Potato aphid lifecycle

Potato aphids, like other aphids, are phenomenally prolific. A single female aphid can produce 600 billion descendants in a single season. Aphids reproduce both sexually and asexually. When females produce offspring without male intervention (parthenogenesis), the offspring are born live and significantly smaller than their co-authored siblings. When reproduction involves a male counterpart, offspring are laid as eggs that overwinter in nearby weeds, or on other host plants. Adult aphids molt four times, leaving behind telltale white skins.


Damage caused by potato aphids

Aphid feeding is usually first seen as deformed leaves. As aphids feed, they damage plant tissue and disrupt the balance of growth hormones. This can reduce or eliminate crop size, and it can kill young plants. These sap sucking pests tend to cluster together, piercing plant tissue and sucking out nutrient rich fluids. They also poop out sugary honeydew, which attracts protective, disease-carrying ants, and creates habitat for sooty mold. 


Potato aphid feeding can certainly weaken plants, but the real problem is that these aphids carry and transmit a number of viral diseases, such as cucumber mosaic, lettuce mosaic, bearded iris mosaic, narcissus yellow stripe virus, tulip breaking virus, potato virus Y, beet mild yellowing virus, beet yellows virus, alfalfa mosaic, and potato leafroll disease. Plants infected with potato leafroll disease will produce potatoes with a network of browning phloem tissue, called net necrosis, that is very unappetizing. Once a potato plant is infected with leafroll, it and three plants in all directions should be removed to prevent further spread of the disease.


Controlling potato aphids

The battle against aphids in the garden never ends. It starts by monitoring plants regularly for signs of infestation. Potato aphids tend to prefer the lower portions of plants, the undersides of leaves, and around new buds. You can dislodge aphids with a powerful stream of water from the garden hose, but it is practically impossible to get every single aphid off your potato plants in this way, and it only takes one aphid to start the whole process over again. Insecticidal soaps can be used with better results, but you have to make sure you wet every surface of the plant. Personally, I wipe them off whenever I see them. I like to think it slows them down a little, if nothing else.


The next step in controlling potato aphids is to remove nearby plants that might harbor these pests. This means keeping weeds away from potato patch. Malva, penny cress, and various mustards, in particular, can act as early season host plants for this pest. 


Luckily, lady beetles, lacewings, syrphid or hoverfly larvae, and parasitic wasps will all help control potato aphid populations. That’s assuming you haven’t used broad spectrum pesticides and wiped out your helpers. 


What's eating your potatoes?

How to prevent potato blight

Fixed copper sprays are the best preventative measures against potato blight. In fact, during WWII, when copper was being used to make artillery shells, farmers faced new threats from potato blight because they were unable to spray their fields. 


Potato blight can find its way into your potato bed through contaminated potatoes, visitors and materials which have come from areas infested with the pathogen, and by rain or irrigation water splashing from contaminated plants to healthy plants. These are excellent reasons for quarantining new plants and avoiding the use of grocery store produce as a plant source. [Just because a plant is healthy enough to eat now does not mean it isn’t carrying diseases that may stay in your soil for years.]


Excess moisture should be avoided in areas susceptible to potato blight. This means allowing the soil to dry out between waterings, pruning for good air flow, and adding organic material to the soil to improve drainage.


A healthy potato bed is a thing of beauty. Let’s keep it that way!

Rain beetle lifecycle

Rain beetles are long lived bugs. From egg, to larva, to pupa, to adult can take 12 years. [Most beetle species only live one year.] That being said, by the time you see a rain beetle, it is probably only hours or minutes from death. Male rain beetles only store enough energy as fat from their more youthful stages to fly for a couple of hours, looking for mates, before dying.


After mating, female rain beetles burrow a spiral-shaped tunnel, as much as 10-feet below the soil surface, laying 40 to 50 eggs as she goes. In 2 months, the eggs hatch and the larvae begin feeding.


Rain beetles were once found throughout California and Oregon. Now, they are generally only found in pockets of foothill and mountain habitats. Being flightless and ground dwelling, female rain beetles have been wiped out everywhere urban development has occurred.


Rain beetle controls

Since rain beetles spend nearly all of their lives underground, chemical controls are ineffective. For the most part, rain beetles are more of a nuisance than a significant pest, though you can catch males in a butterfly net, if they really bother you.

The amount of moisture available to plant roots is called a soil’s plant available water. Plant available water (PAW) can be measured as a percentage of weight, a percentage of volume, or by depth, as inches of water per foot of soil. 

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When plant roots are unable to pull water from a soil, it will have reached its wilting point. The permanent wilting point occurs at 15 to 20% for clay soil, 10 to 15% in loamy soil, and at 5 to 10% in sandy soil.

Since this normally occurs during summer, when evaporation is at its peak, maintaining the proper moisture level makes the difference between healthy, productive plants, and plants that are struggling for survival. As temperatures drop or senescence (preparation for death) begins, the need for water drops dramatically. Adding more than is needed creates a different sort of life-threatening set of conditions. [Can you say fungal disease?]


Caring for your moisture meter

The sensor found at the end of most moisture meter probes is sensitive to damage and corrosion. To keep your moisture meter operating properly, be sure to wipe it off after each use and do not force it into dry, compacted soil. If a reading is needed under those conditions, create a starter hole with a screwdriver. Also, watch out for rocks, which can damage the probe.


As an added benefit, many moisture meters can also provide you with soil pH information. This is one tool every gardener should have on hand and use regularly. Just remember, you get what you pay for.

Bare root trees

Bare root trees commonly start appearing in garden centers in January in the Bay Area. If you shop from knowledgable, reputable growers, the plants they have available will be suited to the local climate. If you are shopping bulk discount stores, well, you may be getting something else entirely. Wherever you get your fruit and nut trees, be sure to inspect the graft union for signs of damage, disease, vine mealybug nymphs, and other insects. Graft unions are delicate, vulnerable areas. Until relatively recently, it was suggested that the graft union be positioned below soil level. We now know that this is a really bad idea, leading to several problems.


Graft union problems

Improper planting depth is currently the primary reason why trees fail. Part of this is due to bacterial and fungal diseases entering the tree through the graft union, causing root rot, crown gall, and phytophthora root and crown rot, among others. These problems can be avoided by ensuring that your plants are installed at the proper depth. This generally means that the graft union will be 2 to 4 inches above the soil level, or more. [The higher the graft union, the smaller the mature tree will become.] If stem growth starts occurring below the graft union, it is called graft union suckering. 


Graft union suckering

Graft union suckering occurs when the graft is less than successful. These suckers start growing out of the root stock portion of the stem, which may sound fine for the root system, but it is bad for the overall plant. Very often, rootstock plants are highly susceptible to aboveground pests and diseases, and they rarely produce desirable crops. If graft union suckers appear, remove them as close to the branch collar as possible, without damaging the collar.


Take a closer look at the trees, shrubs, and other plants in your garden. Do you see any graft unions? Are they above the soil line? I hope so!

Trees growing in low oxygen environments, such as mangroves, have lenticels on specialized roots. Grapes, on the other hand, have lenticels on their pedicels, or flower stems. Grape lenticels react to changes in temperature, rather than oxygen levels.


Did you know that potatoes have lenticels?


Now you know.

Not counting gardeners, there are several types of mammals that may turn up in your garden. Some can be helpful, others can be a royal pain. ​

Finally, our pets.


We love our pets. There’s no denying that cats and dogs have a very special place in our hearts. That being said, we do not want cat feces next to our lettuces, or dogs digging up rows of beans or tomatoes. As much as your cat may love being outdoors, researchers at UC Davis have demonstrated that your cat is perfectly happy and actually safer kept indoors. Being stealthy predators, cats can decimate local bird, reptile, and amphibian populations, and we need those other creatures more than your cat needs time outside. Dogs can be trained to provide several beneficial services in the garden. My two dogs will chase squirrels, raccoons, rats, mice, opossum, jays, and cabbageworm butterflies out of my garden. Since most of my gardening is now done in raised beds, I don’t have to worry about the dogs running through them.


While we need to learn how to live and let live, there is nothing wrong with protecting what is yours.  This is especially true for disease carrying pests. In some cases, it is simply easier to fence in your crops with netting and tree cages. For those mammals in the garden that must be killed, please use the fastest, most painless method. 


How do you manage mammals in your garden?

Local amphibians

There are approximately 7,000 species and 3 orders of amphibians in the world: frogs and toads (Anura), salamanders (Urodela), and blindworms, or caecilians (Apoda).

Each region has its own native amphibian population. The first step to improving the biodiversity of your garden is to learn which amphibians are native to your area. Here in the Bay Area, we have a wide variety of amphibians, just looking for a home:

Frogs and toads 

• Western toad (Anaxyrus boreas) 
• Western spadefoot (Spea hammondii)
• California red-legged frog (Rana draytonii)
• Foothill yellow-legged frog (R. boylii)
• Sierran treefrog, aka Pacific chorus frog (Pseudacris sierra)

While not native to California, the common American bullfrog (R. catesbeiana) and the uncommon African clawed frog (Xenopus laevis) are now both found here. Also, that distinction between smooth-skinned frogs and warty toads has no scientific basis. ​

If a pond is completely out of the question, you can still maintain a moist area that includes rotting logs and leaf litter. Brush and rock piles, a stone wall, and basking areas will also help lure these beneficial creatures to your landscape.


Incorporating native plants will attract other natives, providing both food and family for your amphibians. Under no circumstances should you release a nonnative amphibian into your garden. This is how ecological disasters often start.


Other ways you can help your local amphibians include allowing your lawn to grow a little taller, to provide safe travel corridors, reduce or eliminate your use of chemical pesticides, fertilizers, and snail pellets, keep your cat indoors, and monitor your dog. Also, be on the lookout for hidden amphibians when using a lawnmower or weedwacker.


Indicator species

Amphibians are very sensitive to toxins in the environment. This is why they are considered an indicator species. If you have amphibians in your garden, then you know you have created a healthy place. Similar to the recent decline in insect populations, amphibians are currently facing a mass extinction. 


Recent studies tell us that, before the 1500s, the expected rate of amphibian extinction would be 1 to 11 species lost over a 500-year period. Since the 1500s, 35 to 130 species of amphibian have become extinct. Since 1980, 9 to 122 more amphibian species have become extinct, with an additional 1,896 species in “imminent danger of extinction”. [The numbers are ranges because it is very difficult to prove that a species is finally and irrevocably gone.] 


While most mass extinctions span a couple of million years, the current mass extinctions can be measured in centuries and are caused, both directly and indirectly, by us. The current amphibian population crash is attributed to disease, habitat loss, introduced species, pollution, climate change, and pesticide use, though it is not completely understood. Nor do we understand the long term ramifications of this mass extinction. 


The food web and network of life here on Earth is very complex. The loss of amphibians is bound to have serious implications for all of us. Please, do your part to make life possible for amphibians in your garden.

To attract reptiles, use these tips to provide healthy habitat for reptiles and their prey:

• install native grasses, ground covers, and nectar or berry producing plants
• mulch your plants
• leave leaf litter on the ground
• allow vines or creepers to grow up fences
• provide a variety of sun and shade
• provide rocks. logs, and large pieces of bark as hiding and sunning locations
• provide fresh, clean water in a protected spot
• avoid using chemical fertilizers, pesticides, and snail bait
• keep cats indoors

Declining insect populations

We have been so focused on killing insects off that we didn’t notice, at first, when their populations started to decline, or by how much. Hard, verifiable population facts are still difficult to come by, but recent research has shown a 45% decline in invertebrate populations worldwide. Now, that figure includes more than just insects, but the news is alarming. One German entomological society has recorded nearly 80% less insect biomass in their studies. Another German study reported a 75% decrease in the total flying insect biomass over a 27 year study on 63 different sites. Now, biomass does not mean number of insects. It also does not tell us which type of insects. It simply tells us the amount of insects by weight. Also, not all sites were studied every year, so please do not take this study to say that ’75% of all insects disappeared over 27 years’, because that’s not what the study claims. What it does tell us is that this is a very real problem.


Declining insect populations are the result of many different factors:

• monoculture agriculture - single species crops create ‘biological deserts’, lacking biodiversity
• deforestation - our demand for wood, paper, etc. are eliminating habitat
• pesticide use - chemicals often kill non-targeted insects, creating imbalance
• urbanization - a growing human population and continuing development reduce natural habitat for all other living things
• warming global temperatures - changing temperatures impact all lifecycles
• excessive nitrogen use - nitrogen use allows some crops to thrive, while others, living in more symbiotic relationships with their environment, diminish

The food web ties all living things together. As insect populations fall, so do bird, bat, fish, and amphibian populations. European ornithologists (bird experts) point to declining insect populations as a fundamental reason behind 80% less partridges and turtledove, and 50% less nightingales currently found in the French countryside. In the past 30 years, over half of all Europe’s farmland birds have disappeared, and we have to assume that similar results are occurring locally.


Call to arms

Scientists recognize the critical nature of insect population decline, and the lack of verifiable information. To counteract that lack, large-scale monitoring is being called for, using photos, videos, acoustic recordings, traps, genetic fingerprinting, and citizen science. Automated data collection, worldwide, is the only way we can learn where insects are and how their populations are behaving, and you can help, too.


How you can help insects

There are many things you can do to help insects at home:

• Avoid using broad spectrum insecticides and pesticides.
• Increase your tolerance of insects in the garden.
• Reduce fertilizer and nitrogen use.
• Allow some part of your yard to ‘go wild’.
• Install a hedgerow and a water feature.
• Use native plants, rather than invasives, and install more variety, especially flowers.
• Participate in insect-related citizen science, such as The Big Bug Hunt.

Did you know that earwig mothers clean, protect, and keep their eggs warm?


Now you know.

Ultimately, you want at least two structural roots to be in the top 1 to 3 inches of soil. 


Planting too deeply

The roots closest to the surface are are responsible for a large portion of a tree’s respiration. Tree respiration is not the same thing as human breathing. Tree respiration refers to the process by which a tree performs the gas exchange used to generate or release energy. If a tree is planted too far below grade, those surface roots will still grow horizontally and be unable to get at the air they need. 


Planting too shallowly

The primary vertical roots of trees planted too shallowly (above grade) will not grow out into the air. They simply dry up and die. This reduces the water and nutrients available to the growing tree. These upper roots may also try growing into the mulch, where there is limited food and water, or they will simply go around in circles, becoming root bound in the planting hole. This is one way that girdling roots occur.​

Girdling roots

Girdling roots are those lateral roots found just below the surface that have, for one reason or another, started growing in circles around the tree. This is common with trees kept in containers for too long. Another common way girdling roots occur is when the roots are ‘spun’ into the planting hole, rather than spread out horizontally. Make sure that your planting hole is wide enough to allow those important roots to spread out the way they were meant to grow. ​
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Girdling roots can also occur in compacted soil. If the surrounding soil is compacted, young roots simply cannot penetrate, so they go around and around, looking for a path in their search for moisture, minerals, and air. Curbs, large stones, and building foundations can have similar effects. Girdling roots will kill your tree in 5 to 15 years. It won’t matter how well you fertilize or irrigate your tree.


Speaking of irrigation, be sure to avoid standing water around the trunk of your tree. This can lead to crown rot and other fungal diseases. Instead, use soaker hoses or build an irrigation ring at the tree’s drip line.


Are your trees planted properly?

The easiest way to tell if a tree is planted properly is to dig down an inch or two, with your fingers, next to the trunk. You should come across 4 to 11 substantial roots. If all you find are delicate feeder roots, your tree is planted too deeply. If the roots are visible from the surface, it is too shallow.


How to correct planting depth errors

Trees planted too deeply (below grade) should be dug up, the roots inspected, and then replanted at the proper depth. Trees planted above grade need more soil added around the trunk. First rake the area under the tree to loosen the existing soil. Then add a layer of soil to the proper depth, gently sloping away from the trunk. 


Proper planting depth is critical to your tree’s health. Trees planted above or below grade will never thrive. Believe me, it is much easier to do it right in the first place.

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, grey 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 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.

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 grey 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.

Signs of carpenterworm infestation

The first sign of carpenterworm infestation is stained areas on the trunk. These stains are a combination of sap, sawdust, and frass. You may also see pupal cases sticking 2/3rds of the way out of the tree. Since the stained areas and branch dieback may also be caused by clearwing moths/currant borers, flatheaded borers, bark beetles, and longhorned borers, it is important to identify the pest before trying to control the problem.

Carpenterworm controls

Healthy trees are better able to protect themselves, so start by planting trees in the right location, at the proper depth, with regular fertilization and irrigation.


Because these caterpillars are already protected by the tree, insecticides do not work. There are a couple of specific nematodes, Steinernema feltiae or S. carpocapsae, that have been very successful at controlling carpenterworm larvae. Before you place your order, however, make sure that these are exactly the type of beneficial nematodes you are buying. Any other variety will be ineffective against carpenterworms. And be sure to follow the package directions exactly, or you will have wasted your money.


Small infestations can sometimes be controlled by poking long, sharp, flexible wires into the galleries and skewering the caterpillars. This is tricky because you really can’t see if you killed them or not. The only way to really know is to clear all the frass and other debris away from the area and mark the spot with some paint. Then, check the area every week for signs of frass. If frass and sawdust are seen, you missed and the caterpillar is still alive and busy feeding and burrowing.


Heavy infestations are dangerous and should be left to a professional arborist. This is because tree branches that are compromised this badly are very likely to fall on you. Since none of us are exempt from the laws of physics, and heavy branches can paralyze or kill you, stay away from them, and call an expert.


This winter, take a few minutes each week to inspect your trees for signs of frass and sawdust, or pupal cases, and cut those cute little, hardhat wearing pests off at the knees.

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 grey 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.

If hugelkultur works for you, wonderful! If you haven’t tried it yet, you may want to put all those logs, stumps, or tree trunks to work in the garden in other ways. Larger pieces make attractive stumperies, while logs make excellent path markers. Ultimately, these woody limbs will break down, adding nutrients and improving soil structure but, as nature intended, these things take time.

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.