Distribution of alien plants by speirochory in agrocenosis of Tomsk oblast.
The results of the herbological analyses of the seed lots of Sinapis alba and Phacelia tanacetifolia received in the trading networks of Tomsk oblast are presented. The species composition of weedy plants which are able to spread by speirochory is revealed. A high degree of weed infestation of green manure seeds, including diaspores of invasive and potentially invasive species (as well as quarantine plants), has been recorded. In seed lots of Sinapis alba and Phacelia tanacetifolia supplied to Tomsk oblast in 2017-2018 from the European part of Russia and the Siberian Federal District, diaspores of 58 weed species were found, among which nine species are invasive, including one quarantine species (Acroptilon repens). Along with a large diversity of weed species, a high total contamination (from 340 to 86 500 pcs/kg) of green manure seeds, including the most harmful weeds, is noted. For example, diaspores of seven weed species recognized as dangerous and one species which is especially dangerous for products of plant origin were present in the studied samples of Sinapis alba and Phacelia tanacetifolia. A large threat is also posed by the contamination of the studied green manure seeds by weeds with a pronounced dormant period, the seeds of which replenish the soil bank of agrocenoses, ensuring their contamination for many years to come. To ensure the agricultural safety of the region, strict control of the contamination of imported seed lots, their culling, and preventing the sale of heavily contaminated seed lots are necessary.