Chickens, jays, and mockingbirds can wreak havoc on your fruit and nut tree crops unless you provide protection.
Floating eye balloons, hanging old CDs, motion-sensing sprinklers, and noise cannons are just a few of the countless methods ‘guaranteed’ to protect your fruit and nut crop from marauding birds, but most of them do not work; not for long, anyway. Caging your tree is the only way to be sure that you get the lion’s share of your fruit or nut crop.
The netting used over your tree cage will still allow pollinators easy access. Unfortunately, it also allows codling moths and other flying insect pests to reach your fruit and nut trees. Even so, birds and squirrels can take a big bite out of apple, apricot, almond, nectarine, fig, and other crops. Tree cages can stop that damage before it even starts. Plus, these cages stay up, year round, so there's no wrestling with netting every spring and fall.
Store bought vs. DIY tree cages
Store bought tree cages can be astronomically expensive and most of the really nice ones are in the UK. The added shipping costs make it impossible or unrealistic for most of us. Luckily, it is surprisingly easy to make a tree cage yourself for less than $50. If you can scrounge old tree supports, it’s even cheaper.
Make your own tree cage
This tree cage design is intended for dwarf variety trees that will be pruned to 6 to 8 feet tall and 8 feet wide. You can adjust the measurements for bigger trees, but longer lodge poles can be harder to find and more expensive.
2. Using four lodge poles, flat on the ground, mark out an 8-foot (or smaller) square around your tree. On the inside of each corner, dig a hole at least one foot deep with the post hole digger. [If the ground is really hard clay, like mine, you can use a drill fitted with a large drill bit as an auger. It works surprisingly well.] Place one lodge pole in each hole and gently press the dirt you dug up back into the hole, making sure that the drilled hole runs outside to inside of the tree space, rather than side-to-side. You’ll see why in a minute. Also, dig one more hole to create the doorway space.
3. Take both 1”x2” boards and cut a 1/2-inch notch out of the middle of each, only cutting halfway through. I used a handsaw to make the perpendicular cuts and then a hammer and chisel to knock out the chad. Fit the 1”x2”s together in the middle and hammer together into a giant X-shape.
5. Staple 2’ chicken wire to the lodge poles, all the way around.
6. If you are really handy (which I am not), you can build yourself a fancy door. I opted for something far more simple: I cut a piece of bird netting that was larger than the door opening, attached it to the opening at the top, and ran a piece of thin scrap wood through the holes at the bottom. The wood weighs the netting down enough to keep chickens, mockingbirds, and jays away from my fruit and nut trees, and it’s easy to use. For added stability, you can add a cross piece above head height between one of the four lodge poles and the door lodge pole.
7. Drape bird netting over the X-shape and staple it down to make it taut. Ideally, you want birds and bats to bounce off, not get tangled. Bring the netting down over the sides until it reaches the chicken wire. You can use the wrapping wire from the roll of chicken wire (or string) to “sew” the netting to the chicken wire. I used heavy duty black thread and an embroidery needle.
Pineapple guavas are neither pineapples nor guavas, but they do make a good addition to your foodscape.
Distant cousin to guavas, pineapple guava (Acca sellowiana, or Feijoa (fay-zho-uh) sellowiana) is a member of the myrtle family. Native to Brazil and Argentina, it is well suited to the Bay Area’s hot summers and cool winters. It is somewhat frost tolerant. The edible flowers look like tiny versions of bottlebrush and have a cinnamon flavor. (Of course, if you eat all the flowers, you won’t get any fruit!)
Pineapple guava is a relatively slow-growing perennial evergreen shrub that can eventually reach a height and width of 10 to 15 feet. Leaves are green on top and silvery underneath, which looks really nice when a breeze comes through. Pineapple guava plants grow best in USDA Hardiness zones 8 through 11 and they need 50 chill hours each winter to set fruit (I get 300 in the Bay Area). If temperatures are above 90 °F for too long, fruit set can be reduced. Pineapple guava are very drought tolerant, but they do need to be irrigated as fruit is being produced.
How to grow pineapple guava
Growing pineapple guava from seed is a slow business. It can a full year for seedlings to show any real growth. Most pineapple guava trees are purchased as 1- or 2-year old plants. If you only have room for one specimen, make sure that it is a self-pollinating variety. Most pineapple guavas require a second specimen for pollination. They prefer partial shade, a soil pH of 5.5 to 7.0, and can tolerate some salt spray. They do not respond well to bright, reflected light, so installing pineapple guava next to a driveway probably isn’t the best idea. They can be grown in large containers, and they can also be espaliered or pruned as a small tree, or used to create hedgerows or windbreaks. There are several varieties of pineapple guava to choose from.
Caring for pineapple guava
One of the best things about pineapple guava is how little care they need. You can ignore them completely, once they are established, or you can give them a boost with these maintenance tips:
Harvesting the fruit
Pineapple guava fruit are egg-shaped and can be 3/4 to 3-1/2 inches long. The fruit is described as tasting like a cross between pineapple, apple, strawberry, guava, and mint. Fruit reaches full maturity (and the best flavor) in fall, but it bruises easily. Ripeness can be determined by giving fruit a gentle squeeze. Harvesting fruit too soon is a waste, since unripe fruit is bitter. Waiting for it to fall on its own usually means bruised fruit. Probably the best solution is to set up a net under the tree to gently capture fruit as it falls, but this isn’t alway feasible. Commercially, ‘touch picking’ is used. Touch picking means that if the fruit breaks free when you touch it, it’s ripe. Regularly checking for ripe fruit before it falls will reduce the number of bruised fruit. Some people eat the entire fruit, skin and all, while others cut it in half and scoop the fruit out with a spoon.
Pineapple guava no real pest or disease problems. Black scale and fruit flies may show up, but these shrubs are truly trouble-free.
Pineapple guava fruit does not ship well, so most stores never carry it. Adding these trouble-free shrubs to your foodscape means you will have a ready supply of delicious fresh fruit each fall for many years to come.
As fruit trees begin putting out fruit in spring, it is your job to take some of that fruit off.
It may seem counterproductive. Why on earth would I plant a fruit tree only to take the fruit off when it has only just started growing? Why would you want to reduce your crop that way? Read on and find out!
Why thin fruit?
Most fruit trees will produce far more fruit than can be supported or made flavorful. Too much fruit and branches start breaking. Now, the tree doesn’t care how the fruit tastes, as long as it tastes good enough to cause animals to help with seed dispersal. To get the sweetness, size, and shape that we want, we have to intervene. Thinning fruit also helps reduce the likelihood of pests or diseases getting established in the nooks and crannies between fruit. Finally, fruit thinning reduces the chance of your tree taking a year off of production (alternate bearing) out of sheer exhaustion.
How (and when) to thin fruit trees
Different trees have different thinning needs. Generally, the time to thin fruit is dictated by fruit size. Stone fruits are thinned when they reach 3/4 to 1 inch in diameter, while pome fruits can be thinned when they are 1/2 to 1 inch. This is usually in April and May in the Bay Area. You can also predict the time for thinning by noting it 30 to 45 days after full bloom on your calendar. To actually remove the fruit, give it a gentle twist. Sometimes, pruners are needed. Your fruit tree is working very hard at this stage, so be kind. Do not be tempted to thin your fruit trees too early, as this can lead to split fruit later on, especially in peaches. Of course, thinning too late won’t help your fruit become as large as it might have.
Fruit thinning by species
Some trees do not require thinning. These include cherries, figs, citrus, Bartlett pears, pomegranates, and persimmons. You may want to monitor your persimmons tree, however, as a very productive year can lead to breakage. Use this information to determine just how much to thin, depending on tree species:
Natural fruit drop
We are not the only ones who want to protect our fruit tress from breakage due to too much fruit. These trees have evolved to protect themselves with what is erroneously called “June drop”. June drop normally occurs in May in the Bay Area and it refers to a fruit tree dropping many immature fruits. Fruits that are diseased or infested may also drop prematurely.
Don’t be afraid to get up close and personal with your fruit trees in spring. Thinning fruit will ensure a better crop and a healthier tree. Thinning also gives you a chance to see what’s really going on for your fruit trees, allowing you to halt a minor pest invasion before it causes any real damage.
For those of you (like me) who need ways to remember what and how to thin, give this a try:
Spring season of thinning, no need to despair
Help them grow stronger with inches to spare
Small apricots and plums, give them two to four
Peaches, nectarines, they need three or more
Then muster the clusters of apples and pears
Save just the biggest, only one or two there
Twins, mutants and mummies all must be removed
Leave only the best for flavorful food
Luscious summer pears are one of the most difficult tree fruits to grow in the Bay Area, but the rewards, for many, are worth it.
European pears (Pyrus communis) actually hail from Western Asia and modern day Iraq and Iran. People have been growing pears for over 4,000 years and Bartlett pears have been the standard for over 200 years. In the world gardening and agriculture, that's pretty amazing.
Pears do require a cold rest period, called vernalization, each winter. Silicon Valley only averages 400 chill hours, while Bartlett pears need 800 chill hours each winter. You will need to identify a species suitable to your microclimate. Pears are categorized by the season in which they ripen. Summer pears have thin skins, ripen on the tree in July through September, and most are small to medium sized, and the fruit is fine-textured. Winter pears feature gritty textured fruit that ripens September through November. Below is a list of popular pears with notes, chill hours, and best zones for growing:
How to grow pears
Unless you select a self-fruitful variety, you will need at least two trees for a fruit set. Also, keep in mind that full size trees may take up to 20 years to reach full production, while semi-dwarfs take 5 to 8 years. Most bare root stock available in garden centers are 2 or 3 years old. Choose a site that can accommodate the tree’s full size and provide full sun. Pest and disease problems can be reduced by providing good air flow around each tree. Pear trees are best pruned into a “Y” shape. They tend to grow very upright and need trimming to create a healthier, more spread out growth. Pear fruits do not require as much thinning as apples. You can leave 2 or 3 fruits per cluster without problems.
Pear pests & diseases
More pests attack pears than any other fruit tree in the Bay Area. These pests include aphids, San Jose scale, mites, pear psylla, codling moth, redhumped caterpillars, Eriophyid mites, birds, and squirrels. Common pear diseases include fire blight (Erwinia amylovora), crown gall, leaf spot, pear scab, and apple scab.
Pear tree care
These seasonal chores can help keep your pear trees healthy:
If you allow your pears to ripen on the tree, you will probably never get to enjoy one. Pears are a favorite food of squirrels and birds. I once lost an entire season’s crop because the squirrels were willing to harvest the pears two days earlier than I was. Pears ripen from the inside out. The easiest way to tell if it is time to harvest a pear is to use the Cradle Test. To do this, cup one hand under a pear and use the other hand to swing the fruit from its 6:00 position to a 9:00 position, with a twisting motion. If the fruit falls, it’s ready.
Actually pears taste better if they are harvested when they are mature but not fully ripe. Then place them in the refrigerator for a few days, up to two weeks for summer pears, and 3 to 4 weeks for winter pears. After the fruit has been chilled, bring it back to room temperature and enjoy. Oh, by the way, don’t bruise the fruit at any point in this process. As I said, growing pears is not an easy process.
The sweet, juicy flavor of a fresh, properly ripened pear, however, is exquisite.
Plum orchards once covered The Valley of Hearts Delight (what is now known as Silicon Valley). Many homes are still graced by individual specimens of these prolific fruit producers, and it is easy to add one to your landscape, as well.
Plums are members of the Rose family, in the Prunus genus. This makes them cousins to other stone fruits, such as peaches, nectarines, and cherries. One variety of apricot (Prunus armeniaca) is so closely related that it is actually a plum! Fruits of the plum tree are called drupes.
When deciding on a plum variety, keep in mind that plums can be sweet or tart, early or late blooming and ripening, standard size, dwarf, or semi-dwarf. Two varieties are commonly grown in California: Japanese plum (Prunus salicina) and European plum (Prunus domestica), but there are others. Some European plum varieties do not require cross-pollination, but all plum trees produce far more if there is a second tree nearby. Japanese plums bloom and mature earlier, but European plums tend to be sweeter.
Standard plum trees can grow to 30 feet tall and 25 feet wide, semi-dwarfs can be 15 feet wide, and dwarf varieties rarely need more than 10 feet. Plums come in skins of many different colors, from yellow, to red and purple, to nearly black. The interior fruit can be yellow, white, red, or green. Commercially, plums grown to be consumed as fresh fruit are called “sugar plums”, while the remainder are grown to be dried and sold as prunes. Prunes are almost exclusively made from European plums. You can also find plum-apricot and plum-cherry hybrids!
How to grow plums
Plums love California’s mild winters and hot, dry summers. While they prefer more sandy soil than the Bay Area tends to have,they are pretty tolerant of our clay, as long as the drainage is good. They do need a lot of sun. Plums are best started from certified disease-free root stock. You can also start a tree from a friend or neighbor’s tree by taking one of the many suckers that tend to appear. Suckers root more easily if they are dipped in rooting hormones (auxins), but they will create their own auxins in a day or so. If starting from seed, plums should be planted 3 inches deep. Be sure to mark the spot so you don’t lose track of your new baby!
Plum tree care
Plum trees thrive here in the Bay Area. Trees do require the following seasonal care:
Plum tree pests & diseases
The most common plum pests in the Bay Area are aphids, mites, and San Jose scale. Other pests include Oriental fruit fly, plum curculio, mealybugs, redhumped caterpillars, green fruit beetles (Cotinis mutabilis), and mealy plum aphid (Hyalopterus pruni). Sticky barriers can reduce the impact of many crawling insect pests. Fungal diseases that affected plum tres include canker, brown rot (Monomania fructicola), and shot hole, also known as Coryneum blight.
One of the most common problems faced by plum tree owners is overproduction. Overproduction, or overbearing, can cause broken limbs, so it is important to thin fruit to no more than one fruit every 2 to 4 inches. Don’t be concerned if your plums have a whitish coating on them. This is a protective epicuticular wax known as “wax bloom” and is easy wiped off.
Add a plum tree to your landscape this spring for decades of delicious summer fruit and year-round jams and jellies!
Pheromone traps use chemicals to trick insect pests.
We all know that smell is a powerful trigger for many species. Smell is why we are drawn to freshly baked bread, why we are soothed by lavender and vanilla, and why we wear cologne and perfume. The chemicals that stimulate these and many other responses are called pheromones.
Pheromones are chemicals that stimulate a response within a species. Since most insects only live for a single season, reproduction is critical to species survival. Insects frequently use pheromones to find each other. Pheromones are categorized according to the response they stimulate:
Most over-the-counter pheromone traps are of the sexual variety. They use synthetic female pheromones to attract males. Chemical signals loft into the wind and are picked up by sensory receptors on a male insect’s antenna. He follows the trail in search of love. What he ends up finding, in most cases, is a paperboard tent lined with a deadly stickum, right next to a little tab of luscious pheromones. In other cases, he may find a tray filled with powdered female pheromones. He joyfully rolls in it, finds nothing, and flies away - smelling like a female. Alas for him, in either case.
What pheromone traps can and cannot do
Pheromone traps interrupt mating. They do this by confusing the males with all the extra aromas and by trapping them on the sticky goo. Contrary to packaging claims and popular opinion, pheromone traps are not effective at eliminating a specific type of pest. In fact, they can do just the opposite! Your lone apple tree may have skirted a codling moth disaster until you hung a pheromone trap in it. Suddenly, every codling moth on the block wants to party at your house!
Proper use of pheromone traps
To be effective, pheromone traps are used to monitor specific areas for invasive or particularly destructive pests. Pheromone traps to help you to determine the best time for particular treatments.
How to use pheromone traps
Since pheromone traps are species specific, you must first identify the pest you are trying to monitor. Next, you need to learn the best time of year to employ pheromone traps. These tips can help you make the most of pheromone traps:
As the number of trapped insects changes, you can see become more aware of the rise and fall of breeding populations. This provides you with the information you need when deciding on which insecticide or other treatment plan is best suited to your garden or orchard. [If you feel like getting really technical, you can also calculate degree days for more effective information.]
Insects monitored using pheromone traps
Since reproduction is so important to short-lived species, pheromone traps continue to be an effective monitoring device for a large number of insects. Some of the most troublesome Bay Area insect pests that are monitored using pheromone traps (during specific time frames) include:
Crops best suited to pheromone trapping
Pheromone traps do not provide benefits to all crops. The most common applications of pheromone traps include:
Don’t be put off by this shift from quick-fix solution to data collection and informed decision making. The extra knowledge and effort can spell the difference between hosting a party of undesirables or producing an abundant crop of delicious food.
Fresh figs? Yum!
Figs are believed to be the very first human attempt at agriculture, even before barley, wheat, and legumes, over 11,000 years ago. In Aristotle’s day, farmers and scientists had some interesting ideas about wild fig trees and farmed fig trees: it was believed that tiny wasps flew from the wild (fruitless caprifig) trees to the farmed female (fruited) trees to help them hang on to the fruit! If that weren’t interesting enough, did you know that figs are not actually fruit at all? Read on!
These resilient trees grow very well in the Bay Area, thriving in our hot, dry summers and cool, wet winters. Originally from the Middle East and western Asia, figs are now found all around the world (except Antarctica, of course!) and with good reason. Forget the bagged, dried version of this healthful snack. Plucking a freshly ripened fig from the tree and taking a bite is heavenly. If you decide you have too many figs to eat fresh, you can always dry your own!
How figs grow
Figs (Ficus carica L.) are deciduous trees or shrubs that can reach over 30 feet in height. They tend to send out multiple trunks that create a tree that is wider than it is tall. Fig wood tends to be weak, so pruning may be needed to keep the tree structurally sound, but not necessarily. Their wide, fragrant leaves provide nice shade, but you will want to avoid the sap as it contains a form of latex that can irritate your skin. Fig trees prefer sunny, well drained locations and they are quite drought tolerant. Figs can also grow well in poor, rocky soil.
Figs reproduce several different ways. Naturally, birds and mammals that eat the fruit end up spreading seeds. Fig trees also tend to send out aggressive roots, stolons, and suckers that can be used to create new plants. You can also bend a low-growing branch down to the ground, or a container, and hold it down with a rock or some wire. After roots emerge, the new growth can be separated from the parent plant. Most fig trees are purchased as bare root trees.
Botanically, fig trees are gynodioecious, which means they have hermaphrodite flowers and female flowers on separate plants. Unless you buy a self-pollinating variety, you will need more than one tree. My self-pollinating fig produces more and more fruit every year. Fig pollination is usually completed by tiny specialized wasps called Blastophaga psenes. (Aristotle was partly correct!) Fig flowers are hidden clusters found inside a hollow structure called the syconium. The fruit, which is not technically a fruit, is actually a scion, or infructescence. An infructescence is a fruit head made up of the ovaries from a flower cluster, often called a ‘false fruit’ or a ‘multiple fruit’, depending on the presentation. Within each fig “fruit” are several one-seeded fruits called druplets. Pineapple, wheat, and corn are other examples of infructescence.
How to grow figs
Fig trees can be grown in large containers, but you will want to take advantage of their deep roots. Planting fig trees in the ground practically eliminates the need for irrigation. Like grapes, fig trees have deep roots that allow them to get most of the water they need from the soil’s saturation (or phreatic) zone, so irrigation is rarely needed once plants are established. UC Backyard Orchard provides an excellent list of fig cultivars here.
Fig pests & diseases
Thrips, ants, green fruit beetles, dried fruit beetles, gophers, and birds are the only serious pests. Ants can be thwarted with a sticky barrier around the trunk. I have always found that netting is invaluable for protecting my fig crop. Euryphid mites may not cause significant damage but they can carry mosaic virus. Sunburn protection is a good idea. Simply paint a 50:50 mix of water and white latex (not enamel) paint on exposed surfaces.
Some fig varieties produce two crops a year. The first, or ‘breba’ crop, occurs in mid-summer and the second, main crop ripens in late summer or fall. Be sure to allow figs to ripen on the tree. They will not continue to ripen once picked.
Add figs to your foodscape for decades of delicious fiber and welcome summer shade!
Why grow hazels?
The obvious reason for growing a hazel bush is the delicious nuts. Hazelnut plants can produce food for 80 years! Hazelnut shrubs also make excellent, drought tolerant anchor plants in the landscape. Traditionally, hazels were planted as hedgerows between properties and grazing fields. They were frequently coppiced, or cut to ground level to stimulate new growth, to provide long, slender poles for basket-making and wattle and daub fencing.
Some scientists group the hazels with birch trees, while others claim hazels are their own grouping. All hazels are from the Corylus genus and all of their nuts are edible. Worldwide, there are 14 to 18 species. Only two species are native to North America, with one local variation:
How hazels grow
Unlike most plants, hazelnuts bloom and pollinate in winter. Yellow pollen-crusted catkins release their bounty to the wind, which carries it to tiny red flowers. There, the pollen stays dormant until summer. That’s when the nuts start to form.
Hazels are monoecious, or hermaphroditic, having both male catkins and female flowers on the same plant. Catkins are hanging flower clusters that contain pollen. Hazelnuts are self-infertile, which means you will need more than one plant to produce a crop of edible nuts.
Members of the hazel family are all deciduous. Some are trees and some are suckering shrubs. These suckers can be used to to create new shrubs elsewhere on your property or given to family and friends to start their own. Commercially, the suckers are generally removed and the shrub is trained into a tree form, to make management and harvest easier. What you do with yours is entirely up to you, but it is nice to have options!
How to grow hazelnuts
If you have access to suckers, use them! Otherwise, you can plant nuts in loose soil and water occasionally. Germination rates and speed can be increased by scarification, or scoring the outer layer of the nut. Once seedlings are 12 inches tall, they can be transplanted to their permanent location. They will begin producing nuts in their 3rd or 4th year. These nuts grow in clusters called burrs.
Hazels are shallow-rooted plants that cannot tolerate soggy ground. They are drought tolerant and require little effort on your part, once they are established. Only during the peak of California summers do they need any irrigation.
Hazelnut pests and diseases
One very serious threat to hazelnuts has kept them from being grown commercially in the Eastern U.S. It is called eastern filbert blight. Our native species are resistant, and some are immune. This disease has recently made its way west to Oregon and California. Pests include bud mites, jay birds, and squirrels. Ads claim that giant eye floating balloons are a good way to keep birds out of fruit and nut trees, but I was unable to find any research that verified those claims.
Hazelnut harvesting begins in autumn, as the leaves and burrs turn brown. Remove nuts from the burrs and lay them out in a single layer, in a protected area, to dry for a few days. Roasting makes it easy to remove the inner paper, which can taste bitter, and it brings out that rich hazelnut flavor that we all know and love!
Treehoppers, or thorn bugs, are wedge-shaped, sap-sucking, jumping insects found everywhere on Earth except Antarctica.
All treehoppers have conspicuous eyes and modified dorsal plates (pronotum), commonly called helmets. These helmets are believed to have evolved from what was once a third set of wings. Frequently, these helmets look like camouflaging thorns. [Many thorn-shaped tree hoppers will shimmy around to the opposite side of a stem as you walk by!] Globally, the range of treehopper shape defies description. While most colors are drab, you can also find neon stripes, spots, and squiggles. There are treehoppers that look like ants walking backwards, space ships, curls of dry wood, flower petals, and even bird poop! Nymphs can be equally bizarre, donning such crazy outfits as a puffy cotton bodysuit, a head piece of neon spikes, or a tail made out clusters of el-wire. (Check out more pictures of treehoppers at Mental Floss.) Most treehopper nymphs have Mandelbrot spikes on their helmet. North American treehoppers are far less flamboyant. They tend to be green or brown, smooth-bodied wedges, 1/2 inch long or shorter. In the greater Bay Area, we have Oak treehoppers (Platycotis vittata) and Buffalo treehoppers (Stictocephala bisonia). Oak treehoppers are commonly found in spring, in the lower branches of oak, birch, and other deciduous trees. Buffalo treehoppers can be found in apple trees.
Ants and treehoppers
Just as ants protect and farm aphids, they provide similar mutualistic services to treehoppers. Being sap eaters, treehoppers poop out a sugary waste called honeydew. Ants love to eat honeydew. The relationship is so intimate that treehoppers can send out an alarm when they are attacked and ants will come to their rescue! Some species of treehoppers have the same type of relationship with certain wasps and even geckos!
Eggs are normally inserted into the cadmium layer of stems by a female’s saw-like ovipositor. Sometimes, eggs are laid on leaf surfaces. Many plants are damaged more by egg laying than by treehopper feeding. When eggs hatch, the nymphs are usually too small to produce enough honeydew to attract ants. Some mama treehoppers will stay close by, using her honeydew to attract protective ants. Unlike adults, nymph treehoppers have an extendable anal gland used to deposit honeydew further away. These tubes tend to be longer in solitary treehopper species. I wouldn't bring it up except that this appears to be an important evolutionary mechanism for avoiding infection by fungal diseases, such as sooty mold.
Damage and host plants
Treehoppers have sharp beaks they use to pierce grass blades, twigs, canes, leaves, and branches. As sap oozes out, treehoppers lap it up, taking advantage of the high sugar food source. As treehoppers feed, they can act as vectors for disease. In fact, some treehopper diseases attack both the pests and the host pants, growing in the treehopper’s salivary gland! Predominantly a tropical pest, treehoppers can still damage your grapes, celery, tomatoes, legumes, avocado, and papaya in North America. Their cousins, the leafhoppers, cause far more damage to our local gardens.
In nature, treehopper eggs are frequently parasitized by fairyflies (Mymaridae) and Trichogrammatidae. For this reason, it is better to avoid broad-spectrum pesticides. Horticultural oils can be used to prevent eggs from hatching, and insecticidal soaps can be used to treat heavy infestations of nymphs and adults.
Sweet, flavorful apricots, warm from the sun, freshly plucked from the tree, are one of life’s perfect moments. In my opinion, they rank right up there with their cousins, peaches and nectarines, as foods that define summer.
Apricots (Prunus armeniaca) are also related to cherries, plums, prunes, and almonds. If you look at the pits, you will see the similarities; they are all stone fruits. While dwarf varieties can be grown in large containers, apricots prefer being planted in the ground, in a sunny location. You will be treated to lovely spring blossoms and delicious summer fruit. The trunk will, over time, develop a striking gnarled look, too.
How to plant an apricot tree
Unlike apples, pears, and other members of the rose family, apricots grown from seed have a higher chance of being similar to the parent plant. While there are no guarantees, you can take the pit from an apricot, cover it with an inch of soil, keep it watered and in a sunny location to start your homegrown apricot tree. For faster results, bare root stock can be used. Apricot bare root stock should be planted in January or early February, here in the Bay Area. Apricots prefer well-drained soil, but they can tolerate some clay. Before placing your apricot root stock, be sure to amend the site with lots of compost, to help it get a healthy start. Also, if you have heavy clay, be sure to score the edges of the planting hole. Smooth clay is an impenetrable barrier to young roots.
How to select an apricot tree
When selecting root stock, be sure to match the variety with your microclimate. Chilling hours vary by species, as does disease and pest resistance. Most apricots are self-fertile, so it is usually not necessary to have more than one tree. Contact your local Cooperative Extension Office for the best varieties for your area. The following varieties are good choices for the Bay Area:
Apricot tree care
Each fall, before the rains begin, prune away 20% of last year’s growth, along with any dead, diseased, or poorly placed branches. This will allow more light to reach interior branches, stimulate new spur development, and improve the overall health of the tree. [Spurs are flower-bearing buds]. Spray for pest and disease control in winter and again in spring. Feed mature apricot trees 1 to 2 pounds of urea just before spring irrigation is begun and water it in thoroughly. Young trees should be given the same amount of urea, but spread it out in quarters over a 4 month period. As fruits reach 1/2 inch in diameter, they should be thinned to one fruit every 4 to 6 inches, for the best size and flavor. This also reduces the likelihood of pests and diseases.
Begin irrigating in spring by watering every 2 or 3 weeks to a depth of 18 to 24 inches. This is one of those times where guessing isn’t good enough. I use my soil sampler, but you can use a trowel to gently dig down to the appropriate depth. If the soil isn’t moist, you need to figure out where the water is going and redirect it. Many times, hydrophobic soil will push water away. Watering more slowly can avoid this problem.
Apricot pests and diseases
Peach twig borer, Fuller rose beetle, San Jose scale, mites, and aphids are common apricot pests. Apricot is susceptible to Eutypa dieback, so pruning should only be done during summer, unlike other trees which are pruned during winter dormancy. Autumn and winter sprays of dormant oil, fixed copper, or Bordeaux mixture, as well as the use of sticky barriers, can help protect your apricot tree against other pests and diseases, such as brown rot, bacterial canker, shot hole disease, and crown gall. Despite these fungal diseases, it is better to avoid using sulfur on apricots.
A little space in your yard or on a balcony is all that is needed to start growing fresh apricots - give it a try!
The seeds from this tree may not be edible, but they are certainly a natural way to cut down on your laundry bill!
This discovery started when I was looking for a laundry detergent that wouldn’t hurt my landscape. I have a large diameter vinyl hose attached to the back of my washing machine (in summer) and I use the water to irrigate my fruit and nut trees, lawn, and ornamentals. (This isn’t legal everywhere, and isn’t necessarily a good idea, depending upon your preferred brand of laundry soap.) In my search for living a less polluting (and more cost effective) life, I stumbled upon soapnuts, also known as soapberries. Believe it or not, I was delighted to discover that these tree fruits cleaned my laundry just as well as commercial soap! Not only that, but they have natural fabric softening properties. I don’t know how or why, but the water that came out of my washing machine when using commercial laundry soap usually contained a significant amount of clothing dye, while the soapberry loads do not. Safer, softer, and more brightly colored clothes without the use of chemical additives. In my book, it’s a total win.
What are soapnut trees?
Soapnut trees are members of the Lychee family (Sapindus), which includes 5 to 12 different species of trees and shrubs (depending on who you ask) that all produce saponins. These saponins are found in the fruit, or drupes, of the soapnut tree (as well as in soapwort plants and sea cucumbers). Saponins are surfactants, chemicals that reduce the surface tension between molecules, allowing water to lift away grease, soil, and other impurities from your laundry. In fact, people have been using soapnuts as a sudsy cleaning agent for far longer than commercially made soaps and detergents.
The soapnuts used to clean laundry, hair, and skin nowadays are mostly from the S. mukorossi variety. This particular tree also goes by the names Sapindus detergens, Indian soapberry, Chinese soapberry, Reetha, Areetha, Ritha, and Doda, just to name a few. [If you are feeling particularly nerdly today, you can see this plant’s genetic code here.]
How soapnut trees grow
Soapnut trees prefer temperate to tropical conditions. Some varieties are deciduous, while others are evergreen. The Indian soapberry tree, in particular, is a lovely deciduous tree that can tolerate poor soil. Trees will need the equivalent of 60 to 80 inches of rainfall each year. (San Jose, CA gets an average of 15 inches of rain, so some irrigation will be needed in the Bay Area.)
Ultimately (and under ideal conditions), your soapnut tree can reach a height of 80 feet, with a girth of 15 feet. Most trees, however, end up significantly smaller than that (12 to 16 feet tall). The tree has smooth grey bark and a semi-umbrella shape. Small, greenish-white flowers emerge in summer and fruit appears in July and August. A mature soapnut tree can produce 60 or more pounds of soapberry fruit each year.
How to grow a soap nut tree
To grow your own soapnut tree, you will first have to find a seed. This has become easier in recent years, as more people discover just how effective soapnuts are. You can search online for seeds, or you can give soapnuts a try and hope to find a seed. The drupes (pictured) normally contain up to three seeds. The seeds need to be roughed up a little (scarified) before they can germinate. It is best to plant in spring. You can use a fine-grit sandpaper to score the outer hull, then soak the seeds in warm water for 24 hours. The most common way to keep the water warm is to place the seed and the warm water in a thermos. (My guess is that these prerequisites evolved out of the natural processes of seeds being eaten and then, well, you know.) Start each seed in a large container filled with high quality potting soil, planting them one inch deep. Keep the soil moist down to at least 2 inches, but not waterlogged, and provide plenty of sunlight. It may take a long time for your seeds to germinate. Once they do, they will grow quickly. After 3 or 4 months (or when frost isn’t expected any time soon), you can place your soapnut tree in the ground. Select a site that provides partial shade or dappled sunlight, if possible, and plenty of room to grow.
Using homegrown soapnuts
Once your soapnut tree produces fruit, you will want to collect the drupes in early winter, remove the seeds, and allow the fruit to dry out. A small muslin bag with tie strings can be used to hold 4 or 5 soapnuts and tossed in the laundry. The soapnuts do not have to be removed for the rinse cycle because the normally colder water of rinse cycles does not pull as much of the sudsing saponins as warm or hot wash water. The same bag of soapnuts can be used for up to 10 loads of wash. After that, toss them into the compost pile and reuse the bag!
Other advantages of soapnuts
Besides being disease-resistant plants, soapnuts also have gentle insecticidal properties that have been shown to interfere with mosquito and lice life cycles. Whether this means that washing your clothes with soapnuts will render them mosquito-proof has yet to be shown. Did you know that soapnuts are used to clean cardamom seeds, improving their color and flavor? If you use greywater from your washing machine, soapnuts are a far better option than soaps and detergents sold over-the-counter, and they’re free!
Unfortunately, it may take your soapnut tree up to 10 years to begin producing fruit. (At least it’s faster that stone pines!) The nice thing is, soapnuts are lovely trees, long before they provide you and your family with a lifetime supply of environmentally safe laundry soap and shampoo!
Imagine a world without cabbageworms, leafminers, or whiteflies…
Or one without Sudden Oak Death, bacterial spot, or tomato yellow leaf curl…
Such would be our gardens, had quarantines been in place and enforced sufficiently. Alas, it is not to be.
Imported plants that are not adequately inspected, nursery stock that is sold in spite of being infected or infested, and the use of grocery store produce to start a garden are responsible for a profound amount of damage to the environment. According to The Nature Conservancy, invasive species cost the U.S. economy $120 billion each year. The U.S. Forest Service echoes those figures, adding that 81 million acres of American soil are at risk due to these pests and diseases, and that 42% of threatened or endangered species are being pushed out by these invasives. Scale those figures down to the size of your garden and decide for yourself if it is worth the risk.
What is a quarantine?
To quarantine something means to keep it away from everything else, for a period of time, to avoid the spread of disease. In the world of plants, quarantines are used to halt the spread of diseases, pests, and other plants (weeds). In Italian, quarantina means 40 days and that’s where we get the idea behind quarantine. By isolating plants for 40 days, you are more likely to see signs of pests, diseases, or weeds, before exposing all of your other plants.
When to quarantine a plant?
Plants that are new, infected, or infested should be quarantined whenever possible. The easiest case, and the most useful, is when you bring a new plant home. As much as you want to add it to the landscape, 40 days in quarantine can prevent a whole lot of work later on. Plants new to your property can never be guaranteed disease-, pest-, or weed-free. Blithely adding it to your landscape may work out fine, or it may introduce a devastating disease that can stay in the soil for decades, introduce pests that you will have to battle every year forever after, or add even more weeds to your To Pull list. To avoid these risks, you can place new plants in quarantine until they have shown themselves to be safe for your garden or landscape. Containerized plants that develop problems are pretty easy to quarantine. Established plants are a bit more difficult.
How to quarantine
Ideally, new plants should be kept separate from all others for 40 days. This is especially true for houseplants, because there aren’t very many natural predators in your livingroom. This can be done by placing the latest addition in a different room, across the room, or in a clear plastic bag. The bag method is the most effective because it creates a barrier that you can see through. Established plants, such as fruit trees, are difficult, if not impossible to quarantine. In cases such as Citrus Greening, trees must be destroyed. If you suspect an invasive pest or disease in one of your established plants, contact your local County Extension Office for help.
Alternatives to quarantine
Some of us can’t (or won’t) invest 40 days of waiting before adding a new plant to the garden. When this is the case, use these tips to reduce the likelihood of problems:
Government mandated quarantines
In 1912, the Plant Quarantine Act was enacted, giving the U.S. government the right and responsibility of preventing the spread of pests and diseases through nursery stock and other plants. This act evolved into the Plant Protection Act of 2000. If you’ve ever driven across the California state line, you have seen the inspection stations and you may have been required to hand over an apple, a bag of green beans, or a butternut squash before being allowed in. From a visitor’s point of view, this Orwellian treatment may feel extreme, but it’s not. In fact, too many invasive pests and diseases are making their way around the globe because of too few precautions.
Grocery store produce
As tempting as it may be (I know, I’ve done it), do not use grocery store produce to seed your garden. Garlic, onions, and leeks look easy to start from your discards (and they are), but they can also carry fungal diseases that will never go away. Take a look at the current list of current quarantines in California to see some of the other vulnerable crops.
To quarantine or not to quarantine? That is the question. The answer is up to you. As you think it over, consider the fact that many pests can generate a surprising number of offspring pretty quickly. For example, a single aphid can turn into 600 billion descendants in a single season, according to entomologist Stephen A. Marshall.
Forty days of caution, or a lifetime of reactionary treatment…
Growing apples is highly rewarding, but don’t try starting one from seed.
Apples (Malus pumila, aka Malus domestica) have a rich and varied history. They hold a place in nearly every culture and religion, being one of humankind’s earliest attempt at tree cultivation. Wild apple trees (Malus sieversii), however, bear little resemblance to their domesticated progeny. Wild apple trees, still found in central Asia, can grow up 40 feet in height and the fruit is smaller and more tart than most people find palatable. Most of the apples you see in the grocery store are crosses between Malus pumila and crab apples. To date, there are over 7,500 apple cultivars with various traits of skin color, texture, disease and pest resistance, juiciness, storage ability, and more. In 2010, the entire apple genome was mapped, with over 57,000 genes identified. (Humans are estimated to have up to 25,000 genes - kind of makes you wonder, doesn’t it?)
Bare root apples
The best way to start growing apples is with bare root stock. When selecting your root stock, keep in mind that some apple varieties require cross-pollination, while others are self-pollinating. If you only have room for one tree, you will want to be sure to select a self-pollinating variety or all you will get is summer shade. Bare root stock should be planted in January, February, or March in the Bay Area. According to UC Division of Agricultural and Natural Resources (UCANR) and local Master Gardener trials, and depending on your tastes and microclimate, there are many apple varieties that perform well in Santa Clara Valley. Before you buy, however, you may want to conduct a soil test with a reputable lab. This is an excellent investment in a tree that will probably live and produce fruit for the next 100 years or so. Also, consider the size of your mature tree - it is far easier to pick apples and care for your tree if it is a dwarf or semi-dwarf variety.
Most red varieties will need more chilling hours than they will get in the Bay Area. Red apples generally need 1200 to 1500 chill hours to fully develop their color and flavor, while some microclimates in San Jose only receive 400 chill hours a year, on average. Also, our local fog can cause more russetting. Russeting is when the apple’s skin turns brown and rough.
How to grow apples
Apples grow best in well-drained, nutrient rich soil with full sunlight. Apple trees need some space for good air flow. Full-sized trees will need a 15 to 20-foot circle of space, while dwarf varieties need only 10. Dwarf apple trees do tend to over-produce, breaking branches, so you may need to do more pruning or provide supports. Once your bare root tree arrives, dig a hole that is twice the diameter of the spread out roots and about 2 feet deep. You should remove any grass or weeds that are growing within two feet of this circle. Remove any dead, damaged, or diseased roots and then soak the root stock in a bucket of water for a couple of hours (overnight, if the roots are really dried out). Mix some aged compost in with soil from the hole and spread it out in the bottom of the hole. Be sure to not leave smooth edges in the hole. Our heavy clay can create an impenetrable barrier to young roots. You can help your apple tree get a better start by roughing up and scoring the edges of the planting hole. Place the tree in the hole, making sure that the graft union (the place where the root stock joined the scion) is at least 2 inches above soil level, to avoid crown rot and other fungal diseases. Firmly press the soil down to eliminate big air pockets and give it a good drink of water. You can also grow dwarf apple trees in containers!
Seasonal apple care:
Apple pests and diseases
There are very few pests or diseases that will actually kill an apple tree, but it has many attackers. The use of sticky barriers around the trunk will halt some, such as ants, slugs and snails, and Fuller rose beetles, but most most apple problems are carried on the wind. Stem blight, crown gall, leaf spot, powdery mildew, fireblight, and other bacterial blights are common diseases. Cedar apple rust can also occur if apples are grown near Eastern red cedar trees. Also, apples share a susceptibility to bacteria blast with lilacs and stone fruits. Common pests include codling moths, apple maggots, San Jose scale, redhumped caterpillars, armyworms, and Eriophyid mites.
Find a spot in your landscape for one of these beauties, because plucking an apple from your very own tree and taking a bite, well, it's just one of life's finer experiences. And we all want to keep that doctor away!
Navel orangeworms attack far more than oranges and other citrus. They can seriously reduce your backyard apricot, almond, walnut, pomegranate, pistachio, date, fig, pear, apple, and stone fruit harvests.
You can protect your fruit and nut crops by learning more about this orchard pest. Navel orangeworm moths (Amyelois transitella) can fly in, deposit eggs, and be on their way in a matter of minutes, so monitoring regularly can go a long way toward protecting your foodscape.
Navel orangeworm description
Navel orangeworm eggs start out white. In 4 to 23 days, depending on temperature, the eggs will turn orange just before they hatch. The larvae are off-white or pink grubs with a dark head. If you look closely, you may be able to see a couple of crescent-shaped marks on the second segment behind the head. Adult moths are just under 1/2 an inch long, grayish brown, with irregular silver and black wing markings, and a snout-like appendage on the face.
Navel orangeworm lifecycle
Adult moths are generally present from March through October in California, and females begin laying eggs two nights after they emerge! Those eggs are laid on mummified fruits, newly forming fruits, and on freshly splitting almonds. The first instar burrows into a nut or fruit, where it, and future instars, will feed extensively. Next, the larva pupate in a webbed cocoon within the fruit or nut.
Damage caused by navel orangeworms
These orchard pests will devour an entire almond in the shell without ever being seen. If you examine an infested fruit or nut, you will see tiny entry holes and lots of frass and webbing. As they feed, navel orangeworms also provide entry points for fungal diseases and other pests.
You can protect your crops from navel orangeworm infestation by irrigating trees throughout the summer and by harvesting early and frequently. As always, remove mummies immediately and completely, every time they are seen. I have learned that there is a parasitic wasp, Goniozus legneri, that is supposed to be effective and commercially available. As soon as I can track down a source, I will provide an update.
Once infested, citrus fruits are pretty disgusting, so you will probably want to toss them in the trash. After harvesting almonds, pistachios, or walnuts, navel orangeworm eggs can be killed by freezing the nuts for 48 hours. After that, nuts can be stored at room temperature in airtight containers.
Did you know that the fruit of a pomegranate tree is a berry? That’s if you ask a botanist. Like other berry plants, pomegranates (Punica granatum) have spiny branches and delicious fruit.
When I was a child, growing up in the San Fernando Valley, there was an empty lot down the street. On that lot was a giant old pomegranate tree. It had grown up and out and down, almost like a willow, creating a magical circular space underneath. No one could see us from outside the tree, the growth was so thick! We would pick sun-ripened pomegranates from the outside of the tree and then enter our Secret Clubhouse, where we would tell stories and make wild guesses about growing up, as we munched on the sweet-tart fruity seeds. These healthful fruits are perfectly suited to growing in our drought-prone area. With a small initial investment of time, money, and water, your family can enjoy fresh pomegranates for many years to come.
Before you buy a pomegranate tree, be sure that the variety you are buying is an edible and not an ornamental. There’s no sense dedicating space and water to an inedible variety when you can have an edible! Pomegranates grow in a variety of colors and sizes. Rinds can be red, yellow, pink, orange, green, and even black. Some varieties have seeds that are very hard, while others are softer. The most popular cultivars in California are ‘Wonderful’, ‘Granada’, and ‘Foothill’. The later two are early season varieties. UC Davis offers a helpful Pomegranate Cultivar Chart to help you select the best variety for you and your family. Pomegranates can either be ornamental or edible. Both types can be self-pollinating or cross-pollinated by hummingbirds and insects. It takes a pollinated flower up to 7 months to produce an edible fruit.
How to grow pomegranates
Pomegranates are a very tolerant plant, when it comes to soil types and irrigation. They prefer full sun and hot summers, but they can handle some partial shade. Pomegranates will founder in wet soil or full shade, so choose your site accordingly. Pomegranates can be grown from seeds, but it will take a few years before you get any fruit, and pomegranate seeds do not always grow true to the parent plant. You can also plant rooted cuttings or bare root trees. Grafting does not work for pomegranates. Newly planted trees should be watered every day until new growth is seen. Then water only once a week (assuming it doesn’t rain). Keep weeds away with mulch, just be sure the mulch stays 6 to 8 inches away from your pomegranate.
Pomegranates are deciduous trees that can grow up 30 feet in height and 15 feet wide (most are 6 to 12 feet tall). Pomegranates produce fruit on second-year wood, so you will want to make sure that you leave some of the last year’s growth when pruning. Pomegranates can be pruned as full-sized trees, hedges, landscape anchors, or shrubs. They can also be grown in containers. You can even create bonsai and topiary from pomegranate!
Pomegranate pests & diseases
Like tomatoes and citrus, pomegranates are susceptible to citrus fruit split. Other diseases that can turn up include Alternaria rot, Armillaria root rot, Botrytis blight, and other fungal diseases, especially if plants are over-watered. Common pests include whiteflies, fruit flies, ants, mealybugs, soft scales, leaf-footed bugs, and the pomegranate butterfly.
Eating a pomegranate
Those little seeds are tasty, but getting to them can be a pain. The easiest way I have found is to cut the fruit in half, hold one half peel side up, over a bowl, and beat the bejeezus out of it with a wooden spoon. The seeds fall out and the rest of it tends to stay put. It is easy to remove any other debris simply by adding water to the bowl: the fruit sinks and everything else rises. Viola!
Pomegranates grace holiday tables, a symbol of prosperity, but you can add them to your yard or balcony for some prosperity of your own!
Isn’t this the weirdest lemon you have ever seen?
This fruit has been infested by the citrus bud mite. Just as the name implies, citrus bud mites (Aceria sheldoni) attack those fragrant citrus flowers and buds, causing a distorted rosette growth pattern of the surrounding leaves, flowers, and fruit.
These pests are normally found on lemons and other citrus grown in coastal regions, but Southern California has been seeing them move inland, so they will probably become more of a problem here in the Bay Area before long.
These citrus pests are really tiny. They can only be seen with a 20x hand lens or under a microscope. Citrus bud mites have a tapered yellow or pink body and four legs that look like they are growing out of its head. [For anyone who has read this blog for any time at all - these bizarre descriptions are surprisingly normal - fiction has nothing on real life!] These pests are active year round.
Each summer, females lay up to 50 eggs in the tiny scales that are supposed to protect tender new buds. When the eggs hatch, the young go through 4 instars before maturing. Commercially, citrus bud mites can be a real problem, but most home orchards only see a few affected fruit, and it is still edible. [I’ll bet horizontal slices would actually look pretty amazing… but peeling it would be a nightmare!]
The real problem with these pests is that the distorted shapes caused by their feeding create the perfect hiding spot for other citrus pests, such as citrus mealybugs and the two-spotted spider mite. Researchers have tried using horticultural and dormant oil treatments and found them ineffective, since the pests are in a protected space. If signs of citrus bud mites are seen, you may simply want to monitor fruits for signs of other pests who are taking advantage of the prime real estate.
Have you ever had citrus bud mites in your fruit? I would love to see photos!
Blistered leaves and warty twigs are signs of eriophyid mites.
Eriophyid mites are a family of microscopic plant parasites that include blister mites, gall mites, bud mites, and rust mites. While you will probably never see them without a 20x hand lens, at 1/100” in length, they can be a translucent yellow, pink, white, or purple, with two pairs of legs up near the head.
Symptoms of eriophyid mite feeding include:
Blister mites commonly attack beech, boxelder, cottonwood, elm, maple, live oak, walnut, willow, poplar, roses, privet, and alder. Unfortunately, they also feed on tomatoes, peach, apples, pear, and grapes. I have also heard of them on plum trees in the Bay Area. Eriophyid mites spread on the wind, so there isn’t much you can do to stop them from showing up in your landscape. Luckily, the damage they cause is mostly aesthetic and poses no real threat to otherwise healthy plants. That being said, who wants warty leaves or scabby twigs? Also, eriophyid mites may also carry viruses that can cause real damage.
Insecticidal soaps and horticultural oils can be used on heavy infestations, but simply removing affected leaves, buds, flowers and twigs is really all that’s needed. Sulphur and neem oil have also been shown to be effective. Before you work too hard at getting rid of these minor pests, you may want to keep in mind that the eriophyid mite serves as a replacement food for predatory spider mites and other beneficials, when their foods of choice are absent.
Isn’t it nice to know that some problems in the garden are not big enough to worry about?
Have you ever tried eating an orange that looked ripe but ended up being very unripe?
Major pucker factor!
Citrus affected by the Alternaria citric fungus may look perfectly ripe and ready on the outside, at first. After fruit is harvested, the fungi continue breeding and feeding on the inside. By the time the infection is fully established, the stylar (flower) end of the fruit may show a dark brown or black area. Alternaria rot is also called Black Rot when it appears in Navel oranges. If you cut infected fruit in half, you will see the rotted area has spread into the core of the fruit.
There are several varieties of the Alternaria citric fungi. Most of them do not produce toxins (but you still won’t want to eat the fruit). So, how can you prevent or treat Alternaria rot?
First, healthy plants are better at protecting themselves. Navel orange trees experiencing Citrus Fruit Split and water stress are going to more vulnerable to infection that trees which have received regular irrigation. Fungicides are generally ineffective.
Remove infected or otherwise damaged fruit and delay harvesting for as long as possible. This will allow infected fruits to show themselves and be be disposed of, before harvesting the unaffected fruit.
Highly refined horticultural oils are sprayed onto plants as a pesticide. They are used to control mites and insect pests, and to prevent some fungal infestations.
One big advantage of horticultural oil over other insecticides is that pests are not poisoned, they are suffocated. Chemical pesticides often use deadly chemicals to kill bad bugs, which can then affect human and pet health, as well.
When oil was first used to combat garden and agricultural pests, heavier “dormant oils” were used in the winter, while trees were dormant and leafless, and lighter “summer oils” were used when leaves were present. While both varieties are now much more refined, believe me when I tell you that using dormant oil on leaves in summer is a really bad idea.
Types of horticultural oil
Horticultural oils can be petroleum or plant based. Currently, the petroleum-based horticultural oils provide better coverage without damaging leaves. Most over-the-counter varieties are made from petroleum. Vegetable oils, such as sunflower, soybean, and cottonseed, provide good insect control, but phytotoxicity is a still a problem. Phytotoxicity is anything that is poisonous to plants. Research is continuing. At this time, only Neem oil is a consistently safe vegetable-based horticultural oil, but it acts differently than other oils by adding a naturally occurring chemical to the mix that makes insects ‘forget’ to eat or breed.
How to apply horticultural oil
Horticultural oils are best used when pests are vulnerable. Soft-bodied pests, such as aphids, can be sprayed as populations become troublesome. Scale insects are most vulnerable in the crawler stage, while caterpillars and spider mites are best managed as eggs, in winter and early spring. Heavy infestations of scale insects may require repeated sprayings through June. Once pests have reached a protected stage of growth, such as the hard shell covering over adult scale insects, horticultural oils are not effective. Also, the oil must coat pests completely to work.
WARNING: When applying horticultural oils, it is important that sulphur is not present. Horticultural oils should not be applied 2-4 weeks before or after a sulphur treatment, depending on who you ask. Also, horticultural oils should not be used on water stressed plants. Many horticultural oils are mixed with other ingredients, such as fungicides or insecticides, so it is very important that you read the label and follow the directions exactly, to avoid causing more harm than help.
Most horticultural oils are considered appropriate for organic farming.
Related to jasmine, lilacs, and Forsythia, olive trees have been cultivated since the Bronze Age, some 6,000 years ago, for oil, fruit, and wood.
Unpruned trees can reach a height of 26-49 feet. The trunk tends to twist and becomes beautifully gnarled as it ages. Olive trees are evergreen, retaining their oblong, silvery leaves year round. Small white flowers occur on the previous year’s growth, which then produce the olive fruit. Some people are allergic to the pollen of the olive tree. Botanically, the fruit of an olive tree is known as a drupe, as are plums, cherries, and almonds.
Olive trees (Olea europaea) prefer soil that is less than ideal. Like many herbs, olives thrive in rocky, poor quality soil. They can perform well in clay soil as long as it has good drainage. Soggy soil will kill an olive tree. Olive trees grown in nutrient rich soil are more disease prone and they produce poorer quality oil. Olive trees are very drought tolerant and they love lots of direct sunshine. They also seem to have a preference for coastlines.
When selecting a site for olive trees, keep in mind that they may live for centuries. Most olive cultivars are self-sterile, which means they cannot pollinate themselves, so you may need to plant two trees. Olive cultivars can be primarily for table olives, olive oil, or both. The Santa Clara County Master Gardeners website recommends Ascolano, Manzanillo, Mission and Sevillano cultivars for the Bay area. You can contact your local County Extension office to see which cultivars are best for your area.
Olive trees can be propagated by cuttings and layers, from suckers, or grown from seed. To ensure that you are planting a specific cultivar, it is a good idea to buy root stock from a reputable nursery. Cuttings and suckers can be started by covering with aged manure and watered regularly. Seeds are more likely to germinate if the oily outer flesh (pericarp) is encouraged to rot slightly by placing it in hot water or in an alkaline solution, but olives grown from seed often do not produce fruit.
Once trees are established, fertilizer should be applied annually, just before flowering. Olive tree roots tend to be shallow, so avoid digging nearby. This is also what makes them excellent container plants.
Pruning olive trees
Olives grow very slowly, but pruning is necessary for good health and fruit production. Since fruit is borne on the previous year’s growth, two-year old wood should be removed, to maintain a manageable size. In many commercial orchards, fruit laden branches are simply cut off the tree before the olives are removed.
Pests & diseases of olive trees
The olive fruit fly is a common pest that lays its eggs in the fruit. Once the eggs are laid, the fruit becomes unfit for consumption. Dusting with kaolin clay is an effective organic preventive measure. Rabbits can cause considerable damage to young trees by eating the bark. If the bark is removed all the way around the tree, girdling it, the tree will likely die. Verticillium wilt is a serious threat to olive trees in California. Curculio beetles, black scale, some caterpillars, and the Cycloconium oleaginum fungus can also cause problems. Once an olive tree is established, its extensive root system can recover from the complete destruction of the above ground portion of the tree.
Olives are harvested in September through February, depending on the cultivar and the use for the fruit. Green (unripe) olives are picked September to November, blonde olives are picked October to November, and black olives are picked mid-November through early February. Generally, olives are picked by hand to preserve the fruits’ shape and texture. Oil quality from fallen fruit is not as good as handpicked fruit because of bruising. Semi-dwarf varieties may produce 30-40 pounds of fruit, each year, while full sized trees may produce 100 pounds each year.
Making olives edible
Like acorns, uncured olives are quite bitter. This bitterness is caused by oleuropein and other phenolic compounds. Olives must be cured and fermented before they are eaten. The only exception is the Greek Throubes olive, which is allowed to dry on the tree and can be eaten as is. There are several commercial curing methods:
These slow-growing trees can produce fruit for the next several hundred years or more. Some olive trees are over 2,000 years old and still produce fruit!
You can grow a surprising amount of food in your own yard. Ask me how!
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