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Purpose. To study the influence of predecessors on the formation of weed and pest species composition in spring barley sowings and the grain yield loss. Methods. Field, physical, mathematical and statistical. Results. The most common weed species in spring barley sowings during vegetation season are the following: Cirsium arvense, Sonchus oleraceus, Ambrosia artemisiifolia, Elymus repens, Sinapis arvensis, Consolida regalis, and Polygonum lapathifolium. The number of weeds per 1 m2 of spring barley sowings affected the amount of grain losses. After pealosses, the lowest grain loss (0.01 to 0.24 t/ha) was at the number of weeds from 5 to 10 per m2. The increase in the number of weeds has contributed to the increase in the grain loss. However, this figure varied over weed species. Thus, under the infestation with Sinapis arvensis and Consolida regalis, the grain yield loss was significantly lower compared to the control with the largest number of weeds. The largest grain loss occurred from Cirsium arvense and Sonchus oleraceus reaching 0.53–0.53 t/ha in at the number of weeds 20 per m2. Given the Polygonum lapathifolium, Ambrosia artemisiifolia, Sinapis arvensis, and Elymus repens, this figure ranged from 0.19 to 0.34 t/ha. When spring barley was grown after sugar beet, grain yield loss was significantly lower than under the number of weeds from 12 to 20 per 1 m2. However, the trend of falling grain yield caused by weeds was similar. The smallest grain loss caused Sinapis arvensis and Consolida regalis, while the largest one was caused by root and shoot and rhizome weeds. The number of pests in spring barley crops varied from 1.0 to 1.8 per 1 m2 (plant). In the case of spring barley cultivation after pea, the grain yield loss varied from 0.52 to 0.73 t/ha, while after sugar beet from 0.34 to 0.41 t/ha, varying over the years of the study. Because the air temperature was similar during the pest development period, the number of pests varied little. Lower grain yield loss after sugar beet was due to fewer common pests. Conclusions. It was found that the largest grain yield loss was caused by such weeds species as Cirsium arvense, Sonchus oleraceus, Ambrosia artemisiifolia, and Elymus repens ranging between 0.47 and 0.55 t/ha in the amount of 20 plants per m2. Sinapis arvensis and Consolida regalis caused the lowest grain loss ranging from 0.26 to 0.28 t/ha. Under Sinapis arvensis, this figure ranged from 0.02 to 0.34 t/ha, depending on the weed number. In the sowing of spring barley, Schizaphis graminum Rond., Lema lichenis Voet., Phyllotreta vittula Redt, Carabidae, Aelia acuminata, and Eurygaster integriceps Put. were found. Pest control in spring barley sowings provides 0.52 to 0.73 t/ha of grain yield growth after pea cultivation and 0.34 to 0.41 t/ha after sugar beet. |
