Volume 12, October 2011

By (1) Avigail Heller, Department of Plant Engineering and Botanical Gardens, Extension Service, Ministry of Agriculture and Rural Development; (2) Oren Saban, Landscape Studies, Rupin College; (3) Shosh Einav, Gardening and Landscape Department, Carmiel; (4) Yoram Kapulnik and Wininger Smadar, Department of Agronomy and Natural Resources., Institute of Plant Sciences, ARO, the Volcani Center, Bet Dagan

Slow growth and underdevelopment have been observed in Celtis australis and Koelreuteria bipinnata trees planted eight years previously as street trees in the town of Carmiel, Lower Galilee, Israel.

A novel biological approach, based on use of endomycorrhizal fungi, was used as a means for improving the trees' health and growth.
A product containing vesicular-arbuscular mycorrhiza was applied to the soil around the roots at a depth of 15–30 cm.

By (1) Avigail Heller, Department of Plant Engineering and Botanical Gardens, Extension Service, Ministry of Agriculture and Rural Development; (2) Oren Saban, Landscape Studies, Rupin College; (3) Shosh Einav, Gardening and Landscape Department, Carmiel; (4) Yoram Kapulnik and Wininger Smadar, Department of Agronomy and Natural Resources., Institute of Plant Sciences, ARO, the Volcani Center, Bet Dagan

The effectiveness and benefits of adding endomycorrhiza (vesicular-arbuscular mycorrhiza) to planting soil of two species of orchard trees has been examined, following an observation of retarded development of orchard trees within the town of Carmiel.

A significant tendency to early bud ripeness, as compared with untreated trees, was noticed in young Pyrus calleryana trees, following fungal infection. However, it is uncertain whether this influence is beneficial to the tree development in the area of Carmiel, because early ripening might predispose the buds and trees to damage in cold winters.

It was also established that in mycorrhiza-infected Diospyros kaki there was a significantly higher rate of branch emergence than among the control group of trees. A significant difference in branch length – up to four times greater – in infected trees, has been also noticed.

Infection with mycorrhiza improves growth and development, but the effects might differ in different species, therefore, such effects should be taken into account before applying treatment.

By (1) Anat Madmoni (Anat@Madmony.co.il), Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agricultural, Food and Environmental Quality Sciences, the Hebrew University of Jerusalem, Rehovot; (2)l Aviv Eizenband, KKL Forest Department, Eshtaol; (3) Josef Riov, Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agricultural, Food and Environmental Quality Sciences, the Hebrew University of Jerusalem, Rehovot

Tetraclinis articulata is the only species in its genus, a member of the family Cupressaceae. It originates from dry habitats in North Africa and is considered more drought-resistant than the Italian cypress (Cupressus sempervirens). In recent years some 15,000 seedlings per year were planted in various sites in Israel, and the survival rate, even in the dry south, is over 80%. During the 1998-2000 drought the species clearly proved to be more resistant than the more common Italian cypress.

The aim of this study was to examine the data and existing knowledge about the development of, and invasion risk associated with T. articulate, in order to evaluate the possibility of increasing the number of trees of this species used in forest planting in Israel.

Sixteen stands of T. articulata from locations ranging from Tiberias in the north to the northern Negev in the south were examined, and physical data were collected. The findings showed that the species develops very well under wide ranges of annual precipitation (under 300 mm), soil types, and topography (i.e., gradient and aspect); only a few forest-tree species can grow under such a wide range of conditions. Also, the tree re-sprouts after fires and is free of pests, especially Cypress diseases. Thanks to its pleasing appearance it is also recommended for parks and avenues. We conclude that in dry planting sites it might be an important afforestation species. The risk of invasion is minimal because of the dry climate, competing annual vegetation, and grazing.

By (1) Avigail Heller, Plants Engineering and Botanical Gardens Branch, Extension Service, Ministry of Agriculture and Rural Development (avigail.heller@gmail.com); (2) Israel Galon, Flowers and Plant Engineering Department, and Forest Commissioner, Extension Service, Ministry of Agriculture and Rural Development; (3) Elmalich Danny, Karkur; (4) Helor itzhak, Rehovot; (5) Gavriel Haim, Shefa Department, Tel-Aviv Municipality.

Several incidents of property damage caused by breaking branches or falling trees have occurred in Israel. On a few occasions injuries and even deaths have occurred. This article reviews the attitude to tree-risk assessment that has developed in Israel.

Tree-risk assessment is based upon general appearance, including crown decay or pathogen damage, and on categorization according to tree-risk grouping, i.e., robust trees vs. fragile trees.
Environmental influences such as irrigation and wind regime are also reviewed.

Survey tools and other means for tree-risk assessment that facilitate internal examination of trees, such as those frequently used around the world are also described.

We conclude that the currently available knowledge and experience enable fairly accurate tree-risk assessment, and substantial risk reduction, especially regarding common risks, such as branch breakage.

Nevertheless, there remains a certain amount of inaccuracy and uncertainty in anticipating tree falling and branch breakage.

By (1) Nir Herr, KKL Forest Department, Kiryat Haim (NirH@kkl.org.il); (2) Yossi Moshe, Volcani Center, Bet Dagan; (3) Anat Madmony, Faculty of Agriculture, Food and Environmental Quality Sciences, the Hebrew University, Rehovot.

Quercus ithaburensis acorns were sowed over an extensive area in Ramat Menasheh Biosphere Park (Israel) during 2001-2007. A total of approximately a million acorns were sowed in an area of about 300 Ha; they were sown in open areas, without additional treatment, and the results were checked by sample surveys.

During 2005 through 2007, a quantitative and qualitative study was carried out in research plots in the sown area. It examined the percentages of acorn seedling germination and survival in three adjacent habitats: an herbaceous area, a Sarcopoterium spinosum batha and a thinned pine forest. The surviving seedlings were counted and their heights were measured at the end of each summer.

The germination percentages in the batha and herbaceous area were about 12%, whereas in the forest it was significantly lower. After 3 years, seedling survival leveled off in the batha and in the forest, whereas in the herbal area the number of surviving seedlings continued to fall. There were no significant differences in seedling height between the treatments.