Field studies were conducted in the northeastern part of the Republic of Croatia to determine the influence of the critical period of weed interference on sunflower (Helianthus annuus) yield, yield components, and oil content. For this purpose, different durations of competition were established, allowing weeds to infest the crop for increasing periods of time after planting or maintaining plots weed-free for increasing periods of time after planting. The beginning and the end of the critical period of weed control (CPWC), based on a 5% and 10% loss of sunflower yield, were determined by fitting the four-parameter log-logistic equations to the relative seed yield. The total weed biomass increased progressively in relation to the increase in the competition. The beginning of the CPWC period, based on a 5% acceptable yield loss, ranged from 141 to 234 growing degree days (GDD), which corresponded to the two-to-four true leaf development stage (the V2–V4 growth stages) across both sites and years. The crop had to be kept weed-free until a period when sunflower inflorescence began to open and flower (the R4–R5 growth stage) or from 1365 to 1932 GDD. The sunflower yield and yield components varied between the years and among locations. An increasing duration of weed interference negatively affected crop height, head diameter, and 1000-kernel weight, but not seed oil content.

Airborne pollen monitoring in the city of Vukovar (Northeastern Croatia) was carried out using a Hirst-type spore trap, which was placed on the roof of a building at a height of 15 m above ground level. Over 5 consecutive years of airborne pollen monitoring, 76 pollen types from 45 plant families were identified. Of these, 29 pollen types belonged to arboreal species and 47 to non-arboreal species. Sixty-two percent of the total pollen was non-arboreal pollen. The main pollen types present in the airborne spectrum were Ambrosia artemisiifolia, Betula, Urtica, and Poaceae. Among the arboreal types, the genus Betula is the only taxon producing a high percentage in the pollen spectrum. Regarding allergenicity, A. artemisifolia, Betula, and Poaceae pose the highest allergy risk, while Urtica has a low risk of pollen allergy. Large differences in annual pollen sum and the seasonal dynamics of these dominant taxa during the study period were verified. The presence of the pollen in the air was influenced by weather conditions, showing in particular a positive correlation with the minimum air temperature for Betula and mean air temperature for Urtica, Poaceae, and A. artemisiifolia. However, the pollen concentration in the air was negatively correlated with precipitation for Betula, Urtica, and Poaceae and with humidity for A. artemisiifolia.

Seed germination, growth, flowering and yields of kiwano (Cucumis metuliferus E. Meyer Ex. Naudin) were examined in eastern Slavonia during 2021 growing season. The objective of this study was to determine agro-morphological diversity within kiwano growing under different weed management practices and sowing time. The experiment was arranged as a 3 x 3 factorial design with three replications. Factors included three weed management options (wheat straw mulch, cultivation and un-weeded control) and three planting dates (early, mid and late May). A typical summer weed community that develops during experiment dominated with bristly foxtail (Setaria verticilata (L.) P. Beauv.) and redroot pigweed (Amaranthus retroflexus L.) while the others were with lower relative density and frequency per unit area and with the lower impact on the crop. Weed control was very effective compared to weedy check. However, sowing date appears as a critical factor in kiwano production, influencing not only emergence, growth and flowering, but also fruit number and size. This study concluded that mid sowing time and cultivation as a weed control measure has a highest agronomic potential for a kiwano production following by mid and early sowing time with mulch as a weed control measure.

The tree-of-heaven (Ailanthus altissima (Mill.) Swingle) is one of the most aggressive arboreal invaders, threatening forest health and biodiversity across five continents. Given its rapid spread, severe ecological impact, and management difficulty, this paper (i) synthesises current knowledge of ecological factors driving its invasion in forest settings, (ii) critically evaluates available control methods, and (iii) proposes an integrated, evidence–based management framework suitable for forest ecosystems. Prevention strategies, such as legislation, vigilant monitoring, and the rapid removal of female trees, are essential first–line defences. For control, systemic herbicides applied via foliar sprays, basal bark, cut–stump, or stem injection methods provide the most effective long–term suppression. In contrast, mechanical or physical treatments alone often result in vigorous resprouting. Biological control agents show potential but remain purely experimental. However, the absence of approved biological agents and the limited availability of long–term cost–effectiveness data currently constrain management planning and large–scale implementation in forest ecosystems. This review presents a decision matrix that links control options to tree ontogenetic stages and site conditions, highlighting research needs that balance effectiveness, costs, and ecological safety. Overall, this synthesis offers a clear, evidence–based toolkit for managers and policymakers managing A. altissima in forest ecosystems.

This study focuses on the distribution and impact of the invasive species tree-of-heaven (Ailanthus altissima (Mill) Swingle) in the easternmost county of the Republic of Croatia. The research was conducted from May to September 2022 and 2023, utilizing the systematic random sampling method. The presence of tree-of-heaven was recorded in both rural and urban environments, where only the number of trees having a medium tree trunk diameter at breast height (DBH) of 10-20 cm and a small DBH of 5-10 cm was significantly higher in rural compared to urban sites. The negative effects of the tree-of-heaven population are due to its vigorous clonal growth (biological characteristics; p < 0.001) and dense monoculture stands, resulting in decreased plant species richness and native species diversity (ecological impact; p < 0.001. The harmful effects of invasion depend on the site where plants grow. Still, serious damage, based on significant factor loadings (eigenvalue >1), was recorded not only on environmental but also on functional, safety, and aesthetic aspects, causing economic loss and mechanical damage.

Invasive weeds threaten forest ecosystem sustainability worldwide, underscoring the need for non-chemical management strategies. To address this challenge, the present study investigated the short-term morphological response and survival of the Japanese knotweed (Reynoutria japonica Houtt.) rhizome sprouts subjected to 60-s electrocution at 0–180 V in 20-V increments. The one-way ANOVA showed no significant effect on sprout diameter (p > 0.05), whereas sprout length varied significantly (p < 0.05; η² = 0.540), with Tukey’s HSD post-hoc test revealing that mean sprout length ranged from 20.9 ± 2.1 cm to 42.6 ± 4.6 cm for sprouts subjected to 60 V and 180 V, respectively. In contrast, the Mantel–Cox trend test indicated a significant decline in sprout survival time with increasing voltage (χ²₍₁₎ = 29.028; p < 0.001), as reflected by the Kaplan–Meier analysis. Furthermore, the Cox proportional hazards model showed a 2.60% increase in mortality hazard per 1-V increase (HR = 1.026; p < 0.001). These results indicate that electrocution treatments of ≥100 V induce rapid sprout mortality, with complete mortality observed by day 3 at 100 and 180 V and by day 4 at 120–160 V, a response descriptively referred to as the “flash-kill” effect, and highlight survival analysis as a more informative indicator for evaluating R. japonica electrocution efficacy. Nevertheless, even though short-term sprout mortality is not a definitive measure of control, a long-term evaluation must account for rhizome reserve depletion, bud number and viability, as well as sprout reemergence under forest-oriented, field-scale studies.