You cannot see it, smell it, or taste it, but glomalin is the glue that holds soil together and the path by which nutrients move from beneficial fungi to plants.
When most of us think of fungi, we usually think of mushrooms or disease. Mycorrhizal fungi are an entirely different critter. These beneficial fungi live in soil, and in and around plant roots. They are responsible for helping over 70% of the Earth’s plants get the nutrients they need from the soil. They do this with glomalin.
Soil is made up of 45% minerals, 1-5% organic matter, 25% water, and 25% air, on average. Soil structure tells us the size of the mineral particles, which can be sand, loam, or clay. Air and water are found in tiny spaces, called macropores and micropores. The chunks of organic matter and minerals are called soil aggregates. Those aggregates are held together with glomalin. Soil aggregates improve water infiltration, drainage, nutrient cycling, root penetration, and water retention near roots. They also help counteract soil compaction.
Where does glomalin come from?
Glomalin is produced by mycorrhizal fungi that live in the soil and in, on, and around plant roots. Glomalin is found on the tiny hairs, or hyphae, of mycorrhizal fungi. This coating helps the fungi to retain water and nutrients as they interact with local plant root systems.
What is glomalin?
Glomalin is a tough, resilient glycoprotein that contains significant levels of iron. It does not dissolve in water and it is resistant to decay. Also known as glomalin-related soil proteins (GRSP), glomalin stores carbon and nitrogen, and binds mineral particles together, coating them with the same protective barrier used to protect the fungi. It is now believed that 15 to 20% of the carbon sequestered in undisturbed soil is held specifically by the glomalin. This is one of the reasons behind no-dig gardening, in that it reduces the negative impact on the fungi responsible for creating glomalin and helps the soil hold onto that carbon.
How does glomalin improve soil quality?
Glomalin was discovered in 1996 by Sara F. Wright, a USDA Agricultural Research Service scientist. She discovered that soils depleted of mycorrhizae and their glomalin, whether through exploitation, solarization, or fungicide use, had significantly reduced crop sizes.
Glomalin helps hold organic matter in place, improving soil aggregate stability. Soil aggregate stability is a measure of the combined physical, chemical, and biological properties of a soil sample, as well as its ability to resist degradation and erosion. Without glomalin, every drop of rain and every gust of wind would grind and disperse soil in a global Dust Bowl.
Glomalin is also what gives soil its brown color. Removing glomalin from soil leaves it a grey, rocky color.
So, what’s glomalin to you?
Recognizing the importance of mycorrhizal fungi and glomalin to soil health, you can improve plant and soil health with these tips:
By keeping your soil healthy, the natural processes needed by your plants to acquire nutrients and fight disease can continue.
Zebra chip may sound like a fun new black-and-white striped snack, but it’s not.
Zebra chip is a bacterial disease that attacks potatoes.
Like most bacteria, Candidatus Liberibacter solanacearum doesn’t move around very well on its own. Instead, it lives in the gut of potato psyllids. Potato psyllids are tiny, sap-sucking pests. As they feed, the bacteria move from the insect to the plant, infecting the vascular tissue in both the plant and its tubers.
Symptoms of zebra chip
There are no aboveground symptoms of zebra chip, but potato psyllid feeding causes foliage to turn yellow or purple. It can also cause pink or red discoloration of leaves.
The real symptoms are visible only after you cut into a tuber. The zebra chip bacteria cause potatoes to store sugar, rather than starch. That might sound like a great idea for a new dessert food, but the presence of sugars cause vascular tissue to turn into ugly brown lines. When cooked, these brown lines turn black, hence the name. This condition also reduces crop size by 20 to 50%. Healthy appearing potatoes from plants affected by zebra chip are more likely to sprout while in storage. Seed pieces taken from infected plants either do not sprout at all, or they produce weak, infected plants.
Controlling zebra chip
Since zebra chip is carried in by potato psyllids, that’s where you must work to break this disease triangle. Potato psyllids can be trapped with yellow sticky sheets and spinosad can be used to reduce potato psyllid populations. These treatments won’t get rid of all the psyllids, but they will help. Be sure to inspect potato, bean, and pepper plants regularly for signs of psyllids.
In commercially grown potato fields, where potato psyllids have been identified, a type of systemic neonicotinoid neurotoxin, called imidacloprid, is applied. [While not yet noted in California, resistance to imidacloprid has been documented in Texas.]
Zebra chips might sound like a fun new brand of potato chips, but what they really mean is you need to be on the lookout for potato psyllids as you work and play in the garden.
In the short days of winter, many of your fruit trees look as though they aren’t doing much of anything. Other than collecting chill hours and working to stay alive, that would be mostly true. As the days begin to lengthen, leaf and flower buds start to swell. But, sometimes, those swellings are something else entirely.
Also known as the almond and plum bud gall mite (Acalitus phloecoptes), this pest is native to Europe and the Middle East. As of January 2019, it made its way to California, threatening tens of thousands of plum, pluot, almond, apricot, and many other fruit and nut trees.
What are plum bud gall mites?
Plum bud gall mites are a type of eriophyid mite. Eriophyid mites are a family of microscopic plant parasites. These pests enter stems and buds through lenticels and injury points, and then overwinter under the bark. Very little information is available about this new pest, but knowing what to look for can help you to stop it from spreading.
Plum bud gall mite identification
In late winter, galls begin to form around these tiny invaders. By spring, adults emerge from their protective galls. At 1/100th of an inch in length, these mites are too tiny to see with the naked eye. If you have a 20x hand lens, you may be able to see them, if you look very closely. They can be a translucent yellow, pink, white, or purple, with two pairs of legs up near the head. You are more likely to see galls on new shoots and fruit spurs that plants produce in response to these invaders. Galls are warty, bumpy growths that don’t look like normal tissue.
Controlling plum bud gall mites
Treating your trees with wettable sulfur in March or April, when plum bud gall mites first start to emerge from their protective galls, has been effective in controlling these pests in other regions. Treatments may need to be repeated, depending on the level of infestation. Note that apricot leaves are very sensitive to sulfur, so you can only treat apricot trees with sulfur before leaves emerge. Because these particular eriophyid mites are new to the region, we do not yet know what sort of an impact native predatory insects will have on controlling plum bud gall mite populations.
If you happen to see this new pest on your trees, please contact your County Extension Office right away.
Each spring, pollen grains are normally moved from flower to flower by honey bees, beetles, butterflies and moths, and wind. When the pollen arrives at another flower, fertilization can occur and fruit can grow. Except, sometimes, the pollen needs a little help. That’s where hand pollination comes in.
Plants being grown indoors, or in areas without enough bees and other pollinators, cannot set fruit without mechanical pollination. Some crops, such as cucumber, melon, pumpkin and other squash, can be coaxed into producing far more fruit if hand pollination its used, due to the timing issues related to male and female flowers occurring at different times.
If you grow plants indoors, you will need to pollinate the flowers by hand to get fruit. Container plants that are at a distance from their fellows will also benefit from hand pollination. Loquats, kiwifruit, and mangos, in particular, often require hand pollination. [Due to heavy pesticide use in China, the lion's share of all their fruit crops are now pollinated by hand.]
Hand-pollination is not difficult, but it is tedious. To better understand how hand pollination works, let’s have a quick review of flower anatomy and the pollination process.
For a more detailed description, I urge you to read my posts on flowers and pollination. In the most basic terms, flowers can be male, female, or both, but not necessarily at the same time. Male flowers have a stamen and female flowers have a pistil. The stamen consists of a pollen-producing anther at the end of a filament. Pollen tends to be yellow and sticky. The female pistil, also known as a carpel, is usually found in the center of a flower and it consists of the sticky stigma, which captures pollen, the style, a tube that leads to the ovary, and the ovary itself.
As insects move around, collecting nectar and pollen for themselves, sticky pollen becomes attached to their legs and is carried from flower to flower. The pollen is captured by the stigma, enters the style, and moves toward the ovary, where fertilization occurs. If there are not enough pollinators, the pollen doesn’t get moved and we have no fruit. Unless you hand pollinate. By hand pollinating, you become the mechanism by which pollen is moved from the stamen of the male flower to the pistil of the female flower.
How to hand pollinate
There are two basic methods of hand pollination: removal of the anther, or transferring just the pollen. In most plants from the cucurbit family, the male anther is large and obvious. Without handling the part covered with pollen, simply snip off the anther, cut off or roll back the flower petals, and gently roll it around on the female pistil.
On plants with smaller flowers, such as cucumber, tomatoes, and melons, you can use a small, natural bristle painter’s brush or a cotton swab to transfer pollen from one plant to the other.
Timing is important
Male flowers tend to emerge before female flowers. Also, most flowers are only receptive to pollen for one day. Transfer pollen to freshly opened flowers, preferably in the morning. Do this every day until fruit starts to form.
Concerns about cross-pollination
This comes up every year. People worry that all members of a group, such as the cucurbits, can cross-pollinate. They can’t. Melons, squashes, and cucumbers are too different from one another to pollinate each other. That being said, varieties within a species, such as white pumpkins, Jack O’ Lantern pumpkins, and Atlantic Giant pumpkins can cross-pollinate.
Even if you have bees in your garden, you may want to try hand pollinating. Research has shown that manually applying pollen to female flowers results in larger fruit that is more likely to reach maturity. Also, the seeds within that fruit germinate faster and produce larger seedlings. This is called the xenia effect.
Did you know that researchers at Harvard are creating miniature flying robots, called RoboBees, to be used as pollinators?
Now you know.
Throughout human history, early spring has always been a time for eating fresh new greens. Slightly bitter, rich in iron and other important nutrients, they remind us that winter will not last forever.
Patience dock growth
Patience dock plants start out as broad leaves growing close to the ground. This is the part you want to eat. Next, a single stem emerges and is quickly covered with tiny flowers. Those flowers become pollinated and fertilized to produce triangular seeds, similar to rhubarb seeds. Seed heads hold large numbers of seeds, which darken to a lovely bronze color.
How to grow patience dock
Seeds are generally planted in late spring, slightly less than 1/2 an inch deep, in locations that receive lots of sunlight. Plants should be thinned or transplanted to provide at least 8 inches of space between plants. Lucky for those of us in the Bay Area, patience dock thrives in heavy clay soil. Young plants will require frequent watering, but mature plants require far less. If grown in a container, patience dock plants should be repotted each year with fresh potting soil, or mulched regularly with aged compost. Once established, plants are highly resistant to frost damage. You can divide mature plants every 3 to 4 years, in spring, to generate new plants.
While it might be easier to list the plants not susceptible to beet armyworms, you need to know where to look for these pests. In addition to beets, the list of potential beet armyworm hosts includes beans, celery, cilantro, citrus, cole crops, cucurbits, lettuces, parsley, peppers, strawberries, and tomatoes. Beet armyworms also attack alfalfa and cotton.
Beet armyworm lifecycle
Female moths lay pale, pinkish or greenish striated eggs in clusters of more than 100 eggs, often on the upper sides of leaves. These clusters look fuzzy, due to hairlike scales left behind by the moth. After they hatch, larvae begin feeding on nearby leaves, slowly dispersing throughout the plant. As larvae get older, they also feed on fruit. After defoliating your plant, the mature larva drops to the ground, where it pupates in a shallow depression in the soil, or in a pocket excavated just below the soil surface. An adult moth emerges, and the whole process begins again. This cycle is completed in one month, so there can be multiple generations each year.
Beet armyworm description
Larvae are smooth, pale green caterpillars, with several pale, wavy lines down the back and a broad stripe down either side. You may also see a dark spot above the second pair of legs. Other color variations can occur, depending on the food source and developmental stage. After 2 or 3 weeks of feeding, caterpillars will reach 1.25 inches in length. Adult moths are mottled brown and grey, with a 1-inch wingspan.
Damage caused by beet armyworms
Beet armyworms can destroy seedlings in only minutes. When feeding begins, the damage appears as clusters of circular or irregularly shaped holes in leaves. It can also cause flagging, a condition that slows or halts growth on one side of a plant. Larvae will feed on the crown of lettuce plants, killing them. As caterpillars get bigger, they can skeletonize all the leaves on a plant. Most fruit feeding occurs on or near the surface, and can be cut away, assuming other pathogens haven’t entered the fruit, causing disease or decay. Of course, you will want to wash the fruit thoroughly, to get rid of caterpillar feces. If beet armyworms feed on floral buds, the buds will abort.
How to control beet armyworms
In the home garden, natural predators are your plants’ best defense against beet armyworms. Predatory wasps will parasitize beet armyworm larvae, while big-eyed bugs, and minute pirate bugs will feed on the eggs. Spiders, damsel bugs, assassin bugs, tachinid flies, and lacewings will also feed on beet armyworms, so avoid using broad spectrum pesticides. In severe cases, you can apply spinosad or a specific type of Bacillus thuringiensis (ssp. aizawai).
Prevent beet armyworm invasions by monitoring nearby weeds, especially lambsquarters, goosefoot, and pigweeds for signs of egg clusters.
Harvesting your crops as soon as they are ready can also interrupt the lifecycle of these pests.
Beet armyworms have been known to travel as far as 10 feet during a night, putting most of your garden plants at risk. Monitoring for signs of beet armyworm infestation can help you prevent the problem from spreading.
Today, we are looking at some cutting-edge research in the world of plants. It may not make you a better gardener, but you’ll know more about plants than pretty much everyone else, and you may look at your plants a little differently.
Imagine, if you will, a tiny plant cell. Within that cell is a bubble of fluid, called a vesicle. Vesicles form naturally as plant cells eat and poop and go about their business. You can think of these bubbles as microscopic burps that stick around. Plant cells can also create vesicles on purpose. When this happens, they are called liposomes. [Keep in mind that this is an extreme oversimplification of what is actually going on, but you’ll have the basic idea.] A plant cell may have several vesicles, which cluster together into groups, called multivesicular bodies (MVB).
Vesicles are extremely small. They range in size from 30 to 150 nanometers (nm). A nanometer is one billionth of a meter. By comparison, plant cells range from 10 to 100 micrometers, while animal cells can be 10 to 30 micrometers. Micrometers (μm) are one millionth of a meter. A strand of human hair ranges from 17 to 181 µm.
Ergo, one human hair = 10 plant cells = 300 vesicles
What do vesicles do?
Plant cells use vesicles to move materials around, process proteins, maintain buoyancy, and all sorts of other things that we are only now learning about, though scientists have known about the existence of vesicles for a while now. What we didn’t know, until very recently, is that plant vesicles perform the same function as a type of animal cell vesicle, called an exosome, does. Their job is to take material from the interior of the cell, attach itself to the inner plasma membrane, create an opening, and then release the material into the apoplast, which includes the cell wall and the space between cells. Fungal cells do the same thing, but we didn’t know plants did until very recently.
In animal cells, there are specialized vesicles that check the load being carried by other vesicles, to see if the contents should be destroyed or moved to the apoplast. Plant cells do not have those specialized gatekeepers, so there is still plenty to learn.
Now, this may not sound like a Big Deal, but this is how cells communicate with each other, triggering plant growth and defensive measures. In fact, exosomes are directly related to the production of defensive proteins and RNAs used to fight disease. Exosomes are also used to move those defensive proteins from nearby healthy cells to a cell under attack by a pathogen, to create protective barriers against disease, and they can even enter invading cells to inhibit their growth. [If you are interested in this sort of thing, it is called host-induced gene silencing.] On the down side, exosomes also play important roles in malignancy.
In the not-too-distant future, we may be seeing artificially generated plant exosomes crafted to boost our plants’ ability to fight disease. Similar studies are being conducted to see if plant exosomes can be used in human medicine, such as exosomes found to reduce alcohol-induce liver damage in mice, or how vesicles of the ginger plant may be able to reduce inflammation in the human digestive system. For now, I will stick with ginger tea, but maybe exosomes were the reason it has been helping all along…
Bee's friend is a gorgeous flower that attracts pollinators and other beneficial insects
Also known as blue or purple tansy, or lacy phacelia, bee’s friend (Phacelia tanacetifolia) is a popular choice in agriculture as an annual ground cover. It is also grown as an insectary, to attract bees and beneficial predatory insects, such as hoverflies. Flowers remain open for an extended period with very little water, making it an excellent addition to your foodscape.
Bee’s friend description
Single, mostly unbranched, stems of bee’s friend can reach 4 feet in height, but most plants are only half that height. Curled leaves and stunning lavender-blue flowers make this a uniquely attractive plant. Most domesticated varieties are smooth-stemmed, while wild varieties are covered with stiff trichomes (hairs).
How to grow Bee’s Friend
Bee’s Friend seeds can be sown directly in areas that receive direct sun or partial shade, as soil temperatures warm in late spring. Stagger plantings for a more powerful impact. Seeds must be in complete darkness to germinate, so be sure to follow the planting directions on the packet and use an irrigation method that does not push the soil around too much. Misting is a good choice
Bee’s friend is considered one of the top 20 honey-producing flowers. Whether you raise bees or not, that much nectar is sure to bring bees and other pollinators to your garden in abundance! It makes an excellent plant for under or around fruit and nut trees, as a natural way of boosting pollination rates. The flowers are lovely, too!
We’ve all heard about butterfly gardens and herb gardens, but what about pizza gardens, or sunflower forts?
One of the many attractions of gardening is that you can play with it. We are not limited to the furrowed rows of earlier generations. You can be as creative as growing conditions and your plants’ needs will allow. And deciding on a theme is a way to pull your garden together artistically or aesthetically.
Themes provide a unifying framework, a story, a uniqueness to your garden, and they can be a lot of fun. Themes are more artistic than simply how you grow your plants. Garden themes make it easy to decide on which plants work best in a landscape, a raised bed, or even a single container, by providing a long term, broader perspective on that space.
You can create a theme based on flower color, leaf shape, or even a particular shade of green. You can create a theme that takes advantage of a shady corner, transforming it from a seldom used, mostly wasted space into a storybook hideaway, complete with peek-a-boo elf statues and a reading chaise lounge. [More lemonade, please!] Or, you can create a theme around a favorite book or movie.
Garden themes can be whimsical, or they can be utilitarian. Let’s take a look at some examples of each type:
Gifts garden If you like to give plants as gifts, plan ahead for that. Create a nursery bed specifically for plants to be given as gifts. You can find more tips on this winning garden theme in my post titled Planting Backwards.
Holiday dinners garden Nothing says gardener like fresh Brussels sprouts and baby beets at Thanksgiving, fresh greens at Easter, and a juicy watermelon on July 4th. Planning your planting to coincide with harvests when you are going to want them makes a holiday dinner garden a handy theme.
Pollinator garden Attract beneficial pollinators with a patch of garden dedicated to everything they love, want, and need. Nectar-producing flowers that come in a wide variety of colors and shapes, a nice layer of mulch, and a water source will draw them like flies, where they will stay to pollinate all of your garden crops.
Salad garden Keep yourself in salad ingredients with a continuous supply of spinaches, lettuces, Swiss chard, scallions, peppers, or whatever you prefer in your salad. Growing these healthy ingredients in close proximity adds color and texture to a garden patch, along with convenience for your dinner table.
Tea garden You don’t need to provide the exquisite care needed for a traditional Japanese tea garden to grow plants that taste delicious when steeped in hot water. Peppermint, chamomile, lemon balm, turmeric, garlic, and sage are all easy to grow and can provide a perpetual free source of tea for family and friends.
Those garden themes are all very useful, and they make plant selection simple. But what about some of the more fun ideas? My three favorites are children’s gardens, corn and sunflower forts, and pizza gardens:
Children’s gardens Children love plants they can touch, taste, and smell. Feathery soft yarrow, creeping chocolate mint, and towering fronds of licorice-scented fennel all come to mind for a children’s garden. Also, children need plants that grow quickly. Radishes and beans are always good choices. [You may be surprised to discover that most children love the taste of spinach they have grown themselves…]
Corn and sunflower forts The soaring heights of corn and sunflowers makes these plants perfect for forts and mazes. Simply draw where you want the walls to grow, plant seeds, and top dress the area, watering as needed. You will have to provide protection from feet and paws, at first, but, before long, they will support each other as they grow ever higher. You can even add nice little touches, such as a climbing cucamelon or purple pole beans.
Pizza garden You can set aside a piece of garden for a specific meal. In this case, you can plant tomatoes, peppers, onions, garlic, oregano, basil, thyme, and whatever other herbs and vegetables you enjoy on a pizza. Heck, if you have a 9-foot square space, you could even grow the wheat for your pizza crust! Of course, the garden can’t help with the cheese or pepperoni, but you get the idea.
Garden themes require the gardener to look forward in time. Being the optimists that most of us tend to be, this isn’t hard to do. That’s why we keep putting seeds in the ground, year after year, we know that most of them will grow.
Now, you can stop letting your preconceived notions of gardening stop you from trying something different and unique. Go ahead! Have fun with it!
What kind of garden theme are you going to try?
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 what 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!
Bare, dormant stems begin to swell in spring, transforming from green to red tips, from which tight clusters of pink blossom buds emerge. Those buds will bloom, drop their petals, and generate fruit, assuming they have been pollinated. That is, of course, unless blossom brown rot has taken hold.
Blossom brown rot (Monilinia laxa), also known as brown rot blossom blight, is a fungal disease of almonds, apricots, cherries, and other stone fruits.
Similar to brown rot (Monilinia fructicola), blossom brown rot can affect flowers from pink bud stage through petal fall. All parts of the flower are susceptible.
Symptoms of blossom brown rot
The first sign of blossom brown rot is the death of young blossoms. What should be a colorful, flower-laden tree, buzzing with pollinators, looks more like clusters of brown, dried up tissue paper. [That would be an extreme case.] More often, infected flowers are intermittent (at first).
Gum may ooze from the base of infected flowers and cankers may form on twigs. Those cankers will have tan centers and dark edges. Blossom spurs and their leaves may collapse. Under humid conditions, you may be able to see tan to grey spore masses.
Blossom brown rot lifecycle
Fungal spores overwinter in twig cankers, on mummified fruit, and on any diseased flowers that remain attached to the tree. As temperatures rise in spring, fungal spores begin populating nearby twigs and other blossoms, causing twig and branch dieback, along with blossom losses. Spores are airborne, and spread by irrigation and rain water splash, and by insects.
How to control blossom brown rot
This fungi thrives in rainy weather with temperatures in the 70s. High humidity can also encourage spore development. In fact, this fungi’s growth is almost directly related to humidity and temperature, both of which are difficult to control in the home garden.
Proponents of compost tea recommend foliar sprays as a treatment for blossom brown rot, but research has shown that compost tea either has no effect, or that it worsens the condition.
Unless you want to apply chemical fungicides, you are best off selecting varieties that are resistant to this disease in the first place. In the world of almond trees, the following species are most susceptible to blossom brown rot: Butte, Carmel, Drake, Ne Plus Ultra, Winters, and Wood Colony.
You can also reduce the likelihood of blossom brown rot by removing all mummies, as soon as they are seen, and disposing of them in the garbage. Pruning and training for better air flow can also reduce the amount of time blossoms take to dry.
Curly dwarf may sound like the punchline from a bad joke, but this viral disease can ruin your artichoke plants.
Curly dwarf is spread by insects, and can be fatal, so knowing what it looks like can help you keep it from spreading to uninfected plants. While only found on artichokes, in the field, cardoons, sunflowers, and zinnias have been infected in laboratory tests.
[Unfortunately, I was unable to find a single image of an artichoke plant infected with curly dwarf, but I will keep looking. Please let us know if you have one!]
Curly dwarf, also known as artichoke curly dwarf, is caused by the artichoke curly dwarf virus (ACDV). While very little is currently known about this particular virus, we do know that it is almost found in tandem with another virus (Artichoke latent virus), which seems to have no disease symptoms.
Symptoms of curly dwarf
Severe stunting, leaf curling, and reduced bud production, with buds remaining small and often misshapen, is a clear indication that your plant has become infected with curly dwarf. Leaves may also have dark, dead areas.
Preventing curly dwarf
We do not yet know which insects spread curly dwarf, but we do know that it can be transmitted to uninfected plants. For this reason, it is important to remove any infected plants as soon as they are identified. The curly dwarf virus is commonly spread when infected plants are divided for propagation purposes, so only use certified disease-free plants.
Since the virus also lives on milk thistle (Silybum marianum), keeping those weeds away from your artichoke plant may reduce the chance of infection.
Winter months are an excellent time to prune fruit and nut trees. Naked and dormant, it is easy to see each tree’s structure. This is also a good time to inspect for common pests, such as scale insects and European red mites.
While you will certainly want to get rid of any San Jose scale, walnut scale, Italian pear scale, or frosted scale insects you see, you should leave the European red mites where they are.
Why in the world would you want to leave pests on your trees?
Females measure in at 1/72 inch. Males are 1/80 inch, which means you could line up 4 of them on the edge of a dime.
Females can lay eggs without mating, but these offspring will all be male. [This is called arrhenotokous parthenogenesis. Most parthenogenic offspring are female, as with aphids, so this is different.]
Heavy feeding can bronze leaves. Bronzing may be fine for baby shoes, but it makes photosynthesis impossible.
Whereas other mites produce webbing and cause leaf drop, the European red mite produces little or no webbing and no leaf drop.
Persistent, heavy mite feeding can also cause transpiration burn (leaf blackening), reduced fruit size and quality, shoot growth, trunk and limb growth, and root growth.
If populations of European red mites become significant, you can apply delayed dormant horticultural oil, but that oil may cause sunburn damage. It’s a tough call. Since European red mites have demonstrated resistance to miticides (a type of pesticide geared toward mites), it is better to avoid chemical sprays. Spraying these pests with a hose does nothing.
If your garden or landscape has a lot of biodiversity, odds are pretty good that there will be enough predators to control European red mite populations. Also, keeping plants dust-free makes the environment less hospitable to these pests.
Amaranth is an ancient, drought-tolerant, high protein grain that thrives in alkaline soil.
My first experience with amaranth was disbelief, when someone told me you could pop tiny amaranth seeds like popcorn. They were correct. [Did you know that you can also pop wheat, rice, millet, sorghum, barley, and quinoa? It’s true.]
Cousin to pigweed, amaranth is a pseudocereal. Pseudocereals are grains used as cereals but are not members of the grass family. Quinoa and buckwheat are pseudocereals.
How amaranth grows
Amaranth plants are able to fix atmospheric nitrogen, the same way legumes do, which helps these plants to grow rapidly, even in poor soil. Seeds germinate in only 3 to 5 days, under ideal conditions. Plants grow best in sunny locations, spaced 8 to 10 inches apart.
Amaranth branches little or not at all, putting all their efforts into striking seed heads. These upright flower spikes become weighted down with an abundance of white, brown, black, green, red, purple, or pink seeds, depending on the species.
Native to Central and South America, people started growing amaranth around the same time corn was domesticated, but amaranth only uses half the water needed by corn. A green, prostrate variety of amaranth, the seabeach amaranth, once found in abundance on Long Island’s sand dunes, is now one of the most threatened plants on Earth.
The name amaranth comes to us from the Greek words for unfading flower. Aside from amaranth’s unfading flowers, you would be hard pressed to find a more confusingly diverse group of plants. Botanists and plant geneticists are still trying to sort it out. All we need to know, at this point, is that amaranth plants fall into one of three categories: those grown for looks, greens, or grains.
A single amaranth plant can produce over 2 pounds of seeds. Amaranthus caudatus, A. cruentus, and A. hypochondriacus are the best choice for grain production. These seeds are easy to harvest, easy to cook, and they readily self-sow an area. As autumn approaches, those stunning flowers will have transformed into seed-covered spikes, coveted by finches and other seed-eaters. If you rub a flower head between your hands and the seeds come away easily, it is time to harvest, thresh, and winnow your crop.
To harvest amaranth grain, cut off all ripe seed heads and place them on a clean bedsheet. You can wait until they dry, which makes the job more prickly, or you can thresh the seed right away. [To thresh means to remove grain from a plant.] To thresh amaranth, rub fresh seed heads vigorously between your hands, or walk on dried seed heads covered with another bedsheet, dislodging the seeds in either case. If you opted to work with fresh amaranth, the seeds will need a few protected days to dry. After threshing, you can sift your amaranth through a screen, to remove some of the chaff. Chaff is the inedible seed hull. You can also try using a blow dryer to whoosh the chaff away, just be sure to use the cool setting.
Amaranth leaves, stems, and roots
If you prefer growing amaranth as a vegetable, you will want to plant Amaranthus cruentus, A. blitum, A. dubius, or A. tricolor. Popular in dishes from Africa, Greece, India, Malaysia, and China, amaranth’s vegetative parts are cooked the same way as many other greens and they can be used fresh, in salads. In fact, many people grow vegetative amaranth to fill the dietary void caused by spinach’s tendency to bolt in summer.
Amaranth pests and diseases
Being so well suited to drought conditions, too much moisture can lead to damping off disease, so proper spacing and weed removal are important for young plants. Flea beetles, amaranth weevils, and tarnished plant bugs are the most common pests of amaranth.
Amaranth as a weed
Because of its rapid growth and heavy seed production, unwanted amaranth species are considered invasive and noxious weeds. Amaranthus albus, A. blitoides, A. hybridus, A. palmeri, A. powellii, A. retroflexus, A. spinosus, A. tuberculatus, and A. viridis should be avoided. Just so you know, A. palmeri is glyphosate resistant, and, research has shown that, when grown near soybeans, it can reduce soybean crop by 17 to 68%.
Whether you grow amaranth as an ornamental or food, this sturdy, attractive plant can bring bright colors to your landscape.
Exocortis is a virus-like disease of citrus tree bark. I say virus-like because it is caused by a particle, not a virus, called the Citrus Exocortis viroid (CEVd).
Viroids are the smallest known infectious pathogens, made up of a single, naked strand of RNA. Other diseases caused by viroids include potato tuber spindle disease, avocado sunblotch, and peach latent mosaic.
For one thing, you may also see gum droplets under the loose bark, or stunting. Stunting occurs because nutrients are having a difficult time moving through damaged or exposed vascular bundles. Sunburn damage generally does not cause stunting or gummosis.
Dealing with exocortis
You can’t cure exocortis and it is highly contagious. That being said, it probably won’t kill your tree. What it will do is reduce production and make your tree susceptible to other pest and disease problems. Unless you are ready to commit to complete sanitation of shoes, tools, and anything else that might come into contact with an infected tree, its removal is your best option, if only to protect neighboring trees.
Imagine a container plant that grows a lush 6 feet tall and produces delicious, soft-skinned, seedless tropical fruits. Introducing… the babaco tree.
Also known as mountain papaya, babaco is cousin to that other sweet tropical fruit of mammoth size. Commonly eaten fresh, or used in fruit salads, smoothies, and ice cream, babaco (Carica pentagona Heilborn) is believed to be a naturally occurring hybrid from Ecuador. People have been eating babaco fruit since the 1500s, but I had never heard of it until recently.
These herbaceous shrubs feature thick, mostly unbranched trunks that are covered with leaf scars, similar to other members of the Carica genus. The healthier the plant, the thicker the trunk. Large, palmate leaves, with prominent veins and long petioles, make this an attractive house or patio plant. Flowers are all female and fruit is generated parthenocarpically. That’s a big word which means without seeds. And it’s the fruit that should make babaco worth considering for those of us who prefer growing our own food. Five-sided babaco fruit is large, reaching 12” in length and 8” wide. Said to taste like a combination of strawberry, papaya, and pineapple, the fruit is somewhat acidic and not overly sweet. The skin is also edible.
How babaco grows
Babaco performs best in cool subtropical climates. Too much sun exposure can result in sunburned fruit and immature fruit drop. While it prefers coastal areas, babaco can be grown it semi-protected areas throughout California and other Mediterranean regions. While babaco can withstand brief exposure to freezing temperatures (>28°F), they are best brought indoors or put in a protected place during the coldest part of winter to avoid root rot. Babaco plants can easily be grown in containers and they thrive in greenhouses (or warm, moist homes).
How to grow babaco
Since babaco do not produce seeds, they are propagated vegetatively, or asexually. To do this, one foot diagonal segments are taken from an existing trunk, after fruit production is completed. These segments are first washed with a fungicide and then the bottom (rooting) side is dipped in rooting hormone. Segments are then stored vertically in a location where they can dry out and form calluses, much the way we treat pineapples. In time, roots and shoots will begin to appear and the segment of trunk is planted 8” below soil level. In just a little over a year, your babaco will be producing fruit!
For the best fruit production, prune out any additional trunks as soon as they appear, except for one trunk, sometime around September, every year or two. This new trunk will replace the existing trunk. Trunks are only productive for a year or two. Babaco can also be propagated from cuttings, but with less success.
Babaco grows best in light, well-drained soil. They require frequent irrigation and nitrogen feeding during fruit production. Mulching with composted chicken bedding will help your babaco tree thrive.
Pests and diseases of babaco
Babaco leaves are susceptible to fungal diseases, such as powdery mildew. Phytophthora root rot can also become a problem. Certain mites, specifically the two spotted mite and the strawberry mite can become problematic, as can snails and slugs, and deer.
Add a touch of the tropics to your home or patio with a delicious babaco!
In many gardening catalogs, you can find trees that boast multiple types of fruit. This is done by grafting twigs from various trees onto a parent tree.
A man named Sam Van Aken created a tree with 40 different types of fruit growing on it. His Tree of 40 includes almonds, cherries, nectarines, peaches, and many other stone fruits, all grafted onto a single tree. Grafting is an excellent way of making the most out of a small gardening space and it can look pretty amazing. Grafting is an old technique used to join two plants together. A newer version, called budding, does the same thing, but in a different way.
How does grafting work?
The top half of a graft is called the scion and the lower portion is called the rootstock. Grafting works because plant hormones, called auxins, allow the vascular cambium tissues of both the scion and rootstock to merge. This allows water and sap to continue moving through the xylem and phloem.
Before you jump on the grafting bandwagon, however, keep in mind that grafting is tricky. It takes practice. You also need to know that, after a graft is completed, even though a protective callus has formed, and the vascular tissues have fused, the wood does not. This means that graft unions should always be considered structurally weak. You should also know that the fruit and nuts produced on grafted trees contain seeds that hold the genetic information for the scion wood only, and not that of the rootstock. Also, if you have a plant that is putting out suckers, keep in mind that these are from the root stock, and not the productive aboveground portion of your plant.
Advantages of grafting
It is pretty safe to assume that nearly all fruit and nut trees available today are grafted combinations of hardy, pest- and disease-resistant rootstock and highly productive scions.
Grafting speeds up production because young scions can be grafted onto older rootstock. This is called precocity and it allows growers to skip the 5- to 12-year juvenile phase, when trees are focusing on root system development, rather than fruit production. Grafted trees can also selected for size. Simply graft a scion from a full-sized tree onto dwarf rootstock and you get a dwarfed tree that produces more fruit. In many cases, grafting is used to imbue a tree with pest or disease resistance. This method is also used on watermelon, tomato, eggplant, cucumber, and other vegetative plants for the same reason.
Grafting for the garden
Let me say this up front - grafting requires skill. It easy to do incorrectly. There are several factors that contribute to successful grafts, and all of them are important:
Tools used in grafting
Having your tools ready ahead of time will increase your odds of successful grafting. The last thing you want is for plant tissue to dry out before you are done. [Many gardeners hold scions in their mouth as they work, to keep the plant tissue moist.] You will need sharp, sanitized pruning clippers, stretchable, biodegradable grafting tape, a sharp grafting knife, and sanitizer. You may also want to have some tree sealant or grafting wax handy.
Steps of T-budding: (a) Bud stick with short leaf stems. (b) Shield bud. (c) Inverted “T” and standard “T” cut in stock. (d) Bark opened and ready for bud. (e) Bud inserted and flaps closed. (f) Bud inserted for inverted “T” budding. (g) Rubber budding strip holding flaps and bud firmly in place. (UKY Extension)
Chip budding is similar to T-budding, except that a chip of wood is removed from the rootstock and the bud is inserted into the space.
There are several different types of grafts:
Approach grafting joins two rooted plants together to provide more support for the developing new growth. It is also used in pleaching and can be done any time of year.
Awl grafts are hard to do well as it means poking an awl under the bark of rootstock, but not beyond the cambium layer, and inserting the scion.
Bridge grafting is used in an attempt to save a tree that has been girdled by planting identical species around the injured tree and grafting them above the injury to create a nutrient bridge over the girdled portion of trunk. A similar method, called inarch grafting, uses an existing branch of the injured tree that emerges below to injury to reconnect the supply chain of nutrients.
Cleft grafting is one of the simplest and most popular forms of grafting. It takes advantages of naturally occurring clefts by inserting 3/8” scions into larger (3/4” to 2-3/4”) notches cut into Y or V-shaped joints while both plants are still dormant.
Four-flap grafts (or banana grafts) are a complex method of grafting, commonly used on pecans, in which bark from the rootstock is peeled back, like a banana, and applied to the scion.
Stub grafting is similar to cleft grafting, but the incision is made in a branch, instead of a cleft, and the scion is placed at an angle no more than 35° to the parent tree. After the scion takes, the portion of the branch above the graft is removed
In rare cases, graft hybrids, called chimera, will occur. This happens when rootstock tissues grow into the scion wood. This can lead to trees that produce flowers of both plants, plus strange combination flowers. Chimera are almost impossible to reproduce.
Whichever method you decide to use, grafting or budding, be sure to seal the area completely, either with grafting tape, tree seal, or grafting wax. This will protect against desiccation, pests, and disease, while providing some structural support, as well.
Problems associated with grafting
Grafting can provide you with added control over plants, making them more suitable to your garden theme. It can also make your foodscape healthier and more productive. But grafting requires skill and is labor intensive. Also, it is important that the proper rootstock is selected for your scions. Incompatibility may not kill the tree until several years of watering, fertilizing, and pruning have passed. Check with your local County Extension Office or rare fruit growers club for more information on compatibility before you get started.
When you first try your hand at grafting, don’t be surprised or discouraged when the alignment and pressure are insufficient, or the graft union dries out before the scion “takes” to the rootstock. This happens to beginners all the time.
If your graft works, make sure you plant your new tree at the proper planting depth. This is critical to its health and longevity. Placing graft unions below soil level invites fungal diseases, such as crown rot.
The interaction between rootstock and scion wood can be pretty amazing when it comes to plant hormones. Check out my post on photoperiodism.
Assuming you have already collected, labeled, and kept scions cool and moist, you are now ready to begin. [If not, read my post on scions first.]
Did you know that you can graft a tomato plant onto a potato plant and get food from both?
Now you know.
You may love calico cats (I do!), or have fond memories of calico dresses from a certain prairie-crossing children’s series, but calico in the plant world is something else entirely.
Calico is a viral disease that can infect alfalfa, lentils, potatoes, tomatoes, peas, tobacco, and 600 or so other plants. There are several strains of this virus, most of which are species dependent.
The calico virus prefers warm, sunny days and sap with a slightly alkaline pH of 7–7.5. Research has shown that plants infected with calico causes reduced levels of important plant nutrients such as copper, iron, manganese, and zinc.
Symptoms of calico
Calico, also known as Lucerne mosaic, or alfalfa mosaic virus (AMV), is easy to spot. Clearly visible in dark green sea of potato plants, you will see a bright yellow patch, or yellow blotching. Infected leaves may look shiny, compared to their healthy neighbors. You may also see wilting or severe stunting. Closer inspection will show dead stems and tubers, or dry, corky areas inside your potato harvest.
If your potato plant looks more like a pale yellow Christmas tree, it is probably potato psyllid feeding.
How calico is spread
Calico is spread by several species of aphid, but potato aphids and green peach aphids are the usual culprits. Infection is normally spread when aphids move from alfalfa, clover, or wheat to potato plants. Infected seeds and pollen can also carry this viral disease, as can parasitic dodder. Infected plants should be removed and tossed in the trash, not the compost pile.
To avoid AMV in your potato patch, plant only certified disease-free tubers, keep your potatoes away from clover and alfalfa, and sanitize your tools regularly.
A break in the much appreciated rain and I found myself out in the garden. [Where else?] When I moved a large plant container, I saw something I had never seen before.
Curled up in a perfect spiral, under what had been the very center of my container, I saw a flat yellow worm with a dark stripe down the middle of its back. Of course, I had to collect it for identification. Unfortunately, this particular specimen escaped and is, I believe, lodged in my moisture meter.
Land planarians, also known as land flatworms, or arrowhead flatworms, are a family of flatworms known as Geoplanidae. There are nearly 1,000 different species of flatworm worldwide, broken down into 4 subfamilies, but we know very little about them. What we do know is simply too strange not to share.
Land planarians are native to Indo-China. Sometime around 1901, soil containing these flatworms was transported to the U.S. At first, land planarians were only found in greenhouses. Now they are found in several states including: Alabama, California, Mississippi, New Jersey, New York, North Carolina, Ohio, Oklahoma, South Carolina, Tennessee, and Texas. If you find one in a state not listed, I’m sure that your local County Extension Office would love to see it. At this point, land planarians are only found in places where nursery plants go. They withstand freezing temperatures by hiding in protected areas. They cannot, however, tolerate low humidity or drought.
Land planarian description
Land planarians are flat, slimy worms. Apparently, the slime helps them move and is the only way they can maintain internal moisture levels. That slime is said to taste terrible, though I don’t know how or who figured that out. That bad taste means they have few, if any, natural predators.
Planarians can range from less than one inch to nearly a foot in length. Most planarian species tend to be brown or brownish-grey, but they can also be yellow, green, black, or even bluish-green. Most planarian species have dark longitudinal lines that start at the head. Heads tend to be triangular or crescent shaped. Planarians do not have a mouth, per se. Instead, they have a single opening on the underside of their body.
If the outside of a planarian looks strange, the inside is even more bizarre. Planarians are a mass of squishy tissue and nerves, with a layer of locomotive hairs on the underside. They have no brain, circulatory system, respiratory system, or digestive system. So, how do they eat?
Land planarian feeding
Cousin to parasitic tapeworms, planarians are nocturnal predators that feed on slugs and snails, pillbugs, millipedes, spiders, and earthworms. They use chemical signals that are produced in folds of their skin to detect prey. Some land planarians use physical force to hold their prey, while others have a sticky mucous that entraps their victim.
Now, when I said they feed, it isn’t feeding as we know it. When a land planarian feeds, it slimes over top of a potential food, attaches its “mouth” opening, and vomits digestive juices , liquifying its prey. Then, it sucks up the soupy nutrients. Land planarians do not have an anus, so waste products are released through the same opening used to bring it in. If that wasn’t weird enough, land planarian reproduction is even more odd.
Like many other flatworms, land planarians are able to reproduce either sexually or asexually. Sexual reproduction culminates in eggs being placed in cocoons that hatch in 3 weeks. A single planarian will, every couple of weeks or so, attach its tail to a rock or some other immoveable object and slime away, tearing its tail from its torso. A new tail grows from the wound, as we would expect of a flatworm. The tail segment left behind, however, does the same thing, growing a new torso and head within 10 days. [When food is scarce, it is not uncommon for land planarians to eat their own reproductive tissues.] Scientists love studying flatworms because of those reproductive habits. In one study, it was found that decapitated flatworms retained the memories of their parent worms. [I can’t make this stuff up.]
As far as invasive pests go, planarians are not a significant problem, unless you have a greenhouse or practice vermiculture. [Vermiculture refers to raising worms.] In most outdoor gardens, fluctuations in humidity help keep land planarian populations in check. If you do have a greenhouse, or raise worms, flatworms can wipe out your entire worm population in short order.
The next time you see slime trails, don't assume they were made by snails or slugs. It may be that those garden pests are on the run from something far more terrifying (to them).
Manganese is a micronutrient used by plants to make chlorophyll. Manganese can also be phytotoxic, which means it can be poisonous to plants.
Made by large stars just before they go supernova, manganese is the 12th most abundant element of the Earth’s crust, and early man used manganese as a pigment in cave paintings some 20,000 years ago. How we use it in the garden can help or harm our plants.
You may have heard about the nitrogen cycle, the Calvin cycle, or the carbon cycle, but did you know there is a manganese cycle? I didn’t either. It ends up that manganese can take many different forms, depending on what it is attached to. [Mg2+ is the form most commonly used by plants.]
Unlike many other elements, which can exist on their own in nature, manganese prefers being attached to other minerals, usually iron. This can cause a whole Domino Effect when it comes to feeding your plants. According to studies conducted by Cornell University, high levels of copper (Cu), iron (Fe), nickel (Ni), and zinc (Zn) can make it difficult for plants to absorb manganese. At the same time, plants low in calcium (Ca), iron (Fe), magnesium (Mg), phosphorus (K), or silicon (Si) are also more likely to be sensitive to high manganese levels.
How plants use manganese
Manganese is used by all living things as an antioxidant, to counteract the toxic effects of oxygen. In plants, it is an important component of chloroplasts. Chloroplasts are where chlorophyll is made. Manganese is also used during photosynthesis, in many enzyme reactions, and to make potassium and calcium more readily available. Crops such as oats, wheat, and barley use a lot of manganese, with corn using moderate amounts.
Once inside a plant, manganese stays where it was first used. As a highly immobile plant nutrient, this means that deficiencies are most often seen in new growth, while toxicities are seen in older growth.
Plants can absorb too much manganese in acid soils, or under drought conditions. When acid-forming fertilizers, superphosphates (fertilizers made by treating phosphate rock with phosphoric or sulfuric acid) are used, or when nitrate (NO3-) is used as a nitrogen source, those acidic conditions can occur. Manganese is most available to plants when the soil pH is between 5.0 and 6.5. Soils with neutral or alkaline pH slow the solubility of manganese, so toxicities are less likely.
The most common symptoms of too much manganese look a lot like the symptoms of too much boron:
Too much manganese interferes with root growth and causes overall stunting, especially in alfalfa, small grains, and beans.
While magnesium is needed by all living things, too much magnesium can be very, very bad. At high doses, inhaled magnesium can lead to neurological damage called manganism, a condition similar to Parkinson’s disease. If you have to work with manganese, wear protective gear.
Being an immobile nutrient, manganese deficiencies are first seen in new growth. When manganese is in short supply, you will see interveinal chlorosis (yellowing between leaf veins). If there is a sharp distinction between veins and yellowing, it may be an iron deficiency, or a combination of insufficient manganese and iron. If this symptom is seen in older leaves, it is more likely to be a magnesium (Mg) deficiency.
Manganese deficiencies are more common in mucky soil, which means providing good drainage can prevent this problem. Cold and wet conditions can also interfere with manganese uptake. Due to its immobility as a plant nutrient, foliar (leaf) sprays of manganese are recommended if deficiencies have been identified.
Looking at plant leaves can tell you a lot about what they have and what they need.
You can grow a surprising amount of food in your own yard. Ask me how!