Over-watering

  • Brown or black spots on leaves
  • Stems look mushy
  • Plant is wilted
  • Soil feels wet

Under-watering

  • Plant is wilted
  • Soil feels dry

Insects

  • Holes in leaves
  • Chewed leaves, distorted leaves
  • Pin-size holes in stem
  • Back of leaves look silvery with tiny black spots
  • Leaves look rusty

Fertilizer

  • Too little fertilizer – stunted yellow growth
  • Too much fertilizer – leaves have brown, damaged looking edges, leaves may turn black
  • A slight excess can cause rich lush growth, usually with no flowering which can suffer damage at onset of cold

Microorganisms

  • White powdery substance on the leaves
  • Browning and spotting of the leaves
  • Other Plant Problems

Animals

  • Bark stripped off trees and shrubs
  • If top of plant dies for no apparent reason, roots may have been eaten by grubs or gophers

Tree Graft

  • Union may not be compatible; though the tree has appeared to thrive for several years
  • Tree goes into unexplainable decline

These are just a few of the things which can damage otherwise healthy plants. Hopefully these general guidelines will head you in the right direction to alleviate the problem and prevent future ones!