Table 1.

Some natural site situations in relation to likelihood of disease.

LocationPrincipal advantagePrincipal disadvantageDisease likelihood
Open-grown isolated trees, level groundTrees are isolated from other treesConditions for dew formation on leavesS1 + + +3 L2 +
Trees in forest with closed canopyDew formation minimal on understoryUnderstory trees readily infected from diseased overstoryS + + + S +
Small trees in forest openingCool shaded environment (good for reducing diseases which can be surpressed by shading)Optimum conditions for dew formation on leaves; slow drying conditionsS,L + + + +
Kettle holeConditions for dew formation optimalS,L + + + + +
Even-aged trees of same species in a hedgerowDisease can spread easily from tree to treeS,L + + +
Uneven-aged trees of different species in a hedgerowRapid drying of foliage after wettingHumid zone on lee side of hedgerowS + + L +

  • ↵1 S = tree less than 3 feet tall.

  • ↵2 L = tree taller than 3 feet.

  • ↵3 += least disease, + + + + + = most disease.