Pests and diseases
Trees and shrubs are probably less beset by pests and diseases than most other garden
plants, but they have their share of enemies, which differ from place to place. I
remember seeing a garden in France after a herd of wild boar had passed through in
the night. Even large rhododendrons had been uprooted and smashed.
Fortunately not many gardens have to contend with them, but deer are a common
problem and can nibble almost any plant, or rub the bark off when trying to clean
their new antlers of velvet. Bullfinches are another terrible animal pest, and
can clear a shrub or tree of buds in a very short time. Forsythia, Prunus,
Ribes, Amelanchier and even Deutzia are regularly attacked. Netting the susceptible
shrubs is the only answer, as however many birds are shot, more will come. A pet
sparrow hawk would act as an excellent deterrent.
The worst disease of trees and to a lesser extent shrubs is certainly the Honey
Fungus Armillaria mellea, which can attack and kill almost any genus, though
Magnolias are said to be less affected than many others. Formulations are on the
market, such as Armillaritox, which have been known to kill it in some places.
Mixing a handful of copper carbonate at planting time into the surrounding soil
has been said to keep it at bay but these methods are uncertain; alternatively,
to be more sure of eliminating the problem, dig up the affected plant or plants
and remove all the soil to at least three feet beyond the root system. Honey
Fungus attacks weakened plants, especially in wet, poorly drained soil;
the black rhizomorphs, like thin leather bootlaces grow through the soil,
and can infect the base of the plant, leaving a flat, white mass of fungal
mycelium under the dead bark as a sign of what has caused the sudden or
lingering death of your favourite tree.
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