QUESTION: What is the best way to get rid of Scotch broom? Can someone from the County make our neighbor spray his so it does not seed into our property? We get “hay fever” every year when it comes into bloom.

ANSWER: You are certainly not the first person to complain about Scotch broom! This plant, which was introduced as a garden ornamental by early settlers of the Pacific Coast, has spread far beyond the bounds of cultivation and now covers many acres west of the Cascades from British Columbia to California.

According to Nancy Ness, director of the Grays Harbor Noxious Weed Control Board, each County Weed Board has the option each year of designating target weeds to be controlled. Unfortunately, when weeds like Scotch broom get listed, they are usually placed in the “C” category, which means that the infestation is already so prolific that enforced control is no longer feasible. “The very best we can do is to educate the public on options for control. We are particularly concerned that people become aware of Scotch broom’s potential as a fire hazard,” added Ness.

The seeds of Scotch broom are toxic to humans, horses and livestock. When mature, the seedpods split and eject seeds up to 20 feet away. Over 10,000 seeds can be produced per plant and they can remain viable in the soil for anywhere from five to 60 years! Domestic goats are reported to browse Scotch broom without apparent ill effects. Given time, goats will probably control a patch of Scotch broom if the plants are not too tall. Grubbing out the crowns can also control plants. After removing existing large plants, repeated cultivation will destroy seedlings of this weed. Cutting or mowing the plant down to ground level immediately after flowering has proven to be a fairly effective means of control on mature plants with a stem diameter greater than two inches. Mowing young, green plants is not effective however, and will result in a dense carpet of short broom plants.

Selected herbicides currently recommended by WSU weed scientists for the control of Scotch broom include triclopyr and glyphosate. Both of these materials can be found in most retail garden stores and provide effective control when used according to labeled directions. Glyphosate is “non-selective” and will injure any foliage that it comes in contact with, so make sure it does not come in contact with desirable plants. Triclopyr is selective and works well in pasture situations since it will not kill the grass. Foliar herbicide applications are most effective when applied after full leaf development and prior to fall leaf drop. Basal or cut stump treatment methods are also effective.

Although many people complain about “hay fever” when Scotch broom is flowering, more than likely, the broom is not to blame. Scotch broom is insect pollinated. Being heavy and sticky, the pollen does not become airborne; thus the potential for an allergenic reaction is minimal except perhaps when an individual actually handles a plant in bloom. Most allergenic reactions are the result of wind-borne pollens, which are distributed in large amounts at about the same time that Scotch broom is in bloom. The fragrance however, just like some perfumes appears to have an ill effect on some people.

QUESTION: The leaves on our raspberries are covered with a yellowish-orange spotting that resembles rust! What’s causing this? How do we control it?

ANSWER: Based on the symptoms you described, your raspberry leaves are most likely infected with a fungus disease commonly known as Yellow Rust. This disease is widespread in red raspberries throughout Western Washington, particularly in years when spring rains continue into May. Leaf infections in spring and early summer create a yellowish spotting on the upper leaf surface. At first the spots are very small, yellow- to-orange and slightly raised. Soon after, new yellow-to-orange spore bearing structures (aecia) are produced in a ring around these spots. By summer, another yellow spore stage appears on the lower leaf surface. Some of these structures could be described as orangish without a good comparison.

Fruit often dies on the canes before maturing if leaves on fruiting laterals are attacked by early summer. By harvest, black over-wintering spores appear on the lower leaf surface. All succulent parts of the raspberry plant are subject to infection. Infected canes often are brittle and may break off when old fruiting canes are pruned out.

The most practical control is to destroy fallen leaves and other refuse around plants, as they are a source of innoculum for the next growing season. Applying a delayed dormant spray of lime sulfur when the first leaves are out about three quarters of an inch will also help to prevent infection.