Volume 16, Issue 27 - July 3 - July 9, 2008

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The Bay Gardener by Dr. Frank Gouin

A Rose of a Different Color

A short primer on plant genetics

The other day, a friend came to the farm with a fist full of different colored roses. She said that they all came from the same plant and asked if I could propagate them. Based on the color, size and shape of one of the flowers, I concluded the plant from which the flowers were harvested was an old Chicago peace rose. That rose had the reputation of producing different colored flowers on the same plant, depending on climatic conditions.

It is not uncommon for plants to produce offshoots different from the parent plant. These changes are due to genetic mutations in a developing bud. Horticulturists have taken advantage of such genetic mutation to introduce new cultivars. Some well-known cultivars that have resulted from genetic mutations include red delicious apples, navel oranges, pink grapefruit, pink dogwood, high light Japanese holly and jingle bells poinsettia.

Not all genetic changes are stable, however. The old Chicago peace rose was replaced with a hybridized peace rose in the early 1980s. Thus the Peace rose sold today is a product of plant breeding and not genetic mutation.

When I was an undergraduate student in New Hampshire, I managed a large blueberry farm and apple orchard. One day, the owner noticed that one branch on one of the McIntosh trees was consistently producing McIntosh apples that were larger and darker red than the McIntosh apples in the rest of the orchard. After observing that branch for several years, he started propagating it by grafting and was soon marketing young trees under the name of Big Red Mac.

I once took a college course in cyto-genetics where we induced genetic mutation by subjecting sprouting corn seeds to low levels of radiation from an old dental X-ray machine. Depending on the plant species, some genetic mutations can be caused by exposing seeds or plant parts to liquid nitrogen. However, plants that have resulted from genetic mutation must be tested for many years to make certain that the mutation is stable — unlike the old Chicago peace rose.

Bagworm Update

At the end of June, bagworms had grown to between one-fourth and one-half-inch long. If you find only a few dangling from needles of your juniper, pine, spruce and fir species and scales of arborvitae and red cedar, it is best to hand-pick and roll them between your fingers and let them fall to the ground. If there are many, now is the time to spray with Thuracide or Dipel. Both of these biological sprays will provide 100 percent control without any environmental damage.

Ask Dr. Gouin your questions at [email protected]. All questions will appear in Bay Weekly. Please include your name and address.

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