Plant news

Just a pair of interesting articles coming out of the science community yesterday. For the plant geeks out there.....


Giant Vines & Towering Trees: Ancient Forest Unearthed

Doomsday Seed Vault's Birthday Brings 25,000 Gifts


Enjoy!

Project BudBurst

Phenology. Literally "The Science of Appearances." We're concerning ourselves with the physical manifestation of phenotypes, but in this case, the *timing* of those things. Migration. Reproduction. Flowering. Budburst.

Project BudBurst is a.... well, I'll let them speak for themselves. From their website:

What is Project BudBurst?
We are a network of people across the United
States who monitor plants as the seasons change. We are a national field
campaign designed to engage the public in the collection of important ecological
data based on the timing of leafing, flowering, and fruiting of plants (plant
phenophases). Project BudBurst participants make careful observations of these
plant phenophases. The data are being collected in a consistent manner across
the country so that scientists can use the data to learn more about the
responsiveness of individual plant species to changes in climate locally,
regionally, and nationally. Thousands of people from all 50 states have
participated. Project BudBurst began in 2007 in response to requests from people
like you who wanted to make a meaningful contribution to understanding changes
in our environment.

Project BudBurst is a lot like the Great Backyard Birdwatch in that it is a scientific effort being undertaken by individuals to create a large enough, statistical data base to be relevant in the field. While this is not related to bonsai specifically, the findings and information gathered by the project is useful to environmental and botanical endevours all around. It is free to participate it and you can participate in as small (or as large) of a way as you desire. At the moment, it is limited to the US (though if anyone knows of similar projects for other areas of the world, I would be very interested, drop me a link). Check it out. For SCIENCE!

USDA Cold Hardiness Update

Samazana ni
hana sakikeri to
mishi nobe no
onaji iro ni mo
shimogarenikeru

Fields we saw
blooming with
so many different flowers,
frost withered now
to a single hue.

-Saigyo, Poems of a Mountain Home

Here in the North East we are firmly entrenched in winter. Though it's been relatively mild on the whole, I still find myself staring longingly in to the cold. When I can't stand it any more, I head outside and putter about, but really, there's nothing much to do other than long for spring and contemplate these quiet times.

Now that we've mused a bit, some real news of interest, though admitedly, it effects growing plants in the ground far more than it effects our bonsai. The USDA has updated its Hardiness zones. Discussion about global warming aside, the map has been updated to reflect the trends of warmer winters here in the states since the last time it was updated in 1990. You can find a good copy of the new map here: http://planthardiness.ars.usda.gov/PHZMWeb/. There is an option to search for your location by zip code, which is handy for those folks on the edges of zones.

This may mean little to some people. It may be important to others. It might prompt some to try their hand at a tree not normally viable in their previous zone, but which would more easily survive with the updated map. What it will mean will be some different stock possibly available at local nurseries, and the buyers become aware of this change and can reasonable expand their stock by a whole zone. As bonsai growers, we have always, and will always, offer additional winter protection to our plants, and the change of my own location from zone 6B to zone 7A won't be changing that. But maybe I'll take a gander at a few species I was on the fence about before. Hmmmm.....

Where's the Colour?

Steven Katovich, USDA Forest Service, Bugwood.org
Fall color in northern Wisconsin, paper birch, and red maple.

"Why weren't the leaves as awesome this year?"

"My bonsai were kinda bleh this fall, I don't understand."

"The Japanese Maple in my front yard turns fantastic colours most years, but not this one. Why?"

"Where's the colour?!?"


From all quarters, there has been the same question this fall. "Where's the colour?" Over and over again that question repeated as autumn enthusists gazed over the yellows and browns, eagerly awaiting the vermillion foliage that typifies an East Coast fall. And over and over again, they were disappointed.

Oh, the golds and russets were lovely. But it just wasn't the same. Though there were a few die hard species in this area that, right at the end, put on a quiet, tired display that mimiced their reds of years past, here on Long Island we simply didn't see the autumn display that we usually do.

And we weren't the only ones.

So, what happened? Why was the colour muted this autumn? Why did the trees that turn yellow seem to be ok, but our glorious reds were, well, not so glorious.

For that we have to start with the science of why leaves change colour. During the late spring and summer, leaves are busy. Working hard. Making and utilizing chlorophyll, the green pigment which is where photosynthesis occurs. And therein lies the beginning of the entire cycle of energy on earth – plants take sunlight, water and carbon dioxide and create sugars and oxygen. Without this process, we wouldn’t even be here; there’d be no food, not enough free, breathable, oxygen. If this isn’t amazing enough for you, well, I don’t really know what else to say, and you should probably try a different blog.

Senescence in plants is the period of time between leaf maturity (where they are a sugar factory chugging out that beautiful oxygen by-product) and leaf death. A lot happens in that time, but the part that interests us here is the withdrawal and absorption of the chlorophyll. Triggered by cooling temperatures and shorter days, trees in temperate climates start to shuttle the energy and nutrient rich chlorophyll from their leaves, breaking them down in the process and returning those nutrients to their roots to store for the winter. Some of those nutrients and energy are what that tree is going to use come spring to start the whole process over again.

Now, yellow leaves are pretty straight forward. The yellow colour you are seeing is what is left behind when the more strongly pigmented chlorophyll is gone. As the chlorophyll is broken down and drawn back out during senescence, the yellow colour is unmasked. It was always there, we just couldn’t see it. These pigments are called carotenoids, an antioxidant specifically in place in the leaves to protect them from some of the damaging byproducts of photosynthesis. (For more about that, google ‘oxidation’ and ‘free radicals’ or just leave a note in the comments that you are interested in more SCIENCE in this blog, and I’ll be happy to oblige. For now though, we’re going to try to stay on topic with the science.)

Red leaves are a bit more complex. For the full story on just how complex you can see the original paper on it here: http://treephys.oxfordjournals.org/content/21/1/1.short. That’s just a link to the abstract, but you can get to the whole thing from there. “The physiological significance of anthocyanins during autumnal leaf senescence.” That’s a mouthful, isn’t it? Let’s see if we can break it down a bit and backtrack. A lot of that article is about the selective pressures, explaining WHY some trees tend to be red in the fall when others are yellow. It’s an interesting read, but I’m getting ahead of myself.

The red pigments that you see in autumn foliage are called anthocyanins. While carotenoids are simply left behind during senescence, anthocyanins are actually created by the plant as the chlorophyll is getting broken down. The mystery to scientists of course (which is part of the focus of the above paper), is why a plant would waste precious energy at the time of year where it needed to store every bit of it possible.

As it turns out, anthocyanins protect the leaf from damage from the sun directly. While the chlorophyll is being broken down, the leaves are more susceptible to damage, and would fall sooner, possibly before all of the chlorophyll had been absorbed by the tree. The anthocyanins protect the leaves, buying time and allowing the tree to absorb more of the chlorophyll and other nutrients before leaf death occurs. You might notice that many trees that turn red in the autumn turn a shade of darker burgundy before that brilliant crimson hue. That’s the point where there is enough of a mix of the unbroken down chlorophyll and newly created anthocyanins exist simultaneously in the leaf, creating that intermediate colour.

Trees that create anthocyanins also create carotenoids; the red pigment in the anthocyanins is just stronger than the carotenoids in these species, which is why red is the colour you see. Different species however will make different concentrations, which accounts for the breadth of red and orange hues available in the autumn palette.

There are theories about why some trees create anthocyanins and others do not. Many of those that do not are considered ‘pioneer’ species; species that are the first to colonize open land, and are already evolutionarily more adapted to high sunlight situations. Many of the trees that create them are those that evolved as secondary species, coming in after the colonizers. Many of these species start their lives as understory plants, growing in the shade of the first comers. Though they eventually outgrow their companions and take over a forest, the continued need for some protection from the sun may have led to the development of the anthocyanins. Trees that could tolerate shade in youth and then would be protected by the sun from internal sources at maturity would have naturally outperformed those that could not. This is mostly a concern in areas where fall days are sunny. It’s one of the reasons many native European species (not all, just quite a few) and those in the Pacific Northwest, tend toward the yellow end of the spectrum. In areas where autumns tend more toward the cool and cloudy, there is less biological pressure for those trees that begin life in the understory to protect their dying leaves.

This is all very nice and all. But why was the autumn colour this year so poor?

Many of the trees that normally are yellow in the fall seemed to do just fine. The problems came with our anthocyanin species.

There are many factors that will affect autumn foliage, and these can start as early as spring. Some known factors that will decrease leaf colour in the fall:

-A late spring.
- Summer drought.
-Uncharacteristic high temperatures in summer.

All of the above are likely to stress the tree and/or cause damage to the leaves. Though they do not directly affect the production of anthocyanins, they make the whole thing far more difficult and leave the trees with less resources to work with.

-Longer high temperatures in to autumn than usual, followed by a sudden drop and frost.
-Too warm nights in autumn.
-Not enough sunny days in late summer and autumn.
-Early autumn with cooler than usual days.

These four are situations that will direct impact the formation of anthocyanins. The best conditions for good autumn foliage? Typical (whatever that is for your area) spring and summer conditions, followed by warm, sunny autumn days and crisp, cool (but not freezing) autumn nights. During the warm days, the trees are producing sugars like mad, but the cool nights constrict the veins of the leaves and prevent many of these sugars from being absorbed again. Concentrated sugars and sun are part of what begin the process that spurs the tree to make anthocyanins.

What can we do about it, to bring the topic back around to our bonsai? Unfortunately, there isn’t a lot that we don’t already do. During periods of drought and high temperatures we can water and shade our trees properly, bringing them back out in to more sun again once the end of summer rolls around. The temperature and cloud cover are out of our control largely, and so far as I know, there is no information out there about using grow lamps during cloudy autumns to improve colour (if you try it, document it and document it well).

Here on the East Coast of the USA, our problems were definitely the summer drought and high temperatures of summer(112F days were killer), combined with a very rainy and cloudy late summer. We also kept our unseasonably warm temperatures later than usually, and had an exceedingly short period of properly cool nights with warm days. A lot of factors went in to this year’s autumn being dominated by the yellows and browns. While we can adjust the input to our bonsai far more than the general input to the plants in the landscape, we are still ultimately at the whims of local and global climate.

Fertilizer 101

What is NPK?
NPK is the abbreviation that stands for the elements nitrogen, phosphorus and potassium. These nutrients are the three most important chemicals that plants need to thrive.

What do the numbers mean?
Usually represented by a number like 10-10-10, they are the percentage by weight of the three nutrients. The numbers are always given in the same sequence, NPK, with the first number percentage nitrogen, the second phosphorus, and the third potassium. Fertilizers with different numbers, but the same ratios are equivalent, but have different strengths. Two pounds of 5-10-5 fertilizer has the nutrients as one pound of 10-20-10. Fertilizers that contain all three of these elements are considered ‘complete’. A zero in any of these spots means that a fertilizer does not contain that nutrient. A 4-12-0 fertilizer contains nitrogen and phosphorus, but no potassium.

Nitrogen- Foliage Growth
Nitrogen is needed by all plants and is easily washed out of the soil. It stimulates shoot and leaf growth, and regular application is particularly important for green, leafy plants like grasses, lettuce, and foliage plants. Too much nitrogen, however, can cause other types of growth (such as flowers, fruit and roots) to slow down, and even stop. It can also cause fast growth, but weaken a plant, making it more prone to disease or pests. A low nitrogen fertilizer can be used to encourage flowering and fruiting over foliage growth. Nitrogen is absorbed or washed from the soil within a few weeks of application, and should usually be applied every month during the growing season.
Signs of nitrogen deficiency: old leaves turn yellow, slow or no growth, small new leaves.

Phosphorus – Roots and Flowers Growth
Phosphorus binds with other elements in the soil to form stable compounds. This means it does not leech out of the soil as quickly as nitrogen does, and therefore does not need to be applied in quantity as often as nitrogen does, especially for established plantings and tree. Phosphorus can usually be applied once a year, or when putting in new plantings and trees, and will remain in the soil.
Signs of phosphorus deficiency: leaves are dull green or grayish, purple foliage on otherwise green plants, short stems, few flowers, small fruit.

Potassium (Potash) – Overall Plant Health
Potassium is more soluble in water than phosphorus, but does not leech out of the soil as quickly as nitrogen does. A single application can last several months. It helps with root growth, disease resistance, and temperature tolerance.
Signs of potassium deficiency: Older leaves crinkle and curl upward, leaves turn yellow and scorch begins on leaf edges and progresses in toward veins, shoots die back late season.

Organic vs. Inorganic
The primary difference between organic and inorganic fertilizers is where the raw materials are sources from. Organic fertilizers use naturally occurring ingredients (either animal or plant based, ‘organic’ refers to from materials that were once living), like bone meal, as a nutrient source. Inorganic fertilizers use synthetic chemicals or mineral, like ammonium nitrate, to supply the nutrients. Typically (but not always) organic fertilizers are slow release, while inorganic are released more quickly. Nutrient content varies from fertilizer to fertilizer, but an organic and an inorganic fertilizer with the same NPK numbers will have equivalent nutrient amounts.

Fertilizer Applications:
Fertilizers come in several different forms. Most commonly they come in granules that are meant to be scattered on the soil. Watering will dissolve them in to the soil. Others are liquids or soluble crystals meant to be dissolved in water. These can be applied while watering, either with a watering can, a hose attachment, or through an automatic watering system. Some come in solid chunks or bricks. These are always slow release forms, and are placed individually above the root zone of the plants.
Follow the directions on the fertilizer package for specific application instructions.

Secondary Nutrients and pH:
Calcium, magnesium and sulfur are considered secondary nutrients. Secondary nutrients are no less important than NPK, but seldom need to be added in quantity to soils. Calcium (in the form of lime) is often added to make soil less acidic, while sulfur is used to make soil more acidic. If there is a concern about soil pH, have the soil tested before adding these amendments. There are fertilizers that are mildly acidic, meant for acid loving plants like azaleas, and can be chosen with those specific plants in mind.

Always follow package instructions for application amounts compared to the size of the area you want to fertilize. More than the recommended amount is NOT necessarily better!


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After putting this together for work, I thought I'd share it here as well.

A Closer Look - Bonsai Pests, Scale

A Closer Look - Bonsai Pests

Part 2, Scale

Scale are another ubiquitous garden variety pest in temperate regions. Scale insects are small insects of the order Hemiptera, generally classified as the superfamily Coccoidea. There are about 8,000 species of scale, with many of that rather large number considered pests on our plants. Scale are one of the most destructive insects in the United States, with many species invaders from other areas of the world. They can survive in harsh conditions, from the tundra to the tropics, and thrive on all parts of a plant, commonly the underside of leaves and on branches, but are not limited in their location habits.

There are three general categories scale insects fall in to: most common being Diaspididae, or armored scales; Coccidae, or soft scales; and Pseudococcidae, commonly known as mealybugs. The armored scales are the ones with the most effective outer coating, and subsequently, the most difficult to deal with. (Photo above: Calico Scale)

Scale Habits: Most scale are plant parasites. They feed on the sap of a plant, usually pulled directly from the vascular system. While one or two scale may not be a cause for alarm, a host of these little critters feeding on a tree will quickly lead to problems. Almost every woody plant is a target for one scale species or another. Some scale feed exclusively on one type of plant. Others target a small number of species, while still others are happy to feed wherever they end up.

Scales are around year round. They can over winter in any life stage (see Reproduction/Lifecycle below), but eggs and mated females have the best tolerance and survival of low temperatures. Once the weather starts to warm up in temperate climates, the new flush of growth we see in our plants coincides with egg hatching, though there may be later and earlier hatchers, depending on the scale species and host plant.

Soft scale and mealy bugs can excrete honeydew, sometimes in large amounts. Sooty (black) mould happily grows on this stuff, and while it is generally harmless, it is unsightly. Ants are also attracted to the honeydew excreted, though they do not herd scale the same way they do aphids. Armored scale do not excrete honeydew. (Photo above: Mealy bugs)

Scale Reproduction/Lifecycle: The sexual dimorphism (differences in appearance between male and female) is huge (relatively speaking) in scale insects. Mature female scale are sessile (which means they are unable to move), have no legs or antennae, usually much larger than the males, and are usually the ones we see when we notice a scale infestation. Mature males are smaller, typically have visible wings (one pair, thus making them resemble true flies), do not feed (they don't even have mouth parts), and die in a day or two.

Anatomy of a Scale Insect: Scale insects vary greatly in size, as well as appearance. They can be very tiny, at only a millimeter in diameter, or a little larger, though few are larger than about five millimeters across. Scale come in almost any colour, from brown to green, white to yellow, all depending on the species, and range in shape, including round, oval, pear shaped, oblong or threadlike. They are covered in protective coatings, ranging from shiny waxy covers to pearl-like, from woolly to oyster-like. These coatings are excreted by the insect for protection, the scale living and feeding under the protective coating. While there is a wide range of appearances, most resemble the scales of a fish or reptile, or like scale armor of the medieval ages (hence, the common name!). The armor of female scale are often larger and more obvious than that of the male. The appearance of the armor can vary not only with species, but also the host plant the scale is feeding on, gender, life cycle stage, time of year, and other environmental conditions, which can make identifying the particular species, or even genus, of scale by the layman, very difficult.

All scale have (or had) antenae and six legs, though mature females lose (or almost lose) these features completely. They have piercing and sucking mouth parts.

How do you know if you have Scale: Scale come in all shapes and sizes, but the appearance of small, scale like or woolly *things* on your plants, especially the trunks and undersides of leaves, is usually a good indicator. There may be no other signs until an infestation is serious. A serious infestation will be obvious by stunted growth, yellow spots on the top of foliage (caused by scales feeding on the bottom part of the leaves - these spots will get bigger and bigger the longer the scale feeds), premature foliage drop, and dieback of young twigs and even whole branches if allowed. An untreated scale infestation could easily be the death of a tree. Fortunately however, these are easy to spot early just by keeping a keen eye on your trees. Also keep an eye out for sooty mould or ants, which can be a sign of both scale and aphids.

Scale can live on any part of a plant, so beside checking the most common locations (the stem and under sides of the leaves) be sure to also check in leaf axils, buds, the tops of leaves, along the midveins of leaves and anywhere else you can reach. A magnifying glass can be useful if in doubt, as some scale can look less like bugs and more like naturally occurring bumps on a leaf or stem surface. Crawlers can be detected by wrapping double sided sticky tape around a branch and seeing what pops up over a day or two. Pay careful attention to old wound scars so common to bonsai. The bark may be thinner here, especially if the wound is only a few years old, and the folding of the healing bark can hide scale effectively from view. The colour differences between bark and scale can be very subtle. Wetting the bark can often help differentiate between normal bark bumps and scale.

Examine plants for live scale insects by crushing the wax cover. Dead scales are dry inside. Live ones... well.... are not.

Scale prevention: The best prevention for scale is healthy, happy plants and early detection. When plants aren’t stressed, they have better defenses against infestations. Keep a good distance between your trees to keep good airflow, adequately water your bonsai, and make sure they are getting the right amount of light for their species preferences. Don’t over fertilize. Chemical fertilizers high in nitrogen produce large amounts of just the right kind of growth that attracts aphids and scale. Scale will also lay more eggs on plants receiving more nitrogen. Slower acting, organic fertilizers are better for helping prevent these infestations. While we go for good growth in our trees, this is another reminder for us that balance is the key to all things in bonsai. Scale can also thrive in thick inner canopies of trees, so keep your trees from getting too over grown in the interior. Allowing light and fresh air to penetrate will help prevent other diseases as well. Because they thrive in warm, moist areas, adding additional fans to increase airflow may help. Keep new plants isolated for a week or two before putting them near your other bonsai. This way, if there are scale nymphs (harder to spot than mature females) on the tree that you may have over looked at purchasing, you have a chance to catch it before it spreads to your other trees.

Scale Removal: If despite your best efforts, you notice a scale infestation on one of your trees, don’t panic! There are several steps you can take, ranging from the simple to the more complex. Scale is a difficult insect to get rid of using common insecticides. Because in mature scale (which is usually when we notice an infestation) their waxy coating protects them from most insecticides, other courses must be followed.

In cases of only a few scale, the best bet is to just remove them with your finger nails or a stiff bristled brush. Use a strong jet of water afterward to wash off the plant and any possible eggs that might have been left behind. Continue to check back every few days or so, just in case.

Scale are preyed upon by parasitic wasps. Check for tiny holes in the outer armor which is a sign that the beneficial wasps have already been on the job. Some other beneficial insects, such as lady bugs, green lace wings and praying mantis feed on the nymphs (crawlers), but not on mature scale. These beneficial insects will stick around as long as there is food (i.e. scale crawlers, aphids, etc), but you can encourage them to stick around longer by planting certain things that attract them (yarrow, cilantro, parsley and sweet alyssum are all plants that lady bugs in particular like). Lady bugs and praying mantis eggs can be purchased at most garden centers now, as an alternative to chemical pesticides. If you are going to try beneficial insects, make certain you don’t use any pesticides, as these will kill the good bugs as well as the bad.

Insecticidal soap or horticultural oil (like neem oil or dormant oil) can be used against all stages of scale growth, including mature scale (it suffocates them), and is generally safe for bonsai, but check the label, and if in doubt, do a test on a small portion of the plant to be certain it does not cause an ill effect. An even coat that gets every part of the plant (especially the underside of the leaves!) is necessary. These only work on contact, and do not provide long term prevention. If a spot is missed on the plant, the infestation can balloon again once the oils have dried, and applications may need to be repeated. Do not use oils on water stressed plants (those that have been under watered and have wilted, or those that have been over waters and may have root rot), or if the weather exceeds 90F (30C), as this can harm the plant. Supreme- or superior-type oils will kill overwintering populations when applied in late autumn and again in midwinter. These can be safe to use in conjunction with beneficial insects.

Most insecticides that list scale on their labels are really only useful during the crawler stage, or on mealy bugs. If use of an insecticide seems necessary, use the double sided tape method to watch for crawlers and spray then. If possible, prune off as much of the infested foliage as possible before reating, not only to remove the scale, but also to allow deeper penetration of the insecticides. Follow label instructions, coating the plant thoroughly on all surfaces (especially under the leaves!). Some systemic insecticides may be useful as well. Repeat the process if needed (which is likely) one to three weeks later. Some insecticides are safe for bonsai. Others are not. General guidelines are to follow the instructions on the bottle for usage, including timing and dosage. If in doubt, test it on a small area of the tree. If there are no negative affects (dying leaves, blackening bark), you can probably proceed with the rest of the tree.

Even once scales are dead, they will not always fall from your plant. You can tell a dead scale from a live one by crushing the outer coating. Dead scale are dry on the inside. Live scale will squish. There is no way to remove dead scale, other than manually. Use your fingernails or a stiff brush to remove them from the bark and leaves.

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Want to know exactly what kind of scale you are dealing with? Below are two online resources that may help further identification of your scale infestation. There are too many types to go over here, and it would be a disservice to everyone involved if I tried.

Scale Keys - http://www.sel.barc.usda.gov/ScaleKeys/index.html

Scalenet - http://www.sel.barc.usda.gov/scalenet/scalenet.htm

A Closer Look: Watering - Rain Rain

Tsukuzuku to
noki no shizuku o
nagametsutsu
hi o nomi kurasu
samidare no koro

Staring blankly
at the drops
from the rafter ends,
barely getting through the days -
fifth-month rainy season

****

Samidare wa
iwa seku numa no
mizu fukami
wakeshi ishima no
kayoido mo nashi

Rock-damned marsh-
in fifth month rains
so full of water
you can't pick your way
over the stones any longer

****

Samidare wa
yukubeki michi no
ate mo nashi
ozasa ga hara mo
uki ni nagarete

In fifth month rains
no trace of a path
where I can make my way,
meadows of bamboo grass
awash in mud


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Saigyo, one of my favorite poets, seemed about as irritated, yet resigned, as I am about the rain. Though June is the sixth month of the Gregorian calender, in times past (Saigyo was born in 1118 CE, in Kyoto, for the curious) Japan's fifth month ran from around the middle of May to the middle of June. And Japan's fifth month, was of course, the rainy season.

Here on Long Island, we don't have a rainy season. Yes, like many places, it rains more in the spring than other times..... but this.... this is not typical. It has rained six out of seven days a week (or more) for the last five weeks. Some days it has only showered briefly, but other days (like today) it has just poured down buckets all day long.

This is a problem. Don't get me wrong, my garden is *loving* all of this rain. It is so happy right now if they could, the plants would get up and do the watusi. However, as has been stated over and over again by many, many bonsai enthusiasts... a pot is not the same as the ground. And my bonsai are a little dubious of all this rain.

I can already hear the question, "well, don't you have a good, free draining soil mix? What's the worry?" I *do* have a free draining soil mix. It's great, and I haven't had any issues with root rot, well, ever, but that's as much from watering correctly as it is from the soil mix. You *can* over water, even with a free draining mix, it's just a lot harder, and most people won't be out there, soaking their trees six or seven times a day in my climate.

But the worry is related to that, in its way. The soil never getting a chance to even partially dry out. I repotted a lot of trees this year, including several from over grown nursery containers where I had to put a lot of stress on their roots just to sort out the mess. Let's say that easily a third of my trees are, this season, on sub par root systems, for one reason or another. So what do I want from those trees this season? I want them to grow roots! Lots and lots of roots. But see, here is the problem.

When roots are always wet, they don't need to grow as much to get the water they need. It's all right there! This is noticeable on Jade trees you might have indoors. You can't even get a cutting from one of those suckers to root unless you let it dry out a little. Jades put out roots in response to low water situations. A lot of trees are like this, only it's not so obvious as Jade cuttings that'll sprout roots in a day or two under the right conditions. Ever wonder why they tell you to water lightly after a tree has been repotted? Many people cite that it is because the tree doesn't need as much water, and the roots can't take up as much water, since they've been pruned, and you might rot out the roots. This is half of the story. It's also because if the roots are kept soaking wet, they don't need to *try* to grow. The plant tells itself "there is plenty of water coming up here, we don't need to release hormones that will make the roots grow. We're steady in this pot (they put wires on us for that), so between stability and a readily available source of water (we'll worry about nutrients later), we're good to go!"

So, where does this leave me? Trees that I would have watered sparingly (plenty to keep them alive, just not like this, sheesh) are getting soaked and staying soaked.... every day. So root growth has slowed down considerably. Ok, again, what's the big deal? So the trees need an extra year to recover, right? Maybe, but for different reasons than just improved rootage.

Michael Hagedorn commented on what is going to be my problem in a month or so on his blog, http://crataegus.com/2009/05/31/watering-tip/.

Before the real summer heat hits, consider how you are watering your
trees.
Have you ever seen your trees grow through spring just fine,
only to get fried leaves at the first onset of early summer? Ever wonder why
that happens?

Those trees just don’t have enough roots. Those are the trees that got
overwatered, or simply never dried out, in the cool spring months. Their roots
were never encouraged to hunt out water, so these trees could survive in the
moist cool weather on about three roots. First hot day: bam, they get hit hard
as they have a spindly root system, not enough to support their overlarge, over
long leaves and shoots on dry hot days. (A bonsai version of a company that has
overspent just before a recession…)

Especially on cool overcast days, if you can monitor them, water each
tree only when it is really drying out and not by rote. Watering by a schedule
is the surest way to have some really weak trees that show themselves in the hot
summer!

I discovered this the hard way two years ago, when I thought I was doing my newly repotted trees a favor by giving them extra water to make it easier on them. And, as Michael said *bam*, first hot day, bad news. At the time, I knew the trees weren't getting enough water to keep the leaves from burning, but why? I watered them, plenty! I just didn't know. It took me a couple months and *a lot* of reading (in some very heavy botany books) to figure out what had happened, and why those trees, that had seemed so healthy, that I had been watering (what I thought) was correctly, had ended up like that.

It's just like kids. Making everything easy for them doesn't encourage them to grow. They have no reason to. I'm not saying kids (or bonsai) need to be thrown to the wolves- but a little hard work never hurt anyone.

So in July and August, I can pretty much count on most of the trees I repotted and did serious root pruning on this year having trouble. Too much heat, not enough roots, so not enough water getting up in to the leaves. This, beside the obvious unsightliness, is more importantly an issue because of the stress these trees will be under. Stressed bonsai are more susceptible to disease, pests, die back, and a host of other issues.

If the roots ain't healthy folks, ain't nothing healthy.

There is, unfortunately, little I can do about it at this point. Those trees that were repotted have been placed under bonsai benches and generally shaded from the worst of the rain, but with the humidity so high, the soil is still unable to dry out. When the rain stops, and it starts to get hot, these trees (especially those that I know already have the weakest root systems) will continue to be protected, especially from the sun in the hottest part of the day even if I wouldn't have normally worried about them. These trees will get a changed fertilizer regime, lowering the amount of nitrogen, but keeping the phosphorus and potassium at the same levels. This will help keep the amount of foliage that the roots need to supply with water to a more manageable level (lower nitrogen), but still encourage root growth (phosphorus).

Hey, I said I didn't want to throw them to the wolves, didn't I?

In Japan, watering is considered an art in and of itself, and some apprentices are at a nursery for two or three years before they are even allowed to touch a watering can. I'll be honest, I'm not certain I should be allowed near the hose myself.

But I'm learning.

A Closer Look: Bonsai Pests, Aphids

A Closer Look: Bonsai Pests

Part 1 - Aphids

Aphids are a ubiquitous garden variety pest in temperate regions, as irritating on our tomatoes as they are on our bonsai. Also called plant lice and greenflies, Aphids are part of the insect superfamily of Aphidoidea (which pretty much covers all of the types of aphids but two), with over four thousand species known (over two hundred considered pests to horticulturalists), ranging in size from one to ten milimeters. Soft bodied, tiny, and destructive, they are seriously irritating little buggers that feed on the soft parts of our plants. (photo of aphids feeding on a fennel stalk, open source from wikipedia)

Aphids, for the most part, cause damage to our plants in one of two ways: by feeding off of the sap of the plant, and by potentially introducing viruses to the host plant (though fortunately, this is more common with vegetables than with trees, phew). The first is easier to deal with by dealing with the infestation. And, I assure you, if you see a couple aphids now, deal with it, rather than waiting. A couple aphids might not do much, but if they like your tree, they will reproduce, and *quickly*.

Anatomy of an Aphid: Aphids have soft bodies, ranging in color from green, yellow, brown, black and pink (though green seems to be the most common). Some species may appear waxy or "wolly". Their bodies are squat, and frequently pear shaped, with a tail like protusion (called a cauda). They have two compound eyes. Aphids have antenae, like all true insects, with as many as six segments. They feed themselves through stylets, which are the sucking mouth parts we find so detrimental, which are enclosed in a sheath called the rostrum. They have long, thin legs compared to their squat body shape and size, with double clawed "tarsi", which is just a fancy name for a certain part of an arthropod's leg. Most aphids have a pair of abdominal tubes (called cornicles or siphunculi), through which they exude defensive fluids to help ward off predators. The presence of cornicles distinguishes aphids from all other insects.

Aphid Habits: Some species feed on only one type of plant (these are called monophagous), though there are others that will feed on a large number of different types of plants (the green peach aphid, Myzus persicae, as a for instance). They are passive feeders. This means rather than sucking out the sap of a plant, they use their mouth parts to puncture the phloem of their host plant, letting the natural pressure within the phloem force the sap out to them. Since the sap of most plants is relatively high in sugar (a product the aphids don't need much of) and relatively high in nitrogen (something the aphids do need a lot of), they frequently give off a waste product known as 'honeydew', drops of sweet liquid containing the sugar they didn't need. Ants on a plant can frequently be an indicator of an aphid problem, as ants are attracted to the honey dew. Some species of ants will even 'herd' aphids as food sources, moving them to new plants and protecting them from predators. When host plant quality becomes poor or conditions become crowded, some aphid species produce winged offspring (known as alates) that can disperse to other food sources.

Aphid Reproduction: Interesting note- Aphids give birth to live young, called Nymphs. At least, some do, others lay eggs. There are also species that can reproduce asexually, which, considering how invasive these things are and the fact that they can be spread via wind, goes a long way toward explaining why this family of insects is so darn pervasive. Different species of aphids have different methods of reproduction, which makes it difficult here to give a brief over view. But the general gist is that most aphids reproduce rapidly when conditions are right. In the spring and summer the females (asexually) give birth to live young (all female), some of which may have wings to help them spread. At the end of the summer, males and females are produced, and eggs are laid and fertilized from this generation which will hatch the following spring. But in a warm situation like the tropics or a greenhouse, female aphids can reproduce asexually for years.

How do you know if you have Aphids: Aphids come in a number of colours and sizes, but all are tiny, soft, pear shaped bodies with cauda (tail like protrusion) and cornicales (two tubes protruding from the rear end). If you have an infestation, you'll be able to see them. You can also look for ants that are traveling up your plants (they look like they are on a mission, which is pretty accurate actually). Honeydew, the sweet liquid excreted by the aphids is another sign. Black moulds can grow on the honey dew, but they are generally considered harmless. Ugly, but harmless. Aphids leave pretty distinctive signs, even beside themselves. Leaves in an infested part of a plant will often look wrinkled or folded, even outright distorted. Aphids feeding on the base of a leaf will cause the leaf to curl backward, folding over them. Flower buds may be damaged or fall off completley. Some species of aphids will form a gall (an abnormal lump on a branch) and live inside of it, to help protect them from predators. You may also see yellow, stunted growth, wilting, mottled and brown foliage. Beside the weakening caused by the removal of sap, some aphids' saliva is actually toxic to the plants they feed on.

Aphid prevention: The best prevention for aphids is healthy, happy plants. When plants aren't stressed, they have better defenses against infestations. Keep a good distance between your trees to keep good airflow, adequately water your bonsai, and make sure they are getting the right amount of light for their species preferences. Don't over fertilize. Chemical fertilizers high in nitrogen produce large amounts of just the right kind of growth that attracts aphids. Slower acting, organic fertilizers are better for helping prevent these infestations. While we go for good growth in our trees, this is another reminder for us that balance is the key to all things in bonsai. Aphids can also thrive in thick inner canopies of trees, so keep your trees from getting too over grown in the interior. Allowing light and fresh air to penetrate will help prevent other diseases as well. There are also some studies that have been done using reflective mulches (silver coloured polyethylene sheets) to help prevent aphid infestations, though I'm not sure if anyone has tried them in bonsai cultivation. Keep new plants isolated for a week or two before putting them near your other bonsai. This way, if there is an aphid problem you may have over looked at purchasing, you have a chance to catch it before it spreads to your other trees.

Aphid Removal: If despite your best efforts, you notice an aphid infesation on one of your trees, don't panic! There are several steps you can take, ranging from the simple to the more complex.

The simplest, and cheapest way to deal with a mild aphid problem is to spray the entire plant with a strong burst of water to knock the aphids off. Make sure you get everywhere, especially the bottoms of the leaves and branches where the aphids might hide. Remove any leaves that have curled in on themselves, as aphids will hide in these as well. Don't just knock them on to the soil beneath your benches though, as they will just come back. Find someplace out of the way or over a drive way where you can then wash the whole thing down again. Spray your plants early in the day so they have a chance to dry and you can check them again in the afternoon. A solution of soapy water can also be used to wash over the entire plant.

My personal favorite (an a prevenative measure I take almost every year anyway) is to release insects that feed on aphids in to my garden and amoung my bonsai. The most common are lady bugs, though there are also types of parasitic wasps, aphid lions, crab spiders, syrphid flies and lace wings amoung others. These beneficial insects will stick around as long as there is food (i.e. APHIDS!), but you can encourage them to stick around longer by planting certain things that attract them (yarrow, cilantro, parsley and sweet alyssum are all plants that lady bugs in particular like). Lady bugs can be purchased at most garden centers now, as an alternative to chemical pesticides. If you are going to try beneficial insects, make certain you don't use any pesticides, as these will kill the good bugs as well as the bad.

Insecticidal soap or neem oil can be used, and is generally safe for bonsai, but check the label, and if in doubt, do a test on a small portion of the plant to be certain it does not cause an ill effect. An even coat that gets every part of the plant (especially the underside of the leaves!) is necessary. These only work on contact, and do not provide long term prevention. If a spot is missed on the plant, the infestation can ballon again once the oils have dried, and applications may need to be repeated. Do not use oils on water stressed plants (those that have been under watered and have wilted, or those that have been over waters and may have root rot), or if the weather exceeds 90F (30C), as this can harm the plant. Supreme- or superior-type oils will kill overwintering eggs of aphids trees if applied as a delayed dormant application just as eggs are beginning to hatch in early spring. These treatments will not give complete control of aphids however, and additional controls may be needed later in the season. Earlier applications will not control aphids.

There are also many other, stronger insecticides available for aphids (malathion, permethrin and acephate to name a few). Some of these are safer for bonsai than others. Especially if a certain tree is hit consitantly by aphid infestations, a systemic pesticide might be worth considering. Maples and Elms in particular can be susceptible to repeat attacks. There are so many kinds available it is hard to go over all of them. General guidelines are to follow the instructions on the bottle for usage, including timing and dosage. If in doubt, test it on a small area of the tree. If there are no negative affects (dying leaves, blackening bark), you can probably proceed with the rest of the tree. If you can, however, avoid the use of diazinon and chlorpyrifos; beside diazinon being dangerous for a few species we use for bonsai, both have been identified as serious sources of pollution in lakes and rivers. Carbaryl is not recommended because it is not very effective against aphids. In general, check the labels and see what pests they are effective against.

Keep in mind that if you see ants in conjunction with the aphids, you also have to deal with the ants, as they will simply reinfest the plant. If they have made a nest in the pot itself, repotting and making sure to remove all of the old soil is effective. There are also some insecticides useful against ants, but many are not, so be certain to read the labels. Smaller garden centers can often lead you in the right direction for which pesticides will be the best for your area.



On large, landscape trees, Aphids are seldom a problem. But on small bonsai with limited roots, they can weaken a plant quite a bit, and even lead to death if not taken care of. While it may seem simple, or even not very worrisome if you see only a couple aphids, whether on a bonsai or another garden plant, early reaction and prevention are your best defenses again a full blown infestation.