If you have fruit and nut trees, you can prune those trees to improve both the quantity and quality of your crop, or you might eliminate production altogether.
Normal annual pruning involves removing dead, diseased, and rubbing branches. It also means training trees for shape, size, structure, and air flow. This is normally done while trees are dormant, in winter. There is also renewal pruning, done in autumn, which stimulates new growth the following spring. But, did you know that you can also prune for better fruit production? It’s true!
How fruit happens
Fruit and nut trees produce buds. When those buds are fertilized, they can grow into fruit or nuts. [Assuming the tree of healthy enough and old enough.] But some trees produce fruit on new growth, while others produce fruit on old growth. If you keep cutting off productive wood, you won’t have much of a crop.
Where do trees produce fruit?
Depending on the species, trees produce fruit either on long shoots or on stubby spurs. That fruit can be arranged laterally, along the sides, or at the terminal end. Take a look at the chart below for information about your trees.
This may seem like too much information to be useful, but let’s walk through a few examples together, so you can see how to better prune your trees.
You can see that almond trees produce the majority of their fruit on lateral spurs, and some fruit along lateral shoots. You will also see that each spur is good for 5 years, that very little pruning is needed, and that almond trees are best trained in the open center system. So, what does all this mean to the owner of an almond tree?
First, snipping the tips off of anything on an almond tree won’t harm nut production. Of course, if you snip too much, the tree will have to put energy into healing, rather than filling your hopper with delicious almonds. The open center system is exactly what it sounds like - the center of the tree is left clear of major branches in the middle, creating a bowl shape which allows for plenty of sunlight and air to move through.
Looking at the information for apples, you can see that snipping off the ends of all the spurs would leave you without much of an apple crop, but cutting off the ends of long shoots would only have a very slight impact.
Now look at persimmons. All of the fruit production occurs on long shoots of new wood. Cutting out all of your new growth would hamper fruit production. The same is true for quince. Figs are produced on new wood and one-year old shoots.
Generally speaking, citrus trees do not need to be pruned to improve fruit production.
If you sort the chart by location of major fruiting buds, you have:
Armed with this information, go outside, sanitized pruners in hand, and see where you can prune your fruit and nut trees for improved overall health and a significant increase in production!
They will never jump through a hoop for you, but you can train your trees to be healthier and more productive.
Tree training helps fruit and nut trees stay healthy, produce larger crops, and avoid broken branches. Proper tree training also reduces the likelihood of pests and disease. Too much fruit and strong winds can result in broken branches. Proper training can prevent these problems. You may not want to go as far as pollarding or coppicing, but training your trees for good structure, air flow, and the retention of productive wood is always a good idea, except when it isn’t. Trees that are particularly large or unstable should never be trimmed or pruned by an amateur. It is too dangerous.
When to train trees
Most fruit and nut trees are deciduous. This means they go dormant and lose their leaves in winter. This is handy for several reasons. First, it allows you to remove leaves that may be carrying pests or diseases. Secondly, it allows you to see the true structure of your trees. This makes training them a lot easier. The only exceptions are cherry and apricot trees, which should only be pruned in summer, to avoid Eutypa dieback.
Making a proper cut
You may want to read up on pruning before you start training your trees. Put simply, you will want to make a smooth cut that is flush with, but does not cut into, the branch collar. There is no need to paint or treat these cuts. Your tree will develop a protective callus over the area, all on its own.
Tree training basics
To maintain a healthy fruit or nut tree in your backyard, you will probably want to keep it pruned to a manageable size. This is usually 6 feet tall and 6 feet wide. If it gets too large, you won’t be able to reach. Surprisingly, trees of this size can still produce a lot of fruit. As with any other pruning job, you will want to remove any dead, diseased, or damaged limbs. You will also want to eliminate one of any pair of crossed branches. These will tend to rub against each other, creating points of entry for pests and disease. As you prune, try to work from the inside out and avoid leaving stubs. You can orchestrate the direction new twigs will take by cutting just above buds that face in the direction you want the new twigs to grow. Do not use downward facing buds as these tend to be weak and break easily. Your overall goal should be to expose the tree’s interior to more sunlight, without risking extensive sunburn damage.
The big picture
Before cutting, take the time to really look at your tree’s structure and shape. Learn what is typical for that particular species, and think about what you want from your tree over the next several years. Consider issues such as wind exposure, shifting shade patterns, fruit and leaf litter, and tree maintenance. What is proper training for a tree in one location may be completely inappropriate in a different location. If you’re not sure, ask me. You can also look at this fruiting wood characteristics chart, from UC Davis, that can help you decide what to remove and what to leave for another year. Once you have really looked at your tree and prepared your tools, you will need to select the training style best suited to your tree species. The lowest branches are usually at knee height, regardless of the style chosen.
The central leader training style is best suited to semi-dwarf and standard size trees. This style features a single main, vertical trunk. Competing upright shoots are removed and an alternating spiral of lateral branches is encouraged. This is your classic Christmas tree shape.
Modified central leader
The modified central leader style allows more sunlight into the center than a central leader system. To create this shape, a tree is first trained as a central leader, until it reaches the desired height. Then, the central trunk is topped, or removed, just above the most recent lateral growth. This causes the tree to develop more of an open center. This method is particularly good for cherries and pears.
The open center style seems to be the most popular for backyard orchards. In this style, three or four low-growing scaffold (main) branches are encouraged, with the center kept open, like a bowl. Lateral (horizontal) branches make up the sides of this bowl shape and are trimmed back to approximately 30 inches. Fruiting wood will grow from these branches. This method provides good sun exposure and air flow. Also known as vase-shaped training, it is a good method for almonds, Asian pears, and European plums.
The “Y” system
The “Y” system features two scaffolding branches, heading in opposite directions, creating a “Y” shape. Look at it as a two-dimensional open center style. This method is particularly good for peaches and nectarines. It can also be used for apples, plums, cherries, and pears.
Espalier training is a trellising system used to create a two dimensional shape. This method works well alongside driveways, paths, buildings, and fences.
If you end up removing smaller, new wood, you can save these and use them as scions, to create new trees or modify existing trees. They make good gifts for fellow gardeners, as well!
Also, as you work closely with your tree, keep a look out for scale and other insect pests that may be overwintering in your tree’s bark.
Have you ever seen trees with knobby limbs, bare of all leaves and twigs? It’s called pollarding.
Pollarding is a pruning method that limits the size of trees and shrubs. Unlike shearing, which trims everything past a certain point, pollarding cuts back all new growth. This stimulates regrowth that will bring it back to full size.
Pollarding was first done by the Romans and we still use it today. The word pollarding comes from ‘poll’ which refers to the top of the head (as any horse enthusiast knows). To ‘poll’ someone was to cut their hair. [I wonder if polling at the voting booth came from the same root - asking what is inside someone’s head. It makes sense, but I digress.]
Originally, trees were pollarded to provide food for livestock and fuel for winter fires. [Peasants were allotted a ration of firewood and other materials from the king’s trees in something called an ‘estover’. Pollarding stimulates vigorous upright growth, which turns into straight boards for boats and fence material. Thinner upright stems were also used to make baskets and garden bowers. Pretty smart for 2,000 years ago, eh?
Which trees are pollarded?
Pollarding is not recommended for all types of trees. Many conifers do not handle pruning very well. Their twigs tend to die back to the branch they grew out of, providing entry points for pests and disease. Yew are one exception. Trees that respond well to pollarding are those that tend to send out shoots quickly, a characteristic called ‘epicormic’, including:
When & how to pollard trees & shrubs
Pollarding is normally done annually in late winter. Maple trees are pollarded in summer to avoid bleeding sap. In most cases, each year’s pollard cuts should be just above the previous year’s cuts. Because pollarding large trees involves chainsaws and ladders, this is best left to the professionals. Small trees and shrubs can be pollarded with hand pruners and a tree saw. When evaluating a shrub for pollarding (or other pruning) keep in mind the future desired shape and size as you cut. Where each cut occurs, a mass of new stems will appear.
Advantages of pollarding
In addition to size maintenance, pollarding provides other benefits:
Disadvantages of pollarding
Pollarding is stressful to trees and shrubs and it must be done every year or two, to avoid limb breakage. The sprouts that appear after pollarding are attached weakly to the ‘knob’ and may break off. Mature trees that have not previously been pollarded can be killed by the process if it is done incorrectly. Even healthy trees and shrubs are exposed to pests and diseases after pollarding is done.
Whether you use pollarding or not, now you know what all those knobby looking trees are about!
Nothing compares with the sun-warmed sweetness of a raspberry freshly plucked and popped into your mouth!
Raspberries do not ship well, so the specimens we find at the grocery store, like most tomatoes, are simply not up to par with fresh from the garden varieties. The nice thing about raspberries is that that can grow in some unusual places. When I first moved into our San Jose home, I wasn’t sure where I wanted my container raspberries to end up, so I heeled them in (laid them down on the ground and covered the roots with some soil) in the unlikeliest of places - a 6 inch strip of soil next to a concrete slab, where the property line fence was installed. And then I forgot all about them.
Once the plants are established, they can produce fruit for decades. In addition of the traditional red raspberry, you can also find cultivars that are golden, purple, and black.
How to grow raspberries
Raspberries love water. Sunburn is a common sign that your raspberries are not getting enough water. Our raspberries get nearly daily waterings from the bucket of water we collect in the shower as we wait for the water to heat up, at least when it’s not raining. At the same time, our heavy clay soil can also lead to drowning if there is too much water. Since raspberries have relatively shallow roots, regular light watering is better than less frequent deep watering.
Raspberries prefer cooler, damp weather, but you can recreate those conditions by adding them to a shade garden or growing them in containers under a pergola or on a shady balcony. The plants need lots of sun but they prefer a little shade in the heat of the afternoon. Raspberries grow best in soil with a pH of 5.5 to 7.0. They love raised beds, and fence lines provide the perfect medium for trellising. If the cane tips reach the ground, rather than producing fruit, new roots will form, so trellising is a good idea. That’s how bramble fruits spread in the wild. They also spread using underground stems called stolons.
While you can start raspberries from seed, it is much more satisfying to start with cuttings, dormant bare-root plants, or potted seedlings. You should remove any damaged roots or stems before planting your raspberries in a shallow hole, making sure that the crown is slightly above soil level. Spreading the root mass out, covering with soil, and mudding them in to eliminate air pockets will help your plants get a good start in their new location. Be sure to water well, to help the soil settle. Plants should be placed 2 to 3 feet apart and new plants should be trimmed down to be only 6 inches tall, to encourage strong root growth. Black and purple raspberries should be spaced 3 to 4 feet apart.
Raspberry plants have perennial roots and crowns that grow new canes each year. These new green canes are called primocanes. Then they turn brown and go dormant over the winter, to one degree or another. In spring, these now 2-year old canes are called floricanes. Flowers and fruit are only produced on floricanes, so you don’t want to prune them out.
Fruit production varies between everbearing and summer-bearing varieties. Summer-bearing raspberries bear one crop in summer on two-year old canes, while everbearing cultivars have two crops, one small crop in summer on new canes and one heavier crop in fall on two-year old canes. Everbearing cultivars are sometimes called fall-bearing. It is a good idea to check with your local Cooperative Extension Office to find the best cultivar for your location.
How to prune raspberries
Raspberry pruning methods will vary, depending on the cultivar. Fruit-producing canes of summer-bearing red and yellow raspberries should be cut to ground level after harvest and removed. Thin primocanes to no more than 4 or 5 per foot. Fall-bearing raspberries can be treated the same as everbearing varieties, if you want both the summer and fall crops. Otherwise, leave the canes in place for an extra year. If you are growing black or purple raspberries, you will need to pinch the canes when they reach 2 to 2-1/2 feet in height and then again two or three times during the summer. This will promote lateral cane growth for more fruit. Be sure to remove any dead or damaged canes whenever you are working your bramble fruits. Canes left to grow a third year may produce some fruit on the lower part of the canes but they should be pruned out after that to make room for new canes and to reduce the spread of disease.
Raspberries pests and diseases
Raspberry pests include borers, spider mites, aphids, and Fuller Rose Beetles. Fungal diseases, such as yellow rust, and raspberry leaf curl can also be a problem. Healthy plants are far less likely to be vulnerable, so you will want to feed your raspberry plants each time they start a new bloom cycle. According to UC Davis, 3 to 6 pounds of blood meal, feather meal, or fish meal should be applied for every 100 feet of row. Most of us don’t have a 100 feet row of raspberry plants, so I did the math and it works out to approximately 1 to 2 ounces per plant.
Raspberries are self-fertile, which means you can get fruit from a single plant. If you really love raspberries, and have the room, you can grow a raspberry hedge as part of your edible landscape!
Note: If you have never grown raspberries before, you may be surprised to learn that they ripen unevenly. One part of a berry will look ripe days before the rest of it does. This is okay, simply wait (if you can!) for the entire berry to ripen before picking.
If you have citrus trees, you have leaf miners.
Leaf miners can be found feeding on many edible and ornamental plants, including tomatoes, beans, cole crops, cucurbits, aster, peas, impatiens, petunia and dahlia. While leaf miners are generally not a threat to plant health, they can detract from a plant’s appearance and it is still a good idea to monitor infestations.
Leaf miners are not a specific insect. Instead, they are the larval stage of several moths, sawflies and some beetles. The damage is distinct burrows within leaves, leaving what looks like serpentine, white trails. By feeding within the leaf, leaf miners are protected from predators and pesticides. In fact, applying pesticides actually helps leaf miners by killing off their predators. To make matters worse, all leaf miner species are resistant to carbamates, pyrethroids and organophosphate pesticides.
If you peel back the top layer of an infested leaf, you can actually see the pest, though you may need a magnifying glass.
Dormant oils are specifically designed for use on trees during the dormant season. They have a heavier viscosity than other horticultural oils and they stay on the plant longer, as a result. This is great when you are trying to suffocate insect pests, but it can be devastating to foliage if temperatures rise, a condition called phytotoxicity. Summer or horticultural oils are lighter weight and evaporate more quickly, reducing the likelihood of burnt leaves.
Effectiveness of dormant oils
Dormant oil applications create barriers that block respiration of many, but not all, insects and limit the spread of infectious diseases. Spider mites, San Jose scale, leaf curl, powdery mildew, shot hole, and scab infestations are common reasons for applying dormant oil applications in winter or early spring. Pacific or two-spotted spider mites, peach twig borers, navel orangeworm, and oriental fruit moth are not affected by dormant oils alone. These oils are not recommended for aphid control.
Dormant oils can suffocate the eggs of many garden pests and deter females from laying eggs on specific trees. As a side benefit, the application of dormant oils has been shown to delay bud break, protecting tender new growth against potential frost damage. It has also been found to enhance the aroma of ‘Golden Delicious’ apples and increases the diameter of oranges.
How to use dormant oils
Dormant oil application should be done after pruning and is most effective after a foggy or drizzly day. Pump sprayers can be used to apply dormant oils, but it is important that every surface is sprayed: trunk, stems, twigs, and tops and bottoms of any leaves. If you have several trees, this can be a bit of work.
Problems associated with dormant oils
One of the biggest problems associated with dormant oil is the risk of hot weather. A single sunny day can transform fresh, young, green leaves into cinders. This is especially true up to 30 days after sulfur or other fungicides have been applied. [I speak from personal experience.] Also, heavy dormant oils can harm beneficial insects right along with the pests. Dormant oils are not recommended for use on walnut trees
BE SURE TO FOLLOW PACKAGE DIRECTIONS EXACTLY
Brown rot is a fungal disease of stone fruits, such as nectarine, peach, apricot, cherry, plum, prune and almond trees. It is caused by the Monilinia fructicola fungus.
Brown rot identification
Brown rot appears as brown, withered blossoms (blossom blight), cankers, and rotten fruit. Infected twigs may also display brown, sunken areas that ooze a sticky brown goo that contains millions of fungal spores. Fruit mummies can contain even more potential infestations.
Brown rot control
Removal of mummies and pruning out diseased tissue is the best solution, once an infestation has occurred. Copper fungicides can be used to minimize fungal populations.
How to prevent brown rot
Pruning for better airflow can reduce the likelihood of infection, as can furrow irrigation. Do not allow sprinklers to wet blossoms.
A canker is a sunken wound in bark caused by fungal and bacterial diseases. The wound is an open sore filled with dead plant tissue. Okay, so it’s not the prettiest thing we’ve talked about, but it is important to know where cankers come from, how to prevent them, and how to treat them. Your trees will thank you!
Canker causes & identification
Some cankers are obvious and some are not. They are caused by fungal and bacterial microorganisms that infect the cambium layer of trees and shrubs. Cankers are very slow to heal and often do not heal at all. If the wound travels laterally, the sap found in the xylem and phloem cannot move and the branch dies.
Foliage on infected branches often turns yellow or brown and wilts. Cankers can encircle (girdle) and kill limbs or an entire tree. Common canker diseases include: Eutypa dieback, pitch canker, fire blight, Fusarium wilt, chestnut blight, pine blister rust, anthracnose diseases and sudden oak death.
How to prevent cankers
The best prevention method is planting resistant cultivars. Also, installing plants best suited to the local microclimate helps them to be strong enough to fight off pests and disease on their own. Good cultural care, such as proper pruning, watering and feeding will also help prevent disease. Whenever dead or diseased limbs are seen, they should be removed and destroyed right away. Avoid heavy feeding, since that stimulate vulnerable new growth. Sunburn and overwatering can both make plants susceptible to various canker diseases. Many healthy trees have these pathogens present. Trees that are stressed become susceptible to disease.
Once a fungal disease has taken hold, getting rid of it can be difficult. Most fungicide treatments are ineffective against fungal cankers since the pests are safely inside the plants they infect, and the same is true for bacterial cankers. Maintaining healthy plants allows them to fight for themselves.
If you grow nothing else, grow herbs.
Herbs require minimal care and they repay your efforts in spades. Not only do they add flavor to food, but many herbs can be used to make excellent teas, fragrant sachets, insect repellants, and home decor.
Like other plants, herbs can be annual or perennial. Perennial plants keep coming back. while annuals tend to die off each year and must be replaced. Most herbs require a lot of sunlight. If you are growing indoors in containers, you may need to supplement light. Herbs are well-suited to container gardening, or they can be put in the ground. Below, you will find basic information for several popular herbs.
At my house, we can simply never have too much pesto, so basil gets its own raised bed. Basil is a bit more delicate that many other herbs, so don’t plant it outside until well after the last frost date. It grows nicely indoors, as long as it gets enough light. As your basil grows, you can pinch it off just above where two leaves are emerging to stimulate two new stems to grow and produce more leaves. Basil is delicious, but is also has some surprising health benefits. One-half cup of fresh basil provides 98% of your Vitamin K daily requirement and the oils in basil have been shown to inhibit several species of bacteria that have become resistant to antibiotics.
It wouldn’t be salsa without cilantro, and your body will thank you for adding this pungent herb to your collection. Cilantro has been shown to suppress lead accumulation and, if it goes to seed, you have coriander! Cilantro grows easily from seed and can reach a height of 18-24”. Plants should be spaced at least 10” apart and they make excellent companion plants to spinach, beans and peas. It repels (or distracts) aphids, spider mites, potato beetles and whiteflies. Cilantro prefers soil that drains easily and LOTS of sunlight, but the roots do not like being disturbed. This tends to cause them to bolt and go to seed.
Lemon balm is a lovely, easy to grow, flavorful perennial herb that can grow pretty much anywhere. Traditionally, lemon balm tea has been used to reduce digestive upset and restlessness. Run your hand over the leaves and you’ll see why. The aroma is calming and that’s because the oils on the leaves have sedative properties! Like other members of the mint family, lemon balm can spread. Mature plants can be 2-3’ tall, but some varieties grow more like a ground cover. Lemon balm can be grown in full sun or partial shade and it does best when it is cut back (harvested) regularly. Unlike many other herbs that increase and improve their flavor when dried, lemon balm is best used fresh.
Parsley is a kitchen mainstay and an excellent source of Vitamins A, B12, C, and K. Parsley is a biennial, which means it takes 2 years to go to seed. Parsley seeds should be soaked in warm water overnight before planting. Since parsley has a taproot, it prefers a rather deep pot. Once established, you can snip off bits as you need them - or snag a quick vitamin boost or breath freshener, as you garden. You can grow parsley in full sun or partial shade. They make great kitchen window plants, for easy harvesting!
This plant is a workhorse, indoors or out. Run your hand over its branches and the heady aroma expands around you and it stays on your hand for a good while. Rosemary is excellent on pork, beef, in soups, and chutney. According to WebMD, rosemary is also used to aid digestion, ease gout, eczema, and joint pain, repel insects, and it can help wounds heal more quickly! It’s supposed to reduce age-related memory problems, but I don’t remember how… To grow rosemary, get the smallest plant you can find, or take cuttings from tender new growth, put them in rich soil, and water lightly and frequently, at first, to help them get established. You can also get new plants from branches of existing shrubs, where they have touched the ground and put down new roots. Be forewarned, a mature rosemary plant can easy become 3’ tall and 5’ wide, with the right growing conditions. Honey bees and other beneficial insects love rosemary, but it seems to repel undesirables. (If you live near me and would like a cutting, just let me know.)
Turkey dressing, sausage, and some cheeses just wouldn’t be the same without sage. If taste weren’t reason enough, research has shown that consuming sage can lower blood glucose and cholesterol levels and improve your thinking process! Sage plants prefer rich clay loam and they can get pretty big. A healthy, mature sage plant can reach 3’ in diameter and in height, so plan accordingly! Sage needs plenty of nitrogen, so regular feeding with blood meal is a good idea. Be sure to harvest leaves before the plant flowers for the best flavor.
Tarragon has a shallow root system, so it makes a lovely container plant. It is a good source of potassium and it is said to be able to treat digestive problems and to fight certain bacteria. Tarragon is excellent on fish, vegetable dishes, egg dishes, in soup and white sauce. Once you get a tarragon plant established, you will have more of this herb than you will know what to do with. While it is growing, you won’t smell the distinctive aroma. It’s not until the leaves are harvested and oils become concentrated that the scent will become obvious. Tarragon can reach 2-3’ in height and it prefers moderate sun or a little shade during the hottest part of the day. Propagation is easiest through root division.
There are several types of thyme and they all smell delicious! There are upright and trailing varieties. This woody plant adds flavor to Italian dishes, marinades, eggs, and stews. Thyme oil is used to relieve stomach upset, sore throat, and as a germ killer in mouthwash. Thyme does not grow well from seed. You are better off starting with a young plant. Thyme prefers slightly alkaline soil, so it does well in the Bay area. Thyme is one of those plants that really does best if you leave it alone. It’s oily, woody stem, like rosemary, has evolved to hold moisture in and to repel pests. Interfering with its natural processes isn’t necessary. Thyme makes a lovely container plant. Mature plants can reach 12-18” in height and should be placed 18-24” away from other plants, to give it the room it needs to grow. Once a thyme plant is established, you can snip or break off branches as you need them, without harming the plant (within reason, of course). Since thyme grows slowly, weed control is important early in its life. You can mulch with straw to slow its competitors.
If there are any other herbs that you would like to grow, let me know in the comments section.
If we say something is sustainable, we mean that it can keep going. Since agriculture and gardening are critical to our food supply, being sustainable is pretty darned important.
Until the 1980’s, food production was focused on the industrial production of single species (mono crops), using chemical fertilizers and pesticides, until the soil was exhausted. You can only do that for so long, before you run out of places to grow food.
In 2002, at the International Society of Horticultural Science’s First International Symposium on Sustainability, it was agreed that sustainable agriculture and gardening were critical for the “well being of human societies”.
Sustainable gardening incorporates practices that reduce water, energy, time and chemical consumption, while producing food year-round and protecting the environment. These practices take the following issues into account:
Design for sustainability
Whether you already have a garden or are just starting out, you can design a garden or landscape for sustainability. Native plants are always your best bet because they put millions of years of evolution to work for you, conserving water, reducing the need for chemicals, and freeing up your time. Lawns are notorious water wasters and, quite honestly, most of us are not British aristocracy. Other plants, such as oregano, yarrow, or clover, make excellent, low-growing ground covers that use less water and rarely, if ever, need mowing.
These tips can help you create your own sustainable garden:
While scientists debate over the Latin name of this little fungi (depending on which plant it attacks and who you talk to), Eutypa dieback is no joke. Also known as dead arm disease, Cytosporina, and gummosis, you often won’t see symptoms until it’s too late.
Symptoms of Eutypa dieback
In apricot trees, all of the leaves on an infected branch will wither and die, but remain attached to the tree. This is called flagging. Oozing cankers are found along the lower branch and the bark turns darker than normal. Two years after grape vines are infected with Eutypa dieback, they will begin to display leaf cupping and distortion, chlorosis, and stunted new growth. If you take a cross section of the wood, you will discover V-shaped cankers.
This insidious microorganism works its way toward the trunk, killing the entire tree or vine. Also, the fungus responsible for Eutypa dieback seems to be broadening its dietary preferences to include almond, apple, blueberry, citrus, fig, kiwifruit, nectarine, olive, peach, pear, plum, and walnut, as well as Ceanothus spp., chokeberry, crab apple, oak. oleander, poplar, and native California buckeye, big leaf maple, and willow. It is critical that infected trees and vines be completely removed as soon as they are identified, to avoid spreading to healthy plants.
Preventing Eutypa dieback
Like most fungi, moisture is a key component to its development. These little buggers are opportunists, so best practices must be implemented to avoid infection. While most pruning is done in winter, plants susceptible to Eutypa dieback are best pruned in summer. All pruning cuts are wounds. While trees and vines can develop a protective barrier, called a callus, these cuts need time to dry and heal. Never apply sealants to these wounds. Sealants have been found to hold moisture in, creating the perfect habitat for disease. If it rains 2-6 weeks after a cut is made, the Eutypa dieback fungus can take hold and kill your tree. Improperly aimed sprinklers can cause similar risks.
Eutypa dieback controls
If you discover an infected branch, you may be able to save the plant by removing infected limbs at least 12” below any internal symptoms. This means making a cut where you think the disease has not reached and examining the cross-section for signs of infection. If chaotic, oozing wood is found, pruning tools must be dipped in a household cleaner, such as Lysol, before making another cut, or you will become the infector! Keep cutting down the branch until healthy wood is seen. This does not guarantee the life of your plant - it is only marginally successful.
The bare branches of January make this an excellent time for pruning.
Winter pruning helps improve the appearance and health of trees, shrubs, and roses. The only exception is apricot and cherry trees, which are susceptible to Eutypa dieback. Apricot and cherry trees are best pruned in the dry months of summer.
Different plants have different pruning needs, but the overall goals are the same: a balanced structure, adequate airflow, and the retention of productive limbs. There are two types of pruning cuts: thinning and heading. Heading cuts control height, while thinning improves air flow and sun exposure. Keep in mind, while pruning, that new growth will head in the direction of the remaining buds.
The first goal of pruning is to remove dead, diseased or crossing branches. Dead and diseased limbs can allow pests and disease easy access into healthy tissue. Crossed branches will rub against each other, causing similar problems. You will also want to trim away branches that are angled too closely together and those that hang downward.
Proper pruning protects people and property
Structural pruning reduces the likelihood of uprooted trees falling on you or your house. Trees with too much weight to one side also risk splitting the trunk and killing the tree. Pruning early in the tree’s life can create a safer, more balanced structure. While the depth and spread of tree roots depends on a number of factors (soil structure, irrigation, variety and age of the tree, and more), pruning can help the root system keep your tree upright. To give you an idea of how much weight we are talking about: an average mature hardwood tree, with a circumference of 100” inches at chest height, weighs nearly 13,000 pounds! Your average commuter car weighs 2,800 pounds - so imagine 4 or 5 cars hitting your roof in a storm to see why good pruning is so important.
How to prune larger branches
Pruning larger branches (those with a diameter of 2" or more), it is important to use multiple cuts to avoid peeling the bark beyond the final cut and damaging the remaining branch.
In drought-prone areas with heavy clay soil, moisture retention is an art that most plants have mastered. This also means fungal diseases can be a real problem. Roses and fruit trees are especially vulnerable to brown spot, rust and fireblight. Pruning for good airflow between twigs and branches can help reduce these diseases. It can also provide sunlight to inner leaves, which translates into more vigorous growth and heavier fruit and flower production.
Too much pruning is bad
Now, as I’ve said before, too much of a good thing can be a bad thing. Excessive pruning can expose interior branches to sunburn. Also, while pruning some or a little can promote new growth, heavy pruning can cause irreparable harm or death to the plant. Before you start pruning, research the specific variety of plant to learn about its natural growth and shape. For example, some trees produce fruit on last year’s growth, while others produce fruit on new growth. There's no sense in cutting off your nose to spite next summer's harvest!
The backyard orchardist will generally want trees that are small enough to make harvesting fruit easier, so you will want to use heading cuts to reduce the height of your trees. Branches that grow vertically tend to be more vegetative, while horizontal branches produce more fruit. Branches growing at 45 to 60-degree angles tend to do both.
When you cut off the end of a vertical branch, phytohormones, such as auxins, will cause the remaining buds will send out new growth horizontally. When you tip a horizontal branch, it will send out new fruiting wood. This is also a way to prevent too much fruit developing and risking a broken branch.
It is always a good idea to remove suckers and water sprouts. Water sprouts are flimsy twigs that quickly grow vertically, directly from the trunk or older branches. Suckers are similar growths that occur at the base of the trunk or from the root system. These growths drain energy from the plant without providing any benefits.
In Mediterranean climates, roses never go completely dormant, but winter is still the best time to prune for better spring and summer blooms. Generally speaking, you will want to remove 1/2 to 2/3 of the existing bush. Remove dead, diseased and crossing branches and then reshape the bush for better airflow. You can learn more about pruning roses at the San Jose Heritage Rose Garden.
When pruning, it is best to cut close to the branch collar without cutting into it. You also want to avoid leaving nubs that interfere with a plant’s ability to heal itself. There is generally no need to apply sealants to pruning cuts. Plants have evolved an effective system for that all on their own.
Finally, be sure to keep your tools sharp and to clean your cutting tools between cuts. Use a household cleaner, such as Lysol. Otherwise, you may be spreading disease to healthy plant tissue.
It can be incredibly rewarding to take before and after photographs of your pruning work. Feel free to share them with us!
A nub, or dog's ear, is the piece of a twig or branch that is left behind after a bad pruning job.
Leaving a nub sticking out interferes with a plant's natural ability to heal a wound. It also creates a foundation that can catch leaves, providing the perfect shelter for problem bugs and fungi. The nubs themselves, being too far from the branch collar for proper healing, often take longer to heal or don't heal at all. This provides an easy entrance for fungi and borers.
To properly prune a twig or small branch, it is best to cut as close to the branch collar as you can. The branch collar is the ring from which a twig emerges. Do not cut the branch collar. There is no need to paint or treat a properly trimmed branch. Plants already know how to handle that on their own.
So, off with their nubs!
You can grow a surprising amount of food in your own yard. Ask me how!
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