Effetti a breve e medio termine di defogliazioni artificiali sull’accrescimento del pioppo euramericano (Populus × canadensis clone I-214) in piantagione in relazione all’intensità e all’epoca di defogliazione

Abstract

Abstract: The impact of artificial defoliations on the growth of euramerican poplar (Populus × canadensis clone I-214) was investigated in three field assays. Young poplar trees (1st-3rd cultivation year) were subjected to 25%, 50%, 75% and 100% defoliation either in the early or in the late growing season (or in both periods), and their growth was measured in the same year and during the following 2-3 years. Only trees treated to 75% and 100% defoliation exhibited a significant growth decrease compared to control trees: the diametric growth of early defoliated trees was reduced up to 20-40% in the year of defoliation, whereas trees defoliated at the same rates late in the season, or defoliated twice in a single year, suffered the heaviest damage, showing a growth loss up to 50% in the year following the defoliation events. In the latter cases, a delayed sprouting at spring and the death of branchlets were observed. A financial analysis showed that the economic damage caused by the highest defoliation rates, mainly when occurring late in the season, definitely exceeds the cost of treatments, thus suggesting the adoption of appropriate control strategies.