Characteristics and patogenitet an local isolates of race Xanthomonas causing walnut bacterial blight in Bulgaria

Maria Andonova, Milena Dimova

Abstract: A walnut bacterial blight caused by Xanthomonas arboricola pv. juglandis is major bacterial disease occurring in all walnuts growth regions in Bulgaria. Damage an this disease is mainly associated with necrosis premature fruits loss and reduction of yield at harvest. Isolation of leaves, buds, shoots and fruits were collected three years – from early of April to late September (2009 to 2011) of young and old walnuts growth gardens from south and southeast part of country. The obtained isolates were identified on four culture media. Pathogenicity tests carried out on plants of tobacco, young walnut fruits and walnuts seedlings (Lara – open pollination) in a greenhouse. Isolate № 3-2-9 inoculated directly on young, green fruits from a variety Izvor10 shows typical symptoms of bacterial blight with black spots still soft shell and partially or completely blackened, destroyed nuts in the form of paste consistency. Several methods are used for artificial infection of walnut seedlings – by scrub of bacterial suspension with quartz sand on leaves, directly spraying the bacterial suspension and through the stem cutting and direct application of bacterial mass. By the second method we observed on the fifth day after inoculation symptoms of bacterial blight in the form of watery-necrotic wed, soaked spots.

Keywords: Juglans regia; walnut; walnut bacterial blight; Xanthomonas arboricola pv. juglandis

Date published: 2017-07-12