Native to South Asia, mangos (Mangifera indica) were part of the spice trade of the 15th and 16th centuries. They were brought to the colonies in the 17th century but, because refrigeration was unavailable, those mangos were pickled. Due to poor communication, other pickled foods, such as sweet peppers, were also referred to as mangos. For a time, the word mango was a verb that meant “to pickle”. But I digress.

Types of mangos

You may be surprised to learn that there are over 500 mango cultivars. In commercial mango orchards, these cultivars are often interplanted to improve pollination. The current market leader is the ‘Tommy Atkins’ variety, due to its nice appearance, productivity, disease resistance, and shelf life. Other, less resilient cultivars, such as ‘Alphonso’, are said to provide better eating enjoyment. With so many cultivars to choose from, home growers can afford to be picky. And those mangos you buy in the store? Many of them (like many other fruits) are picked unripe, so they will never attain the rich flavor of a tree-ripened mango. These climatic fruits do continue ripening after leaving the parent plant, but their flavor is never quite what it could have been. [Keep in mind, when you buy mangos at the store, each fruit is picked by hand, then washed, polished, and stickered by people working in warehouses.]

The mango tree

Mangos are stone fruits, right along with apricots and cherries. And that large flat seed - it’s a drupe. Like legumes, pineapple, sorghum, and sweet potatoes, mangos have evolved alongside a helpful bacteria (Gluconacetobacter diazotrophicus) that fixes atmospheric nitrogen, making it available to to the plant and its neighbors, until it goes to seed.

Mangos are evergreen trees with large, broad leaves that start out orangish-pink, and then turn dark shiny red before maturing to dark green. Mangos produce small, white, fragrant flowers in clusters, called panicles. These flowers are pollinated by insects, but it is estimated that less than 1% of the flowers produced by a mango tree will every mature to form a fruit. It takes 4 to 5 months to go from flower to harvestable fruit. And you know that red blush on mango fruit? It has nothing to do with ripeness or sweetness. Instead, it is an indicator of how much sun that side of the fruit was exposed to as it grew.

Inside that delicious fruit is a drupe that fights being removed with every fiber of its being. The reason for this is because mangos, along with avocados, lychees, and cocoa seeds cannot tolerate being dried out or too cold. This type of seed is called recalcitrant. Recalcitrant seeds, also known as unorthodox seeds, lose their viability when stored. Other orthodox seeds can tolerate varying degrees of cold, dryness, and storage time. [Note, the stories about seeds from King Tut’s tomb germinating are bogus.] If you want to grow a mango tree from a pit, your odds will improve significantly if you start it right away. Most commercially grown mango cultivars and bare root stock are grafted onto sturdy rootstock.

​Before you start growing your own mango tree, you may want to find out if you are sensitive to the oils found in mango stems, sap, and leaves. Some people are sensitive, while others can be severely allergic. Also, mango trees are killed by extended exposure to temperatures below 30°F. If your microclimate receives substantial frost, you may need to protect your tree in winter. If you enjoy snowy winters, you may want to try growing a dwarf mango indoors and pollinating it by hand.

Commercially grown mango trees are often girdled by professionals to increase the sugar content of the fruit, but I advise against this practice, as it can kill your mango tree if done incorrectly.

Mango pests and diseases

Sadly, mango trees are susceptible to a wide variety of pests and diseases. This list is so long that I encourage you to skip it (unless you are really into this sort of thing). If you own a mango tree, you should familiarize yourself with each of these conditions and their treatments. 

According to Wikipedia, bacterial diseases of mango include bacterial fruit rot, crown gall, and bacterial canker. Fungal diseases of mango include alternaria leaf spot, anthracnose, black banded disease, black mildew, black mold rot, black rot, blossom blight, blue mold, branch canker, branch necrosis, ceratocystis wilt, charcoal fruit rot, charcoal root rot, crown rot, crusty leaf spot, curvularia blight, felt fungus, fruit rot, galls, gray leaf spot, hendersonia rot, leaf blight, leaf spot, macrophoma rot, fusarium dieback, mucor rot, mushroom root rot, phoma blight, phyllosticta leaf spot, pink disease, powdery mildew, Rhizopus soft rot, various root rots and seed rots, scab, sclerotinia rot, shoestring rot, sooty blotch, sooty molds, stem canker, stem end rot, stem gall, stemphylium rot, stigma leaf spot, tip dieback, transit rot, trunk rot, twig blight, verticillium wilt, white sooty blotch, wood rot, and various forms of dieback. Fixed copper sprays are the most common treatment for many of these fungal diseases.

If that weren’t enough, dagger, lance, and sheathed nematodes, vine mealybugs, guava fruit flies, Mexican fruit flies, melon flies, polyphagous shothole borers, and Oriental fruit flies will attack mango trees, as will an algae that causes red rust, along with a parasitic lichen. Copper, zinc, and boron deficiencies can also cause problems, while too much nitrogen combined with not enough calcium can cause a condition known as soft nose. It’s a wonder we get mangos at all!

Mangos, like most other tropical fruits, produce significant amounts of ethylene gas, a ripening agent. If you need to speed ripen an avocado for guacamole, put it in a paper bag with a mango.

Did you know that mangos are related to cashews?

Now you know.

Choosing plants for a salad garden

Start your salad garden plant selection with foods you and your family will eat and enjoy. There’s no sense using up valuable growing space on plants you don’t want. To select the best plants for your salad garden, consider the time of year each plant will be able to grow in your area. Check with your local County Extension Office and read those seed packets. You can also get all the information you need right here, online. If you will be growing outdoors, be sure to check with the USDA Hardiness Zone Map to identify your zone. You will also want to identify which plants are perennial, which are annuals, and which are biennials:
   Salad perennials — chives, patience dock, Malabar spinach, nasturtiums, perennial rocket, sorrel [If you have the space, rhubarb and artichokes provide HUGE, ongoing crops each year]
   Salad biennials — kale, parsley, Swiss chard    
   Salad annuals -- arugula, bok choy, cilantro, dill, lettuces, mizuna, radish, spinach

The perennial plants will serve as year-round anchors in your salad garden, the biennials may take 2 or 3 years before going to seed, and annuals will have to be replaced each year. Or, maybe they won’t. We will get to that in a moment.

While visiting the Missouri Botanical Garden, I was delighted to discover an entire section of the gardens dedicated to stumperies. Coming around a curve in the path, I was met with a cool, green peaceful bit of gardening that featured logs, branches, sheets of bark, tree trunks, and skyward bound tree roots, surrounded by wispy ferns, colorful lichens, and fuzzy mosses. The effect was soothing and peaceful - and who doesn’t need more of that these days?

Stumpery design

Stumperies are based on what naturally occurs in a forest. As a tree ages, it eventually falls. When it does, it slowly decomposes, absorbing rain water, improving nearby soil structure, and acting as a ‘nurse log’ to plants that have adapted to growing on rotting wood. To design your own stumpery, you must look at each piece of wood and bark as an artistic component. Try different arrangements until you have achieved something you like. Don’t worry, there are no wrong answers. Here are some tips to creating a healthy stumpery:

1. If possible, prepare the ground by loosening the soil to a depth of 6 to 8 inches, digging in some compost. If the soil is too compacted, just clear the weeds and cover the area with a few layers of newspaper. [Eventually, the soil structure should improve.]
2. Arrange your wood. And don’t expect to get it just the way you want it the first time around. It may take days, or even weeks, to get an arrangement look naturally haphazard and appealing. Single branches can provide a focal point, or you can use several pieces to create an arch, a dome, a circle, or whatever suits your fancy.
3. You may want to use branches to create an outline of your stumpery.
4. Line any pockets created by the arrangement of wood with moss, to help hold soil and retain moisture.
5. Add soil to these growing pockets.
6. Install shade-loving plants.
7. Mulch the exposed areas with 2 to 3 inches of wood chips to mimic the leaf litter that is normally present in a woodland. This will add nutrients, reduce competition from weeds, and help retain moisture.
8. Water the area frequently, until plants are established.

Plants used in stumperies

The most common plants found in stumperies are mosses, ferns, and lichens. Hostas, hellebores, epimedium, rhododendrons, bleeding hearts, and some bulbs can also thrive in a stumpery. ​

You can encourage moss growth on logs and stones by smearing them with yogurt [or that carton of soured milk from the back of the fridge]. You can also install shade-loving edibles, such as arugula, basil, blueberries, bok choy, celery, chervil, chives, cilantro, fenugreek, garlic, ginger, kale, lettuces, Malabar and other spinach, mint, mustards, nasturtiums, onion, parsley, potatoes, raspberries, sorrel, tarragon, and tomatillos. The perennials will continue indefinitely, and you can allow some of the annuals to go through their full lifecycle and propagate themselves!

Benefits of stumperies

Stumperies create micro habitats for local flora and fauna, increasing your garden’s biodiversity. Beetles, toads, and lizards often find sanctuary in all the hidden nooks and crannies provided by a stumpery. Of course, slugs and snails and other pests do, as well. But birds enjoy the extra perches and snacks, so it all balances out.

Carpenterworms (Prionoxystus robiniae) are the larval form of a common moth, and they love to burrow into apricot and pear trees. They can also be found in many ornamental trees, such as maple, oak, birch, cottonwood, ash, and willow. Once these pests are inside your trees, they can be difficult to evict.

As you can see, this is a robust caterpillar. They can be 1/2 an inch in diameter and 2 to 3 inches long. They have a dark, brownish head and a yellowish white body that is covered with fine hairs. They have sharp, hooked legs on the middle section (thorax) and distinct fleshy legs on the abdomen

Damage caused by carpenterworms

​These wood-boring insects live in galleries, feeding on sapwood. Knowing the signs of infestation can help you get a handle on this pest before the damage becomes irreversible. The galleries created by carpenterworm feeding tend to be vertical, except for the entrance. These entrances are often found in branch crotches and in bark crevices. Tunnels are 1/2 an inch in diameter and 6 to 10 inches long. This tunneling creates points of entry for many other pests and diseases. Adult female carpenterworms seem to prefer areas that are already infested for egg laying, which can result in multiple galleries in the same area of the same tree. All that feeding and tunneling can weaken branches, making them more likely to break in strong winds, or when supporting heavy crops. Branches can also become girdled by carpenterworm feeding and tunneling, and die.

Carpenterworm description

Adult carpenterworms are large, mottled gray moths that can have a 3-inch wingspan. Their coloration blends with tree bark and lichen. This camouflage makes them difficult to see. If you are able to catch one and spread out its wings, you wing be able to see if you have a male, with orange hind wings, or a female, with off-white hind wings.

Drapernaud’s glass-snail

Drapernaud’s glass-snail (Oxychilus draparnaudi) is larger than the other glass snails, being slightly more than 1/2 an inch in diameter, and the shell is a waxy yellowish-brown on top and somewhat lighter underneath. The body is a dark blue and gray color. Drapernaud’s glass-snail is carnivorous.

How to control snails

Unless you are enjoying artistic versions of this common pest, managing snails is an ongoing task. It comes as no surprise that these snails’ peak breeding season in the Bay Area is autumn, just before our rainy season begins. 

The first step in snail management is to inspect and quarantine new plants. A single snail can lay over 400 eggs. Putting new plants into isolation for a couple of days, with a beer trap nearby, can prevent years of frustration. Once infestation occurs, try to reduce hiding places, such as boards, stones, and other debris. Regularly applying slug and snail bait, and using beer traps, can take a big bite out of the snail population, before they start taking bites out of your plants. Going outside with a flashlight at night, you can catch them feeding - handpick them and feed them to your chickens or dispose of them in the trash.

Did you know that snails have a powerful sense of smell?

Now you know.

Walnut trees, like citrus and many other fruit and nut trees, tend to produce heavy crops one year and a light crop the following year. Known as alternate bearing, these fluctuations allow trees to recover from heavy production years.

Toxic walnut

You have probably heard that walnut trees put out toxins that make it impossible to grow other plants nearby. This is only partly true. Many plants use a type of chemical warfare, called allelopathy, to reduce competition. Walnut trees produce do produce toxins that can cause some other plants to wilt. Tomatoes, potatoes, eggplant, peppers, blackberries, raspberries, blueberries, and asparagus do not grow well when planted near a black walnut tree, according to the University of Illinois Extension. At the same time, according to the PennState Extension, onions, beets, squash, melons, carrots, parsnips, beans, yarrow, stonecrops, and corn can all be grown near a walnut tree without any problems. In fact, in commercial walnut groves, a type of agroforestry, called alley cropping, is used to plant other crops, such as corn, between the rows of walnut trees.

Propagating walnut trees

While you can certainly buy a bare root walnut tree, there are other ways. You can plant a raw walnut in the ground, or, if you know of someone with a walnut tree, you can use air layering. Layering is a form of vegetative propagation. Strawberry runners are an example of layering. The nice thing about air layering is that the parent plant continues to feed and care for the newly developing plant, since they are still attached to one another. To air layer a walnut, pull a stem down until it touches the ground at what would have been a leaf node. Instead of developing into a leaf, that bud will start putting out roots.

Pruning walnut

Walnut trees can produce nuts on the same spurs for several years. Because of this, mature walnut trees do not require renewal pruning. The only pruning needed is occasionally thinning branches to maintain overall shape and good health. Young walnut trees are trained using the modified central leader system. In this method, a single, strong shoot is encouraged up the central line of the tree. Two or three lateral branches, spread evenly around the tree, both vertically and horizontally, are allowed to grow. All other branches are removed. Eventually, there can be five to seven lateral branches in place before the central leader is removed.

Walnut pests and diseases

Walnuts are susceptible to an astounding number of pests and diseases. Luckily, walnuts are rugged trees that rarely need assistance in fighting off these foes. It’s still a good idea to know what your tree might be up against. Many varieties of scale insects, including walnut scale, frosted scale, European fruit lecanium scale, San Jose scale, Kuno scale, and Italian pear scale may be found on walnut. Walnut husk flies, aphids, southern fire ants, walnut twig beetles, fall webworms, Pacific flathead borers, navel orangeworms, false chinch bugs, redhumped caterpillars, American plum borers, and Mediterranean fruit flies prefer walnut, as do tortricid moths, such as the light brown apple moth, which can cause leaf roll of walnut. A type of eriophyid mite, called the blister mite, will also attack walnut trees, as will European red mites and webspinning spider mites. Codling moth larvae will burrow into the nut meat of English walnuts, starting in April. You can monitor your trees for many of these pests by using pheromone traps.

Diseases, such as crown gall and walnut blight can be prevented and treated with Bordeaux mixture or fixed copper. Walnut trees may also become infected with anthracnose, armillaria root rot, phytophthora root and crown rot, branch wilt, and several canker diseases. If that weren’t trouble enough, squirrels, voles, pocket gophers, rats, and deer will try to get at as much of your walnut crop as they can.

While many trees are treated with horticultural oils during dormancy, oils should not be used on walnut. Dormant oils are phytotoxic (poisonous) to walnut trees. Like apricot trees, walnut trees are also susceptible to Eutypa dieback. This fungal disease can kill a tree. The easiest way to avoid it is to only prune your walnut tree during summer, when there are no rains expected. Also, make sure that your sprinklers are not hitting the tree’s trunk.

Walnuts contain high levels of oils that can turn rancid. To keep walnut meats fresh, they are left in their shells and placed in cold storage. If you buy walnuts from a store and plan on using them within one month, store them in your refrigerator. Since walnuts can absorb odors, be sure to keep them away from fragrant foods, such as cabbage, broccoli, and fish. Longer storage should be done in the freezer.

Walnut trees can make a magnificent addition to your foodscape, providing decades of delicious nuts and welcoming shade from the summer sun.

Mealybugs have been around for a long time. There is a relatively new, invasive mealybug that may be attacking your grapes.

​Traditionally, grape growers have had to watch for grape mealybugs, obscure mealybugs, and long-tailed mealybugs. These species generally do not cause significant problems, as long as their populations do not get out of hand. They are easy to recognize because of the clusters of gray, soft-bodied females gathering on the underside of leaves and in nooks and crannies. The invasive vine mealybug is another problem altogether.

Vine mealybugs (Planococcus ficus) are native to the Mediterranean areas of North and South Africa and Europe. Vine mealybugs were first seen in California in the mid-1990s and had spread to 17 California counties by 2011. Vine mealybugs are now considered a significant pest of grapes, figs, avocado, apple, bananas, mango, citrus, date palm, and several ornamental plants.

​Vine mealybugs are difficult to see because they spend most of their lives protected under the bark, on roots, and around developing buds. Only during spring, when they become active again, can you sometimes see them moving away from the roots and trunk and into the leaf canopy. By summer, vine mealybugs may be found under the bark of first- and second-year canes, among fruit clusters, and under leaves. Sometimes, ants can be seen providing the mealybugs with transportation to their summer feeding grounds.

Vine mealybug description

Vine mealybug females are 1/8 of an inch long, pink, oval-shaped, and covered with a white, mealy wax that also covers filaments (spines) along the sides and posterior end. These filaments are shorter than those seen on other mealybugs, and there are no long tail filaments. Like their cousins, vine mealybugs have a segmented body. Males are tiny, winged, and you’ll probably never see them, unless you have a 30x microscope. They are 0.7 inches long, amber colored, with beaded antennae, one pair of wings, and 4 tail filaments that may stick together.

It is important to know which mealybugs you are dealing with. If you see mealybugs, try to collect some and place them in a sealed plastic bag, or in a container of alcohol, and take them to your local County Extension Office for identification. This also helps authorities better understand the spread of this invasive pest.

​Vine mealybug lifecycle

In summer, females lay 300 to 700 eggs in the leaves above the fruit in little pouches, called ovisacs. First instar nymphs, called crawlers, are orange and very tiny. During winter, only nymphs are present. They can be found hiding under the bark around the graft union, below the base of spurs, and around pruning wounds. There can be 3 to 7 generations a year.

​​Damage caused by vine mealybugs

Vine mealybugs are phloem sap suckers that produce significantly more honeydew than native mealybugs. This honeydew attracts protective, disease-carrying ants and creates a growth medium for sooty mold on fruit clusters. These invasive pests can also carry grapevine leafroll viruses and corky bark disease. Vine mealybugs reproduce at a much faster rate than their native cousins.

How to control vine mealybugs

Being an invasive pest, vine mealybugs do not have as a many natural predators as their native cousins. Because vine mealybugs are such a serious threat to California grape growers, parasites of these particular mealybugs have been released in the state. This has helped somewhat, but eradication appears to be impossible at this point. Since these beneficial insects are unavailable to the home grower, the best things you can do to protect your vines is to inspect them regularly, especially during spring, monitor and control ant traffic with sticky barriers, and to quarantine new vines and other plants before installing them. Also, sanitize your tools regularly. Vine mealybugs also feed on burclover, malva, black nightshade, sowthistle and lambsquarters, so controlling these weeds can also help prevent infestation.
​
Small, red delta pheromone traps (if you can find them) may also be used in April through June, depending on where you live. Check your trap every 2 weeks through November. The California Extension Office has an excellent male vine mealybug identification information sheet.​

Protecting your grapevine from vine mealybugs is an important step toward providing your family with fresh, delicious, organic, homegrown grapes.

Cousin to beeches and oaks, the roasted chestnuts of holiday fare fame should not be confused with horse chestnuts, which are mildly poisonous, or water chestnuts, which are aquatic tubers. No, chestnuts, or Sardian nuts, as they were called in their native Asia Minor, or Jupiter’s nuts, from the Roman Empire, have been cultivated since 2,000 B.C., and they have a rich, delicious history.

Chestnuts as food

Brought to Europe by Alexander the Great and the Roman Empire, chestnut trees thrive in the Mediterranean climate, providing a high carbohydrate food to the masses. Unlike most other nuts, chestnuts are not particularly high in protein or fat. Nutritionally, they are closer to grain or potatoes than nuts, containing 40% carbohydrates.

Chestnuts were a primary food source for much of southern Europe, until the potato was introduced. From the 1500s through the 1700s, Genoan landowners were required to plant four trees each year: olive, fig, mulberry, and chestnut. As a result, that area has rich, productive forests and farmland. [Imagine how productive your yard could be if you plant 4 food-producing trees each year!]

Being high in calories and carbohydrates, chestnuts were often ground into a flour to make a type of flatbread [chestnut flour does not rise, as it does not contain gluten]. Unfortunately, this earned it a reputation as a poor man’s food, which lead to a decline in interest. This was unfortunate, because chestnuts are a highly nutritious food.

Across the pond, Native Americans enjoyed local chestnut species long before Europeans arrived. Regions of the Appalachian Mountains were fully one-fourth chestnut trees. Since a mature American chestnut tree can produce 50 to 100 pounds of fruit each year, that ends up being a lot of food.

Epic chestnuts

There have been some impressive chestnut trees. The Tortworth Chestnut, also known as the Great Tree of Tortworth, found in South Gloucestershire, has been around since Stephen, King of England (1092-1154). This beast has a circumference of 50 feet! [If any of you have a photo of this tree, please share it in the Comments!] Even larger, the Hundred Horse Chestnut grows on Italy’s Mt. Etna and is believed to be the oldest living chestnut tree, at approximately 4,000 years.

Chestnut species

There are 8 or 9 different deciduous trees and shrubs that are called the chestnuts. These are placed into one of four groups: American, Chinese, European, and Japanese, for obvious reasons. Each species has distinct characteristics.

European and American chestnuts tend to grow more tree-like, with a single erect trunk, while the Asian varieties tend to be multilayered and more spread out. Also, the former varieties offer stunning fall foliage. There are hundreds of chestnut varieties to choose from. UC Davis offers an excellent list of chestnut trees suitable for growing in California.

Chestnut flowers

Like avocados, chestnuts have both male and female flowers. Chestnuts are not self-compatible, which means you will need at least two trees or shrubs to produce fruit. Flowers appear in late spring and early summer. Male (staminate) flowers are shaped like a cat’s tail and are called catkins. Catkins mature before the female flowers, and the pollen has a rich, sweet aroma. The female, fruit-producing (pistillate) flowers grow together in groups of 2 or 3, which end up forming a prickly, 4-lobed structure called a calybium. The calybium is what ultimately develops into the hull that protects the fruit. Pollen is moved predominantly by wind, though beneficial insects also perform some pollination.​​

Chestnut fruit

The fruit of chestnut trees is held in sharp, pokey burrs, called cupules. These burrs tend to be clustered. The burrs of some varieties each contain one nut, while other varieties can hold up to severn. Burrs turn yellowish-brown and split open as the fruit matures. Each fruit has a pointed end, called a flame, and an attachment scar end, called the hilum. Chestnut fruit has two skins: the hard outer pericarpus, called the heel, and an attached, thinner skin, called the pellicle or episperm. Chestnuts are both culinary and botanical nuts, unlike almonds, peanuts, cashews, and walnuts.

​
Chestnut lumber

Chestnut lumber is lovely, but larger pieces tend to split. Most chestnut lumber is now produced through coppicing. Young chestnut lumber is more durable than oak of the same age. Both species contain high levels of tannins. Chestnut wood was a common source of natural tannins for tanning leather.

How to grow chestnuts

Chestnuts are in high demand and the supply is limited. This keeps prices high, and is a good argument for growing your own (assuming you are not in a hurry). Going from bare root sapling to mature, productive tree takes about 10 years. Chestnuts need specific chilling hours to produce flowers and fruit. If the dormant period does not get cold enough, you will still have a beautiful tree, but no homegrown chestnuts. Also, if two chestnut trees are planted such that their canopies touch, they produce no fruit. We don’t know why.

Allowed to fall to the ground, chestnut seeds germinate right away. You can start them in a cold frame, container, or seedbed outdoors, where they will experience winter temperatures. Seedlings require protection from squirrels and other rodents.

Chestnut trees prefer full sun. They need good drainage and regular irrigation (31 inches per year). Once established, chestnuts are drought resistant. They do not grow well in heavy clay or alkaline soil. Chestnuts prefer a soil pH of 5.5 to 6.0. If you live in the Bay Area, where alkaline clay is pretty much the rule, don’t despair. Chestnut scions can be grafted onto oak rootstock! Chestnut trees are managed much the way walnut trees are grown. Chestnut trees should be trained into a modified central leader scaffold system for the best sun exposure and overall health.

Chestnut pests and diseases

Squirrels, rabbits, deer, wild boar, livestock, and birds can all take a bite out of your chestnut harvest. You may want to consider a tree cage, at least while the tree is small. Chestnut gall wasps (in southeastern states), some moths, the oak roller weevil, oak aphid, filbert worm, oak leaf mining moth, shot hole borers, and the chestnut weevil are common pests of chestnut, depending on where you live.

In 1904, some Asian chestnut trees that had been planted on Long Island, were found to be infected with chestnut blight (Cryphonectria parasitica, formerly Eudothia parasitica). Over the next 40 years, 4 billion chestnut trees died, nearly wiping out the American chestnut. Reforestation efforts, started in the 1930s, using seeds from the few remaining living stumps are giving this majestic tree a new lease on life, but it’s a slow process. There are now blight-resistant cultivars. Chestnut trees are also susceptible to Armillaria rot. On the other hand, chestnuts are believed to be naturally resistant to oak rot fungus. You can protect your chestnut tree against sunburn by whitewashing the trunk, and help it stay healthy by mulching under the canopy (but not touching the trunk).

Roasting chestnuts

Chestnuts have been candied, soaked in wine, and roasted as a holiday tradition throughout Europe for a very long time. To early Christians, chestnuts symbolized chastity, while in modern day Japan, they symbolize both good times (mastery) and bad times (strength).

You can roast your own chestnuts at home in the oven. Start with raw, unpeeled, chestnuts. Cut an X on the rounded bottom of each nut. Some people soak their chestnuts in water for 30 to 60 minutes before baking, others use wine, and still others don’t soak at all. You decide. If you do soak them in water, drain and pat dry before roasting.

Spread the nuts out on a baking sheet. Bake for at least 15 to 20 minutes, or until the skins have pulled away from the cuts and the nutmeats have softened. Take them out of the oven and let the nuts rest for a few minutes. Peel and eat!

Did you know that chestnuts are the only nuts that contain vitamin C?

Now you know.

Most needle-bearing trees are evergreen, though there are a few deciduous species. Just as the leaves of deciduous trees change colors and fall in autumn, the needles of many evergreens also change color and fall, it’s just not as obvious. This is a natural occurrence, much like citrus June drop. Most evergreens hold onto their needles for 2 or 3 years. Discarded needles are usually those found closer to the trunk. If needles are lost elsewhere on the tree, or if needles are discolored, it can indicate fungal disease.

Needle pests and diseases

Pine wilt can also cause discolored needles. Pine wilt is caused by pinewood nematodes, which attack the vascular tissue. Pinewood nematodes move from tree to tree by catching a ride on pine sawyer beetles, in a behavior called phoresy.

Pine needles are a favorite food of some moth and butterfly species, as well as the pine sawfly. Goats will eat pine needles, too, but you wouldn’t want to drink the milk they produce after that snack. It’s nasty.

Acidic pine needles

There is a popular misconception that pine needles can be used to acidify soil. While it is true that fresh pine needles are slightly acidic, and a thick layer of needles on the ground can interfere with the growth of competing hardwoods, the dried needles, often called pine straw, are not acidic. While they will improve soil structure by adding organic material as they decompose, pine needles will not, I’m sorry to say, acidify your soil.

Pine needles can be steeped in boiling water for a refreshing tea that is high in vitamins A and C. Pine needles have long been used to make baskets, trays, and other crafts. Here is a pine needle basket made by my grandmother.

​Types of guava

There are many varieties and cultivars of guava. You may have heard of apple guava, strawberry guava, and pineapple guava. While the first two are actually guava varieties, pineapple guava is a different species altogether. In the world of guavas, plants are sorted by fruit skin and flesh color, skin thickness, and sweetness. To find the best variety for your microclimate, contact your local County Extension Office.

Guavas are extremely drought tolerant, but plants require up to 39 inches of water each year to produce a good crop. Feeding roots only go down 9 inches, so top dressing with aged compost is an excellent way to keep guava trees fed.
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Guava pests and disease

Guava wood is naturally resistant to insects and fungal disease. They are, however, susceptible to attack by weevils, mites, and guava fruit flies, and they are a host to the Caribbean fruit fly. Many moth and butterfly caterpillars will also feed on guava leaves, and the Erwinia psidii bacteria can cause rot diseases.

Guavas contain a lot of pectin, so it is easy to make guava jams, jellies, and marmalades.

New diseases or pathogens are rare these days. But scientists found one carried by a common pest. It is called Fusarium dieback, and it can kill your trees. [See a map of its presence in SoCal here.]

Fusarium dieback is a fungal disease carried by invasive borers. As borers burrow into trees, they spread three different fungal pathogens. These fungi form colonies within a tree’s vascular system, blocking the flow of water and nutrients. Trees infected with Fusarium dieback must be removed and disposed of by professional arborists.

Symptoms of Fusarium dieback

Since this disease affects many different types of trees and has multiple pathogens, it is no wonder that there are a variety of symptoms. Infected avocado trees, for example, will exhibit sawdust-like frass (bug poop), gumming, and sugar volcanoes. Sugar volcanoes are white discharges of sugary sap. On other host trees, you may see dark, greasy-looking areas on the bark, withered leaves and stem tips, and white mycelium under the bark. Mycelia are the vegetative growths of fungi.

As the infestation progresses, perfectly round, tiny borer entry and exit holes may become visible. These holes are only 0.03 inches in diameter, so look very closely, usually just below areas showing disease symptoms. Eventually, branches will start to die. If you cut into an infected limb, you will see that the wood is discolored, brown, or black. If you scrape the bark away from entry or exit holes, you will also see discoloration. After each cut, disinfect your tools with a household cleaner to avoid spreading the disease.

Disease background

Fusarium dieback originated in Israel and spread to Southern California by 2003. Botanists are not sure how far the disease will spread from there. At first, scientists thought the tea shot hole borer was the carrier, a common pest of tea plants in Sri Lanka. DNA testing, however, showed that this was an entirely new species, now named the polyphagous shot hole borer. 

By 2010, this borer, and the disease it carries, had become a serious threat to Southern California’s box elder trees, palm trees, black locust, and our beloved avocado trees. In 2015, a second carrier, the Kuroshio shot hole borer, joined the party and started infecting the popular California palms (Washingtonia filifera). This disease currently threatens 25% of all the trees lining Southern California’s streets.

Beetle description

The two borer species responsible for Fusarium dieback look identical at first. Female beetles are tiny and black, only 0.07 to 0.1 inches long. Males are brown and even smaller, at only 0.06 inches long. Female beetles can fly and will leave their birthplace to find other host trees to use as nurseries, carrying the disease with them when they go. Males do not fly and generally stay in the tree of their birth. These beetles are most active during summer and fall.

Fusarium dieback hosts

Shot hole borers feed on and breed in over 200 species of woody plants. That’s a lot of potential hosts. While this disease prefers gums, palms, pines, and privets, it is also a threat to apples, bay laurel, carob, chestnut, elderberries, figs, grapes, olive, persimmons, pineapple guava, pistachios, pomegranate,  stone fruit, and stone pine are also vulnerable to Fusarium dieback.

How infection occurs

This disease starts when female beetles bore into tree trunks and branches, creating galleries of tunnels. Within the tunnels, they build egg chambers. Female beetles have developed a symbiotic relationship with three different fungi, which they carry around in their mouths, much the way we have bacteria in our gut. [The fungal pathogens of Fusarium dieback are Fusarium euwallacea, Graphium euwallaceae, and Paracremonium pembeum if you enjoy the Latin.]

Those fungi set up housekeeping within the tree and become food for the newly hatched beetle larvae. By eating the fungi, the larvae then become carriers of the disease. These fungal colonies develop rapidly once inside a tree, and there is no known treatment at the time of publication. Not all infected trees will show signs of infection. Some infected trees serve as breeding grounds without showing any signs of disease. We don’t yet know why.

Preventing disease

Healthy trees are far better able to protect themselves against borers. So select plants appropriate to your microclimate, irrigate and fertilize them properly, and provide healthy soil. Also, monitor your trees regularly.

If you suspect Fusarium dieback on a tree, contact your local County Extension Office. Together, we may be able to slow or stop the spread of this disease.

Growing Jerusalem artichokes
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To grow your own Jerusalem artichoke crop, begin by selecting a site. Remember, these plants are going to be around for a long time, and they can become rather tall. Unlike many other plants, sunchokes seem to enjoy being clumped together, but they should still be planted 8 to 12 inches apart. Create soil mounds over the plantings, 2 to 3 inches deep, and water regularly, allowing the soil to dry out between waterings.

Starting with a single Jerusalem artichoke tuber, you will eventually find your garden overrun with these perennials. Each plant can produce 75 to 200 tubers every year. Left unharvested, each of those will produce tubers of their own. In my book, that’s a good thing - but you may feel differently. Since tubers left in the ground for too long tend to deteriorate, and they can become invasive, Jerusalem artichokes are a good candidate for large containers or raised beds. This will facilitate crop rotation and control the number of Jerusalem artichoke plants you end up with each year. Any little piece of tuber left in the ground is likely to sprout, to plant accordingly.

Grown in containers, Jerusalem artichokes do not need to be fertilized if you start with nutrient rich potting soil mixed with aged compost. Plants will need to be watered deeply, once a week, throughout the summer. Staking may be needed to keep plants from toppling over, or you can grow them along a fence or against a building.

Harvesting Jerusalem artichokes

As the leaves, flowers, and stems begin to die back at the end of the growing season, usually around October, you can dig up the tubers and allow them to dry, unwashed, for storage. Each plant will produce approximately five pounds of tubers. Sunchoke stems can be chopped and used for mulch, while the tubers to be used for the next year’s crop are simply placed back in the growing bed, along with some aged compost, and the cycle begins again.

[Mostly] edible sunchokes

Surprisingly low in starch, Jerusalem artichokes contain a type of carbohydrate sugar, called inulin, which gives them an underlying sweet taste. While the human gut cannot digest inulin, bacteria further down can, so some people may experience a certain ‘airiness’ after eating sunchokes. If they are not bothersome to you, they also provide a lot of potassium, iron, fiber, and B vitamins. ​

Or, if you prefer, you can ferment your Jerusalem artichoke crop to make brandy, the way they do in Germany.

As an older native plant, sunchokes have very few pests or diseases to worry about. So, mark your calendar to start Jerusalem artichokes in March or April, and start preparing the planting space today!

Hardpan is a layer of soil so dense that air, water, and roots can barely move through it, if at all. Think of it as a saucer under the teacup of life. Unlike compacted soil, which is a general condition of not enough macropores and micropores, hardpan is a distinct layer, usually found 4 to 40 inches below the surface, that reduces or halts drainage, roots, and gas exchanges altogether.​

Causes of hardpan

Plowing, digging, or rototilling to the same depth every year can compact the underlying soil so much that it becomes hardpan. In addition to digging and plowing, there are several other things that can cause hardpan to develop:

• heavy traffic, such as the construction equipment used to build your home
• heavy chemical use, which kills beneficial soil microorganisms
• extended drought and improper watering can also cause hardpan

Hardpan can also occur naturally when layers of silica, iron oxides, salt, or calcium carbonate fuse and bind soil particles together. Glaciers can cause hardpan, by compressing layers of those minerals.​ ​Soil pH and soil structure are major factors in the development of hardpan.

Acidic soils are far more likely to cause calcium and iron to form hardpan layers, than alkaline soil. Soil structure is another important factor. Clay particles are very small and already tend to become compacted. In clay soil, rain or irrigation followed by high temperatures can also create hardpan. However it occurs, plant roots don’t like it.

Do you have hardpan?

Poor drainage is the first sign of hardpan, followed by a general failure to thrive. If you have a soil tester, you can take a few 2 or 3 foot deep samples of your soil, to see if there is a hardened layer. If you have a post hole digger, you can basically do the same thing, with more soil and more effort. The important thing is to look at the layers of soil as you bring them up. If you reach a layer where all the plant roots start growing horizontally, you have hit hardpan.

Managing hardpan

Once a layer of hardpan has formed, it takes brute strength and proper soil amendments to correct the problem. Basically, you can either dig down into the hardpan layer, breaking it up, or add significant amounts of organic matter and let nature takes its course.

If you opt for the brute strength method, you will have to wait for the soil to be dry. [Digging wet soil is never a good idea.] You can use a digging fork, spade, or broadfork to break through the hardpan layer. As you do this, you will want to make sure that the subsoil is not brought up and mixed with the topsoil.

To prevent compounding the problem by even more digging, it is important to add significant amounts of organic matter, in the form of aged compost or manure, or peat, to improve the soil structure, as you dig. Earthworms and other soil dwelling creatures will, over time, break through a thin layer of hardpan, but only if enough organic material is added to the soil.

Treating acidic soil with lime can help break up the chemical bonds that hold a hardpan layer in place. This is not an option in regions with alkaline soil. You can also top dress an area repeatedly with organic matter to treat hardpan, but it may take years before you see results.

Soybean pests and diseases

Spider mites are the most destructive pest of soybeans, followed by corn earworm moths, Mexican bean beetles, bean leaf beetles, and cyst nematodes. Fungal diseases, such as stem blight, rust, and white mold can infect soybean plants, along with bean yellow mosaic and other viral diseases. But don't let that stop you!

If you have the space, give soybeans a try in your yard!

Wrapping your trees to protect against winter cold sounds like a good idea, but it probably isn’t.

For decades (centuries?) people have wrapped their trees to protect against frost cracks, winter sunscald, and other forms of cold weather damage. While this sounds like a great idea, it ends up that those wraps can actually cause more harm than good.

The theory behind tree wraps

Winter tree and plant damage can occur in several ways: flat out freezing; temporary warming, followed by freezing; and cracks caused by the water within the plant freezing, expanding, and pushing its way out. When you get down to it, it is rapidly fluctuating temperatures that cause the most damage to trees in winter.

Types of tree wraps

Tree wraps, also known as tree guards, or tree liners, can take many forms. Commercially available tree wraps include white plastic guards, white adhesive tape, foil-backed fiberglass panels, capillary mats, landscape fabric, reflective greenhouse insulation, and watering bags. DIY growers have used paper, bubble wrap, burlap, cardboard, shredded newspaper, foam, and I have a neighbor who knitted sleeves for her trees! ​

It's very colorful, and I like to think that the good airflow allows moisture to evaporate enough to keep the trees healthy.

​Some people make their own tree wraps by creating a tube of chicken wire fencing around the trunk and filling the space in-between with shredded leaves. All of these methods require frequent inspections to avoid becoming problematic.

​Problems with tree wraps

According to the International Society of Arboriculture (ISA), studies have shown that tree wraps do not actually prevent temperature fluctuations. In some cases, temperature variations are even worse with the wraps. Also, tree wraps provide protection for many wood-boring insects, wasps, and earwigs, just to name a few. This is especially true with snugly fitting wraps.

Manufacturers and many gardening sites suggest that tree tubes be left on young trees for several years, until they are well established. They claim that tree tubes insulate the trunk against winter sunscald and shade it against summer sunburn. These tubes may also prevent a tree from swaying in the breeze so much that it fails to get strong, through a process called thigmomorphogenesis. [How’s that for a cool garden word?]

Wrapped too tightly, tree wraps can interfere with normal growth, causing girdling. Depending on the material used, it may cut into the bark, causing points of entry for pests and disease.

Often bare root stock and young trees are sold with tree wraps in place. These wraps can provide protection during digging and shipping, but they can also hide injuries, insects, and improper pruning.

Wrapping your trees may reduce mechanical damage and rodent feeding, but it is more likely to result in insect damage and fungal disease. And it will not protect your trees against frost cracks or winter sunscald. Personally, I prefer whitewashing, mulch, and proper irrigation to prevent cold weather damage.

Summer sunburns hurt, but winter sunscalds are worse (for trees).

You might not think sunscald, or sunburn, could occur in winter, but it can. [Ask any of your skier friends. They know.] Unlike summer sunburns, like the sunburns we get, winter sunscald occurs when it gets warm enough in the daytime for plant cells just under the bark to break dormancy.

Breaking dormancy

Several chemical changes occur as plants enter dormancy. These changes protect plants against the cold. Warm, sunny days can trick overeager cells into breaking dormancy and losing those protections. Then they die, leaving a sunken area below the bark.

If there are any fruits present in winter, they, too, can be affected by winter sunscald. Going from protective shade to direct sunlight can damage the outer skin enough to allow insects and diseases to enter. In other cases, the fruit exterior may look normal, but the underlying tissue becomes damaged and is usually inedible.

Winter sunscald is rarely fatal, except to one- or two-year-old trees. But it can weaken a tree and make it susceptible to wood-boring pests and canker diseases. Nearly all fruit trees, and all newly planted trees, are vulnerable to winter sunscald. Other thin-barked trees, such as ash, beech, birch, maple, and willow, often develop winter scald if unprotected.

Preventing winter sunscald

There are several ways you can prevent winter sunscald from damaging your trees. First, irrigate your trees properly. A water-stressed tree is far more likely to develop winter sunscald. Also, avoid damaging the trunk with lawnmowers, car doors, and weedwackers. Damaged tree trunks have a hard time protecting themselves. You can prevent mechanical injury and stabilize soil temperatures with a thick layer of mulch around the tree. Just keep the mulch from touching the trunk, which can set the stage for fungal disease.

If watering and mulching aren’t enough, whitewashing the trunk and exposed surfaces of major branches can help prevent winter sunscald. It will protect against summer sunburn, too. Just don’t whitewash your trees with enamel paint. They will suffocate. Instead, combine equal parts water and white latex paint (preferably one without extra chemical additives) and use that to paint your trees.

Traditionally, people wrapped their trees to prevent winter sunscald, but now we know that those wraps can harm trees. Tree wraps allow moisture to collect, setting the stage for rot, and they provide an excellent hiding place for pests and fungal diseases. Also, cracks that occur under the wraps do not heal as well. Bottom line: don’t wrap your trees.

If your trees tend to get winter sunscald, you can block or shade the southwest side of your trees to provide some protection against winter sunscald.

Winter sunscald care

Once the damage has occurred, you can speed up the healing process by smoothing the edge of the wound with a sharp, sterilized knife. Do not remove more than 1/2” of the bark. Also, resist the urge to paint tar or sealant over the wound. Sealants trap moisture in the wound, increasing the chance of disease and decay.

Finally, you know that adage about getting lost in the woods and looking for moss on the north side of trees? Well, that piece of advice is useless. Moss grows on the side of the tree with the most moisture and sun protection. What you can do, however, is look for winter sunscald, which nearly always occurs on the south or southwest sides of trees in the northern hemisphere.

Now you know.