenter bee trivia: they are the only bees able to regulate their own temperature, which is why you may see them buzzing around when it's too hot or too cold for other bees.
These solitary bees got their name because of the way they tunnel into unfinished soft woods, such as pine, redwood, and fir. They also burrow into fences, sheds, and other wooden garden structures. These tunnels are used as nests for overwintering and creating new brood in the spring. Some of these tunnels can be as much as 10’ long!
This tunneling can weaken wood. Fill holes with steel wool and wood putty to protect trees, buildings and fences, once the bees have emerged. After treating the area, painting over the surface will help discourage the bees. You can use insecticides, in extreme cases, but it is better to create a habitat for them, because they are beneficial insects. Like honeybees, they are heavy pollinators. As they collect nectar and pollen from flowers, they pollinate your crops, increasing productivity.
One way to protect your fences and buildings, while enjoying the advantages of higher pollination rates, is to build a Carpenter Bee habitat. Simply take a chunk of soft wood and drill a bunch of 1/2” holes in one side. You can also use a bundle of 1/2” bamboo segments. Then mount it to a fence or post, to get it off the ground, and cross your fingers.
NOTE: The male carpenter bee in the video was released after filming. ;-)
Spring is the time of year when it is common to see white powdery patches appear on leaves. This bane of gardeners is called powdery mildew, and it can occur in autumn, as well.
Cucumber, melon and other cucurbits are susceptible to powdery mildew. You may also see it on tomatoes, roses, snapdragons, chrysanthemums, peas, artichoke, beets, grapes and wheat.
What starts as a small white spot, powdery mildew expands to engulf an entire leaf as the nutrient-sucking fungi bleed the life from your garden. It can be found on either side of a leaf and sometimes on stems.
Powdery mildew identification
Powdery mildew is a fungal disease. It is caused by different types of fungi (e.g., Erysiphe spp., Sphaerotheca spp.), depending on which plant is affected. Contrary to common belief, moisture and humidity are not needed for these fungal beasties to appear.
The white powder seen on leaves is actually thin layers of fungal tissue (mycelium). Other symptoms of powdery mildew include:
How does powdery mildew grow?
Powdery mildew fungi simply need living plant tissue to survive and thrive. To make matters worse, their spores are carried on the wind, so the battle never ends. The reason powdery mildew seems to disappear in the heat of summer is that these microorganisms prefer shade and temperatures between 60° to 80°F. Our California summers are simply too hot for the spores to reproduce. Instead, they remain dormant until conditions improve.
Not only does powdery mildew cause leaf loss, it can also weaken a plant. This lowers production and increases susceptibility to other pests and diseases, such as citrus blast. Leaf drop can also lead to sunburn damage.
Powdery mildew management
Prevention and vigilance are the best ways to counteract powdery mildew. These tips can help, but nothing will eliminate powdery mildew in the garden:
Some people recommend spraying plants with a baking soda solution, but this can add too much salt to your soil.
More recent research shows that spraying the soil with milk before planting and then spraying the leaves of susceptible plants when the disease is most likely to start appearing can significantly reduce the incidence of powdery mildew in your garden.
If you slice into a stalk of celery, you will be able to see vascular bundles that carry water, nutrients and hormones throughout the plant. These vascular bundles, or veins, are made up of the xylem and phloem.
The xylem mostly carries water. Xylem is Greek for wood, so an easy way to remember the word meaning is to think “water wood”. The xylem also carries some mineral salts, but that is mostly the job of the phloem. Generally, the xylem is found closer to the center of a stem, while the phloem is closer to the outer edge.
The most interesting thing about the xylem is that it pulls water upward from the ground, against gravity. If you’ve ever picked up a bucket full of water, you know this isn’t always easy. There is some debate about how this actually occurs, but most botanists agree that it has a lot to do with surface tension.
Water molecules like to stick together. As a plant breaths, evapotranspiration occurs, reducing the amount of water in the leaves and stem. The water in the ground in then pulled upward by the water in the above ground portion of the plant. The structure of the xylem helps support the water molecules as they are drawn up.
Xylem vessels are actually made up of elongated cells that are dead. Weird, right? These cells are arranged end to end, with little openings between each cell. There are secondary xylem cells that contain lignin. Lignin is found in cell walls and it is what holds plants upright.
Diseases of the xylem include Fusarium wilt, root rot, damping-off, and tomato spotted wilt.
Children's activity: This is crazy easy and the kids seem to really enjoy it. Simply take several celery stalks and place them in separate cups or glasses. To each cup, add some water and a few drops of different colored food coloring. As the stalks pull the water up, they bring the dye too, and the color changes can be striking. (It works faster if you trim the base of each stalk to create fresh openings for the vascular tissue.)
Ants are amazing and they’ve been around since the time of dinosaurs. There are over 12,000 species of ant. They are found on every continent except Antarctica and their biomass is estimated to be the same as that of humans (approx. 80 billion pounds) They hear with their feet, lift 20-50 times their own weight, and even enslave other insects to do their bidding!
In the garden, ants can be both beneficial and a pest.
Most ants dig tunnels in the soil. These tunnels facilitate the movement of air and water through the soil. Also, food collected by ants (and their excrement) add nutrients to the soil. Some ants are predators and some even pollinate flowers and spread seeds.
At the same time, ants will defend and even farm aphids, mealybugs, and soft scale in exchange for excreted honeydew. This honeydew is also the perfect breeding ground for fungal diseases, such as sooty mold and rust.
It is a good idea to monitor your plants for ant invasions. Heavy ant populations often indicate other pests. To safely reduce ant populations in your garden, you can try these methods:
One way to keep ants out of fruit and nut trees is to wrap the truck with duct tape and slather the tape with sticky barriers. Ants cannot cross this barrier, so they will be unable to defend other pests.
Dinner wouldn’t be nearly as delicious without plants from the Allium genus. Ornamental Alliums also attract beneficial insects to your garden.
Attracting beneficial insects
Planting Allium in the garden is sure to attract beneficial insects. The convenient landing platform and sweet nectar will bring them in from blocks or even miles around. Allium tanguticum, the Lavender globe lily (pictured), attracts hoverflies. These beneficials look like tiny bees and they devour aphids and mealybugs. Spritely black Trichogramma wasps are also attracted and will lay their eggs in moth eggs, preventing caterpillars, such as the tomato hornworm from attacking your garden. If you enjoy the flavor of garlic and chives, you can always plant Garlic Chives (Allium tuberosum) another favorite of beneficial insects.
How to grow alliums
These shallow-rooted plants prefer soil that holds a lot of organic material and that means adding compost before planting. They will grow just about anywhere, but our heavy clay soil can slow growth. Allium can be grown in partial shade to full sun. Alliums grow well in raised beds and containers. You can grow chives in a pot on your kitchen windowsill for easy access while cooking!
Growing Allium from seed can be hit and miss. The plants are slow starters and they don’t handle competition (weeds) very well. You can plant seeds in containers or directly in the garden. Seeds should be sown 1/2” deep and 1/2” apart. Thinned plants can be eaten as scallions.
Another way to plant Allium is in the form of “sets”. Allium sets are mature bulbs that can be planted directly in the ground or a container. Follow the package directions for depth and spacing. The only downside to sets is that they tend to bolt. Bolting is the beginning of the going-to-seed process. If you are growing onions, leeks, or garlic, plants that have started bolting should be harvested right away, unless you plan to collect your own seeds.
Garlic and onions are best planted October through January.
No, we’re not talking about faulty wiring, or that jar full of pennies.
Copper (and sulfur) have been used as fungicides and bactericides in gardens and agriculture for a really long time. Unlike Bordeaux mixtures, which use highly soluble copper sulfate, fixed copper takes much longer to break down. Each time it gets wet, fixed copper releases just a little more metallic copper onto plants. Copper kills bacteria and fungi by breaking down protein molecules within the organisms.
Shopping for fixed copper
When shopping for fixed copper products, it is not uncommon to see a wide range of active ingredients. To get your money’s worth, look for higher “metallic copper equivalents” (MCE) on the label. MCEs are listed as a percentage by weight, with the most common rating being 8%.
Fixed copper can take any of these forms:
There is also a copper soap (copper octanoate) available that has shown good performance.
How to use fixed copper
The effectiveness of fixed copper against fungal diseases can be improved by adding 1% of a horticultural (not dormant) oil. The oil will help the copper stick to plants longer. It will also reduce damage caused by aphids, mites, and scale. Fixed copper is normally applied using a hand pump spray tank (pictured) or a hose end sprayer.
Fixed copper should be applied while plants are dormant. It is important that you get complete coverage of each and every surface. Once new buds and shoots begin to emerge, phytotoxicity can be avoided by spraying on days when the fixed copper will dry quickly.
Avoid using other foliar (leaf) sprays when applying fixed copper. According to the Michigan State University Extension, “[A]void the use of spray additives such as foliar nutrients, and any surfactants with penetrating characteristics when applying coppers. Fixed copper and lime should not be used with Guthion, Imidan, Sevin, Thiodan, Bayleton, captan, carbamate (Ferbam), syllit, or phosphorus acid-type compounds (Fosphite, ProPhyt, Phostrol, Agri-Fos, Aliette).”
Problems associated with fixed copper
Even though fixed copper is an acceptable organic control, excessive use can raise copper levels in the soil to toxic levels. Once in the soil, copper may leach into ground water. It can also be toxic to aquatic organisms and many animals (but not humans).
As with the use of any chemical in the garden, be sure to read the label completely and follow directions exactly.
Native to South and Central America, nasturtiums are rugged plants that provide lovely edible blooms.
The history of nasturtiums
When nasturtiums arrived in Spain in the 1500’s, they were called “Indian cresses” because of their peppery flavor and their use in salads. Nasturtium flowers have been gracing gardens since Roman times. Back when the Romans defeated an army, they would set up a trophy (tropaeum) pole on which they would hang the shields and helmets of the losers. Nasturtiums (Tropaeolum) earned their Latin name because, to Carl Linnaeus*, the rounded leaves reminded him of shields and the flowers looked like blood-stained helmets. (The word nasturtium literally means “nose tweaker”.)
The botany of nasturtiums
Nasturtium are perennial and annual dicotyledons, depending on the variety and local conditions. There are climbing and bushy nasturtiums. Nasturtium stems are somewhat succulent and the roots can be tuberous. One particularly rugged variety from Chile, T. polyplyllum, survives at altitudes of 10,000 feet! (Most of us would be out of breath and a bit wobbly at that elevation!)
Nasturtium flowers can be yellow, orange, reddish-brown, white, red, or even blue. Flowers have five clawed petals, with the bottom three looking different from the top two. Each bisexual flower has 8 whorled stamens. Nasturtium seeds look like naked nuts with three segments. Leaves may be rounded or deeply lobed. Leaf stems tend to be rather long. There are about 80 species of nasturtiums. Nasturtium are the only members of their genus.
How to grow nasturtiums
Until recently, it was believed that nasturtium seeds required scarification (damage to the seed hull) for germination to occur. We now know that this is not true. Seeds can be planted directly in the ground after the final frost date. Seeds should be planted 10-15” apart and 1” deep. Water regularly, unless a drought-tolerant variety is selected. Nasturtiums prefer well-drained or sandy soil. They perform best in full sun or partial shade. Once nasturtiums are established, you can easily end up with far more plants than you need. When this happens, simply transplant seedlings into a nice little container and gift them to family and friends!
Uses of nasturtiums
All parts of the nasturtium plant are edible, but most people only eat the flowers. The flowers look lovely in salads and add a nice peppery flavor to stir-fry. Nasturtium flowers contain the highest amount of lutein of any edible plant. Lutein is an antioxidant that protects the retina from free-radical damage by blue light, helping prevent macular degeneration. Unripe seed pods can be pickled in spiced vinegar and used like capers. The tuber of the Mashua variety (T. tuberous) is used in the Andes as a major food source.
In herbal medicine, nasturtiums are used for their expectorant and antiseptic qualities. They are believed to promote the formation of new blood cells and to relieve chest colds.
Nasturtiums attract butterflies and other pollinators. They can also be used in companion planting as target plants, to distract pests such as cabbageworms and mites away from more vulnerable plants. Nasturtiums are believed to repel Asparagus beetles, squash beetles, aphids, Mexican bean beetles, cabbageworms, and whiteflies.
Nasturtiums readily self-seed and they take little or no care once established. Add these lovelies to your garden or windowsill for some bright, flavorful blooms!
* Carl Linnaeus created our modern system of naming plants and animals in something called binomial nomenclature.
Wireworms are the larval stage of click beetles. They look like yellow worms, about 1-1/2” long and tend to be yellow to brown. Unlike worms, their skin is hard.
Mature click beetles are not much of a threat to garden plants. They are a lot of fun hold, however. One moment they are sitting on your hand and the next (Click!) they are gone! Their larval forms are something else altogether. Wireworms burrow into the roots, stems, and tubers of many garden plants. Favorite foods include potatoes, beets, carrots, peas, beans, melons, and onion.
If you suspect wireworms, leave a couple of carrots out on the ground overnight and monitor for wireworms. If wireworms are present in significant numbers, the area may need to be plowed and allowed to go fallow. Drying out the soil significantly reduces wireworm populations. If you are not fully committed to going organic, there are some pesticides that are effective against wireworms, including ETHOPROP (Mocap). If pesticides are used, be sure to follow package directions exactly and completely. Small populations are not a big concern.
You can grow a surprising amount of food in your own yard. Ask me how!
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