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Diagnosis: If you see the symptoms mentioned
above, you should check for spider mites. Since they are
so small, they are difficult to see with the unaided
eye. One approach is to take a tablet or clipboard with
white paper on it and hold it beneath the suspect
foliage. Tap the foliage with your fingers and small
green, red or yellow specks will fall onto the paper. If
the specks move around, they are spider mites. If not,
it is just dust.
As their name implies,
spider mites are not insects but are actually relatives
of spiders. They have 8 legs instead of the 6 found on
insects. They have sucking mouth parts and, during
feeding, they pull chlorophyll molecules out of the leaf
or needle. This is what causes the stipling color
effect.
Different types of mites
thrive in different environmental conditions. Some are
favored by temperatures above 70° F while others do best
in cool, moist weather of the spring or fall. The damage
of either type shows up most when the weather is hot and
dry and the injured tissues dies.
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Symptoms: Damage by
spider
mites usually results
in a discoloration of the leaves or needles into what is
called a "stipled" effect. The may have yellow, white or
bronze colors mixed randomly in with the green
Treatment: Always check to be sure that the
spider mites are still present before using any
treatment. Often, populations will expand rapidly, cause
the damage and then more or less disappear. So, be sure
they remain on the plant before reaching for the spray
can.
