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.

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.

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.


Flower anatomy

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. ​

Pollination

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.

Patience dock pests and diseases

Slugs and snails, aphids, and the sorrel maggot are the most common pests, and I couldn’t find any mention of diseases, so this is a relatively trouble free plant.

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.

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 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). ​

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!

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?

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.


Almonds

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. ​

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:

•     Lateral long shoots — fig, nectarine, peach, persimmon, and quince
•     Terminal long shoots — young walnut
•     Lateral spurs - almond, apricot, cherry, and plum
•     Terminal spurs — apple, pear, and mature walnut

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!
    

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.

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.

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. ​

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.
​


Grain amaranth

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.

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.

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:

• Compatibility - Clones and members of the same species are the easiest to graft because they have identical structures [peach to peach]; two different species within the same genus can sometimes be grafted [peach to cherry]; plants in the same family, but different genera can only occasionally be grafted successfully [peach to apple]; monocots, because they lack vascular cambium, cannot be grafted.
• Alignment and surface contact - The vascular bundles of both the scion and rootstock must be in firm contact with each other, and oriented in the same direction.
• Timing - Successful grafting occurs when the scion is dormant, the rootstock is able to produce a protective callus, and temperatures are not too warm or too cold. In the Bay Area, most grafting is done January through March. 
• Site protection - Graft sites must be protected against dehydration, pests, such as vine mealybugs, and diseases until they have healed. This means using very sharp cutting tools that have been sanitized frequently throughout the process. Tapes and waxes are commonly used to seal the grafting site. Structural supports may also be needed.

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.​

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.

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.

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. 

Invasive planarians

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. ​

Flatworm reproduction

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 toxicities

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: 

• darkening of leaf veins, especially on older leaves
• leaf cupping
• older leaves exhibit pale, sunken, irregularly shaped patches of interveinal tissue, with patches closest to leaf margins turning black [these spots are more regularly spaced in boron toxicities]
• minor veins on the underside of leaves may appear black in older leaves
• soybean leaves crinkle and cup downward
• apple stems develop pustules in a condition called apple measles
• watermelon plants may wilt and drop leaves in only days, in a condition called sudden crash
• chlorosis occurs on younger leaves due to an induced iron deficiency

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.