Page 49 - Ebook cây cảnh Art of Bonsai

Troubleshooting 49

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Wire scars This mechanical damage is caused when wire Spent flowers should be removed: left
has been left on a branch for too long before removal. The on a tree they can cause fungal problems
shoots thicken around the wire, which causes the wire to to develop. Also, remove flowers on trees
dig into the bark. The only solution is to remove the branch like azaleas to keep them from using
or wait for it to grow out. energy to form fruit or set seed.

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Green spruce aphids cause Picea foliage Gall mites Abnormal growths appear on Spider mites affect several species
to mottle and fall in winter or spring. the leaves caused by infection or, in this and will cause foliage to change color
Trees can take several years to recover. case, insects feeding and laying eggs. as mites suck their sap. Spray with
Preventive spraying in the fall reduces The damage is unattractive but rarely pesticide twice—a week apart—to kill
the risk of damage from these pests. causes serious problems for the tree. hatched eggs before they reach maturity.

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Powdery mildew A superficial fungal Woolly aphids Sap-feeding insects that Winter moth damage is easy to spot.
disease that grows on the surface of cause fluffy white patches on branches, It is caused by caterpillars feeding
deciduous tree leaves, especially English especially on pruning cuts. Swellings on on the leaves, which can be quickly
oak. It is unattractive rather than fatal, young shoots show where aphids have destroyed. Pick off the caterpillars
and easily treated with fungicide. been feeding. Can be difficult to control. and spray with insecticide.