Curly needle syndrome of loblolly pine seedlings

Abstract

Curly shaped needles developed on loblolly pine (Pinustaeda L.) seedlings grown in lysimeters in two greenhouse studies. Nearly 80% of the seedlings from five half-sib families developed curly needles when watered weekly with one of four acid rain solutions. No abnormal needles developed on seedlings from the same seed lots growing on an adjacent bench and watered daily. In a second study, curly needles developed within 2 weeks after seedlings were transplanted into the lysimeters. Weekly misting of the foliage significantly reduced the proportion of fascicles with curly needles. Results indicate that curly needle syndrome is induced by water stress during needle elongation and suggest that wetting the foliage decreases the strength of the fascicle sheaths.