The walnut twig beetle, Pityophthorus juglandis Blackman, and associated fungus Geosmithia morbida Kolařík, Freeland, Utley, & Tisserat constitute the insect-fungal complex that causes thousand cankers disease in walnut, Juglans spp., and wingnut, Pterocarya spp. Thousand cankers disease is responsible for the decline of Juglans species throughout the western United States and more recently, th...

Molecular phylogenetic analyses of ITS-LSU rDNA sequence data demonstrate that Melanconis species occurring on Juglandaceae are phylogenetically distinct from Melanconis s.str., and therefore the new genus Juglanconis is described. Morphologically, the genus Juglanconis differs from Melanconis by light to dark brown conidia with irregular verrucae on the inner surface of the conidial wall, whil...

The amplified fragment length polymorphism (AFLP) technique was applied to 109 strains of pv. pruni and one strain of pv. juglandis of the species Xanthomonas arboricola and to five strains of other Xanthomonas species. Groups of 12 and 41 strains of pv. pruni were isolated at the same time from fruit lesions in two peach orchards in the province of Verona (Italy). The other strains of pv. prun...

use of irradiation has long been proved to be effective in inducing new T z n e t i c variability in a quantitative trait. SCOSSIROLI (1954) irradiated D ~ o sophila mlanogaster populations that had ceased to respond to selection for sternopleural bristle. The irradiated populations now responded to further selection: the response to upward selection was remarkably high, while that to downward ...

The plum curculio, Conotrachelus nenuphar, is a major pest of pome and stone fruit. Our objective was to determine virulence and reproductive potential of six commercially available nematode species in C. nenuphar larvae and adults. Nematodes tested were Heterorhabditis bacteriophora (Hb strain), H. marelatus (Point Reyes strains), H. megidis (UK211 strain), Steinernema riobrave (355 strain), S...

Aspects of the susceptibility of English walnu~ to infection by Xanthomonas campestris pv. juglandis, the bacterium which causes walnut blight, were investigated. Leaves of 15 mature English walnut trees were inoculated with the bacterium which causes walnut blight, and after 35 days each cultivar was rated for infection severity. During the following dormant season, the buds associated with th...