There are approximately 1000 ha of natural populations of Buxus sempervirens, a small evergreen tree widely used in ornamental landscaping, in Turkey. These populations usually occur as an understorey in forests. Since the outbreak of boxwood blight epidemics in the Eastern Black Sea region in 2011 approximately 90% of the trees in the affected areas have died. In this paper we discuss the possibilities to save boxwood in Turkey.

Keywords: boxwood blight, Turkey, disease management

   Dothistroma needle blight (DNB) is one of the most serious and widespread needle diseases of pines. Its current distribution was investigated in high altitude native and planted pine forests in Montenegro. The suitability for the disease under different climatic conditions is discussed. Using molecular methods, polymerase chain reaction (PCR) with species specific primers, Dothistroma septosporum (Dorog) M. Morelet was detected from needles of Pinus nigra Arn., Pinus nigra ‘Dalmatica’ (Visiani) Franco, Pinus sylvestris L., Pinus mugo Turra, Pinus heldreichii H. Christ, Pinus peuce Griseb. and Picea abies Karst. in different parts of Montenegro, at altitudes between 800 and 2150 m. Dothistroma pini Hulbary was detected from P. sylvestris, P. nigra and P. mugo from restricted area in Northwestern part of Montenegro at altitudes between 800 and 1850 m. This is the first report of DNB on P. mugo and P. abies in Montenegro, and the first time that D. septosporum was detected from P.nigra ‘Dalmatica’. Also, D. septosporum was detected through native forests of P. heldreichii and P. peuce. The climatic conditions and altitudes where DNB was detected were different from what has previously been reported for this region. From this study, we can conclude that DNB is present in high-altitude pine forests throughout Montenegro. However, the intensity of the disease is low due to prevailing environmental conditions, which are probably not favorable for DNB development.

Keywords: Dothistroma septosporum, Dothistroma pini, Pinus heldreichii, Pinus peuce, Pinus mugo, Pinus nigra ‘Dalmatica’, climate.

   Fusarium circinatum is an ascomycete fungus that causes Pine Pitch Canker (PPC) of pines. The disease is causing damages in forests and nurseries all around the world. In Europe, is present in northern Spain, and also has been detected in Portugal, France and Italy. Fusarium circinatum seems to require fresh wounds on trees as infection court. Notwithstanding, the susceptibility of these wounds to infection could decrease significantly with wound age. Fusarium circinatum has been reported to be phoretically associated with P. pubescens in California. In northern Spain, T. piniperda is a major candidate for being an effective vector of F. circinatum due to the maturation feeding it practices in the crowns of healthy pines and subsequent overwintering. At present there are no means of controlling PPC disease in adult trees in forest or plantations. However, given the seedborne character of F. circinatum, some encouraging results have been obtained by the use of different strategies to reduce the presence of the pathogen in pine seeds. For example hot water treatments (51–52ºC for 30 min) were found effective in reducing F. circinatum contamination in seeds. Endophytic species which do not cause any damage that could be used for biological control of Fusarium spp., have been reported related to pitch canker diseased in P. radiata trees. The use of mycoviruses to control fungal diseases of plants could be a promising method when the genetic diversity of the populations of the pathogen is low, for example, when the introduction of the fungus in a region is recent or when sexual reproduction is absent as occurs in PPC. Recently, three different strains of mycoviruses co-infecting a Spanish isolate of F. circinatum were found and characterized. More studies are essential to prevent the rapid spread of the disease from southern to northern Europe.

Keywords:

   Black sawfly (Tomostethus nigritus), the foliage browsing pest of common ash (Fraxinus excelsior) after several years of depression was registered in forest stands, forest shelter belts and urban ornamental stands of the East Ukraine. The aim of this research was to reveal the peculiarities of ash defoliation by black sawfly during three years of outbreak and to recognize the changes in health condition of defoliated trees. Research was carried out for 2013–2015 in Molodezhny park of Kharkiv (50°00' N; 36°25' E) (Ukraine, Forest-steppe natural zone) in two groups of common ash trees (forest belt and compact stand). For each labeled tree, defoliation of the whole crown and separately of upper, middle and lower layers, outer and inner parts of crown was assessed in June of 2013, 2014 and 2015, and additionally in July 2015. Health condition of each labeled tree was assessed in June 2013 and July 2015. Defoliation of common ash trees did not significantly differ in 2013 and 2014. It almost twice increased in 2015 and in average exceeded 90 %. Dependence of defoliation from crown layer, crown part (outer or inner) or tree diameter was not proved statistically, but correlation analysis shows the better health condition of larger trees. The fast recovery of ash crowns after severe damage by black sawfly in 2015 can be explained by favorable weather conditions. Analysis of ash trees distribution by categories of health condition show the improvement of their health after three years of foliage damage by ash sawfly, but forest stand continues to be weakened. Considerable parts of the trees, which belonged to the 2nd, 3rd and 4th cate-gories of health condition in 2013, changed it by one-three grades. Totally 50 % of trees did not change the category of health condition, 35.3 % of trees improved it and 14.7% worsened it.

Keywords: black sawfly (Tomostethus nigritus), common ash (Fraxinus excelsior); defoliation, crown condition.