Skip to Left navigation Skip to Main content Skip to Footer

University of Minnesota Extension

Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous > Basswood/Linden > Thinning canopy

Print Icon Email Icon Share Icon

Basswood/Linden > Trunk/Branches > Thinning canopy

1 of 3
  • Image: Stem girdling roots 1
  • Image: Stem girdling roots 2
  • Image: Stem girdling roots 3

Stem girdling roots

  • Affected trees are often stunted, exhibit poor summer color, change color and lose their leaves early in the fall
  • Affected trees commonly exhibit water-stress symptoms such as marginal leaf scorch, wilting, sudden leaf fall
  • Affected trees commonly exhibit excessive and abnormal winter damage including true frost cracks and dieback
  • A root circling or running against one or more sides of the trunk of the tree may be seen at the soil line
  • The trunk may become sunken in or compressed where it contacts the root
  • If the girdling root is below ground, the trunk will lack the natural widening or flare at the soil line so will go straight into the earth like a telephone pole; trees often exhibit an abnormal lean
  • Many weak young shoots/sprouts at the base of the tree
  • Trees break off at the soil line during wind storms
  • More information on Stem girdling roots
2 of 3
  • Image: Linden borer 1

Linden borer
Saperda vestita

  • Thinning of the canopy
  • Lower branches, lower trunk and surface roots are attacked resulting in limbs in canopy dying; eventually the entire tree is killed after high infestation
  • Round exit holes ¼ inch wide in trunk
  • Adults up to ¾ to 7/8 inch long, longhorns, black body covered by dense olive-yellow hairs; larvae are legless, cylindrical and 7/8 to 1 inch long
  • Littleleaf lindens are preferred hosts
  • More information on Linden borer
3 of 3
  • Image: Introduced basswood thrips 1
  • Image: Introduced basswood thrips 2
  • Image: Introduced basswood thrips 3

Introduced basswood thrips
Thrips calcaratus

  • Defoliation usually occurs when infestation is high resulting in a thin canopy
  • Buds are attacked resulting in bud drop or deformed, ragged appearance of new leaves in spring
  • Typically a forest pest, usually not a landscape problem
  • American basswood is primary host
  • More information on Introduced basswood thrips

Don't see what you're looking for?