Impacts of Pear Thrips Damage on Root Carbohydrate, Sap, and Crown Characteristics of Sugar Maples in a Pennsylvania Sugarbush

Abstract

Abstract Fall root total nonstructural carbohydrate concentration (TNC), spring sap sugar concentration and volume, and summer crown condition were compared for 2 years among sugar maples (Acer saccharum Marsh.) that exhibited different degrees of crown damage following a 1989 attack of pear thrips (Taeniothrips inconsequens Uzel) in a Pennsylvania sugarbush. Trees with heavy damage had lower root TNC the fall following attack and greater crown transparency in both years following attack compared with trees with less damage. In the first year following attack, sap sugar concentration and volume were greater for trees with light damage than trees with moderate or heavy damage. In the second year following attack, sap volume was still greatest for trees with light damage while trees with heavy damage had the highest sugar concentration of all damage classes. Calculated syrup production based on sap sugar concentration and volume was greatest for trees with light damage and lowest for trees with heavy damage in both years. Trees with heavy damage in 1989 had earlier 1991 spring budburst than trees with light damage, and early budburst was associated with greater 1991 thrips infestation. The results indicate that pear thrips damage had a detrimental impact on tree health and syrup production for the next 2 years. For. Sci. 38(2):381-392.