Repeated Lophodermium needle cast has a cumulative impact on the growth of Scots pine for up to 12 years.

The study investigates the long-term impact of Lophodermium needle cast on open-pollinated Scots pine progenies in Latvia. A significant impact of cumulative needle cast damage on growth and survival was found. Notably, 51% of trees experienced severe damage after the 4th growing season. Genetic factors played a role in survival at 12 years. Height growth was significantly affected, with height at age 3 and cumulative needle cast damage as key predictors for heights at ages 12 and 16. Genetics demonstrated a substantial impact, with heritability coefficients of 0.25 for cumulative needle cast damage and 0.24 for height, and negative genotypic correlations (r_G ≥ -0.71) between the traits. Selecting the top 10% families based on height at 12 years yielded a 14.2% improvement in height and a simultaneous 8.4% reduction in cumulative needle cast damage, enhancing survival by 9.8%. Thinning somewhat mitigated the negative effect of needle cast. The findings highlight the need for adaptive forestry strategies in the Baltic Sea region. [ABSTRACT FROM AUTHOR]