Pine Wilt Disease and Possible Causes of Its Incidence in Russia.

Surveys of forests and stockpiled timber of pine, spruce, larch, and silver fir in 14 administrative subjects of the Russian Federation revealed widespread occurrence of the coniferous wood parasitic nematode Bursaphelenchus mucronatus. Twenty species of bacteria belonging to 13 genera have been detected in 25 B. mucronatus isolates, and their identity has been determined by direct sequencing of the 16S- RNA gene. The most frequently occurring were bacteria from the genera Pseudomonas, -Stenotrophomonas, Pantoea, Bacillus, Burkholderia, and Serratia. Prevalence of Pseudomonas brenneri and P. fluorescence, which were also found in the nematode dauer larva (Liv) isolated from the fir sawyer beetle Monochamus urussovi, have also been assessed. Two nematode B. xylophilus isolates from Portugal and one isolate from the United States have been examined, and 10 symbiotic bacteria species have been isolated, including Agrobacterium tumefacience, P.fluorescens, P. brenneri, Rahnella aquatilis, Stenotrophomonas maltophilia, S. rhizophila, and Yersinia mollaretfi.

[Distribution of the nematodes from family Trichodoridae, vectors of the tobacco rattle virus, in the Moscow oblast].

Three nematodes species for the family Trichodoridae, Trichodorus similis, T. primitivus, and Paratrichodorus teres, vectors of Tobacco Rattle virus (TRV), have been found in the vicinity of Moscow. Frequency of the joint occurrence of the above species and TRV infection was 73%. Trichodorids occurred more often in agrocenoses, where their frequency of occurrence in some years was 50% in potato fields and 25% in barley fields. The effects of the environmental factors (soil type, pH, and soil texture) on the distribution of trichodorids and seasonal dynamics of P. teres are established. A high level of the infection with TRV, against the background of complex viral infections, in plantings of different potato breeds in revealed.