Special aspects of the development of black currant bushes depending on weediness level in the Ukrainian polissia
We studied the weeds species composition in the black currantplantations of Ukrainian Polissia. The species composition of weeds has been analyzedand is was typical for thisarea. Twelve weed species were found during the study; they included annual (89.8%) and perennial ones (10.2%). A number of species were prevalent among the perennial weeds, namely common dandelion (Taraxacum officinaleWigg.) –2.5 pcs/m2, field milk thistle (Sonchus arvensisL.) –2.8 pcs/m2, couch grass (Elytrigia repensL.) –8.8 pcs/m2, and field sorrel (Rumex acetostellaL.) –3.2 pcs/m2. The most common annual species of weeds were lamb’s quarters (Chenopodium albumL.) –44.2 pcs/m2, shepherd’s purse (Capsella bursa-pastorisL.) –36.3 pcs/m2, smooth meadow grass (Poa annuaL.) –25.1 pcs/m2, and Amaranthus retroflexus(Amaranthus retroflexusL.) –19.6 pcs/m2. Throughout the study period, the least common weeds in black currant plantations were chickweed (Stellaria mediaL.) –14.8 pcs/m2, annual nettle (Urtica urensL.) –1.6 pcs/m2, quickweed (Galinsoga parvifloraCav.) –9.1 pcs/m2, and field pansy (Viola arvensisMurr.)–2.6 pcs/m2. We registered that with theweediness of 8-9 points the area of black currant leaves from a bush decreases by 1.9 m2, while the chlorophyll content in the leaves reduced by 20.8mg/100g. On the contrary, the dry matter content inleaves increasedfrom 29 to 61%. Significant negative effect of weeds on the activity of black currant and leads to a decrease in plant tolerance againstthe sucking pests and diseases. Thus, under high and very high weediness (8-9 points),the development of anthracnose (Gioesporium ribisMont.) was 32–48%, powdery mildew (Sphaerotheca mors Uvae.) and septoria blight (Mycosphaerella ribisLind.) were 16 and 15% respectively. We proved that a high weediness level reduces the yield of berriesby 56%in black currant plantations.