Pears
are a cool climate fruit, they require winters that are long enough and
cold enough to provide them with a sufficient "chilling
requirement" if they are to fruit reliably. They are a little
more demanding than apples - a similar cool climate tree fruit - in that
they need more sheltered, warmer conditions in the growing season and in
particular shelter at flowering time which happens earlier than with
apples. Bad weather at flowering time can inhibit pollination and reduce
that years pear crop.
Pears make good ornamental trees too as well as
providing fruit. They have decorative furrowed bark and do a really
good line in old-and-gnarly from a relatively young age. The blossom is
very decorative and plentiful in the spring and there are many varieties
that give good fall color too. Wall training shows off these attributes
very well, one of my neighbors has a pear about 15ft high and wide
trained onto the wall at the side of his house and it looks good pretty
much all through the year.
Pears are best regarded as not being
self-pollinating. Some are (sort of) but almost all do better when
they have a pollination partner. The variety "Conference" can
form almost banana shaped fruits when self-pollinated for instance, but
reverts to the usual pear shape when cross pollinated. Others varieties
don't set fruit hardly at all without a pollination partner.
Rootstocks - pears do not come true from seed and
so the variety is grafted onto a rootstock that determines the eventual
vigor and size of the tree.
Training and pruning - pears are pome fruits
(they have many small pips rather than a single large stone such as plums)
and so are pruned while dormant in the winter months. The best time is
after the harshest of the winter weather is over, but before the buds
break for spring. Winter pruning should be to thin out the fruiting spurs
with the removal of one or two larger branches as appropriate to promote
younger growth. Fruit thinning may be required sometimes as a very heavy
crop may be set.
Pear Problems
Pear Scab - black/brown scabs appear on the fruits with
similar scabs on the leaves, though green/gray in color. Fruit may also be
small and misshapen, secondarily split and become infected with fungal rots.
This is caused by a fungus Venturia pirina which over winters on
stems and fallen leaves. Fallen leaves should be raked up and burnt or otherwise
disposed of out of the garden. Spray the tree with a fungicide containing
carbendazim or mancozeb, some apple cultivars are resistant. Trees with
overcrowded branches are more susceptible, so pruning to open the crown will
help, the disease is more prevalent in damp years.
Aphids - Twisted curled or puckered leaves and shoots
which on inspection have hundreds or thousands of tiny green, black or
pale colored insects. Spray at first sign with a systemic insecticide or
your preferred organic alternative.
Pear Leaf Blister Mite - Like all mites, tiny
little creatures (not insects, related to spiders) these cause small
raised yellow/green blisters on the leaves. Spray with thiophanate-methyl
at the end of March.
Pear Midge - Tiny
caterpillars or grubs appear in the small fruits which may fall. Spray
with fenitrothion before the flowers open and as they are fading, don't
spray while flowers are open as you will kill pollinating insects.
Fire
Blight - A very serious disease of many plants, but particularly of pears.
The plants look like a fire has been burning below the branches with
leaves and shoots first blackening and then shrivelling brown, hence the
name. Diseased wood should be cut out and burnt. The disease is most
common at flowering time starting at the blossom which goes black and
withers. It then passes back to the stems which die back leading to
cankers in the bark at the stem bases. Eventually the disease can pass to
the trunk which will kill the tree. A bacterial disease with no real
treatment other than good husbandry practices such as pruning at the
correct time of year and not too drastically at any one time. Pruning
tools used to remove diseased wood should be placed in a 10% bleach
solution between cuts for at least 5 seconds.
