Despite the African Bagrada bug’s scientific name, Bagrada hilaris, there isn’t anything funny about this garden pest. These painted stinkbugs arrived in Los Angeles in 2008 and now they are found throughout the western states.
Bagrada bugs travel in large groups and they love to eat plants in the mustard family (Brassiceae). This includes your cabbage, broccoli, cauliflower, arugula, turnips, kale, rutabaga, collards, radish and sweet alyssum. They are also known to eat strawberries, potatoes, peppers, melons, tomato, capers, papaya, okra, peas, beans, wheat, corn, soy, millet, stock, nasturtiums, wallflowers and candytuft. This pest has few natural enemies, being new on the scene and they can cause considerable damage in the garden.
Because Bagrada bugs can fly, pesticides generally do not work. Bugs simply fly away until the chemicals have diffused and then they return to feed. Also, commercial stinkbug bait does not work on Bagrada bugs - their pheromones are different. Insecticidal soaps have been found to be only marginally effective against nymphs. With all of our Californian wild mustard, shepherd’s purse, London rocket, and pepperweed, Bagrada bugs are going to become a serious pest in short order.
Bagrada bug identification
Bagrada bugs look like miniature Harlequin bugs. They are only 1/4” long, with a black, shield-shaped body. They have distinctive white and orange markings. Females are larger than males.
Bagrada bug damage
Bagrada bugs suck sap from new leaves, stems, seed, and flowers, and damage growing tips (meristem tissue) with needlelike mouthparts. Starburst-shaped lesions can be seen on leaves and stems. Bagrada bug feeding can cause leaf spotting, stippling, wilting, small white areas on leaf tips, and prevents broccoli and other head crops from forming. Severe infestations will kill the plant. When the Bagrada bug first hit southern California, broccoli and cauliflower farmers saw 70% of their crops become unmarketable due to Bagrada bugs.
Bagrada bug lifecycle
Our native stinkbugs lay eggs on the underside of leaves, where they are vulnerable to parasitic wasps. The African Bagrada bug lays most of its eggs in the soil, near food plants, where it is safe from parasitization. A female Bagrada bug can lay as many as 150 eggs in 2 weeks. Eggs are laid singly or in clusters, on or near host and non-host plants, and on mesh and row covers. The eggs start out white and turn orangish-red as they approach maturity. Wingless nymphs are bright orange when they hatch, turning red with dark markings, as they mature. These nymphs outgrow and shed old exoskeletons, in a process called molting, in five different stages, called instars, before reaching adult size. The nymphs are often mistaken for lady beetles, but they lack the shiny hardened shell. Bagrada bugs overwinter in soil and leaf littler.
Monitoring for bagrada bugs
As quickly as populations of this pest can grow, it is important to monitor susceptible plants every 2 or 3 days. Bagrada bugs should be removed by hand and destroyed as soon as they are seen. These pests are most active when temperatures are above 75° F, so afternoons are a good time to go on a Bagrada hunt. If an infestation is found, you can place a sheet of cardboard or tarp under the plant and give it a good shake. The majority of the bugs will fall onto the barrier, where they are collected and dropped into soapy water to drown. Personally, I feed them to my chickens. Shop vacs work, too, but you’ll want to make sure you really clean it out when you’re done! Severe infestations should be reported to your local County Extension Office.
We see them in the garden frequently, but what makes a beetle a beetle?
Entomologists estimate that there are 400,000 - 1,000,000 species of beetle in the world. Beetles make up 40% of all insects and 25% of all life forms! They are members of the Coleoptera order. That name comes from Greek words that mean “sheathed wing”. The word beetle comes from the Old English word bitula, which means 'to bite'. Fossil records show that beetles have been around for 300 million years.
Basic beetle anatomy has stayed relatively the same since their prehistoric beginnings. [If it ain’t broke, why fix it - right?] Like most insects, they have three major body parts (head, thorax, abdomen), antenna, wings, compound eyes, and protruding jaws. They are protected by an especially hard exoskeleton made up of plates called sclerites and they have claws on the lower segment (tarsi) of each leg.
Wings - Most beetles have two pairs of wings. The front pair have evolved into hardened shell coverings called elytra. The back pair are used for flying. (Some species have lost the ability to fly.)
Jaws - Beetle jaws (mandibles) move side-to-side, rather than up and down. Generally, males have more elongated mandibles than females.
Eyes - All beetles have compound eyes, which means their eyes are made up of many viewing screens. Among insects, honeybees are considered to have pretty good vision at 1/60. [What we can see from 60 feet away, a bee could only see 1 foot away] What they lack in vision, they more than make up for with adaptability and resilience. For example, aquatic whirligig beetles have split eyes that allow them to see both above and below the waterline!
Antenna - A beetle’s segmented antenna are used to smell things and to feel around.
Beetles are found everywhere on earth except for the polar ice caps. They go through distinct developmental stages that look very different from other stages. This is called complete metamorphosis. They start out as eggs that hatch into larvae. Beetle larvae eat a lot! Then they enter a resting pupal stage, where they are transformed into an adult beetle. Beetles tend to be very territorial and mating rituals are particularly brutal. Burying beetles wage war against their neighbors until only one male and one female are left to reproduce, ensuring the strength and fitness of there local gene pool. A female beetle may lay as many as several thousand eggs in her lifetime. Most species abandon the eggs as soon as they are laid, while a few create nurturing habitats for their young and stick around to protect the eggs from predators.
Beetles use chemicals called pheromones to communicate and to seek out mates. The aggregative pheromone calls other to a feeding site, while the anti-aggregative pheromone tells others to stay away. Some beetle species use a scraper on their abdomen to make sounds that are not audible to us humans. Pheromone traps, strong winds, and loud noises can really mess up a beetle’s romantic intentions.
Feeding habits of beetles
Most beetles prefer eating dead plant material and dung. Many beetles are host-specific, which means they have favorite foods, and some are omnivores, eating plants, earthworms and snails. There are only a few predatory beetles and a handful that prefer carrion.
Beetles use camouflage, toxicity, mimicry and active defense measures to stay alive. Some species look like bird poop, while others look too much like wasps for predators to give them a taste. Other species use color to blend into the scenery. They can also secrete chemicals that make themselves taste bad. Some of these chemicals also provide protection against microbes. Very often, beetles get these chemicals from the plants they eat. Some species can spray these chemicals with surprising accuracy! Larger beetles have horns or spines, used to attack would-be predators.
Beetles as pollinators
While not significant pollinators, beetles are generally attracted to large, flattened or cup-shaped off-white or green flowers, such as dill, carrot, and other umbellifers, or those with heavy scents similar to decaying matter.
Beetles as pests
Since larval beetles tend to feed voraciously on agricultural crops, they are mostly considered pests. According to a study by Mississippi State University, the boll weevil came into the U.S. from Mexico in 1892. Traveling an average of 100 miles a year, this little beetle has cost the cotton industry an estimated $13 billion! Beetles are also responsible for destroying American elm populations because they can carry Dutch Elm Disease.
These are some common beetles found in the garden:
So, beetles can be good or bad, from a gardener’s perspective. Take a stroll through your garden and see what’s crawling (or flying) around!
There are several fungal diseases that result in stem blight.
Once they enter, usually through a wound, fungal spores spread through the xylem and phloem (plant veins), clogging the arteries. Without free flowing sap, twigs quickly die of dehydration and starvation. They die so fast, in fact, that leaves stay attached to the twig, rather than falling off. This is called flagging. Generally speaking, fungicides do not control stem blight.
Being shallow-rooted trees, avocados (pictured), citrus, apples and peaches are vulnerable to water stress during hot summer months. Proper irrigation can help them to protect themselves against Botryosphaeria and Neofusicoccum parvum fungal infestations. Initial symptoms include reddening and wilting of leaves. Once infected, trees may display a condition called “salt and pepper syndrome”. This occurs when fungal spores have entered the vascular bundle and spread to various parts of the tree, killing off random branches. Oozing cankers may also be present. This ooze is actually millions of fungal spores, so treat it accordingly. Remove infected branches as soon as they are seen and monitor closely for further damage.
Blueberries can be attacked by a fungus called Botryosphaeria dothidea. Young shrubs are especially vulnerable. It takes 7-10 days for symptoms to appear, and when they do, you need to work quickly to save the plant. Diseased stems will be brittle and dark brown, with dead leaves still attached. Cut 8-12” below the affected area and treat the trimmings like toxic waste. Bag it or burn it, but don’t leave it laying around and certainly do not add it to your compost pile!
Cucurbits, such as pumpkin, zucchini, and melon, can be infected by the Didymella bryoniae fungus. This is called gummy stem blight. Unlike trees and shrubs, cucurbits show symptoms on leaves, stems and fruits. Round brown lesions and cankers exude a brown ooze that can contain millions of fungal spores. Gummy stem blight can affect plants at any stage of development. Fungicides can be used as a preventative measure, but are only marginally effective.
Pod and stem blight in soybeans is caused by Diaporthe phaseolorum sojae. These fungi work in conjunction with another fungus called Phomopsis logical, which attacks seeds. Green beans, peppers and tomato plants can host these fungi without any symptoms, but planting soybeans nearby can be problematic.
Southern blight affects over 500 hundred plant varieties, including azalea, potato, apple, tomato, hydrangea, peanut, begonia, and marigold. Also known as southern stem blight or southern stem rot, Sclerotium rolfsii kills more plants in the south than any other pathogen, along with root knot nematodes. Our warm weather allows this fungus to attack plants at or below the soil line. Also known as white mold, the spores produce white mycelia that can be seen around infected plants and in and on the soil. Once soil is severely infected, solarization or fumigation with methyl bromide are the only known treatments. (Methyl bromide has been banned in most countries as an ozone-depleting chemical - it’s not something I would use, ever.)
Rather than risking the use of chemicals or the loss of desirable plants, these good cultural practices can help prevent stem blight:
Roly-poly, pillbug, doodlebug, or sowbug, whatever you call them, the more you know about these creatures, the weirder they get.
First, they are not really bugs. They are a type of crustacean, called a woodlouse. Our garden-variety woodlice are in the Armadillidium genus, making them cousins to armadillos! Like armadillos, pillbugs can roll up into a ball, and often do, when disturbed. Other woodlice cannot do this.
Even stranger than being related to armadillos, female woodlice carry fertilized eggs in a marsupial pouch, like a kangaroo! They can also reproduce asexually. If that weren’t enough, sowbugs breathe through trachea-like lungs in their feet! These fascinating creatures can live for several years, producing two or three generations each year. Each brood can include 30 to 80 offspring. In particularly rainy years, pillbugs can be a problem in the garden.
Woodlice prefer cool, dark, moist places - under planters, bricks, hoses, dense vegetation, whatever they can find. Having evolved from sea-going crustaceans, such as lobster and crab, water is critical to their survival. [Note: don’t eat them. Wikipedia says they taste like “strong urine”. I don’t know how they found out and I am certainly not going to try it myself!]
Dead plant material is a woodlouse’s favorite food. This makes them very helpful in compost piles and soil aeration. They also eat stinkbug eggs! Unfortunately, they frequently eat ripe strawberries, lettuces and cabbages, and plants with fruits that lay on the ground, such as squash and melons. These pests can chew tender seedlings down to the ground in a single feeding! Most of this feeding is done in the evening and at night. Other favorite foods of pillbugs include zinnias, blue lobelia, verbena, alyssum, pansies, and cardinal flower.
While pesticides can be effective, there are better ways of controlling these pests. The best way to take advantage of the benefits, without the risks, is to reduce dark, moist hiding places, and to keep mulch and other dead plant material away from seedlings, until they are large enough to survive being gnawed by a woodlouse.
Cycads are living fossils and they make beautiful additions to many landscapes.
Cycads are called fossils because they have remained unchanged for over 200 million years. By comparison, our modern apple tree is a mere 4,000 year resident. Dinosaurs from the Jurassic and Cretaceous periods are believed to have used cycads as their primary food source. While these plants were abundant in prehistoric times, they are now seriously threatened and could use a little help.
While cycads look like a cross between a palm and a fern, they are more closely related to pine trees and Ginkgo plants, botanically speaking. Cycads feature a thick trunk that does not branch and a crown of large, stiff evergreen leaves that grow directly from the top and center of the trunk in a rosette formation. Cycad leaves are very large, when compared to the trunk, and are pinnate, which means they are shaped like a feather. The Sago Palm (king sago, sago cycad, Japanese sago palm) is the most well known variety of this family. Breadtree and the Jamaican Sago are two other varieties. Cycads can be as small as a few centimeters or as tall as several meters.
Like pine trees, cycads are gymnosperms. This means they produce naked seeds in cones. These seeds are pollinated by specific varieties of beetles. Plants are either male or female, a condition called dioecious. Once a seed germinates, the plant may live for 1,000 years, but it grows very slowly. Just as legumes have evolved with soil microorganisms to fix nitrogen, cycads have a similar arrangement with a bacteria that lives in its roots.
Currently, there are less than 300 existing species, most of them found in tropical and subtropical areas. Most varieties of cycad are critically endangered, according to the CITES Appendix. Microcycas, in particular, has only 600 living specimens. These primitive plants are dying off for a variety of reasons, including habitat loss, over-collecting, forestry, and pesticide use. Since cycads rely on specific beetles for pollination, the death of the beetles leads to the death of a species. Armored scale infestations have also become a serious threat.
Cycads are strikingly beautiful plants and they require little or no care, once they are established. In fact, watering a cycad is a bad idea. Simply leave them alone and they will be fine. By planting cycads in your landscape, you are increasing the global population of this threatened form of plant life. Once your cycads produce seeds, you can share them with friends and neighbors!
Biodiversity refers to the variety of life forms found in a specific habitat or ecosystem. Your yard is its own ecosystem, with distinct weather patterns, soil structure, rainfall (or irrigation), and insect, invertebrate, microorganism, plant and critter populations. To better understand what happens in a limited gene pool, check out Eddie Izzard’s hysterical video about Royals.
Limiting genetic diversity, such as the monoculture of commercial agriculture, makes it easy to decide when to plant, how to plant, and what treatments to apply. It also makes a crop (or species) profoundly vulnerable to pests and disease. The more diversity found in a habitat, the more likely that that habitat will be healthy.
Urban and suburban areas are considered concrete deserts by birds, bats, and beneficial insects. Creating a diverse environment, suited to your microclimate, in your yard, garden, or even on a balcony, provides many benefits. These include natural pest control, increased pollination, water and energy conservation, and emotional well being. Read on!
Natural pest control
In a diverse ecosystem, everything is relatively balanced. Natural predators and processes limit the population of pests and disease. For example, rodents are considered pests in the garden and in our homes. Gophers can be poisoned or trapped, but barn owls will eat 1 or 2 rodents every night. Would you rather catch an occasional glimpse of an owl, soaring across an evening sky, or dispose of a squished or poisoned gopher? The choice is yours. Family Food Garden has a nice comparison of good bugs and bad bugs.
Rather than automatically spraying for pests, such as aphids, you can leave the earliest pest populations to their own devices. Lady beetles, soldier beetles, and lacewings will be attracted to this easy food source and you get to eat chemical-free produce. In a bird-friendly environment, caterpillars and other larval pests are gobbled up each spring, before they can destroy tender new plants.
Pollination processes work in tandem with healthy environments and population diversity. Spraying pesticides and herbicides can interrupt this balance. Honeybees are not the only pollinators in a garden. Beetles, hummingbirds, bumblebees, ants, moths and butterflies, and bats help to pollinate garden produce. Whenever the life cycle of one member of a community is interrupted, it affects all members of that habitat.
Water & energy conservation
Encouraging biodiversity can also protect waster and energy resources, especially when that biodiversity is geared toward indigenous plants and animals. These living things have evolved to thrive in specific microclimates, which reduces the need for water, feeding, and weeding. For example, most varieties of lawn seed originated in areas with significantly more rain than we get in the Bay Area. Current estimates for water consumption in this area see an increase of 40% in the next 25 years! Since most of our water is already imported from other areas, we need to do what we can to conserve.
The Children and Nature Network research, in conjunction with their No Child Left Inside program, has shown that children behave and learn better in more natural environments. The same must be true for adults. Also, one type of soil microorganism has been shown to improve mood!
Basics of backyard biodiversity
So, what are specific things you can provide to improve biodiversity in your habitat?
Food (natural sources):
* Native Plants
Plants are near the bottom of the food chain. They have evolved to create a fixed set of protections and processes that depend upon other native flora and fauna. Native plants have evolved in tandem with local climate, soil, flora and fauna populations, and seasonal changes, without human assistance. These plants require the least amount of water, weeding, pruning, and other resources. They reduce pollution because they do not require pesticides, herbicides or fertilizers. There is no runoff pollution from a native plant garden. These plants commonly emit chemicals that minimize weeds in their immediate area. Native plants are far more resilient, which means less work for you!
Plants and animals have co-evolved over thousands of years. Local birds, insects and animals are looking for plants that have certain characteristics. Those characteristics are found in native plants. [Did you know that some plants have indicators that let nectar eaters know how much nectar is available?]
Native bunch grasses, which were replaced by the eastern grasses that cover local foothills, were able to stay green all summer. The golden hills we see are the result of an invasive plant that has interfered with many native life cycles. Another example: Sudden Oak Death. Our live oaks have evolved to deal with drought each summer. As the live oaks are watered, the fungus that causes Sudden Oak Death is able to overcome and kill these massive beauties.
You can learn more about native plants from the CA Native Plant Society.
The rhizosphere is the area of soil that is directly impacted by root secretions and related soil microorganisms.
Plants interact with the surrounding environment through chemical reactions, ion exchanges and complex trade agreements with soil microorganisms. The majority of these interactions occur below ground, in the rhizosphere.
Root secretions contain acids, sugars and amino acids. These secretions help plants obtain nutrients and protect against pathogens. They also stabilize soil aggregates.
The rhizosphere is broken down into three regions:
From the inside out
Working from the inside and just around the roots of most plants, microscopic fungi (mycorrhizae) exchange water, hormones and mineral elements found within the soil for sugar created by the plant through photosynthesis.
Rhizobium bacteria have a symbiotic relationship with members of the legume family. They detect flavonoids secreted by plant roots, which stimulates the bacteria to generate nod factors. These nod factors trigger the plant to form root nodules. The rhizobium bacteria then provide the plant with valuable fixed nitrogen from the atmosphere. There are other nitrogen fixing non-symbiotic bacteria within the rhizosphere that aid other plants in exchange for sugars and other nutrients.
Some plants also produce allelochemicals within and beyond the rhizosphere that prohibit other plants from growing nearby.
Just as we constantly lose skin cells, plants also shed cells. These cells fall to the ground (rhizodeposition) and are eaten by bacteria. The bacteria, in turn, are eaten by nematodes and protozoa. This process enriches the soil, making nutrients available to plants and improving soil quality.
Any word that ends with ‘-cide’ means death to something. In the case of herbicides, it means death to some or all plants that it contacts.
Herbicides are chemical weed killers. Non-selective herbicides kill everything, while selective herbicides are, well, selective. Until the 20th century, cultural controls and good old fashioned elbow grease were used to rid an area of weeds.
Chemical warfare research from WWII determined that synthetic plant hormones and other chemicals could be used to kill many broadleaf plants. There are several chemical reactions going on when these chemicals are applied. Some grass herbicides work by halting cell production in the meristems (growth tips). Other chemicals starve plants by interfering with the production of amino acids or by halting photosynthesis.
Using herbicides can lead to several problems:
Loss of biodiversity is another serious problem. Nature’s balancing act is delicate and the full effects of chemical use is not completely understood at this time. For example, Roundup (glyphosate) has decimated global Monarch butterfly populations and increased the use of pesticides that end up in our food and water.
If you feel that you absolutely must apply chemicals in the garden, follow the directions exactly. Make sure it is the correct herbicide for the site and the weeds in question. Apply too much and the excess simply enters our water supply. You will also want to make sure that the weeds are in the correct life stage for the herbicide to be effective. If a chemical claims to be preemergent, it will attack germinating seeds. Postemergent herbicides attack growing plants and they work better on young plants. Postemergent herbicides can be foliar (leaf absorption), root, contact or systemic. Systemic herbicides are absorbed and spread throughout the plant.
Be sure to read product labels carefully and completely, and dispose of the container properly.
Did you know that thorns are modified leaves?
Leaves are food producing factories for most plants. This is where photosynthesis takes place. The only exception is succulents. Succulents are modified stems and the thorns on a cacti are modified leaves. Weird, right?
So let’s learn about the amazing leaf.
In addition to photosynthesis, leaves breath and sweat - sort of. On the underside of a leaf, there are small openings called stomata. The stomata control moisture and gas exchanges that regulate temperature and water content within the plant.
Inside a leaf
The inside of a leaf is surprisingly complex. It has an outer layer called the epidermis, which is covered with a waxy cuticle. The cuticle changes thickness depending on how much light is present. The epidermis also has hairs that provide protection.
Inside, under the epidermis, there are columns (parenchyma) called the palisade layer. The parenchyma contain chloroplasts for photosynthesis. Chloroplasts hold the chlorophyll that harvests the sun’s energy and begins turning that energy into sugar.
Under the palisade layer is a thickened area called the spongy mesophyll. The spongy mesophyll is a collection of loosely packed parenchyma tissues that allow oxygen, water vapor, and carbon dioxide to move around within the leaf. The xylem and phloem make up the vascular bundle, which is also held in this spongy mass.
On either side of the stomata are guard cells. When there isn’t enough water, the guard cells become flaccid (through sugar and ion osmosis) and the stoma close, preserving whatever water is already in the plant.
Understanding the vocabulary related to parts of a leaf can go a long way toward plant identification. These are the basic parts:
Another helpful tool in plant identification is leaf arrangement. This describes the way leaves are positioned along a stem. Leaf arrangement can be alternate (taking turns on either side), opposite (in pairs), whorled (several leaves at one position), or rosette (a spiral cluster at the base of the plant, like a dandelion).
Leaf arrangement also refers to the way a leaflet is positioned on the petiole. A simple leaf is a single blade. Compound leaves have many leaflet at the same petiole. Palmately compound leaves look like a hand, with leaflets radiating from a central point, while the leaflets on a pinnately compound leaf share a common leaf stalk (rachis). Double pinnately compound leaves have a double set of compound leaflets.
The shape of the blade is probably the most important when it comes to plant identification. When considering leaf shape, we look at the edge, or margin, and the apex, or tip.
Not only do leaves help with plant identification, but they can also help narrow down pests and diseases. Leaf damage falls under these categories:
Leaves from the garden can make beautiful additions to home decor and welcome gifts. Leaves can be used for many crafts and the variety of shapes is practically limitless!
Go outside and find a leaf. Any leaf will do. Bring it inside and draw it as well as you can. Then label all its parts. Try different species to see how they are similar and how they are different. You might be amazed and it’s a lot of fun.
Known as ladybugs, lady beetles, or ladybirds (Brit.), these voracious feeders are a welcome site in any garden.
Members of the Coccinellidae (Co-see-nell-e-day) family, they are not true bugs at all. True bugs have piercing and sucking mouthparts, wings that are membranous or hardened only at the base, and they are born as miniature adults. Lady beetles (the correct name) have grasping jaws, a hard shell, and they go through distinct developmental stages. The ladybug of your childhood is actually a beetle.
Lady beetle anatomy
Lady beetles have a protective exoskeleton made out of a protein much like our hair and fingernails. They have 3 main body parts: head, thorax, and abdomen.
Thorax - strong muscles that control the legs and wings
Abdomen - contains organs for digestion, reproduction and respiration [Adult lady beetles breathe air through body openings, called spiracles, on the sides of the abdomen and thorax.]
There are more than 4,500 species of lady beetle worldwide, with nearly 200 species in California. These include:
Most lady beetles are beneficial insects. The Mexican bean beetle is a close cousin and it destroys many bean crops. Mexican bean beetles are orange with 8 black spots and they interfere with photosynthesis by turning leaves into lacework. Also, introduction of the Harlequin variety (Harmonia axyridis) has been devastating to native populations.
Like skunks and the Monarch butterfly, the familiar bright coloration is a warning to predators. Lady beetles can secrete an alkaloid toxin from the joints in their legs which tastes awful. This behavior is called “reflex bleeding”. A threatened beetle may also play dead to protect itself.
Do you have room for an almond tree?
I planted a bare root almond tree two years ago and it just started to blossom last week. The flowers are so pretty!
Almonds are California’s third largest agricultural product and the drought has caused prices to skyrocket. Almonds are an incredibly healthful snack and the trees are lovely additions to a landscape.
According to Wikipedia, “The pollination of California's almonds is the largest annual managed pollination event in the world, with close to one million hives (nearly half of all beehives in the USA) being trucked in February to the almond groves.” Imagine that! Unless you get a self-pollinating variety, you will need to plant 2 or 3 trees to get any fruit.
Almond's bittersweet history
Now, I’m not sure how people started eating almonds because the fruit of wild “bitter” almond trees is poisonous. Bitter almond trees contain a chemical called glycoside amygdalin, which turns into deadly hydrogen cyanide (prussic acid) when the fruit is injured by chewing. Apple, cherry, peach, plum, pear, and apricot seeds, and cassava root (tapioca) also contain cyanide compounds, but it takes an awful lot of any of these to get sick. The trees we buy now are called sweet almonds and they are safe and they taste better!
The almond tree
Almonds are deciduous, which mean they drop their leaves in winter. They can grow 13-33 feet tall, with a 12” diameter trunk. The canopy is 10-15 feet wide. Dwarf varieties are being developed, but their productivity is still questionable. Almonds do not do well in containers. Unlike avocados, which can take 10 years or more to produce, almond trees bear fruit as early as their third year! To improve root development, remove flowers the first couple of years.
Almonds are related to peaches, nectarines, cherries, plums, and apricots, all members of the Prunus genus, which, in turn, is a member of the rose (Rosaceae) family. The nut we are all so familiar with is actually the fruit, or drupe, of the almond tree. Botanically, it is not a nut at all. That’s why they are called stone fruits.
How to grow almonds
People have been growing almond trees for 6,000 years, in South Asia and the Middle East, and you can, too. Almonds were introduced to California in the 1840s. Almonds grow very well in the Bay Area’s Mediterranean climate. Your first decision will be location. Almonds need lots of sunlight and they prefer temperatures between 59 and 86°F and the buds have a chilling requirement of 300 to 600 hours below 45°F. Chilling requirements are accumulated hours of cold temperatures that cause vernalization, or the ability of a plant to bud and flower. They do best in mild, wet winters and hot, dry summers. Almonds do not like soggy, heavy soil. They are a deep rooted tree and should be planted 20-25 feet away from any other tree. Almond trees benefit from the following seasonal care:
Almond pests & diseases
If you are going to grow almonds, you will need to know what problems to watch for. This include leaf spot, mites, leaf-footed bugs, voles, crown gall, Eutypa dieback, brown rot, shot hole disease, bacterial canker, navel orangeworms, redhumped caterpillars, rust, and peach leaf curl. The better you understand what to look for, the quicker you can nip the problem in the bud.
Rather than planting an ornamental tree, almonds can provide 30-40 years of delicious food for you and your family!
Trails of slime and damaged leaves are clear signs of a slug or snail infestation in the garden. But, before we attack this problem, let’s take some time to learn more about these amazing creatures.
Slug & snail taxonomy
Slugs and snails are members of the mollusk phylum. The name mollusk evolved out of Aristotle’s name for cuttlefish, which meant “the soft ones”. Most mollusks are nothing more than a head attached to a foot. [Try picturing some of your friends that way!] They are included in the class known as Gastropoda, which means “stomach foot”. Unlike clams, which have two shells and are called bivalves, snails have a single valve (shell).
Slugs are simply snails without shells. There is also a group of gastropods that have a shell, but it is too small to retract into. These are called semi-slugs. Some snails have clear shells and are called glass snails. Aside from insects, there are more Gastropods on earth than any other animal. They are invertebrates, which means they have no backbone.
Snails and slugs excrete a mucous path in front of themselves as they travel. This mucous is a glycoprotein, similar to egg white, that smooths the ride and reduces friction. Imagine driving a car that fixed every pothole before you got to it! Of course, snails don’t win any speed records. In fact, they are the slowest animal, at 0.03 mph.
According to the Journal of Drugs in Dermatology, slug and snail slime helps reduce wrinkles, scars, dry skin, and acne, which is why it is included in many cosmetics! It also helps wounds heal faster and better. Some people allow a snail to crawl over a cut to help it heal. Just remember, slugs and snails can carry salmonella and other bacteria and a parasite that can cause meningitis, so wash your hands after handling them.
Slug and snail reproduction
Snails are hermaphrodites, which means they are both male and female, though not always at the same time. Snails mate in late spring and early summer after an extended courtship. Imagine that! How do you think snails court each other? They press their heads together!
It take 2-8 weeks for eggs to develop and 1-2 days for a snail to deposit 30-50 eggs in a hole dug in the ground. Three to four weeks later, depending on temperature and humidity, baby snails emerge. Now, if you have never seen a baby snail, you have really missed out. These translucent beings are perfection and elegance in action. Put your revulsion aside and grab a magnifying glass to really appreciate these tiny creatures. Seriously.
Slug and snail diet
Most land snails are herbivores (as gardeners well know!), but some are omnivores and some are predators. Snails eat a lot of calcium. The calcium is used to build their shell. The shell provides protection from the elements and some predators. Most of the calcium eaten by garden snails comes from dark, leafy greens, such as spinach and chard.
Not all land snails are edible, but most of them are. Raising snails for food is called heliciculture. People have been eating snails since prehistoric times. In France, the Helix pomatia snail is called “Petit gris” (little grey) and it is considered a delicacy. It’s close cousin, our American Helix aspersa snail, is larger, whiter, and just as edible. I haven’t tried escargot just yet, but if you do, let us know in the Comments!
Snails as pets
I recently learned that many people also keep snails as pets. Most apartment managers won’t even notice their presence and you never have to take them for a walk! Snails are very sensitive to noise, light, vibration, irregular feedings, unsanitary conditions and being touched. They are a very low maintenance pet, but they won’t do any tricks.
If you consider all snails around the world, they can range in size from less than a millimeter long to the 35” 40-pound marine giant, Australian Trumpet. The largest land snail, the Giant African Snail, is over 15” long and can weigh 2 pounds. The Giant African is commonly raised on discarded banana leaves and then consumed as food. [I think I'll pass.]
Snails have two pairs of highly mobile tentacles on the head. The larger pair features light-sensitive eyespots, while the smaller pair is used to smell and touch. Most land snails have lungs, but a few still breath using gills. Slugs and snails have a serrated tongue, called a radula, that looks a lot like a jagged shag carpet. They use the radula to rasp plant tissue free, before swallowing.
Slug and snail control
Now that you have a better understanding about these beasties, let’s get them out of the garden! Handpicking is highly effective if you do it often enough and at the right times. Since slugs and snails prefer moisture and darkness, predawn and nighttime are the best times for hunting. Use a flashlight and they are surprisingly easy to find. You can wear gloves, which makes picking up slugs easier and less yucky. Toss them in a plastic bag and trash them, or drop them in soapy water. You can also spray them with a 5-10% ammonia solution. I feed them to my chickens.
There are many predators that love to eat slugs and snails. Create a welcome habitat for these predators and they will find their way to your garden:
Concentrated garlic or wormwood solutions have been found effective against slugs and snails in commercial agriculture. Copper strips are advertised as effective slug and snail control, but I have never heard of them actually working. Bordeaux mixture (a copper sulfate and hydrated lime mixture) or copper sulfate alone can be brushed onto tree trunks to discourage snails.
Some gardeners introduce decollate snails (Rimuna decollata) into the garden as a control measure. Decollate snails hunt, capture and eat garden snails and slugs. Of course, introducing a non-native species isn’t without it’s own problems. These heavy feeders will eat many beneficial insects, as well. Decollate snails are banned in most California counties due to the risk to native species.
Slug and snail bait is a highly effective control method when used in conjunction with other plans of attack. Most people, however, use it incorrectly. At the first sign of irregularly shaped holes in leaves and telltale slime trails, lightly sprinkle bait around plants being eaten. Snails and slugs tend to return to the same feeding areas each day. Do not pour it into piles or apply heavily. There are a few different types of bait and you need to understand the risks associated with different ingredients:
It is a good idea to apply bait after watering. The moisture will encourage snail and slug activity and you won’t wash the bait into the soil.
Some people use traps to capture these nighttime feeders. You can leave melon rinds turned upside down to catch a fair number. Simply collect them in the morning and toss them to your chickens or kill the slugs and snails and add it to your compost pile. Beer traps sound great, but I’ve never had luck with them. I think it has something to do with my dogs drinking all the bait when I’m not looking…
In Britain, aphids are called plant lice, and for good reason. Considered one of the most destructive pests in the garden, aphids suck valuable nutrients from your plants, leaving behind a “honeydew” (sugary bug poop) that creates the perfect habitat for fungal disease. And they don’t work alone!
Ants and aphids
Ants actively protect and “farm” aphids in exchange for honeydew, but there is so much more to this complex relationship. Prepare to be amazed!
One type of butterfly (Niphanda fusca) lays its eggs on plants where ants are tending aphids. When the caterpillar hatches and starts eating the aphids, it emits a pheromone that fools the ants into thinking it is one of their own. The ants take the caterpillar into the nest, where they feed and tend it. In return for their efforts, the caterpillar produces honeydew, which the ants eat. When the caterpillar is grown, it walks to the colony entrance and builds a cocoon. When it emerges as a butterfly, the ants would attack it, but it produces a sticky wooly substance on its wings that temporarily paralyzes the ants’ jaws! Aphids also have arrangement with certain bacteria, as well, but I digress…
Damage caused by aphids
Besides sucking the life out of garden and landscape plants, aphids are vectors of disease. As they walk from one place to another, they can carry fungal diseases such as rust and Fusarium wilt, viral diseases, including cucumber mosaic, potato Y diseases, tobacco mosaic, and many, many more.
If you’re not sure what an aphid looks like, go outside and take a close look at plants in the garden and on citrus trees. As long as temperatures are warm enough, you are likely see clusters of grey, orange, brown, black, green, yellow, pink, or nearly colorless bumps, or tiny green crawlers on the underside of leaves and where new growth emerges. These are signs of an aphid infestation.
Aphids are tiny. Most varieties in the San Jose area are less than 1/8” long. They have soft, pear-shaped bodies, segmented antennae, and long, thin legs. They feed through sucking mouthparts, called styles, that emerge from a sheath called a rostrum. Aphids are wingless until conditions change for the worse. Somehow, somewhere in their genetics, the need for wings is communicated and voilà! Wings emerge!
There are over 4,000 species of aphid worldwide, and 250 that pester U.S. gardens. In the San Jose area, there are 17 species of aphid that regularly cause trouble, including:
Aphids communicate using pheromones. Pheromones are chemicals that cause others to react. (Perfume and cologne try to replicate the effect of human pheromones.) When aphids are attacked, they release pheromones that tell other aphids to run for it. Lady beetles have learned to follow those pheromones to find the aphids’ hiding place! Even more amazing, scientists have learned that plants release their own chemical communications when they are attacked, calling in reinforcements of lady beetles and other beneficials! Who knew?!!?
One reason why aphids are so successful is that they can reproduce asexually. This is called parthenogenesis and it means aphids do not need to mate to reproduce! A single female aphid can give birth to 12 live offspring every day. These offspring are called nymphs. Some aphids lay eggs that overwinter but you’ll probably never see them because they are often tucked into tiny hiding places.
Aphids grow to adulthood in a week and each adult aphid can produce 80 nymphs a week. According to entomologist Stephen A. Marshall, in his book Insects: Their Natural History and Diversity: With a Photographic Guide to Insects of Eastern North America, a single aphid could produce 600 BILLION descendants in a single season. Try wrapping your brain around those numbers!
Aphids have been recorded sacrificing their body fluids to fill up holes in their colony's hiding places.
Applying sticky barriers to plant stems and tree trunks can help eliminate ant support. You can also use kaolin clay or diatomaceous earth (DE) to prevent infestation. Research has also shown that growing different types of plants close together, in a practice called polyculture, can confuse aphids and reduce their success in your garden.
Being pretty fragile, aphids can be wiped off plants or squished, but that gets messy. Insecticidal soap can be sprayed on heavily infested plants, but this will only affect the bugs that it contacts directly. The easiest way to reduce aphid populations on specific plants is to simply hit them with water from the hose and to encourage beneficial insects in the garden.
Photosynthesis is the process plants use to convert the sun’s energy into glucose (sugar). When the sun’s electromagnetic energy hits living plant leaves, some crazy chemistry starts to happen!
Photosynthesis occurs in an organelle called a chloroplast. (Organelles are organs held within a cell) The chloroplast holds chlorophyll. Water (H20), oxygen (O2), carbon dioxide (CO2) and glucose (C6H12O6) are also present in the chloroplast.
How photosynthesis happens
Photosynthesis is a two step process. The first step is the light dependent reaction. This is when the sunlight is absorbed and transformed into a chemical called ATP. To do this, electrons are torn from water molecules, creating oxygen as a waste product. When this happens, hydrogen (H) is released and used to create two compounds: NADPH (nicotinamide adenine dinucleotide phosphate) and more ATP (adenosine triphosphate).
The second stage of photosynthesis is the light independent reaction, or the Calvin Cycle. This is when the ATP is converted into glucose using carbon dioxide.
Once the glucose is formed, it is used by garden plants to grow and thrive. These sugar molecules are also used as currency with the microorganisms that provide the plant with mineral elements found in the soil.
Any interruption in photosynthesis leads to chlorosis. Chlorosis can be the result of disease, a lack of mycorrhizae, or sunburn. If you see chlorosis occurring anywhere in your garden, your plants are starving. Of course, if you want tall, light-colored stalks of celery, you must block photosynthesis from happening by wrapping the stalks with newspaper or some other material.
Fertilization is the act of bringing male and female gametes together to create a new life (zygote). Gametes are single strands of unpaired chromosomes.
In the animal world, a female egg comes together with a male sperm for fertilization. Because we are so familiar with that process, many people assume that pollen is the same thing as sperm, but it isn’t. Instead, plants use a method called double fertilization to create seeds for future generations. Before double fertilization can occur, the pollen must make it to the flower.
Pollination is the movement of pollen from an anther (male) to a stigma (female). This can occur within a single flower, between flowers of the same plant, or between different plants. Approximately 90% of pollination occurs with the help of other living things, usually beneficial insects. Once a flower is pollinated, the really amazing stuff starts to happen!
Without getting too technical, flowering plants (angiosperms) use one female cell (gametophyte), also called an embryo sac, and two male cells (sperm) to create a seed. Conifers and other gymnosperm plants work pretty much the same way, but without creating flowers or fruit.
Did you know that pine cones are actually modified branches?
Once attached to an appropriate flower, the pollen granule germinates, sending a tube down to the female sex organs, or ovum. This tube is used to move male gametes (sperm cells) to the egg cell. One pollen grain fertilizes an egg that becomes the baby plant, or embryo. Another pollen grain fertilizes a different cell, which becomes starchy food for the embryo, called endosperm. So, forget your 6th grade sex ed movie. Flowering plants do it doubly!
The bright colors and sweet smell of flowers tell pollinators that the sugary nectar and nutrient rich pollen they love to eat is inside. As pollinators feed, sticky pollen clings to their exoskeleton. If you look closely at a honey bee, you can often see yellow clumps attached to their legs. Those clumps are pollen.
When the pollinator travels to the next flower, some of the pollen is knocked off and new pollen is collected. The pollen that is dropped then enters the egg cells and fertilizes them. Fertilized eggs grow into seeds. Pollination is the process of moving pollen grains from one plant to another.
There are many ways that pollination can occur:
When pollination rates are low, prices for food, clothing, shelter and other products increase.
Just as there are two types of plants, there are two structures that support pollination. In flowering plants (angiosperms), pollen is created in the anther (male) and transferred to the stigma (female). Gymnosperms (non-flowering plants) produce pollen in male cones. Wind moves the pollen to female cones (micropyle), where pollination occurs. Sometimes flowers are male and sometimes they are female. In some cases, they are both. Avocados are both, but at different times!
Process of pollination
The process of pollination was figured out by Christian Konrad Sprengel in 1898. Pollination can occur within a single flower or it can occur between flowers of the same or different plants. Cross-pollination (allogamy) occurs when the pollen of one plant is moved to the flower or cone of a different plant. Self-pollination can be within the same flower (autogamy) or between flowers of the same plant (geitonogamy).
To increase production in the garden, add plants that provide nectar, color, and landing platforms for beneficial insects. Bees prefer the bright blue and violet of catmint, borage and lavender. (Did you know that bees cannot see the color red? To them, it looks green!) Hummingbirds will flock to the red, fuchsia and purple of phlox, hollyhock and butterfly bush. Fragrance is another way flowers attract pollinators. This is especially true at night, when moths and bats are out. The shape of a flower can also attract pollinators. Hummingbirds prefer long, tubular flowers, while butterflies prefer flowers with wide, flat petals.
By creating habitat for pollinators and other beneficials, you will add color to the garden and increase productivity. You will also be helping to offset harsh conditions created by concrete, smog and invasive plants.
If you were to add just one plant to your garden to improve pollination, which one would it be? Let us know in the Comments section!
Seeds are where the miracle of plant life is stored.
All plants, aside from mosses, liverworts* and some ferns, can be grown from seed. Seeds come in all shapes and sizes. They can be as tiny as an orchid seed, which weighs in at 1/1,00,000th of a gram, to the oceanic giant, coco de mer, at 40 pounds!
After a flower is pollinated, a seed develops. Most seeds aren’t very impressive looking from the outside. Usually, a hard shell, or seed coat, covers what looks like starch. But locked in that seed coat is an embryo, waiting to be born.
Seeds are categorized as either angiosperms or gymnosperms. Angiosperms are flowering plants. Their seeds are surrounded by fruit, such as the apples, tomatoes, and cucumbers in your garden. In contrast, gymnosperm seeds are naked. Conifers and ginkgoes are examples of gymnosperms.
A seed is called viable when it can sprout on its own. Most garden seeds only remain viable for 1 - 5 years, but the oldest recorded viable seed was 1,300 years old when it sprouted! In 2007, scientists extracted embryos from Siberian Arctic flower seeds. The seeds were germinated in vitro. These test tube babies grew, flowered, and created their own viable seeds. They were nearly 32,000 years old! Outside of the lab, a 2,000 year old Judean date palm seed that was excavated from Herod's garden was germinated in 2005. How’s that for tenacity? What makes this even possible? Let’s find out.
Seeds have six stages of development:
Once a seed has developed fully, it can float on a breeze, sit in the ground, or, in some cases, pass through someone’s digestive system, unscathed and still viable.
Seeds are fertilized eggs called ovules. There are three parts to a seed: the embryo, endosperm, and seed coat.
The seed coat surrounds its innards, providing protection from the elements, insects and disease. The seed coat also helps keep water out. This prevents germination from occurring at the wrong time of year. It takes a specific combination of moisture, heat and sunlight to break the seed coat.
Held within the seed coat is a large food supply called endosperm. Endosperm is made of carbohydrates, proteins, or fats, depending on the type of plant.
The embryo is a miniature version of the mature plant, held in a state of limbo. The embryo has several parts:
Seeds also have scars. One scar, called the hilum, is formed where the seed was attached to the ovary wall. Another scar, called the raphe, occurs where the seed was attached to the placenta, making it the seed's bellybutton.
It is the structure of a seed that makes it so durable. Until the correct conditions exist, that little bundle of potential will stay the way it is for a good long while. So, what triggers it to change?
Germination only occurs when all the conditions of light, temperature, moisture, air, and seed viability are right. When these conditions occur, certain enzymes are activated. From the Greek words that mean “leavened within”, enzymes are protein molecules that act as catalysts for biochemical changes.
These newly activated enzymes start converting the endosperm (carbs) into sugars that the plant can use for energy. At this point, the seed coat ruptures, the stems (plumules) go up and roots (radicles) go down and a new plant is born!
Today's garden challenge
Take half a dozen paper cups, fill them soil, and place a bean or sunflower seed in the medium, about 1/2" down. Gently saturate the soil with water and place the cups on a sunny window sill. While you're at it, pop a couple of seeds open and see if you can identify its parts! Use the Comments section to let us know which seeds you planted and how long they take to germinate!
*Liverworts (and hornworts) are the simplest form of plant life. They have no roots or vascular bundles. Liverworts are believed to have been the first group of plants to evolve from algae.
January and February are the time to collect scion wood.
Scions are young twigs that are grafted onto a mature tree. Very often, a single tree trunk can support several varieties of fruit or nut. Grafting scions to an orange tree can convert it to a lemon/lime/orange tree! I once had a single tree that produced nectarines, plums, pears and peaches! Grafting scion wood is an easy way to propagate multiple varieties of fruit from a single tree. This comes in handy especially when working with a small yard or a containerized tree.
Look for vegetative growth, rather than flower buds. If you can’t tell the difference, lean towards more vertical growth twigs. If possible, collect scions from the previous year’s growth.
Because scions are still alive, be sure to treat them gently. Do not use cuttings that show signs of disease or pest damage. If you are pruning at the same time, be sure to not step on them as you work around the tree.
Scions can stay dormant in the refrigerator until it is time to graft, which is when outdoor buds begin to swell.
Tubers are ‘taters, but there’s more to them than that.
Tubers are modified underground stems (geophytes) that store water, sugar, and other nutrients, to get plants through winter and drought, to help them start back up in spring, and to regenerate themselves, asexually. Some people say that underground runners (stolons) are also tubers, but not everyone agrees.
Potatoes and yams are stem tubers. These structures are modified stems from thickened stolons (runners) or rhizomes (underground stems). The ‘eyes’ you see on a potato are buds. New plants can grow from these buds, as well as from the distal (far) end of the tuber.
Root tubers, or tuberous roots, on the other hand, are modified lateral roots which store nutrients and sugars in the same way as stem tubers. Sweet potatoes, dahlias, and cassava (tapioca) are examples of root tubers. These tubers do not have ‘eyes’ that can generate new plants. Instead, growth occurs at the far (distal) end, as well as from the crown area where foliage is already growing. Tuberous roots are biennial:
What sort of tubers are you growing?
Cells are the building blocks of all living things. Your garden plants are no exception.
All animal and plant cells both contain the following:
Differences between plant and animal cells
Animal cells are generally rounded and irregular, while plant cells tend to be rectangular and more rigid. This rigidity comes from cellulose, pectin, hemicellulose, and occasionally lignin. This is also what holds your garden plants upright. When they are suffering water stress, they lose some of that rigidity and start to wilt.
Plant cells are also different from animal cells because they have cell walls and an organelle called a chloroplast. Animal cells do not have chloroplasts because they do not produce their own food. If we had chloroplasts, we would probably be green! Chloroplasts contain the chlorophyll used in photosynthesis.
You can grow a surprising amount of food in your own yard. Ask me how!