Lichen on trees

My Corylus contorta has greenish yellow lichen on the branches. Should I be concerned and if so what should I do?

The lichen will not harm your Corylus contorta. Lichen is actually a sign that the air is relatively unpolluted.

You may find this page of discussion from University of British Columbia
Botanical Gardens of interest.

Here is an excerpt from a 2007 entry formerly available on the site of Treelink, now part of the Alliance for Community Trees:

“No need for a preemptive strike against the lowly lichen. Lichens are
composite, symbiotic organisms made up from members of as many as three
kingdoms.
The dominant partner is a fungus. Fungi are incapable of making their own
food. They usually provide for themselves as parasites or decomposers.
“Lichens are fungi that have discovered agriculture”– lichenologist
Trevor Goward.

“The lichen fungi (kingdom Fungi) cultivate partners that manufacture food
by photosynthesis. Sometimes the partners are algae (kingdom Protista),
other times cyanobacteria (kingdom Monera), formerly called blue-green
algae. Some enterprising fungi exploit both at once.
Most lichens grow very, very slowly, often less than a millimeter per
year, and some lichens are thought to be among the oldest living things
on Earth.

“Lichens are important in many ways in the habitat. Some make
the nitrogen in the air usable to plants, They are homes for spiders,
mites, lice, and other insects. All are important in the nutrient cycle
in the places where they grow. Many lichens are very sensitive to
pollution in the air. When there are too many harmful things in the air,
lichens die. If you live where there are many lichens it probably means
the air is clean. But, if there are only a few lichens in your
neighborhood, the air you are breathing is probably clogged with
automobile fumes or industrial wastes. Some trees and shrubs can develop
a layer of fungi, algae, lichens or moss on their bark. These are
non-parasitic organisms and do not injure the plants on which they grow.”

Corylus

broom plant used in Japanese flower arrangement

While living in Japan and practicing flower arrangement, I often used a branch known as ossified broom. It was always available at flower stores there. The color is gray-green, has the typical multiple straight stems as Scotch Broom but also had some thick and twisted branches that are very attractive in arrangements. I would like to plant it so that I would have a ready supply. Can you help me find the correct name?

I consulted a number of books on Japanese flower arrangement, including The Art of Arranging Flowers: A Complete Guide to Japanese Ikebana, by Shozo Sato (Harry N. Abrams, 1965). ‘Broom’ may be the common name of a number of different plants, such as Spanish broom (Spartium junceum), Scotch broom (Cytisus scoparius), and broom cypress (Kochia scoparia). Unfortunately, these plants are considered noxious weeds in the State of Washington.

You may want to consider a type of broom (Genista or Cytisus) that is not considered invasive.

From your description of the branches, I wonder if the appearance would be similar to
Corylus avellana ‘Contorta’ (Henry Lauder’s walking stick).

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.

planting to stabilize a steep slope

Can I plant groundcovers, shrubs, and trees to stabilize a steep slope?

There are several resources which will help you in
selecting plants to prevent erosion and mudslides on
your slope.

Please note that these articles are merely suggestions and should not be construed as advice. We are librarians, not engineers!

None of our standard books on trees mentions the soil binding quality of tree roots. However, the Miller Library does have very good technical books and articles on slope stabilization. (For example, Slope Stabilization and Erosion Control: A Bioengineering Approach, edited by R.P.C. Morgan and R.J. Rickson, 1995.)

I do want to note one thing that many articles mention: no amount of established vegetation will hold a steep slope if other forces are present that would contribute to a landslide.

The Department of Ecology website has a list of appropriate plants.

Additionally, there are a number of books with
information on the subject. Vegetative Contribution
to Slope Stability at Magnolia Park (by Kathy Parker, 1996)
recommends Oregon grape (Mahonia), which she suggests
for gentle slopes.

Other smaller plants she lists are:
Polystichum munitum (native sword fern)
Vaccinium ovatum (evergreen huckleberry)
Symphoricarpos albus (snowberry)

Larger shrubs in her list:
Alnus rubra (red alder)
Philadelphus lewisii (mock orange)
Sambucus racemosa (red elderberry)

Small trees:
Acer circinatum (vine maple)
Amelanchier alnifolia (serviceberry)
Corylus cornuta (hazelnut)

For steeper slopes, Parker says that they may not be
good candidates for vegetative rehabilitation unless
you put in some kind of structure. She says that Jute mats can be used in conjunction with native seed, mulch, and shrubs, if carefully anchored. She also mentions a Weyerhaeuser product called Soil
Guard.

Steep Slope Stabilization Using Woody Vegetation (by
Leslie Hennelly, 1994) has a plant list, as well as a chart which indicates plants used to control erosion, the degree
of the slopes, and the rate of success in resisting
erosion.

Two titles which focus more on the garden design
aspect of planting on a slope are
Hillside Gardening : Evaluating the Site, Designing
Views, Planting Slopes (by William Lake Douglas, 1987) and
Hillside Landscaping (by Susan Lang and the editors
of Sunset Books, 2002).