Rosaceae includes, but is certainly not limited to: rose (duh), hawthorn, Indian hawthorn, loquat, firethorn, apple, pear, strawberry, Ribes spp. (raspberry, blackberry, boysenberry, etc.) and Prunus spp. (apricot, plum, cherry, peach, almond, etc.). Knowledge of what is rosicious is useful because all rosicious species are susceptible to the current epidemic of fireblight.

Fireblight is a bacterial disease that has proliferated during the variable warm, humid and rainy spring weather—which are coincidentally the same environmental conditions that have caused the proliferation of anthracnose fungus among ash and sycamore. Like species susceptible to anthracnose, those susceptible to fireblight exhibit distinct susceptibility. For example, fireblight is not often observed among blackberry brambles but may be very severe among various pears. Even among pears, some cultivars are less susceptible than others are.

Any vascularly active tissue may become infected, but floral parts are much more likely to become infected. Vascular activity is disrupted and subsequent necrosis becomes suddenly apparent as infection expands into adjacent vegetative tissue. The black or dark brown foliar necrosis develops so rapidly that foliage cannot become abscised and remains suspended as it would if it had been scorched by fire—hence "fireblight." Severe symptoms may currently be observed among evergreen pear and flowering pear because pears are generally among the most susceptible, and perhaps because they were blooming during variable warm, humid and rainy weather.

Copper fungicides (not bactericides?) might have inhibited infection prior to bloom but cannot eliminate active infection. Continued infection is unfortunately only inhibited by removal of the affected stems. Because the disease extends proximally (inward from stem tips) through the vascular system, it may have extended farther than is apparent by external symptoms. Pruning should therefore be at least six inches below obvious infection, and shears should be disinfected after each cut, because they might have cut through infected tissue. Unfortunately, removal of more substantial limbs may be severely disfiguring or justify removal of the most severely infected specimens.

News from the San Jose Heritage Rose Garden is certainly more pleasant. More than 3,700 roses need to be deadheaded. That is, of course, not the pleasant news; but after the volunteer deadheading workshop scheduled for 5:30 to 7:30 p.m. on June 10, ice cream sundaes will be served in the garden center. More experienced volunteers will instruct on appropriate deadheading technique that should promote continued bloom. Guests should bring bypass shears if possible. The San Jose Heritage Rose Garden is located on Taylor Street at Spring Street, just east of Coleman Avenue in San Jose. More information may be obtained, or reservations may be arranged, by telephoning volunteer coordinator Lucy Perez at 408.298.7657 or by email at lperez@grpg.org.


Flower of the Week: Autumn salvia

The common name of autumn salvia is less commonly known than the Latin name Salvia gregii, even though some are actually Salvia X jamensis, a hybrid of questionable lineage. Autumn salvia may bloom during autumn but usually bloom during early spring or summer. Salvia gregii blooms with variations of rose, red, pink and white. The floral color of Salvia X jamensis includes purple, dark red, pink, coral, orange, yellow and white. Several tubular, inch-long flowers are suspended by each delicate floral rachis. Mature specimens are usually less than 2 feet tall but can become taller. The delicate evergreen leaves are approximately a half-inch to an inch long. Unlike most perennial salvias, these prefer regular irrigation and tolerate minor shade.

Horticulturist Tony Tomeo can be contacted at 408-358-2574 or at LGHORTICULTURE@aol.com.