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PAL Questions: 830 - Garden Tools: 346 - Recommended Websites: 680

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Keywords: Insect pests--Control, Integrated pest management

PAL Question:

Is it normal to have many different insect pests in one garden? Is it a sign that I am not taking care of my plants well? Everything looks fine except for one infestation after another!

View Answer:

As far as I am concerned it is perfectly normal to have all of these pests (because I also have many)! But some gardeners are more ruthless than I am. They would rip out the plants. Others would assault their garden with chemicals. I prefer the middle ground of tolerance of some damage and using low-toxic controls.

The mantra these days is RIGHT PLANT RIGHT PLACE and HEALTHY SOIL = HEALTHY PLANTS. For further information (and support) go to the Seattle Public Utilities website, which has a number of great publications on Natural Lawn and Garden Care. There are lots of links to browse.

There is also information about Natural Pest, Weed, and Disease Control.

Other good resources are Washington Toxics Coalition and Northwest Center for Alternatives to Pesticides.

Season All Season
Date 2006-12-08
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Keywords: Flowering of plants, Syringa

PAL Question:

I have a lilac shrub that is about six or seven years old and blooms every other year. This seems very odd to me. Most lilacs bloom every year. Is blooming every other year normal? It is planted in optimal conditions and looks very healthy.

View Answer:

Quoted directly from Lilacs for the Garden, by J. Bennett (2002, p. 99): Some lilacs, especially cultivars of the common lilac (Syringa vulgaris) bloom better—or only—in alternate years. Pruning the plant soon after it does bloom may encourage flowers the next year. University of Nebraska Extension says that "removing the seed capsules soon after flowering has been reported to alter the every-other-year flowering cycle in some lilacs. This is because less energy goes into the current year's seed production and more into the next year's flower production. Some researchers agree with this recommendation and some do not. Removing seed capsules also improves the plant's appearance."

I could not find a list of which cultivars do this. Here is an example of another species, Syringa reticulata, which also tends to bloom in alternate years. You might consult the International Lilac Society to see if a list exists.

Another resource is the Hulda Klager Lilac Gardens (in Woodland, WA about 30 minutes north of Portland).

Season Spring
Date 2008-01-17
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Keywords: Color guides

PAL Question:

I need a reference that lists the greenscale color of leaves (or plants).

View Answer:

It would be helpful to have more information about what you are trying to do. There are charts which show different shades of green in leaves as evidence of nitrogen levels, but these are mainly used in agricultural settings, such as rice cultivation.

If you are looking for charts used in horticulture, one tool for answering questions about plant colors is the Colour Chart put out by the Royal Horticultural Society. This is a set of numbered cards, in every imaginable color, that you can hold up to a flower or leaf in order to determine the standardized color. There is an extensive set of colors in the green scale. The problem with the RHS color chart is that it is expensive. If you are able to visit the Miller Library, we have a copy of this color chart that you are able to check out, or you are welcome to use the chart in our Reference section.

In addition ot the above-mentioned color chart, there is a miniature version of the chart available through the Royal Horticultural Society, which can be found at:
http://www.rhs.org.uk/Plants/RHS-Publications/RHS-colour-charts

If you would like to see a sample of Red-Green-Blue web-based colors, you can type Color Chart into Google and get a nice list of possibilities.

Season All Season
Date 2008-01-17
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Keywords: Climatic zones

PAL Question:

I have seen references to Climate Zones or Plant Zones, could you please point me to a reference that would help me to find what areas of the country or climates that these zones refer to.

View Answer:

The handiest way to tell what part of the country a given zone covers is to consult a map. Here are two web sites that will help you do just that.

The National Arbor Day Foundation web site has a concise explanation of Hardiness Zones. Just enter your ZIP code in the search box and press the Look it Up button. A map will pop up telling you the zone in which your town falls.

In case you would like to compare the above site to another one, The United States National Arboretum has a clickable map that will also allow you to determine your zone. Just click on your state on the map or, alternatively, click on the state abbreviation below the map and you will be able to tell what zones apply to your area.

The American Horticultural Society has produced a "heat zone" map, which serves to address drought and heat tolerance in different regions.

If you are on the West Coast, you may find the Sunset climate zones more helpful, as they take into account other variables besides just winter minimum temperatures. Search for keyword 'climate' or 'zones.'

Another great resource at the library is The New Sunset Western Garden Book, edited by Kathleen Norris Brenzel. Menlo Park, CA : Sunset Pub. Corp., 2012.

Season All Season
Date 2006-12-08
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Keywords: Plant care, Jasminum

PAL Question:

I have a question about the common jasmine plant. Can it be planted in a pot and left on the patio all year round? It will be attached to a fixed trellis. What should we do to protect the plant in the winter?

We live in Langley BC, so our weather is quite similar to yours.

View Answer:

The American Horticulture Society's A to Z Plant Encyclopedia reports that Common Jasmine (Jasminum officinale) is only hardy to zone 9. (Seattle is zone 8, Langley may be a touch cooler)

However, local author (I believe she lives in BC) Christine Allen reports that Jasminum officinale, also known as poet's jasmine, is hardy in our climate if protected from cold, drying winter winds. I think if you move your pot against a wall out of the wind you should be ok.

Season All Season
Date 2006-05-26
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Keywords: Origanum, Herbs

PAL Question:

I have marjoram and/or oregano growing all over. I like it and use it as filler, left over from herbs I bought several years ago. But, to cut them and use for seasoning, I don't know which is which and they don't seem to be so fragrant. Should I just start over and buy new plants to know what I have? How can I tell the difference between the two plants?

View Answer:

Everytime I get this question (this almost qualifies for a frequently asked question) I have to look it up again because even the authorities get mixed up.

Oregano and marjoram are the same genus, Origanum, but different species/hybrids.Marjoram usually refers to Origanum majorana. Marjoram leaves tend to be more gray green in color than oregano, and the leaves are generally smaller. Oregano usually refers to Origanum vulgare. It has a more pungent flavor, while marjoram is sweeter and milder. If you are interested in learning more, this guide from the Herb Society of America goes into great depth on oregano and marjoram.

The short answer to your question is YES, you should start over with new plants if you want good flavored herbs. You could bring in (or mail) a sample to the Hyde Herbarium here at the Center, 3501 NE 41st St. Seattle: http://depts.washington.edu/hydeherb/

Season All Season
Date 2008-01-17
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Keywords: Pyrus, Fall foliage

PAL Question:

Which semi-dwarf pear tree should I plant to get good fall color? I want to eat the fruit and have beautiful yellow to red fall leaves in my landscape.

View Answer:

Not many of our resources on pears describe the color of the fall foliage, as they tend to focus on the taste and appearance of the fruit. However, I did consult Lee Reich's Landscaping with Fruit (Storey Publishing, 2009), and on page 146 he features "seasons of visual interest." Here is what the author has to say:
"Come autumn, leaves of many pear varieties, including many Asian varieties and such Europeans as 'Colmar d'Ete,' 'Durandeau,' and 'Triomphe de Vienne,' take on very attractive coloration. Ripening pears among the leaves, especially yellow varieties, also contribute to the show."

I suspect that the varieties mentioned above are heritage varieties that may be challenging to find. You might find these links of interest:

By doing an internet search, I came across a reference in a book entitled Growing Shrubs and Small Trees in Cold Climates by Debbie Lonnee et al. On page 233, the authors mention that the variety 'Golden Spice' has "nice fall color." The 'Luscious' variety is said to "turn a nice red in fall." This book confirms what I have read elsewhere, which is that ornamental pear trees are better known for their fall color.

Another approach would be to talk to pear vendors at farmers markets or talk directly to fruit farmers in your area, and ask if there are particular varieties which are notable for their autumn foliage.

An additional consideration is choosing pears which are late-ripening. If you want the fall color to coincide with the pears, you should probably choose a late-ripening variety. Pears are harvested before they are fully ripe, so later varieties will give you a better chance of night temperatures being sufficiently cool for leaves to begin changing color. Oregon State University's publication, "Picking and Ripening Apples and Pears," by R. L. Stebbins et al., has additional details on different pear varieties.

Season Fall
Date 2011-11-02
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Keywords: Magnolia grandiflora, Trees--Pacific Northwest

PAL Question:

I was reading a Seattle Times article and was hoping that you could tell me more about Magnolia grandiflora 'Alta' and its hardiness in the Pacific Northwest and what its mature dimensions would be.

View Answer:

Magnolia grandiflora 'Alta' is a trademarked Monrovia introduction. According to their website, it is "very slow growing to 20 ft. tall, 9 ft. wide in 10 years." Since this is a relatively recent introduction, there is not going to be much information about its hardiness in our area until more gardeners have grown it and shared their experiences. The longevity of the species Magnolia grandiflora and its cultivars can only be estimated (between 50-150 years, according to SelecTree.) Trees grown in urban settings are often affected by root disturbance, pollution, and the like, so their lives may be somewhat toward the short end of the expectancy range.

The local website of Great Plant Picks lists two different cultivars of Magnolia grandiflora, which may give you some idea of how well they do in our area. Here is an excerpt:

"Provide southern magnolias with good drainage and full to partial sun. They thrive in hot spots, where the extra heat encourages better flowering. These flowering evergreens prefer well-drained, sandy soil, but they tolerate average garden soil. Best growth and flowering requires occasional summer watering, but once established, southern magnolias withstand considerable drought. Garden gently under magnolias, for they have fleshy roots that can easily be damaged. The best approach for companions plants is to tuck in natural spreaders and let them flourish untouched."

From my observations, they do not do well in the occasional winters when we have heavy snowfall, as their evergreen leaf-laden branches are prone to breaking under the weight of snow. Otherwise, they seem to survive here.

Season All Season
Date 2008-01-24
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Keywords: Grapes--Diseases and pests, Vitis, Viticulture

PAL Question:

I am looking to install wine-producing grapes in my back yard, but I want to purchase vines from a reputable company, especially since I want to minimize the chance of exposure to Phylloxera. Where would you recommend I shop for the 12-20 vines I would like to install in my back yard?

View Answer:

While I cannot guarantee that any of these nurseries sell stock that is free of Phylloxera, here are three reputable nurseries that may have what you are looking for:

Raintree Nursery
Burnt Ridge Nursery & Orchards
Cloud Mountain Farm

Source: Susan Hill. The Pacific Northwest Plant Locator 2000-2001.

If you would like to know more about Phylloxera, Oregon State University's booklet, Grape Phylloxera: Biology and Management in the Pacific Northwest discusses the subject in great detail.

Season All Season
Date 2006-12-08
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Keywords: Perovskia, Lavandula, Botanical nomenclature

PAL Question:

I am looking for rare Siberian lavender. Can you help?

View Answer:

I think what you mean is Russian sage, Perovskia atriplicifolia. You might want to phone your favorite retail nursery to see whether they carry it (it is very popular). If it is not available, here are two Oregon nurseries that list it in their current catalogs:

Forestfarm in Williams, OR.
Joy Creek Nursery in Scappoose, OR

The following article from University of Illinois Champaign-Urbana Extension describes the confusion between Russian sage and 'Siberian lavender:'
"To the best of my knowledge, there is no such plant as Siberian Lavender. I have heard of English lavender, French lavender and Spanish lavender. By law all of these offers must list the Latin name of the plant; although sometimes it is in the tiniest of print. Check the ad again and see if you can find the words Perovskia atriplicifolia anywhere in the ad. Russian sage. It is a really fine plant, but it is not lavender. It does not look like lavender and it does not smell like lavender.
Do your homework and read the fine print. I know many people are not familiar with botanical names, but that is the only way to know what you are getting. Once you know the botanical name, even if you cannot pronounce it, you can find information about the plant. Botanical names are unique. Common names can be very misleading. A good example is an ad I saw recently in the newspaper. It was touting the luxurious beauty and fragrance of Siberian lavender. I had never heard of anything called Siberian lavender so I kept reading. The ad stated (with lots of exclamation points) how Siberian lavender produces thousands of flowers and has the delicate scent of lavender perfume year after year. Wow, sounds pretty fantastic. I continued to look to find the botanical name. In the minuscule fine print it said, Variety: perovskia atripliafolia (which I assume to be the misspelling of Perovskia atriplicifolia) also known as Russian sage. Russian sage is a nice perennial plant with silvery white leaves and soft bluish-purple flowers held in loose spikes. However, even from far away on a foggy day I doubt Russian sage would hold even a slight resemblance to lavender. Russian sage does have a fragrance, but it is more reminiscent of sage than of lavender."

Season All Season
Date 2008-01-24
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Keywords: Shade trees

PAL Question:

We would like to plant a special evergreen tree that would be a large heirloom or heritage tree. We would like this to be the centerpiece of our back yard. We know the type of trees that typically fall into this category will be slow-growing, so we want to plant it soon so that it will be big enough for our grandchildren to climb in, swing from, play under, etc.

We would like a tree that is quite large and wide (possibly even wider than it is tall, around 40 feet tall x 40+ feet wide), with branches that start relatively low on the trunk, but do not go all the way to the ground (so you could both climb into it and have a picnic table under it).

View Answer:

Following are websites that I use frequently when trying to narrow down tree lists. (Note: Some of the sites have a zone option—i.e. where the trees grow best. You are in USDA Zone 8 & Sunset Zone 5). In some cases, you can narrow down the selection even further, by selecting tree attributes (see the SelecTree site below).

From Virginia Tech. Go to ID Fact Sheets. This site is best for descriptions when you already have a species in mind.

Search the SelecTree database from CalPoly.
The best way to get a good list (with TONS of options) is to click on Select Tree by Attribute.

A classic source is the USDA Forest Service internet version of Silvics of North America. It will not help with selection since you will need to know what species you want, but it will provide more information than you will ever need!

Season All Season
Date 2008-01-24
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Keywords: Aphids, Integrated pest management, Viburnum

PAL Question:

I have a small snowball bush that I planted three years ago. Each spring this plant is inundated with more and more ants and aphids. I try to garden organically and could use Safer Soap on it, but it is large and the leaves are all curled under and withering from the insects. Is there anything other than Safer Soap that I could use to help the plant, either systemic or otherwise?

View Answer:

Following are the best sources I have found about environmentally friendly control of aphids.

Aphids (order Homoptera)

Host/Site:
Almost all plants have an aphid species that may occasionally feed on them. Many aphid species attack several plants rather than having only one host. Trees (esp. birch, beech, maple, apple, peach, apple, plum, cherry, spruce, dogwood, willow); annuals (esp. nasturtium, snapdragon); perennials (esp. lupine, roses, lilies, begonias, columbine); vegetables (esp. peas, beans, brassicas, lettuce, spinach); fruit (esp. apple, peach, cherry).

Identification/appearance:
Small (2 mm long), pear-shaped, softbodied insects in a range of colors (green, brown, red, yellow, black). Most are wingless, but winged aphids appear at certain times, especially when populations are high or during spring or fall. A few species appear waxy or woolly. A magnifying glass will reveal the long, slender mouth parts used to suck plant fluids. Aphids are usually found in clusters, especially on new growth. Signs of aphid infestations include sticky honeydew on leaves or under plants, distortion of leaves, stunting of shoots, or large numbers of ants on the plant.

Life Cycle:
Overwintered eggs of some common garden species hatch in spring. These wingless females reproduce asexually, bearing live young (up to 80 per week) that already have the next generation developing inside. Young aphids, called nymphs, molt four times before becoming adults. There is no pupal stage. This simple, rapid reproduction allows for very large population increases in a short time. Late in fall, males and females are produced, mate, and the females subsequently lay eggs. Winged aphids may appear at certain times, allowing the colony to move to other locations. Not all aphid types have this reproductive pattern, but many do.

Natural Enemies:
Aphids have many natural enemies, including birds, spiders, ladybird beetles, lacewings, syrphid fly larvae, and braconid wasps. A naturally occurring fungal disease can also kill aphids when conditions are right. Ants have a symbiotic relationship with aphids: ants milk the aphids for honeydew while protecting the aphids from natural enemies.

Monitoring:
Check plants often, since aphid populations can rise rapidly. Inspect growing tips and undersides of leaves. On trees, clip off leaves from several parts of the tree to look for aphids. If you see large numbers of ants on tree trunks, check for aphids on limbs and leaves. Look also for associated signs, such as yellowed leaves, stunted or distorted growth, or dripping honeydew. Sticky traps can be used to monitor for winged aphids. Check for signs of predators (named under Natural Enemies above), aphids that have been parasitized (look for a small exit hole on a dead, brown aphid body), or that have been killed by disease. Substantial numbers of any of these natural control factors can mean that population numbers will fall rapidly without the need for treatment. Because of the rapid changes that can occur in aphid populations, it is important to record monitoring data to detect changes due to predators or treatments.

Action Threshold:
Due to the incredibly high numbers that may be present, counting individual aphids is usually not practical. Action thresholds can be based on general descriptions of aphid density, plant damage such as stunted or distorted growth, or unacceptable amounts of honeydew beneath trees. Treatment should be triggered by rapidly rising numbers, unacceptable plant damage, or by honeydew falling on structures and people. Aphids seldom kill a plant, but they can cause defoliation. They also carry diseases from one plant to another. It is usually not necessary or even desirable to treat at the first sign of aphids, since low populations are needed to sustain predators.

Cultural/Physical Controls:
Plant selection: If possible, avoid or consider replacing varieties such as birch that have ongoing, serious aphid problems. Check transplants for aphids and remove them before planting.

Water spray: A strong blast of water knocks aphids from the plant, and most will not return. Water also helps rinse off the honeydew. Do this early in the day to allow leaves to dry and minimize fungal diseases.

Pruning: Where high aphid populations are localized on a few curled leaves or new shoots, prune these areas out and drop in soapy water to kill the aphids.

Fertilization control: High nitrogen levels favor aphid reproduction. Avoid over-fertilization and use slow-release rather than highly soluble fertilizers.

Sticky or teflon barriers: If you see ants crawling up the trunk of trees or other woody plants, place a band of sticky material (such as Tanglefoot or Stik-Em) around the trunk. Place a protective band of fabric tree wrap or duct tape underneath the barrier first. Teflon tape barriers may also be effective. Prune out branches touching the ground, buildings, or other plants.

Biological Controls:
Since aphids have many natural enemies, biological control usually means protecting these enemies from ants and avoiding broadspectrum pesticides that kill beneficial insects. Recognize that predator populations usually lag behind aphid populations in time. A number of aphid enemies can be purchased for introduction into landscapes. Ladybird beetles, lacewings, and parasitic wasps and flies are all available. Although such introduced predators may not remain where released, some benefit is likely, especially if releases are staggered in time. Many of the natural predators of the aphid are especially attracted to a garden with plants in the Umbelliferae family, such as angelica, sweet cicely, dill, and Queen Anne’s lace. The flowers of these plants provide a good food source for insects, especially parasitic wasps, who may stay to prey on some aphids as well.

Chemical Controls:
Insecticidal soap is widely recognized as the least-toxic chemical aphid control. Although its effect is temporary, it can help to bring aphid numbers down so that natural enemies can take care of them. Repeat applications within a few days may be necessary. Soap works only by direct contact with the insects. Be sure to cover both sides of the leaves. Although readily biodegradable, soaps are highly toxic to fish, so avoid runoff or direct application to water. Avoid using when temperature exceeds 90 degrees F.

Oil sprays:
Supreme or superior-type oils will help to kill overwintering aphid eggs on fruit trees if applied as a delayed dormant application in early spring. Although perhaps not justified for aphid control alone, oils can also control other overwintering fruit pests. Oils may, however, kill some beneficial species. Summer weight oils are also available, but they can burn tender leaves when applied in hot sun.

Conventional chemical control:
Foliar applied insecticides (malathion, diazinon, carbaryl, pyrethrin) are broad spectrum and will kill beneficial insects. They should be avoided, especially in home gardens and landscapes. Remember that allowing some aphid population in the garden helps to keep predators available.

ProIPM Integrated Pest Management Solutions for the Landscaping Professional
The Green Gardening Program is a collaborative effort of Seattle Tilth, Washington Toxics Coalition, and WSU Cooperative Extension, King County.
Sponsored by the Seattle Public Utilities in an effort to promote alternatives to lawn and garden chemicals.
Funded by the Local Hazardous Waste Management Program in King County.
Written by Philip Dickey • Graphic Design by Cath Carine, CC Design

Pest description and crop damage:
Aphids are soft-bodied insects that typically feed on leaves and succulent stems. They may vary in color from pale green or reddish to dark or black. Aphids are usually less than 1/8 inch in length.

Feeding damage to the plant is usually minor, although some leaf and shoot distortion can occur if populations are high. Aphids also produce honeydew, a sweet, sticky secretion that collects on plant tissues and encourages growth of a black sooty mold. This can interfere with photosynthesis of the plant. Honeydew is also a nuisance when it falls on decks, cars, or other landscape surfaces. They are a problem in early summer.

Biology and life history:
Most species of aphids have similar life cycles. Aphid females give birth to live offspring all year without mating. When other hosts are not available, aphids live on a wide variety of weeds. Aphids usually are found in colonies on new growth, the underside of leaves, and near flower and fruit clusters. In summer and fall, aphids may produce winged females and, later, winged males. They mate and produce eggs for overwintering, especially in colder climates. Otherwise, adult aphids overwinter on crops, weeds, or trees. There may be as few as 2 or as many as 16 generations each year, depending on the species and climate.

Management—biological control:
Aphids have many natural enemies, including ladybeetles, syrphid fly larvae, and green lacewings. Avoid broad-spectrum insecticide applications that would disrupt these controls.

Management—cultural control:
Wash aphids from plants with a strong stream of water or by hand-wiping. Aphid populations tend to be higher in plants that are fertilized liberally with nitrogen and heavily watered, as this produces flushes of succulent growth. Avoid excessive watering, and use slow-release or organic sources of nitrogen. Control ants, which farm aphids and protect them from predators in order to harvest their honeydew.

Management—chemical control (home):
It is important to cover foliage thoroughly, including lower leaf surfaces.
1. Beauveria bassiana
2. horticultural oil
3. insecticidal soap

Source:
http://pnwpest.org/pnw/insects

Season All Season
Date 2006-11-14
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Keywords: Acer circinatum, Fall foliage

PAL Question:

I have a vine maple tree whose leaves turn a very plain, rather ugly brown in the fall. It gets full sun from about noon until sunset. From what I have read, its leaves should turn red, orange, and yellow. What can I do to trigger this? I am thinking of how Hydrangeas are different colors depending on the acidity of the soil. I would like a tree with attractive fall color. I have also read it likes moist places in the shade, and it has not had that environment in my yard. Could the amount of water it gets in the summer, or lack of water, be affecting this?

View Answer:

According to J. Harris in The Gardeners Guide to Growing Maples (2000, p. 119), "Autumn color is due to a chemical change in the leaves and a combination of the remains of the chlorophyll grains and a substance called anthocyanin. The color assumed by leaves depends on soil and air conditions and on the amount of moisture. If conditions are very dry in the autumn, then the color will not last for long. After a frost, colors appear more intense, but the frost can check activity. It will also not be so good in very wet conditions."

The National Arboretum provides a complete explanation of why autumn leaves turn color.

There is an excellent article in the Seattle Times (September 25, 2008) by former Washington Park Arboretum Collections Manager Randall Hitchin which also describes this process.

There are other possibilities why your vine maple is not producing good fall color:

1. It might be getting too much light. The natural habitat for the vine maple is under an overstory of large conifers (Japanese Maples, by J. Vertrees, 2001, p. 247). Afternoon sun is the most intense and could be stressing the tree. Harris (2000) notes that while tree-like species prefer open sites, woodland conditions and dappled shade are ideal environments for shrubby maples. (Harris., p. 118).

2. Other than light, the environment might be a little off. Vertrees (2000, p. 247) notes that with vine maples, intense color does not develop in environments where abundant moisture and fertility keep the trees from being under stress, i.e., they need stress to produce good color.

3. Trees of the same species will exhibit different fall colors depending on the growing environment and peculiarities of each individual tree. (As identical twins can be quite different). When selecting a tree for fall color, it is best to first view it in autumn -- then remember it will change somewhat when it is installed in a new home.

It is not likely that changing soil pH will have an effect. I have been disappointed in fall color a couple of times and finally replaced the trees -- after viewing them in full color in the nurseries.

Season Fall
Date 2008-01-24
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Keywords: Crataegus, Trees--Diseases and pests--Washington

PAL Question:

My Hawthorn tree has black spots on the leaves. Can you tell me what disease this might be? In general, what diseases affect Hawthorn trees?

View Answer:

To learn about diseases most common to Hawthorns in the Pacific Northwest, visit the Pacific Northwest Plant Disease Management Handbook and search on the word hawthorn. You will get a list of five diseases -- click on any of them for a full explanation.

Season All Season
Date 2008-01-24
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Keywords: Malus, Trees--Diseases and pests--Washington

PAL Question:

My Fuji tree is infected with Cherry Bark Tortrix. Can the branches, leaves, and bark be used as mulch? What should be done with the wood? Can it be stored, and burned in our fireplace?

View Answer:

The leaves and branches can be mulched. The wood can be used, but it is a good idea to strip the logs of the bark and store the wood barkless. Removing the bark will destroy most of the caterpillars in the process. The wood is easier to chop when the bark has been removed, too! If you cannot remove the bark, use a mallet to tap the bark where ever you see galleries. This will most likely squash the caterpillars that are still in the wood.

Season All Season
Date 2006-06-01
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Keywords: Trees--Wounds and injuries, Neighbor law

PAL Question:

How can I find out if my Monkey Puzzle tree was poisoned by my neighbors? I found 6 holes drilled into it on their side.

View Answer:

Before assuming the tree has been poisoned, make sure that the holes were not actually caused by woodpeckers or flickers, since this is common behavior among such birds--and less common behavior among neighbors, one would hope!

In order to determine for sure whether your trees have been poisoned, you may wish to consider contacting a certified arborist. For a fee, an arborist will visit your property and make a diagnosis or recommend another plan of action.

For a list of arborists, contact Plant Amnesty, an organization of arborists and vetted gardeners at 206-783-9813 or visit the Pacific Northwest Chapter of the International Society of Arboriculture. Here is their web address: http://www.pnwisa.org/.

To pursue a legal solution to the problem contact the King County Law Library where County law librarians will be happy to help you with your research. Here is the web address: http://www.kcll.org/index.html.

The book Neighbor Law by Cora Jordan (Nolo Press, 2006) is also a useful resource.

Season All Season
Date 2008-01-24
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Keywords: Weigela, Color guides, Dwarf shrubs, Nandina domestica, Ornamental shrubs

PAL Question:

Can you give me some information on Weigela Midnight Wine and dwarf Nandina? Are there any plant lists of purple-leafed shrubs?

View Answer:

Following is a good description of Weigela “Midnight Wine.” The information comes from the Missouri Botanical Garden, so it is tested and accurate.

WEIGELA

‘Elvera’ Midnight Wine is a dwarf version of the popular Weigela ‘Wine and Roses’ (W760). It is a dense, rounded, low-growing deciduous shrub that typically grows to only 1.5-2 feet tall and as wide. Features profuse reddish-pink flowers and burgundy-purple foliage. Reddish-pink, funnel-shaped flowers (to 1.25 inches long) appear singly or in clusters along the branches of the previous year’s growth in mid- to late spring, with sparse and scattered repeat bloom often occurring on new growth as the summer progresses. Elliptic to obovate, glossy, burgundy-purple leaves (to 3 inches long) turn very dark purple in autumn. Hummingbirds are attracted to the flowers. Original cultivar name is ‘Elvera’, but plants are being marketed under the registered trademark name of Midnight Wine. U. S. Plant Patent #12,217 issued November 20, 2001. Source.

NANDINA

There are several varieties of dwarf Nandina, such as 'Harbour Dwarf,' 'Firepower,' 'Nana,' and 'Nana purpurea.' University of Florida Extension has a feature on dwarf Nandina on their website. There are also plants available from nurseries such as Forestfarm Nursery and Greer Gardens in Oregon, and Whitney Gardens in Washington.

PLANT SUGGESTIONS As far as lists of plants with purple foliage, you should find a wealth of information in the book Black Magic and Purple Passion, by Karen Platt, 2004. There are also lists online, such as this page from Iowa State University Extension, entitled "A Passion for Purple." You can also search Royal Horticultural Society's Plant Selector and other similar resources by leaf color.

Season All Season
Date 2007-05-30
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Keywords: Cornaceae (Dogwood family), Trees--Diseases and pests

PAL Question:

I live in Kitsap and my 50-year old maple is dying -- what should I do?

Also, my Dogwood trees seem to be infected with anthracnose. Can you give me some information about this disease?

View Answer:

To get some information about your maple, you can consult with a Master Gardener at a WSU Kitsap County Extension Diagnostic Clinic: http://kitsap.wsu.edu/hort/clinicloc.htm.

Regarding dogwood anthracnose (Discula destructiva), it is a shame that so many of these beautiful trees are infected. You may be somewhat reassured to know that although the disease often causes tree death in the northeastern U.S., here in the Pacific Northwest, many trees survive. Douglas Justice, Curator of Collections at University of British Columbia Botanical Garden, discusses this on the UBC discussion forum.
Excerpt:
"Weather is probably the deciding factor in infection. A cool, wet period seems to be most conducive to infection, and such factors probably have to coincide with a specific time of tissue susceptibility. In other words, the conditions have to be "just right" for the disease to take off and become established. However, it is well documented that stress predisposes plants to disease susceptibility. Stressors for Cornus nuttallii (Pacific dogwood) would include compacted soil, poor drainage, full exposure with overly dry soil (C. nuttallii is adapted to a summer drought regime, but let's be reasonable!) and wet soil in summer (e.g., irrigated soil -- see previous comment). Nearly all the local anthracnose-affected dogwoods recovered, including the wild natives and the even some of the more severely affected C. florida (eastern dogwood). Anthracnose has visited us subsequently, but mostly only on C. florida and urban C. nuttallii. This suggests that the there isn't much anyone can do to prevent the disease from occurring and that as along as trees aren't overly stressed, they will eventually recover. "

A U.S. Forest Service article entitled How to Identify and Control Dogwood Anthracnose includes images which may help you to determine if your tree has anthracnose.

Master Garden Products.com provides a short article about dogwood anthracnose that contains a “What to Do” list.

University of Maryland College Home and Garden Information Center's Integrated Pest Management Series HP #12 offers information about dogwood diseases and pests, including anthracnose.

Oregon State University Extension’s Online Guide to Plant Disease Control describes cultural controls for anthracnose. There is also an extensive list of chemical controls, which you may choose to ignore after reading Douglas Justice's comments from the UBC discussion forum mentioned earlier:
"The application of fungicides is probably a waste of money and also likely counter-productive, particularly with a systemic such a benomyl, which will kill most of the good fungi, but probably not the target pathogen. Common fungal pathogens frequently develop resistance to this fungicide."



Season All Season
Date 2008-01-24
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Keywords: Transplanting, Bamboo

PAL Question:

I transplanted some bamboo and now some of it is dying. Can you give me some information on how to transplant bamboo correctly?

View Answer:

The following is an excerpt from the American Bamboo Society webpage.

Q. How do I transplant part of a large clump of bamboo?
Transplanting is hard work and involves digging a large chunk of root ball out of the ground. Never transplant bamboo when it is shooting. Dig bamboo either very early in the spring before there’s any chance of shooting or wait for the growth period to be over late in the autumn. You should look for a clump of culms that has come up in the last year or so and which includes at least three or four healthy-looking culms. A good size for the clump would be at least two feet in diameter. Bamboo roots (rhizomes) are tough but must not be allowed to dry out even for a few minutes. You may have to use a very sharp shovel, ax or saw to separate the roots from the rest of the grove. If you will be transferring the division by truck, then water the leaves and roots well, wrap the whole thing in plastic and get it into the ground as quickly as possible.

Season All Season
Date 2006-06-02
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Keywords: Antirrhinum, Capsicum, Vegetable seedlings, Seedlings, Tomatoes

PAL Question:

I started some seedlings of tomato, pepper, snapdragon and lettuce in my sunroom under shop lights in peat pots. The temperature in the room is in the 60s at night and 70-80 in the day. I keep the soil evenly moist, but after 3 weeks, none of the seedlings that have germinated have true leaves. No secondary leaves of any kind. I cannot imagine why this would be under those conditions. Can you help me?

View Answer:

There are a number of variables that may be at work here. Are the seeds new? If not, were they stored properly? Also, seeds have varying lifespans. Some seeds require light to germinate and others do not. Some must be sown on or near the surface, and others must be sown more deeply. Seeds require varying degrees of heat. Oxygen is another requirement: is the seed-sowing mixture in your pots compacted? That might prevent germination. The steady moisture you are providing is good, and the temperature in the room is about right for most seeds.

University of New Hampshire Extension has useful general guidelines for starting seeds indoors.

The temperature of the water or the time of day in which the watering takes place may be influencing the growth of the plants. According to an Ed Hume’s Garden Questions Archives article entitled, Starting Vegetable Seeds Indoors, seedlings should be watered with water that is just a little warmer than room temperature. If the water being used is too cold or if watering occurs in the evening as the temperature of the room drops, this could be slowing the plant growth.

I am wondering if the day time temperatures are too high. To quote from The Seed Starter's Handbook by Nancy Bubel (Rodale Press, 1988): "Plants grown indoors in warm rooms put on weak, spindly, sappy growth that is difficult to manage… Start seeds warm and grow seedlings cool."

Lastly, Starting from Seed by Karan Davis Cutler (Brooklyn Botanic Garden, 1998) says: "Since both heat and light fuel plant growth, the relationship between the two is critical. A common mistake among home gardeners is to keep plants at too high a temperature for the amount of light they receive. What often happens is that the gardener tries to compensate for slow growth with more fertilizer and higher temperatures. The result is limp, leggy seedlings that are hard put to cope with outdoor conditions… On cloudy days, the experienced gardener lowers the temperature to compensate for the lower light levels. While every plant has a temperature range it likes best, within that range, the cooler you keep the temperature, the better off the plant will be. Do not take things too far, though. A combination of low temperature, low light and overwatering is ideal for the development of damping-off fungus."

Season All Season
Date 2008-01-24
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Keywords: Lolium, Ajuga, Vinca, Hedera helix, Festuca, Arctostaphylos, Achillea, Grass varieties, Land treatment of wastewater, Turfgrasses, Ornamental grasses, Landscaping drain fields

PAL Question:

We have a new house that we have to landscape around. The biggest problem is that we have to be careful what we plan due to the septic system. It is an evaporation system, with two huge cement tanks buried under the ground in the front of the house and plastic pipes running through the side yard. We are planting grass in a rectangle right above the biggest bunch of the plastic pipes, but what can go around it or by the cement tanks that will not grow long roots and dig into it? In looking at the planting information on the packages and in my Western Garden Book, nothing seems to mention root depth.

View Answer:

Below is an article entitled What to Plant Over the Septic System by Mary Robson (originally published in her Regional Garden Column for Washington State University Extension, December 6, 1998):

"As more and more people move into rural areas, questions about septic systems and landscaping have become quite common. This column deals with some of the basics. A new brochure from Washington Sea Grant called: Landscaping your Septic System, offers considerable detail on the subject and provided much of this material.

"First, be sure that the septic field is clearly identified, and you know where the reserve area is. Keep all construction away from these areas. Understanding the functioning of the system is vital. Get information. (Some of it is available in video form.) The drainfield will not work well if overloaded with extra surface water, so be certain that it is not in the path of downspout run off or irrigation systems.

"Sunlight and air circulation also help the drainfield perform properly. Avoid surrounding it with tall trees. (Some shade is fine, but you would not plant an oak on the edge of a drainfield.) Set up some barriers so that it is not compacted by frequent foot traffic. Occasional mowing or moving through the field to check the system is certainly fine, but you do not want the drainfield in the middle of a heavily used path.

"There are advantages to using plants over the drainfield. Plants do help provide oxygen exchange and contribute to evaporation necessary in the drainfield area. Choose plants with shallow, non-invasive roots. You do not want breakage or damage in pipes from root intrusions.

"Grasses are most commonly recommended for the septic area. Lawn can be attractive. Do not overload the system by watering it a lot. Meadow grasses or a mixture of turf grasses like perennial rye and some broadleaf flowers (such as yarrow) can also look good and require little maintenance. Several mixes sold as Eco-Turf or Fleur de Lawn have these components.
"Small, shallow-rooted ornamental grasses (for instance, Festuca ovina 'Glauca' 4-10 inches) can also be good looking. Very tall grasses like Stipa gigantea are not appropriate. Avoid over-active plants like English ivy (Hedera helix), which is becoming a menace in forested areas by moving in and stifling trees.

"Edible crops are not suggested. Vegetable gardening requires frequent cultivation, and digging in the drainfield area is inadvisable. Also, the brochure notes that: Sewage effluent is distributed through the soil in the drainfield area. Any root vegetables planted in this area may be directly exposed to septic tank effluent.

"Other possibilities are low-growing ground covers. Some, such as bugle weed (Ajuga reptans) and vinca (Vinca minor) grow vigorously and would fill in quickly. The native kinnickinnick (Arctostaphylos uva-ursi) grows well in full sun but is slow to establish. A mulch around the plants may help with weed control while the plants spread.

"The green growing layer over the septic tank helps the system to function, adds to the appearance of the landscape, and should, ideally, be set up to allow easy monitoring and maintenance. Keep landscaping simple and straightforward, remembering that the object is the good performance of the system."

To get more information on septic systems, contact your local health department. The brochure Landscaping Your Septic System (pdf) is available through the Sea Grant Program.

Here are links to publications that might also be helpful:
Mounds: A Septic System Alternative
Understanding and Caring for Your Sand Filter System
Care and Feeding of Septic Tanks

Season All Season
Date 2007-04-10
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Keywords: Persicaria

PAL Question:

I have a plant called, Chevron Plant in my yard. There is a distinct v-shape pattern on the upper side of the leaf, and it gets red tiny flowers in the spring/summer time. It grew about 1.2 in height. Can you tell more about this plant?

View Answer:

Our sources don’t include the common name Chevron Plant, but an internet search led to Persicaria, in the family Polygonaceae. Its most familiar common name is Knotweed. The genus includes 50—80 species of annuals and perennials, often rhizomatous or stonoliferous. They may be evergreen, semi-evergreen, or deciduous. There are several varieties with interesting v-shaped leaf patterns, and some have red flowers. To verify whether this is what you have, try searching the plant's botanical name on Google or another search engine and then click on Images and search for Persicaria.

If that is correct, they are best grown in any moist soil in full sun to part shade. If they get out of control they can be cut to the ground in late fall or winter. Some species can be aggressive and even officially invasive and need to be controlled.

If that is NOT your plant, the Hyde Herbarium at the Center for Urban Horticulture can provide a positive identification.

There may be people at your local nursery who can help you as well.

Season All Season
Date 2008-01-24
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Keywords: Nymphaea, Pond plants

PAL Question:

I am looking for information about planting floating emergent plants (e.g., water shield, yellow pond lily) in natural ponds. If planting young plant material in the soil, what is the recommended water depth? Is it okay to submerge the entire shoot? If yes, what is a safe depth from top of shoot to water surface?

View Answer:

There are several different types of plants that are grown in ponds. A great resource on planting floating plants is The Water Gardener’s Bible: A step-by-step guide to building, planting, stocking, and maintaining a backyard water garden by Ben Helm and Kelly Billing (Rodale Inc., 2008). In the book they explain that floating plants “will either float on the pond surface or be slightly submerged.” The most popular floating plants are Frog’s bit (Hydrocharis morsus-ranae), Water hyacinth (Eichornia crassipes), Water chestnut (Trapa natans), and Water soldier (Pistia stratiotes). They also explain submerged plants that “will inhabit a pond at all levels, from those whose roots sit on the bottom to those that emerge from the pond, getting only their feet wet.” For planting a water lily, “place on a stack of bricks in the position where the lily will be sited, so that the top of the planted basket is no more than 1 inch (3 cm) below the surface. As the leaves start to extend, remove the bricks until the basket is on the pond bottom.”

Another great book is Plants for Water Gardens: The Complete Guide to Aquatic Plants by Helen Nash and Steve Stroupe (Sterling, 1998). The book contains a huge list of a variety of lily plants and specifications for planting and survival.

The University of Illinois Extension has a website on Water Gardening that has useful information on planting aquatic plants. You may want to check your local list of invasive species before planting.

Season All Season
Date 2008-01-24
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Keywords: Persea, Plant care, Indoor gardening

PAL Question:

We have a large avocado plant (indoors) that is mystifying us. A couple months ago, it shed most of its leaves. The leaf would get droopy and the tips of the leaves would turn brown and dry out and then spread up the leaf. It got down to its last seven leaves and then seemed to stop, although all of these leaves have varying degrees of this leaf tip burn. Now over the last month or more, small new growth is appearing. They have not grown much at all and are only about an eighth of an inch long.

View Answer:

When growing an avocado (Persea species) indoors, you will need to be sure it is getting enough light. It is normal for the plant to drop older leaves. You should also keep the plant in a cool spot. According to The Houseplant Expert by D. G. Hessayon (Expert Books, 2001), your plant will do best if you repot it annually and pinch the tips to encourage bushy growth. Lee Reich discusses growing avocados indoors in an article for California Rare Fruit Growers. Here is an excerpt:

"Indoors, avocado plants are often gangly and sparse with leaves. One reason for the plant's gawky appearance indoors is light. Lack of sufficient light causes stems to stretch for it. Another reason is that avocados shed many buds along their stems, buds that might have grown into side branches. The result is a plant stretching out for light, sending out new growth mostly from the tips of the branches and shedding old leaves.
There are several things indoor gardeners can do to keep their plants more attractive. Most obvious is to give an avocado tree bright light. Also, the stretch for light is exaggerated when warmth stimulates growth, so the ideal spot for the plant is at the brightest window in the coolest room. Beyond that pruning back a stem or pinching out its growing tip stimulates branching by awaking dormant buds (not all are shed) further down the stem. There is nothing that can be done about the shedding of older leaves."

Grown outdoors in an agricultural setting, avocado plants sometimes get leaf tip burn from salt accumulation, as this article from California Rare Fruit Growers explains. If you are using especially salty tap water or overfertilizing your plant, that might be causing the burnt leaf tips. Other causes could be lack of water, too frequent light watering, or poorly draining soil.

Season All Season
Date 2008-01-24
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Keywords: Persea, Plant care, Avocado

PAL Question:

We know avocados like dry soil, but are there specific guidelines to follow?

View Answer:

"Growing conditions: Give avocado direct light; insufficient light will cause spindly growth. Provide a warm temperature and medium humidity. Keep the soil evenly moist but not wet and soggy. Fertilize once a month throughout the year... Use an all-purpose soil mix for repotting... Avocado is vulnerable to aphids, mealybugs, scale insects and thrips."
Source: The Time-Life Gardener’s Guide; Foliage Houseplants, 1988, p. 125

"Growth habit: The avocado is a dense, evergreen tree, shedding many leaves in early spring. Growth is in frequent flushes during warm weather in southern regions with only one long flush per year in cooler areas."

"Foliage: Avocado leaves… normally remain on the tree for 2 to 3 years."
Source: California Rare Fruit Growers Association website

Season All Season
Date 2008-01-24
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Keywords: Capsicum, Plant care

PAL Question:

For the past several years, I have tried to grow green peppers in our garden. The problem I have had is that they never grow very big, and the peppers never get much bigger than a small plum. I fertilize my garden, add compost, but still get small peppers.

View Answer:

Peppers are tricky in our climate. Quoting from Growing Vegetables West of the Cascades by Steve Solomon: These heat-loving plants do not readily adapt to climatic conditions north of the Yoncalla Valley…..they are often irreversibly shocked by outdoor night-time temperatures below 55 F….Many gardeners make the mistake of setting peppers out at the same time as tomatoes—right after there is no frost danger. This, however, will almost certainly expose them to overnight temperatures of 45 F or even worse. Any surprisingly cool night during June can shock peppers sufficiently to stop their growth for a time…. North of Longview, Washington, and along the coast, only the hardiest pepper varieties will grow in cloches or greenhouses…
Source: Growing Vegetables West of the Cascades, by S. Solomon, 2000, p. 210, 236.

Oregon State University has an article entitled "Spice Up Your Garden with the Perfect Pepper" with a link to a guide to growing peppers in the Northwest.

Season All Season
Date 2008-01-24
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Keywords: Plant care, Narcissus

PAL Question:

I'm having a problem with my daffodils. They came up, but very few of them are blooming. This is the third year for them, and the worst turn out. They seem to be turning yellow at the bottom of the plant. They have multiplied well, and came up looking fine. Several of my friends are having the same problem. Could it be because they had so many days of below freezing weather this winter?

View Answer:

We found a helpful article from the American Daffodil Society. Potential causes for a lack of flowers include lack of fertilizer, too much nitrogen fertilizer, shade, competition with other plants, poor drainage, virus, foliage cut off too soon, need to be divided, or weather stress (such as early extreme heat) in the spring.

The cold weather should not have been a problem provided the bulbs were planted deep enough.

Season Spring
Date 2008-01-24
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Keywords: Soil testing

PAL Question:

I would like to know if there is some place where I can have my vegetable garden soil tested. For the last two years my vegetable plants were abysmal except for tomatoes and lettuce.

View Answer:

The Natural Lawn & Garden Hotline, sponsored by Seattle Public Utilities, provides the following recommendations on how to take a soil sample:
1) Take about 10 vertical slices of soil from the top 6-8 inches of your garden bed. If there is an area that you suspect to have problems, test this soil separately.
2) Place soil slices in a plastic bag and mix thoroughly. You are getting the average of the soil in your garden bed.
3) Take 1 cup from this mixture and dry it at room temperature. Do not dry in oven, on radiator or in microwave!
4) Put dry soil sample into a Ziploc bag and seal.
5) Label the outside of the Ziploc bag.
6) Mail to one of the soil testing labs below with completed order form and payment.

A WSU has a publication on soil testing for vegetable crops but it is mainly for agricultural growers.

Another option is the University of Massachusetts, Amherst soil testing laboratory.
This page has information and forms to send in with your samples.

The Soil and Plant Laboratory is based in California.

For testing of toxics see: King County's Resident Self-Testing Page.

A & L Western Laboratories, Inc. in Portland, OR can provide soil and plant analysis.

Season All Season
Date 2008-01-24
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Keywords: food safety, Malus domestica

PAL Question:

Is it safe to eat windfall apples if I cut away any sections that look bad? Or should I only use them in cooking?

View Answer:

If you want to err on the side of caution, you should use them neither for fresh eating nor for cooking. There is a toxin produced by fungi called Patulin which may be present in apples which have dropped from the tree and have been lying on the ground, according to a news release from University of Illinois Extension, dated September 21, 2012.

According to the Ontario Ministry of Agriculture, there are ways of diminishing the risk, but the processes involved are more appropriate to commercial apple processors than backyard orchardists. Excerpt:
"Current research suggests that varieties with an open calyx are a greater risk for patulin development within the core of the apple. In such a situation, damage to the fruit is not easily detected [...]

"Patulin is also destroyed by fermentation, which means it is not found in either alcoholic fruit beverages or vinegar produced by fruit juices. Patulin will however survive the pasteurization process if present in the juice."

The website of Food Safety Watch has more information about Patulin.

Season Fall
Date 2012-11-03
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Keywords: Rhododendrons--Varieties, Root weevils, Rhododendrons--Diseases and pests

PAL Question:

My rhodies are being devastated by root weevils. They have stripped many of the branches clean of their vegetation, and have destroyed ~50% of the remaining leaves. My rhodies look like they will require years to recover, if they ever do.

If I replace them with resistant varieties or plants that are not susceptible to these pests, will this eliminate the weevils?

View Answer:

Root weevils are the most common pest attacking Rhododendrons in the Pacific Northwest so they can only be temporarily eliminated from any garden. If the environment is right and their food source returns, so will the root weevils.

If you want to keep your current Rhododendrons, the weevils can be controlled if you’re diligent (forever!?). An article by Caroline Cox in the summer 2005 issue of the Journal of Pesticide Reform discusses their control. However, it sounds as if you’re willing to remove them and start fresh. Some of the most susceptible (host plants) are Rhododendron and Azalea, Heather, Salal, Manzanita and Kinnikinnick, Pieris, Maples, Viburnum, most Conifers, Astilbe, Cyclamen, Helleborus, Hosta and Primrose.
(Source: Root Weevils in the Nursery and Landscape; Identification and Control, by J. DeAngelis and G. Garth, EC 1485, Oregon State University Extension Service).

The extension bulletin from the Washington State University Extension website has an excellent list of resistant Rhododendron varieties.

Season All Season
Date 2008-01-24
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June 24 2013 12:55:25