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What Are The Symptoms.
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- Are
the leaves yellow or turning a brown
colour? Where is the colour worse?
Is it worse on the leaf edges or in
the middle of the leaf?
- Are
all the leaves showing symptoms or
is it the older or younger leaves
showing these discolouring symptoms?
- Are
there any brown/black spots on
leaves and stems? Are these spots of
a uniform size or are they of many
different shapes and sizes?
- Is
only the upper of lower surface of
leaves showing symptoms or both tops
and bottoms?
- Are
the plants wilting
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Is There a pattern? |
- Do
all the plants show symptoms or is
it specific to a certain plant
within your garden, i.e. only the
tomatoes and not the lettuces?
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Does the problem seem worse in a
specific area in your garden, eg on
the perimeter or is there no
pattern?
- Do
the affected plants sit in
particular soil conditions, poor
drainage area, or an area with
obviously compacted soil?
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Trace the History. |
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When were symptoms first noticed?
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What types and concentrations of
fertilizer and lime were used?
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What pesticides and/or herbicides
were used?
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What were the weather conditions
like before you noticed the problems
-- cool or warm, wet or dry, windy,
cloudy, sunny?
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Examine the Plant Closely. |
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Insects: Look for their
presence or feeding signs on leaves,
stems and roots. Sometimes it's
easier to find insects early in the
morning or early evening.
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Disease: Look for dead areas
on roots, leaves, stems and flowers.
Are the plants wilting even though
soil moisture is plentiful? Are the
leaves spotted or yellowed? Are
there any signs of bacterial or
fungal growth (soft rots, mildew,
spores, etc.)? Look for virus
symptoms the plants stunted or do
they have obvious growth
malformations? Are all the plants
showing symptoms, or are just a few
scattered around the field?
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Could there be nutritional problems?
The table at the right is a list of
characteristic deficiency symptoms for
the major and minor nutrients.
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Nutrient |
Symptoms |
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Nitrogen |
Light green or yellow older
foliage. |
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Phosphorus |
Stunted plants and purplish
leaves. |
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Potassium |
Brown leaf margins and leaf
curling. |
|
Calcium |
Stunted plants, stubby roots.
(Causes blossom end rot of
tomatoes, tip burn of cabbage,
brownheart of escarole, celery
blackheart, carrot cavity spot).)
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Magnesium |
Yellowing between veins of older
leaves. |
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Sulfur |
Yellowing of hew leaves, stunted
plants. |
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Boron |
Growing points die back and leaves
are distorted. |
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Copper |
Yellowing of leaves which become
thin and elongated, causes soft
onion bulb with thin scales. |
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Iron |
Light green or yellow foliage on
youngest leaves. |
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Zinc |
Rust-colored spots on seed leaves
of beans, green and yellow
striping of corn, yellowing of
beet leaves. |
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Manganese |
Mottled yellow area appearing on
younger leaves first. In beets,
foliage becomes deeply red. |
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Molybdenum |
Distorted, narrow leaves, some
yellowing of older leaves;
whiptail leaf symptoms in
cauliflower. |
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Could there be a nutrient toxicity?
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Soluble salt injury may be seen as
wilting of the plant even when soil
is wet.
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Burning on leaf edges could be a
sign of chlorine damage -- are
symptoms worse near a pool?
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Have wood ashes been applied to the
garden? Using more than 5 pounds per
100 square feet can dramatically
increase soil pH which can result in
both nutritional deficiencies and
toxicities.
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Could soil problems be to blame? |
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Soil problems such as compaction and
poor drainage can severely stunt
plants.
- Are
gutter emptying water into the
garden keeping the soil too wet?
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Could pesticide injury be at fault?
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Were any insecticides or fungicides
applied. Remember, copper and sulfur
fungicides can burn plants if
applied in hot weather.
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Broadleaf weed killers applied to
lawns can cause abnormal growth or
even kill many garden plants nearby.
Tomatoes are especially sensitive.
Beware of using a lawn clipping
mulch which may have residual
herbicide.
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Could the damage be caused by
environmental conditions?
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Have temperatures been excessively
high or low? Plants that die
practically overnight may have been
touched by frost.
- Has
it been very dry or wet for long
periods of time?
- Has
there been strong winds that could
have caused the damage?
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Don't overlook air pollution. Ozone
levels may rise as hot, humid
weather settles in for long
stretches. Look for irregularly
shaped spots which may look similar
to feeding of mites and certain
leafhoppers. Ozone flecks are
usually concentrated in specific
areas of the leaf, while feeding
damage from insects is spread
uniformly across the leaf
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