watercore and apples

It’s late August, and some of my newly harvested Akane apples have a strange condition. From the outside they look normal, but when I cut into them, there are areas that look transparent and watery. They taste fine, but their appearance is kind of unappealing. What is causing this? Is there anything I can do to prevent it?

What you are describing sounds like a condition called water core, where the plant tissue has started to break down. According to Washington State University’s Tree Fruit Research and Extension Center there are many potential causes of the condition. Certain varieties are more susceptible than others. “Advanced maturity” (i.e., apples that have been on the tree a bit too long), and a lack of calcium may also be a factor. We have had a hot summer, and intense sunlight and heat may also have contributed. On the plus side, the watery areas tend to taste sweeter than the rest of the fruit, and people in some parts of the world (such as Japan ) actually seek out watercored apples for just this reason. The main problem is that affected fruit will not last long in storage. You may want to test your soil to detect any nutrient imbalances and then amend the soil accordingly.

on Artemisia ludoviciana

Can you tell me about an herb called Estafiate (I think it’s Spanish)? What would the English name be, and how is it used?

There isn’t always a straightforward link between a common name and a specific scientific name, but it seems that Estafiate usually refers to Artemisia ludoviciana, possibly the subspecies mexicana, which goes by several different English common names, including white sagebrush, prairie sage, Louisiana sage, and Mexican wormwood. The USDA taxonomy website has information about this plant, as does their general plant database.

Duke’s Handbook of Medicinal Plants of Latin America by James A. Duke (CRC Press, 2009) lists Estafiate as Artemisia ludoviciana and several other synonymous names. Its diverse uses include analgesic, antiseptic, and fungicidal but it also has dermatitigenic and carcinogenic properties and is elsewhere (FDA) classified as a poisonous plant. One should never attempt to use a medicinal plant without full medical knowledge and consultation with a health professional! The plant has been used by Native American (Blackfoot, Apache, Cheyenne and other tribes)as well as Mexican practitioners.

Another Spanish common name for the same or similar plant is Ajenjo, which may refer to Artemisia absinthium, which is the same plant from which Absinthe is historically derived. Missouri Botanical Garden has a website with information about this species Artemisia.

arbor climbers and clematis companions

I’m planning an arbor in my garden which will be 6′ wide, 4′ deep, and 6-7′ high. I’d like to plant on one side Clematis ‘Polish Spirit’ . Can you suggest a climber that would go with the Clematis for the other side? The other climber would be in partial shade. Great Plant Picks says that Clematis, with pruning, can be managed to 12′ long. How wide can it get or, a different question, would I need to plant one or two for coverage of the planned arbor? Also if you have other favorite arbor climbers and combinations of climbers I would love to know about them.

There are many choices for combining with your Clematis. Climbing roses are considered a natural companion of clematis and, depending on your color preferences, perhaps something which contrasts with the deep purple would be nice: either white or a pale pink. When you say the other side is in part shade, I wonder how many hours of sunlight it does get. Once the prospective climber reaches the top, will it be in sunlight? You could also plant a clematis of contrasting color or flowering season on that side. There are many books in our library on combining clematis with other plants, such as Companions to Clematis by Marigold Badcock (Master Craftsman, 2000), and Clematis as Companion Plants by Barry Fretwell (Cassell, 1994). There is even an entire book on clematis and roses: The Rose and Clematis as Good Companions by John Howells (Garden Art Press, 1996).

If you like roses but not thorns, you could grow a Lady Banks rose which is thornless, but you would have to keep it pruned (it wants to be 20 feet high). The Northwest-based gardening website, Paghat’s Garden, describes it.

Rosa ‘New Dawn’ is a very popular choice in the Northwest, and is recommended by virtually every local garden writer I have come across. Here is a (non-local!) description from Missouri Botanical Garden.

Another option might be the white variety of potato vine, Solanum laxum ‘Album,’ though it may be a bit tender in cold winters.

Eventually your clematis will cover the width of the arbor, but Clematis viticella cultivars like yours are easy to prune (late winter/early spring) and keep to a manageable size. If you like the idea of having more than one color/plant/flowering season, it’s perfectly fine to add another climber. I would avoid anything that is highly aggressive or rampant (Passiflora, Akebia, Campsis, Clematis montana, and others), as you don’t want to overpower ‘Polish Spirit.’

propagating black mondo grass from seed

Last year, I collected and propagated seed from my black mondo grass. I now have about a hundred healthy starts which are green in color, with leaves thicker than those of the parent black mondo plants. Is this just their immature color, or do they not come true from seed?

Most of the resources I consulted recommend propagating Ophiopogon planiscapus ‘Nigrescens’ by division of clumps in fall or late winter, but The Plantfinder’s Guide to Ornamental Grasses by Roger Grounds (Timber Press, 1998) says the following:
“The flowers are mauve, but the berries are black, and if sown will produce about one-third black seedlings, the rest being green.”

If all of your plants came up green, I would guess they will stay that color (in other words, they must have reverted to the species, Ophiopogon planiscapus, which has wider green leaves).

evergreen Irises for the PNW

I would like to use Iris foetidissima ‘Variegata’ in large numbers in my landscape.I have heard that this plant is evergreen in our Pacific Northwest winters.
As I have never grown this iris, I would love to hear what you have to say.
Is it really evergreen? I live in Portland, Oregon. Some people I asked say otherwise.

In my experience, this Iris is evergreen in the Seattle area. Its leaves remain over the winter. The following information confirms this.

From Paghat’s Garden, written by a Seattle gardener:
“This thoroughly evergreen iris loves moderate shade but also does well in considerable sunlight. It grows to three feet tall or so, with large evergreen sabres of leaves that simply never fade away in the manner of the vast majority of irises.

There is no better iris for a ‘permanent’ feature of sword leaves, though where winters fall into the teens Fahrenheit, the leaves may be damaged and need to be thinned late in winter to remove injured leaves, being quick to recover in spring. In our moderate winters, Iris foetidissima has no leaf damage in the least.”

Portland gardener Ketzel Levine (page now archived) has this to say:
“Like most variegated plants, the striped iris are grown for their foliage rather than for their flowers–which is a good thing in the case of the exquisite though unreasonably rare Iris foetidissima ‘Variegata’, since its pale mauve flowers are unlikely to attract attention. All the better, though, to enjoy its dramatic eighteen-inch evergreen leaves, brilliant fans of white-streaked foliage that blend with anything in summer, bring drama to winter, and thrive in shade.”

managing black spots on roses

What can I do about black spot on my roses? I heard that burying banana peels in the soil might help.

According to The Organic Gardener’s Handbook of Natural Insect and Disease Control (edited by Barbara Ellis; Rodale Press, 1996), there are several steps to dealing with black spot on your roses. First, avoid wetting the leaves, and do not handle the plants when foliage is wet. Prune the plants to make sure there is good air circulation. Make sure the roses are in sun, and are not shaded by large shrubs or trees. Avoid using high-nitrogen fertilizers, and only fertilize based on a soil test’s indications. If you expect an appearance of black spot (based on past experience), spray plants weekly with sulfur or fungicidal soap. Once you see symptoms, it is hard to control black spot. Remove and dispose of any affected parts of the plant (don’t compost). Make a solution of 1 teaspoon baking soda in a quart of water, and spray the infected plants well.

University of California, Davis’s Integrated Pest Management website says the following about black spot (Diplocarpon rosae):

“The fungus requires free water to reproduce and grow, so leaves should not be allowed to remain wet for more than 7 hours. (When hosing off aphids, do it in the morning so leaves have a chance to dry by midday.) Provide good air circulation around bushes. Remove fallen leaves and other infested material and prune out infected stems during the dormant season. (…) Miniature roses are more susceptible than other types, although a few varieties are reliably resistant to all strains of black spot.(…) A combination of sodium bicarbonate or potassium bicarbonate plus horticultural oil (as discussed above under “Powdery mildew”) or neem oil has also been shown to be effective in reducing black spot.”

Brooklyn Botanic Garden has information on natural disease control, including the following:
“Baking soda (sodium bicarbonate) is non-toxic, readily available, and very inexpensive. It can be effective against powdery mildew and somewhat useful against black spot. If you repeatedly spray leaves with bicarbonate, though, it will eventually reach the soil below, where it can accumulate and lead to slower plant growth. Bicarbonate can form insoluble particles with calcium and magnesium ions when it concentrates in the soil, making these important nutrients unavailable to plants. High levels can also prevent plants from absorbing iron and can lead to chlorosis.
Bicarbonate is most likely to build to damaging levels in drought-stressed areas where there is little rain to flush it away. It is also likely to build up when applied in a small area, and when used in conjunction with drip-type irrigation. Garden situations are so complex that it is hard to predict the point at which you will see adverse effects. Stop applying bicarbonate sprays, however, at the first sign of plant damage or lower quality blooms.”

Brooklyn Botanic Garden also mentions a beneficial bacterium which may provide some help:
“Preliminary research shows that the beneficial bacterium Bacillus laterosporus (sold as Rose Flora) is as effective at protecting black spot-susceptible rose cultivars as some chemical fungicides. It probably protects against black spot through competition, but this agent is still relatively new and experiments detailing its mode of action have not been completed. As a ground spray, it can help control new sources of black spot infection. As a foliar spray, it seems to be more effective when mixed with the antitranspirant sold commercially as Wilt-Pruf. The powdered formulation can cause eye irritation, so use eye protection when mixing solutions and applying.”

About the practice of using banana peels to control black spot on roses, I found the following item on Gardening Folklore from Ohio State University Extension, which suggests the peels might be a good fertilizer, but does not say they will control the fungal problem.
Excerpt:

“Placing several banana peels in the planting hole was popular among rose growers in the 18th century, but they had no idea why the peels seemed to yield healthier roses. Today, we know that banana peels contained many useful nutrients, including calcium, magnesium, sulfur, phosphates and sodium. The peels rot quickly which means these nutrients are readily available to the plant.”

Some sources recommend using compost tea or milk sprays on black spot-affected leaves, but Washington State University Horticulture Professor Linda Chalker-Scott dismisses these methods as ineffective. She also states in an article in Master Gardener magazine (Spring 2009) that baking soda sprays may only be of limited efficacy in combatting black spot. Studies have shown that it works better when combined with horticultural oil.

To sum up, I would pay attention to the cultural practices (not wetting the leaves, etc.). You can try a baking soda spray (always test on a small area of the plant first), but it may not have lasting power as a treatment. Prof. Chalker-Scott mentions that coarse organic mulch (such as wood chips) reduces incidence of black spot, so you may want to adopt this mulching practice.

fruit trees and lack of fruits

I planted numerous fruit trees about 7 years ago. These
included almond, pear, apple, hazelnut, and plum. The almond and apple
trees have done really well.

The pear, plum, and hazelnut trees have
never even bloomed, let alone borne fruit. Am I doing something wrong or
do I just need to be a little more patient?

All of your trees should be mature enough to flower and bear fruit, given
the right conditions. There are many potential causes of failure to
flower. Are your trees that have not flowered in a location that receives
high nitrogen fertilizer (such as near a lawn)? This would lead to lots
of leafy growth at the expense of flowers. Cold winter weather can also
damage buds and lead to no flowers.

The lack of fruit could be due to lack of pollination in addition to the
causes listed above. Do you have two or more pears (Pyrus) and hazelnuts (Corylus)? Is your
plum (Prunus) a variety that needs a pollenizer, or is it self-fertile? Raintree Nursery has information on flowering and fruiting for Corylus that says”Two different varieties or seedlings of similar flowering period,” are needed, and that “European Filbert flowers winterkill at -15 F. Others are hardier.”

Oregon State University Extension has fruit pollination charts, and there is an example from Burnt Ridge Nursery for European pears.

General information from University of Vermont Extension on failure to flower and failure to bear fruit from Washington State University Extension.

Pacific Madrone and fungal diseases

We recently bought a house on San Juan Island with lots of beautiful madronas (Arbutus menziesii) on the property. Two of them show no signs of life… others have the occasional dead branch here and there. We have been advised that this is likely caused by a fungus and that it can spread rapidly. We have been shown blackened excavated areas on the trunks of the dead trees.. and similar though less extensive areas on some of the others. What can be done to save our beautiful madronas?

It is possible your trees are suffering from canker fungus (Nattrassia mangiferae), or some other type of fungal disease. Here is a link to a file called “The Decline of the Pacific Madrone” edited by A. B. Adams (from a symposium held here at the Center for Urban Horticulture in 1995).

You may want to call a certified arborist to look at the trees, determine the extent of the disease, and help you decide whether the trees can be salvaged. (Search the Pacific Northwest Chapter of the International Society of Arboriculture for a local arborist.)

Below is a response to a question similar to yours from the
University of British Columbia Botanical Garden and Centre for Plant Research:

“What you describe are the classic symptoms of ‘Arbutus decline,’ which is postulated in the literature as being caused by mostly naturally-occurring, weakly pathogenic fungi, made more virulent by the predisposition of Arbutus to disease, caused by urban stresses, especially root disturbance.” (see also: “Arbutus Tree Decline” from Nanaimo. B.C.’s Parks, Recreation and Culture department)

Nevertheless, I am convinced that much of the die-back we are seeing on established Arbutus trees stems not from disease, but primarily from the complications of damage, competition, shading and especially, drought stress (we have had a run of very droughty summers). Typically, the most affected natural stands of Arbutus are very dense, with poor air-circulation, internal shading and intense competition for resources (characteristic of rapid growth after clearing). And because this region is becoming increasingly urbanized, with more vehicular and marine traffic (marine traffic evidently accounts for a huge proportion of the pollution in the Fraser Basin air-shed), I would not discount atmospheric pollution as a contributor to the decline (one more stress).

I think the reason your shaded trees are not as affected is that their roots are probably deeper and less exposed, and there is reduced evaporative demand on the leaves. However, as the shade increases, these plants, or at least their shaded branches, will succumb.

What to do? I do not think there is anything you can do to save the existing trees, except, perhaps, to minimize human influence around them. You should avoid both disrupting roots and damaging above-ground portions of the trees (with pruning, for example), as any wound is an open invitation to disease-causing micro-organisms. Interestingly, a friend of mine who kayaks has seen black bears foraging for fruit in the tops of Arbutus trees on Keats Island (he should have told them they are not helping the situation any).

Irrigation of established plants is nearly always counter-productive because it encourages surface rooting (which is typically short-lived and considerably less resilient than deep rooting), and summer irrigation is worse, as Arbutus are well adapted to our conditions (at least, where we find them growing naturally) and normally somewhat dormant in summer.

You can plant more Arbutus, as a previous correspondent in this thread has, to replace what you are losing, but there is no guarantee that these plants will survive the next drought or indeed, your well-intentioned meddling. (I suspect his plant was lost for the same reason most young Arbutus are lost–by root damage from saturated or compacted soil conditions). The natural succession on your island is probably (as elsewhere in similar places along the coast) tending toward open Douglas fir forest with a few scattered Arbutus in the more inhospitable places. In other words, you can plant what you will, but the larger the Douglas firs, the fewer Arbutus will be able to survive around them. Neither species is particularly shade tolerant and resources are pretty limited on rocky ground, where both prefer to grow locally. Expect change.

removing burls from trees

I would like to remove a burl from one of my fir trees. Can I do this without causing harm to the tree?

I was unable to find any information on the incidence of burls (lignotubers) on fir trees (Abies), but I did locate information about redwood (Sequoia sempervirens) burls from a version of The Sempervirens Fund website which is no longer available:

About Redwood Burl

by Chris Brinegar, PhD

“The swollen tissue at the base of some redwood trees is commonly known as a “burl” although scientifically it is referred to as a lignotuber (from the Latin for “woody swelling”). All redwoods have lignotuber tissue but not all have large visible burls. Lignotuber tissue is derived from cells that exist in the tree’s seedling stage and then proliferate near the base of the tree as it ages. Buds form within the woody burl and remain dormant until stimulated to grow by damage to the main trunk (usually by fire or logging). The resulting shoots grow rapidly using carbohydrates stored in the surrounding cells and minerals transported through the parent tree’s root system. Lignotubers can also form their own roots.

Lignotubers are responsible for vegetative (clonal) reproduction common in redwoods. Without this mode of propagation, the redwood forest would appear far different than it does currently. The second and third-growth redwoods in our coastal forests were generated vegetatively after 19th and 20th century logging of the original forests. If redwoods were solely dependent on reproduction from seed, their numbers would only be a small fraction of what we see today.

Most people think of burl as the “sliced redwood” sold in gift shops and roadside stands, but they do not realize that many of these burls were obtained illegally. There is a growing black market for burl with much of it coming from unscrupulous dealers who harvest it from healthy redwoods on protected forestland. In some cases, removing burl can kill a tree or, at the very least, deface it and reduce its reproductive potential.

Burls can be planted under the appropriate conditions to allow the shoots to form roots and then grow into trees, but the typical buyer of a redwood burl places it in water, watches the shoots grow, then disposes of it after the shoots die from lack of nutrients. If you are determined to grow a redwood tree we suggest that you purchase a small seed-derived tree from a reputable nursery rather than trying to grow one from a burl that may have been acquired through questionable methods.”

According to the information here, it seems that by removing a burl, you may risk harming or killing the tree. You might want to contact a certified arborist in your area, and ask them what they recommend. Here is a link to the website of the Pacific Northwest chapter of the International Society of Arboriculture, where you can find lists of certified arborists.

removing unwanted bamboo

I recently moved to a property that used to be a bamboo
farm. About 1 acre of bamboo remains. It is of the Henon species and
about 20-25 feet in height and it appears to have some mite infestation.
I want to remove all of the bamboo, and restore the land to native plant
habitat. What is the most economical way to remove bamboo and its root
clumps? I have hand dug (and burned) a lot of bamboo, but frankly feel
overwhelmed by the task at hand because there is still a lot of bamboo on
the property. Any suggestions you can offer would be immensely
appreciated.

The American Bamboo Society website (page now archived) has information on getting rid of
unwanted bamboo, excerpted below. Henon bamboo is a name for a variety of
Phyllostachys nigra, which is a running bamboo.

REMOVING A RUNNING BAMBOO

If new shoots of bamboo are coming up all over your yard, it is a running
bamboo. To get rid of it, there are four steps:

Cut it off.

Cut it down.

Water the area.

Cut it down again.

Cut it off. All of the culms (stalks) of bamboo in a clump or grove
are interconnected underground by rhizomes (underground stems) unless you
have cut them by digging a ditch or cutting a line with a spade. A bamboo
grove is usually one single plant, not a group of plants. Many people
have the impression that every bamboo culm is a separate “tree.”If the bamboo in your yard has come across from your neighbor’s yard,
separate your grove from his by cutting the connecting rhizomes, which
are usually quite shallow. If you don’t, and his part is healthy and
vigorous, the rhizomes in your part will still be supported by the
photosynthesis in the leaves of his part, and your efforts will be in
vain. On the other hand, if you do manage to kill your part with a
herbicide you may also kill his part. Lawsuits or at least hard feelings
can result.Therefore, be sure to isolate the portion you want to keep from the
portion you want to kill. Cutting rhizomes with a spade or a saw will do
the trick if you do it every year. If the growth is old, you may need to
use a mattock or a digging bar the first time. Digging a ditch and
putting in a barrier* is a more permanent solution.

Cut it down.Cut the grove to the ground. All of it. If there is any part you want to
keep, see (1).

Water and fertilize the area, to cause new growth.

Cut it down again. And again.

New shoots will come up from the rhizomes. Break them off or cut them off
with pruning shears. Keep doing this until no more shoots come up. This
will exhaust the energy stored in the rhizomes underground. Without green
leaves to photosynthesize and produce new energy, they will no longer be
able to send up new shoots. The rhizomes will be left behind, but will
rot away.That’s all you need to do. You need a saw, a pair of pruning shears, and
patience, and maybe a spade and/or mattock. The widely advertised
herbicides don’t work well on bamboo, probably because so much of the
plant is underground. Since cutting the bamboo down will do the trick,
and you have to cut the bamboo down anyway to remove it from your yard,
herbicides are a waste of time and money in this case.

The method described above sounds labor–and time–intensive for a large
area like yours. However, if you can cut it all down as close to the
ground as possible, and then repeatedly mow any new growth, you may be
able to kill it. Here is what the USDA recommends:

Eradicating bamboo is accomplished by first removing all top growth, and
then destroying the new shoots as they emerge. If the ground is level and
the canes can be cut off very close to the ground, mowing is the best way
to destroy new shoots. If the ground cannot be mowed, the canes should be
cut down and the area plowed to destroy new shoots as they emerge.
Several plowings or mowings will be necessary, but the rhizome need not
be removed; it will become depleted and die.

This information is from gardening expert Mike McGrath, via a
commercial garden supply business, and there is a possibility that his
suggestions of sheet mulching the area (also labor-intensive if you have
an acre to deal with) or using high-strength vinegar-based products (use
extreme caution with these, even though they are ‘natural,’ as they are
still quite hazardous) might help.