Persimmons & More

I love persimmons. The first crops are coming into the specialty supermarkets. Soon, I'll be eating some from my own trees. I was fortunate enough to visit and taste some of the 81 varieties in the Wolfskill collection near Davis, CA.

The photo on the left documents that foggy, exciting day. The one on the right is just a few of the rare varieties of persimmons.

The Wolfskill collection is a fascinating occurrence between the private sector (Francis Wolfskill’s) and the public sector (the University of California at Davis.)

In 1934, when John Wolfskill’s daughter Francis died, she left approximately one hundred and seven acres of the grant to the Department of Pomology of the University of California, Davis, with the understanding that the property was to be used as an experimental horticulture station and the line of olive trees planted by Wolfskill in 1861 was to remain standing.

The collection is a virtual Noah's Ark of common and uncommon fruits and nuts such as:

As of 2009:

Actinidia (kiwi) 79

Diospyros (persimmon) 81

Eriobotrya (loquats) 36

Ficus (figs) 303

Juglans (walnuts) 552

Morus & Maclura (mulberries) 69

Olea (olives) 148

Pistacia (pistachio) 239

Prunus (all stone fruits) 1457

Wingnut (Pterocarya stenoptera, used to develop rot-resistant walnut rootstocks) 31

Punica (pomegranate) 180

Vitis (grapes) 3113

TOTAL # of varieties in the entire collection = 6309

USDA National Clonal Germplasm Repository (NCGR),
Wolfskill Ranch,
4334 Putah Creek Rd., Winters, CA

Here’s how to get some scions for your edible landscape:

Almost all plant material from the Davis gene bank is distributed as cuttings and deadlines for orders are those appropriate for such cuttings. These cuttings must be rooted or grafted/budded to produce a plant. Material of Juglans, Pistacia, and most Prunus are very difficult to root and the recipient must obtain appropriate rootstocks prior to receipt of scion cuttings.

Domestic orders are sent Priority Overnight by Federal Express. A packing list and certificate of quarantine compliance are shipped with the plant material when required. When orders are shipped within the U.S, it is necessary for the recipient to obtain and submit a Fed Ex account number. Fed Ex account numbers may be obtained by calling 1-800-GO-FEDEX.

Please indicate dormant cuttings, budwood/scionwood, or summer cuttings or budwood. Please use accession numbers when ordering material. Orders for dormant cuttings or budwood must be received by December 1^st, and are shipped in January/February. Orders for summer budwood/cuttings and open-pollinated seeds must be received by May 1^st, and are shipped in June-August. Orders for pollen must be received by January 31^st, and are shipped at appropriate times for each crop.

*Summer request for Punica and Morus germplasm should only be made if propagation will occur under mist.

*Due to great demand for dormant cuttings and their higher rooting success rate, we will no longer have routine distribution of Ficus summer cuttings.

Please be sure to include a phone number, email address, and Fed Ex/DHL account number.

Orders must be submitted via email to Bernie Prins (bernard.prins@ars.usda.gov)

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NOTE: The comments section at the bottom of the post has disappeared. Click on the "___ Comments" button or the title under the "Blog Archives". Thanks, Robert

The Myth of the Range of Tree Roots

The following is text from my book: Roots Demystified, Change Your Garden Habits to Help Roots Thrive.

The best book on the topic of fruit tree roots is The Root System of Fruit Plants compiled by a Russian named V. A. Kolesnikov. (As with most scientific papers, only initials are used for all but the surname.) Kolesnikov’s scientific papers appeared from 1924 until 1968, indicating that the USSR regime certainly valued his distinctive research.

Kolesnikov’s primary modus operandi for studying roots was the one he called “The Skeleton Method.” As with Professor Weaver’s studies, this method entailed precise excavation of the roots. In imitation of archaeological techniques, shovels were used first, followed by scoops and, eventually, brushes. This approach preserved more fine root hairs during excavation than the most common practice of using water forced from a hose, or even more than simple washing of the roots.

Kolesnikov’s conclusion is that fruit tree roots grow one-and-one-half to two and even three times the width of the foliage above them. More amazingly, he states that this ratio is maintained throughout the life of the tree, regardless of the rootstock, species, and soil (my emphasis added). This is clearly seen in the apple tree illustration depicted in the left side above. (Click on the image to get a better view.) Each type of fruit tree maintains a slightly different ratio of root mass to canopy. The best place for water, fertilizer, compost, and mulch is beyond the foliar dripline (canopy). This applies to most trees, not just fruit trees. The roots of fruit trees are studied more than ornamental or native trees because they are economic crops.

The illustration on the right is the misguided imagination of a graphic artist. Pretty to look at, but dead wrong. The roots in no way mirror the above-ground foliage.

The relationship of the width of a tree’s root-mass to the amount of moisture it should receive is critical. Applying water near the trunk is wasteful in any climate. In a climate that routinely experiences short droughts of a month or so up to six months (as in parts of the Southwest), drip irrigation is the most efficient way to distribute water to an entire root system.

The climate, however, need not be arid for trees to benefit from drip irrigation. In a study of established pecan trees in humid Georgia, trees with added drip irrigation showed a 51% increase in yields.

It's nuts to irrigate any other way.

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NOTE: The comments section at the bottom of the post has disappeared. Click on the "___ Comments" button or the title under the "Blog Archives". Thanks, Robert

Pop goes the weasel (tree)

As written in my book Roots Demystified, Change Your Gardening Habits to Help Roots Thrive, amendments are materials such as sand, peat moss, compost, and rice hulls have been added to the planting holes to supposedly improve drainage and keep the soil loose and friable. Fertilizers, such as blood meal, cottonseed meal, greensand, and wood ashes, are those ingredients added to provide mostly nutrients. Some amendments, such as compost, are thought to do both improve drainage and act as mild fertilizers.

One of the best studies of the effect of amendments for fertility was done at Oklahoma State University at Stillwater by Joseph Schulte and Carl Whitcomb. They planted 108 silver maple trees with 11 different soil treatments and a control (untreated planting hole). One conclusion was: "no benefit was derived from the use of soil amendments either with a good clay loam soil or a very poor silt loam subsoil." They found that the control plantings with no additional amendments generally outperformed the plantings with amendments for drainage and fertility.

The loose soil of the amendments in a traditional planting hole makes something like an underground swimming pool full of water when it rains hard, drowning important root hairs. Adding a lot of amendments only leaves the roots unprepared for the shock of what lies beyond the amended area. (And nobody can amend the area of the mature root system seeing as how much wider it is than the foliage.) Often the roots fail to make it out of the well-amended hole and merely circle around in the loose planting medium, rendering the trees likely to blow over during a storm. The trees most tolerant to wind are those with the widest root systems. Or, as the photo shows, not spreading the roots when planting can allow the tree to simply pop out of the ground when hit by a car or pulled out by hand.

Please post a comment - I want to know what you think.

Visit my web site to learn about my gardening books.

NOTE: The comments section at the bottom of the post has disappeared. Click on the "___ Comments" button or the title under the "Blog Archives". Thanks, Robert

Tattletale Lichens

Lichens are both beautiful and good. They indicate healthy air.

Last month when I was helping some friend assess their trees they were worried about the lichens “eating away” at their fruit trees’ wood. Assuming they were parasitic, he had used a wire brush to remove all the lichens from one tree. It jogged my memory.

Such trees are covered with a wonderful patina of various colors and shapes of lichens. The lichens take so many fascinating forms: circles of warm orange, furry gray-brown wavy circular fans, wavy greenish-brown circles, and the many other curious forms.

My friends were worried that a horrible fungus has invaded the trees’ living tissues. Fortunately, lichens are not parasitic. They live on the outer bark without effecting the living cells. (A lichen is an odd combination of both fungal filaments algae cells, usually a green algae.)

In 1866, William Nylander, a Finnish naturalist, was the first to link the disappearance of lichens and air pollution. He noticed that some lichen species present within Luxembourg Gardens, Paris, were missing in other parts of the city. He attributed these differences to air quality. Over the next thirty years, fumes from coal-burning industrial furnaces gradually led to the eradication of the lichen population within the park.

Sulfur dioxide (SO2), the result of industrial and urban emissions, does the most widespread damage to lower plants, even though it is only one of several air pollution components in the atmosphere.

Why are lichens sensitive to air pollution? Since lichens lack roots, surface absorption of rainfall is the only means of obtaining vital nutrients which are dissolved in rainwater. Lichens act like sponges, taking in everything that is dissolved in the rainwater, and retaining it. Since there is no means of purging the SO2, the sulfur content accumulates within the lichen and reaches a level where it breaks down the chlorophyll molecules which are responsible for photosynthesis in the algae. When the photosynthetic process stops in the algae, the algae die and this leads to the death of the fungus.

Since it is known that different species of lichens vary in sensitivity to air pollution, scientists can use these organisms as monitors of air pollution and as indicators of air quality. This is very useful because modern air quality instruments cannot measure the effects air pollution has on living cells and they are limited to measuring present conditions.

Most importantly, the lack of lichens on fruit trees would be a sure indicator that their orchard is not free from the harsh chemical sprays that harm and kill lichens.

I could readily tell that the air quality was fine in their backyard just by looking at what is growing on the bark of older trees. Take some time and look at the bark of some of your older trees. Hopefully, a few scattered patches of gray or orange lichens can be seen growing on the bark. Near a city, there is an obvious change in what is growing on tree trunks. Here there are areas where lichens don’t exist, such areas are termed "lichen deserts". As the air quality in these lichens deserts improve, lichens will begin to reappear in a slow process of recovery.

Lichens are sensitive to air pollution and have disappeared from many metropolitan and industrial areas over the last century. Lichens’ sensitivity to pollutants are actually used as biomonitors—like a green version of a canary in the coal mine.. Lichens are valuable research tools and through the information they provide, we can have a better understanding of the impact air pollution has on the environment.

There many books on the subject. Here are two:

T.H. Nash (Ed.). Lichen biology. Cambridge University, Press, 1996. Pp. 303
ISBN 0 521 45368 2

"This book is in the tradition of the work of ME Hale 'The biology of lichens', the third edition of which appeared in 1983 (first published in 1967). It provides a comprehensive and up-to-date account of the fascinating world of lichens. The last chapter explains the role of lichens as indicators of air pollution and the pollutant effects on lichen biology is discussed."

Another book with less jargon is: By D. H. S. Richardson, Paperback; Naturalist's Handbook Series: 19. Pollution monitoring with lichens. Published by Richmond Publishing Company, 1992, ISBN 978- 0855462895



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All rights reserved. Copyright 2008

Visit my web site to learn about my gardening books.

Note: I seem to have lost the usual way to leave comments. To do so, either click on the "___ comments" button or click on the title of the blog under "Blog Archive". Thanks, Robert

Deer versus Predators

When it gets down to it, deer are beautiful, graceful animals. They can leap a four-foot cattle fence with a elegant and simple leap. Before I wax eloquent, I notice the deer are now sampling even the Euphorbias in my garden. How can they stand the bad-tasting, poisonous sap? Hopefully it was just a sampling and they discovered it’s not a plant for even the most distraught of times.

Until this year, does were dropping two fawns each year. Now they are sometimes giving birth to only a single fawn. I wonder what is going on.

In years past, natural predators—bobcats and mountain lions—helped balance the deer herd, perhaps preventing excessive population explosions. With the encroachment of human habitat and agricultural endeavors on the forest and wilderness (sheep in my “backyard”), the role of predators in moderating or regulating deer populations has been greatly diminished or eliminated. Unfortunately, the predators of deer often don't mix well with suburbia or livestock. The predators of deer require large areas for their territory and are often quite shy of human activity. Furthermore, agricultural activities such as dairy and sheep herds and poultry flocks fear such predators and the farmer usually attempts to exterminate these wild cats.

I know one rural resident who was upset when a bobcat killed some of the chickens in his tiny, ram-shackle coop. But he was even more distraught when he couldn't get a clear shot at this pesty intruder. For the sake of a few eggs which were the last symbols of his back-to-the-land lifestyle—his vegetable garden had long ago been decimated by deer leaping the short, inadequate fence. This self-proclaimed environmentalist was willing to kill one of the only remaining natural predators of deer. This was the same environmentalist; who was, at the time, promoting ocean wave generation of electricity as the non-polluting answer to our coastal energy needs. He was willing to kill the first bobcat to reappear in the area in years for the sake of a little symbolic cholesterol-in-a-shell. This example clearly shows how environmental issues can so easily be segmented into seemingly unrelated fragments. A better chicken coop, a proper deer fence and a little tolerance or reverence for the sleek, marvelously-patterned bobcat could begin to strike a more normal balance with respect to deer and bobcat alike.

Ah, there is now a grape vineyard where the sheep used to graze. The vineyard manager has a “predation permit” to shoot deer that happen to get through the eight-foot fence that surrounds the 30 acres of grapes. Now the predators of deer are slowly beginning to return. I spot bobcats, or their scat, at least four times a year. I was woken up from a nap by a cacophony of many species of birds. I knew this meant they were trying to drive a bobcat away. I raised my head to see, not a bobcat, but a young mountain lion (cougar) slowly walking four feet from my house a casually through the garden. Being on the second floor, he didn’t even know I existed. The main predator of deer was back after 20 years of no sightings. I can often tell when he returns because I find the scat on the driveway and the deer don’t walk past my office every day as they used to like clockwork. I found the skeleton of a mature buck on the hillside next to the creek. Only a mountain lion is big enough to take down a mature five-point buck.

Until the return of the mountain lion, and still unto this day, the deer have had to fear another predator—the mechanical hunter called the automobile? On many a dark night, on a lonely country or suburban road, the metal meets the flesh. Sometimes the car wins and in the morning buzzards find a tasty meal. Sometimes the car looses and a radiator is pushed into the engine block and the local repair shop makes a killing—and the deer usually suffers a fatal blow. Occasionally, the car's occupants take some of the impact.

An individual deer is just small statistical blip in the population he or she belongs to. If said deer happens to be munching on your favorite rose buds, then all this highfalutin talk about the return of predators may seem like a waste of time. Your pissed at that *#^&$#@ deer, and he's got to go! Right. You can shoot what seems to be all the deer in the area, and they can recover to be a problem in a relatively short period of time. Even if you can tolerate the sight of a 150 pound mountain lion prowling around your kid's sandbox, predators most likely won't be able to keep the deer population low enough to solve many urban and suburban deer problems. One deer may not make a population in the eyes of a naturalist, but it's big enough to make a mess out of my much-beloved apple trees.

Please post a comment - I want to know what you think.

All rights reserved. Copyright 2008


To see more detail of the illustration(s) put you cursor over the image and double click.

Visit my web site to learn about my gardening books.

NOTE: I have lost the usual way to leave a comment. Try clicking on “__ comments” below or click on the title of the blog under “Blog Archive”. I’m still trying to fix the problem. Thanks

Rant - Too long winded?

Some of my friends say I’m too long winded, that some of—if not all—of my blogs are too long. Well they might be right.

However, I might just proceed with some long blogs.

So, this is a short rant blog.

Why my longer blogs? Because I’m tired of cute little garden blogs that tell you what coffee they’re drinking while they putz around in their garden. It may be satisfying to them to “document” every little detail of their day, but it sure doesn’t give me much useful information as to what I might use in my own ornamental deer-resistant garden and fruit tree orchard.

Short blogs are like sound bites. Enough to capture one’s attention, but no real depth to expand what I might already know. It’s like what I’ve always told my friends—USA Today broke through as a successful newspaper because each article is no longer than the time it takes to read on the john each morning.

I will blog at various lengths as I proceed. But I will continue to give short or long blogs depending upon what I think the subject deserves so some real content (or opinion) is offered. If you’re too busy to read one of the longer blogs, that’s OK by me. It’ll still be available when you have the time.

Please post a comment - I want to know what you think.

Note: I somehow lost the usual section "Post a comment". To leave a comment, simply click on the area/button that says "___ Comments". Clicking on the title of a Post under "Blog Archive" also gets you to a view that gives the option of leaving a comment. I hope to figure this out soon. Robert

Shaping, Not Just Pruning, Fruit Trees

I love Asian pears. They are flavorful yet crispy. And they ripen on the tree instead picking European pears early and letting them ripen in a dark, cool place.

I just got done pruning an Asian pear tree for a friend last week. It’s not easy pruning, or rather, shaping these trees.

Asian pear trees are inclined to sprout new growth that is even more vertical than European pear trees. This tendency to form vertical shoots with a narrow angle of attachment, which makes for a weaker crotch, must be dealt with in the first few months of each season's growth.

Shaping rather than pruning is the way to treat an Asian pear tree. I prefer to spread the young shoots in the early summer to a healthier, and more productive, 45- to 60-degree angle. I use toothpicks to spread the very young shoots once they are ten- to 16-inches long. When the shoots are this young, they are flexible enough to bend to any angle without snapping. I insert one point of a round, wooden toothpick into the new shoot a few inches above its point of origin. Next I bend the shoot out to the desired angle, and insert the other end into the bark of the tree's trunk. By the end of August, I can remove the toothpicks, and the new branch will stay mostly in the position it was trained to by the toothpick.

The tree I was working on last week hadn’t had its stems forced into a 45^o angle when it was young. The owners had missed several seasons. However, there are several ways to spread the older, more-stubborn limbs.

Spreaders can be made out of various lengths of one-by stakes with a nail point at both ends. In the photos you'll see that I used some used 1" X 4" pieces of wood. (You can make these by nailing an eight- or ten-penny box nail halfway into the each end and clipping off the nail's head with a wire-clipper.) Insert one nail point into the newer shoot or limb, bend it down to the correct angle, or a bit further, and insert the other nail point into the trunk.(See the left photo.)

A non-intrusive option is to find a nice heavy rock. Tie a sturdy string to the rock, bend the limb down, and tie the string to the limb. You can adjust the angle of the limb by moving the rock toward or away from the tree. With both methods, you'll need to keep the limb bound into the new position for several or more years to allow the branch to stiffen-up enough to hold its own position.

A neighbor filled Styrofoam cups with cement an inserted a wire before the cement hardened. Then the weights were added to the new growth to weight down the limbs to a proper angle.

Once the limbs come into bearing, the weight of each year's fruit is usually heavy enough to spread the limbs without assistance. In fact, the trees are usually prolific enough that too much spreading should be the gardener's concern—the branches break off. Thin the young fruits to a single fruit every five- to eight-inches apart along the limb. Keep an eye on the fruit-laden limbs, as they still may require propping to prevent torn limbs.

Please post a comment - I want to know what you think.

To see more detail of the illustration(s) put you cursor over the image and double click.

Note: I somehow lost the usual section "Post a comment". To leave a comment, simply click on the area/button that says "___ Comments". Clicking on the title of a Post under "Blog Archive" also gets you to a view that gives the option of leaving a comment. I hope to figure this out soon. Robert

All Rights Reserved. Copyright 2008

Visit my web site to learn about my gardening books.