Septoria leaf blotch (SLB), caused by Zymoseptoria tritici, is one of the most important foliar diseases of wheat. The management of this disease is assisted by selecting a sowing time and seeding density that is less favorable to the pathogen. The aim of this research was to evaluate the severity of SLB on winter wheat cv. ‘Etana’ sown at three different sowing times and three seed rates. The severity assessments were performed on the upper two leaves three times during the growth stages using the phenological growth stage key developed by the Biologische Bundesanstalt, Bundessortenamt, and Chemical industry (BBCH), namely stages 37–41, 59–65, and 75. The area under the disease progress curve (AUDPC) was evaluated in each plot. In 2022, seed rates showed significant differences (p = 0.0047), while sowing times did not show significant differences. In contrast, both seed rate and sowing time showed significant effects in 2021 (p = 0.0004 for sowing time and p < 0.0001 for seed rate). During the 2021 growth stage BBCH 75, late sowing times exhibited a significant reduction in SLB on the first leaf. The reduction ranged from 47.0% to 52.6% compared to the optimal sowing time, and from 59.2% to 66.2% compared to the early sowing time. At optimal sowing times (between 11 September and 25 September), seed rates of 400 and 450 seeds/m² resulted in a low SLB. At late sowing times in 2022, a lower SLB (43.2% compared to the early sowing time) was obtained from seed rates of 400 seeds/m². No significant interaction was observed between sowing time and seed rate across both study years. In the absence of interaction, the effects of sowing time and seed rate on SLB severity were independent and not additive. In 2022, the highest values of AUDPC were recorded for the early sowing time and the highest seed rate. Increasing the seed rate (450 seeds m⁻²) gave higher AUDPC at early sowing time with significant differences compared to other seed rates at optimal or late sowing times. In conclusion, our findings highlight the significant influence of sowing time and seed rate on SLB severity in winter wheat. Understanding these factors can inform agricultural practices to better manage SLB. Future research should explore additional agronomic practices and environmental factors to develop comprehensive strategies for SLB management.

Tan spot (Pyrenophora tritici-repentis) is presenting a persistent challenge to the plant health and yield of all wheat-growing regions. This research is focused on tan spot disease management in spring wheat when planted at three distinct times and with three different seeding rates without the use of fungicides. Across all years, higher seed rates (500 and 600 seeds per m²) generally resulted in lower tan spot intensity compared to the lower seed rate (400 seeds per m²). Significant differences in tan spot intensity were observed across seed rates at all sowing times. In 2021, the percentage of the AUDPC was significantly higher in the late sowing time (324.58%), with about a 2-fold difference compared with the early (167.48%) and optimal sowing time (191.80%). This suggests that delayed sowing significantly exacerbates disease occurrence. The combined effect of sowing time and year on the AUDPC was notably significant. The AUDPC of the tan spot in all seed rates was the highest in the late sowing time plots in comparison to the ideal and initial planting dates plots. Our results demonstrate how important seed rate and sowing timing are in determining the degree of tan spot in spring wheat. Growing crop methods may be improved by taking these elements into account to better control tan spots. More agricultural methods and environmental aspects should be investigated in future studies to create all-encompassing tan spot control plans.