Cumulative effect of needle cast on Scots pine saplings

Abstract

Premature needle cast, affecting the needles on one-year old shoots, thus shrinks the size of green crown of Scots pines, and can cause reduction of increment or even death of trees, especially during first years of their growth. Aim of our study was to evaluate the lasting impact of pathological needle cast to young Scots pines and its implications for tree breeding. Assessment of needle cast damages in 5 grade scale and measurements of height were done repeatedly in Scots pine open pollinated progeny trial, consisting of 65 families, located in central part of Latvia. Proportion of saplings with different level of needle cast damage differed significantly between the years of impact: severely damaged were 51%, 30% and 17% of saplings in growing seasons 4, 5 and 6, respectively. Both the needle cast damage grade at current growing season, as well as height of the sapling before the needle cast infection (at the end of the third growing season) had a significant effect on its grade of needle cast damages in the next growing season. Cumulative level of needle cast damages at the age 4 to 6 years had significant negative effect on height of the saplings at the age of 12 years both at individual tree and family mean level, as well as on survival. Selection of best growing families in such trial would also lead to selection of genotypes least affected by the disease.

Long-Term Effect of Lophodermium Needle Cast on The Growth of Scots Pine and Implications for Financial Outcomes

“…Severe defoliation due to L. seditiosum infection is a common type of damage that affects Scots pine in nurseries and young stands in the Baltic sea region [11,18,20,23,31,46]. In our study trial, more than half of the trees were severely damaged by Lophodermium needle cast in the sixth growing season, yet damage had likely occurred for several years.…”

“…It was supported by strong negative correlations (r = −0.62, −0.70, p < 0.01) between survival and height at the age of 17 years and the proportion of severely damaged trees (Table 1) at the family mean level. Significant effects of provenance and genetic entries on resistance have been reported in earlier studies [18,[30][31][32]47]. The results indicated that, if the risk of needle cast damage could be minimised by applying such measures as the selection of more resistant genotypes, the EAA financial outcome might be improved regardless of the decisions concerning a desirable management regime and final harvest time.…”

“…20% and 80%, respectively) indicated a substantial negative impact on survival (Figure 2). Although the loss of dead needles could not necessarily be a direct cause of death for the infected tree, seedlings had reduced viability and weakened new shoots [13,15], thus becoming more susceptible to other abiotic and biotic risks [18]. Needle cast damage is also reported to negatively affect survival in open-pollinated progeny trials, where the mortality of severely damaged trees reached 85% at the age of 12 years [18].…”

“…As a result, the growth of initially smaller but more-resistant trees after 12 years surpassed the dimensions of the trees that were initially larger but less resistant. The height of Scots pine saplings at the age of 12 years was reported to be negatively affected by cumulative needle cast damage during the fourth to sixth growing seasons [18]. The three youngest needle sets reported to have a significant influence on the current year's height and radial increment [49].…”

“…Trees retain needles for several years; however, older needles are less photosynthetically active than younger ones [17]. Thus, a current year needle infection leads to reduced growth (annual increment) and survival [18]. Moreover, biotic disturbances may interact with each other [19], and the damage to forest stands could be the result of a complex of infections.…”