Thursday July 2, 2009 at 7 pm

Presentation by Dr. Mary Olsen, Ph.D.

"Diseases of Cacti and Succulents"

Despite their special adaptations such as thick waxy cuticles, modified leaves (spines), dehydration induced dormancy and other tactics, cacti and succulents suffer from diseases, insect pests and cultural problems just as all other plants. There is relatively little known about the diseases of these plants, but fungi, bacteria, viruses and parasitic nematodes can cause problems in cacti and succulents. Many of these problems are avoidable, but others are problematic in cacti and succulents even in their native habitats. Recognizing these problems is the first step toward knowing how to control or avoid them. Mary will discuss the problems with which she is familiar, and engage audience participation in expressing problems they may have encountered.

Dr. Mary W. Olsen, is an Extension Specialist in Plant Pathology with the Department of Plant Sciences at the University of Arizona. She received her Ph.D. in Plant Pathology at the University of Arizona in 1982 and a B.S. in Botany, University of Arizona in 1976.

Mary has been the Extension Specialist in Plant Pathology at the UA since 1997 and works at the the University of Arizona main campus in Tucson. She will diagnose plant diseases for clientele in Arizona including growers, landscapers and homeowners. She also provides information on the identification, prevention and control of diseases of plants in commercial agriculture, landscapes and native sites. Mary currently conducts research on the etiology, ecology and control of important diseases of cotton, grains, vegetables and turf. Information on many diseases of plants in Arizona is provided on her web site (http://www.ag.arizona.edu/PLP/plpext/), as is information for submitting plant samples for diagnosis.

If you would like to learn more about disease and pest problems, please be sure to attend this meeting!

July Refreshments
Those with family names beginning with K, L, M, N, O and P, please bring your choice of refreshments to the meeting.

FREE PLANT GIVEAWAY

Ceropegia stapeliiformis ssp. serpentina
From the Republic of South Africa and Swaziland, this is one very "snaky" species of Ceropegia. The stems creep and twine, possessing peduncles that grab onto convenient surfaces to hold the plant up. The flowers are dark brown and white.

Orbea variegata
From the Western Cape Province of the Republic of South Africa, this widely distributed species is one of the mostpopular stapeliads. The stems are rather generic and unremarkable, but the flower is large, multicolored, and stinks to high heaven. In Tucson, these plants get leggy; it is best if the stems are short and densely packed.

Huernia keniensis var. keniensis
This small asclepiad grows among basalt rocks and on other rocky ridges in the Great Rift Valley of Kenya and Tanzania. The fragile stems resemble innumerable Huernia, but the flowers are bell-shaped and dark purple and about an inch across.