Floristic and ecological analysis of weed flora in organic walnut orchards

Organic walnut (Juglans regia L.) production in Serbia is becoming increasingly important; however, data on the composition and ecological structure of weed flora in young orchards remain limited. The aim of this study was to determine the floristic composition, biological spectrum, and dominant weed species in an organic walnut orchard in the village of Trmčare (municipality of Kruševac, Serbia). A total of 59 weed species were recorded, including 32 weed-ruderal, 21 weed, and 6 ruderal species. The flora was dominated by representatives of the class Magnoliopsida (50 species), while 9 species belonged to the class Liliopsida. Life form analysis showed the predominance of therophytes (52.54%), followed by hemicryptophytes (37.29%), geophytes (8.47%), and therophyte-hemicryptophytes (1.69%). A high level of weed infestation was recorded, mainly due to the absence of inter-row soil cultivation, as well as the fact that deep plowing (rigolage) was not applied during primary soil preparation before planting, together with the use of uncomposted cattle manure during soil preparation. Immediately after orchard establishment, a massive occurrence of Rumex obtusifolius was recorded, which was likely introduced through contaminated organic fertilizer. The most frequently recorded species, in addition to Rumex obtusifolius L., were Lamium amplexicaule L., Galium aparine L., Taraxacum officinale Weber, Agropyron repens (L.) P. Beauv., Bromus arvensis L., Bromus sterilis L., Poa pratensis L., Stellaria media (L.) Vill., Veronica persica Poir., Capsella bursa-pastoris (L.) Medik., Lamium purpureum L., Plantago media L., Plantago lanceolata L., and Plantago major L. The results indicate that weed community structure in young organic walnut orchards is strongly influenced by reduced soil tillage intensity, the application of organic fertilizers, and orchard management practices. This study contributes to a better understanding of weed vegetation dynamics in organic walnut production and provides a basis for developing sustainable weed management strategies adapted to local agroecological conditions.