Plants are vulnerable to many diseases. These diseases are mostly caused by fungi and viruses. There are also a few bacterial infections
that attack plants and produce similar symptoms to those of fungi.
Their is a long list of ways plant diseases can sneak into a garden and
attack the plants. They can already be present in the seeds you sow.
They could be in the soil around the roots of a plant, or carried in the
soil on the soles of your shoes. They may also come in on new plants or
plant material from the nursery or garden store where you purchased
them. They can even arrive in the garden on a wind. Here is a list of
some very common plant disease, what they infect, symptoms and how to
prevent and control them.
MILDEW: This affects peas, onions,
lettuce, spinach and cabbage. The powdery and downy mildew produce a
white or gray mold, it is often found in round patches. Downey mildew
appears on the undersides of leaves in cool, damp conditions. Powdery
mildew forms on the top in dry conditions. To prevent this disease do
not overcrowd plants or over water them. Look for mildew resistant
varieties. Remove any plant debris promptly. To chemically control them
you will use green and yellow sulfur for powdery mildew and for down
mildew you will use the chemical mancozeb.
BLIGHT: This
disease affects potatoes and tomatoes. Blight favors warm,wet weather.
It progresses rapidly on potatoes. The first signs are dark blotches on
the leaves, followed by rapid wilting and yellowing of the foliage and
stems. Then the plant will usually collapse in a few days. Blight is
less dramatic on tomatoes, but is still serious. The leaves start
collapsing and the fruit develop brown rotting patches. A different
organism is responsible for early blight, which causes brown spots on
the leaves it is much less serious. Warnings are often given when the
right combination of humidity and temperature are present. To prevent
further damage when you spot the disease on potato foliage remove and
burn the top growth. If you harvest the crop right away the tubers may
be unaffected. Destroy infected crop remains by burning them. Planting
tomatoes in greenhouse are less likely to be attacked by this disease.
There are a few different types of chemicals you can use on this disease
they are mancozeb, copper sulfate and copper oxychloride.
BOTRYTIS (GRAY MOLD):
This disease affects many different crops, especially lettuce and
tomatoes. It produces a fluffy gray mold growth, under this growth the
plant tissue rots. This fungus starts on dead tissue but spreads quickly
to live parts. It is found quite often in greenhouses. It prefers cool,
damp places. To help prevent this disease keep greenhouses well
ventilated. Make sure your plants are not overcrowded, water early in
the day and do not splash water. When you spot any of this disease clear
all the dead and dying plant debris away.Cut out and destroy any
affected parts.
WILT: This disease affects tomato and
cabbage family. Fusarium wilt is the most common type. Young plants
become pale and stunted, lower leaves yellow and wilt. The symptoms move
upward and plants may die. Verticillium wilt causes similar symptoms
but without one-sided effects. Wilt diseases are worse in the hot
weather. To prevent this disease grow only disease resistant plants.
Clear away any infected plant debris and rotate crops. Their are no
chemicals to use on this disease.
