Q.
I have a fruit tree with leaves that are brown on the edges and a dust that
covers the leaves. Some of the leaves are turning gray green on branches and
the tree does not look healthy.
I have a fruit tree with leaves that are brown on the edges and a dust that
covers the leaves. Some of the leaves are turning gray green on branches and
the tree does not look healthy.
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| Spider mites our famous for causing damage to Italian cypress. They cause Browning and branch death, usually there is webbing seen as well. That’s why these critters are called “spider” mites. But they are more closely related to spiders than they are insects.It’s always a good idea to wash off Italian cypress with a hose when they get dusty. |
A.
Most likely the tree damage was caused by spider mites. Spider mites are a
summer pest problem during hot, dry weather.
Most likely the tree damage was caused by spider mites. Spider mites are a
summer pest problem during hot, dry weather.
Another telltale sign that you
mentioned is the “dusty” appearance of the leaves. This “dust” results from
dead spider mites left behind as the population grows.
mentioned is the “dusty” appearance of the leaves. This “dust” results from
dead spider mites left behind as the population grows.
Look for feeding damage to the
leaves caused by spider mites. This feeding damage causes tiny yellow dots
scattered all over the surface of the leaf and accompanied by tiny black dots
the size of this period. By the way, the tiny black dots is mite “poop”. Even
though mites feed on leaf bottoms, the yellow dots can be seen on the top of
leaves.
leaves caused by spider mites. This feeding damage causes tiny yellow dots
scattered all over the surface of the leaf and accompanied by tiny black dots
the size of this period. By the way, the tiny black dots is mite “poop”. Even
though mites feed on leaf bottoms, the yellow dots can be seen on the top of
leaves.
A common misconception is that
webbing must be present if mites are the problem. Spider mites leave behind
“webbing”, like the weak form of a spider’s web. But not all mites that cause
plant damage spin webs.
webbing must be present if mites are the problem. Spider mites leave behind
“webbing”, like the weak form of a spider’s web. But not all mites that cause
plant damage spin webs.
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| Leaf damage and webbing scene on tomatoes caused by spider mites. |
So, finding webs when there is
damage is not a “dead giveaway” that the damage is from mites. It could be one
indicator, though. There are real spiders who are “good guys” that spin webs
and hang out in plants. These spiders can be beneficial.
damage is not a “dead giveaway” that the damage is from mites. It could be one
indicator, though. There are real spiders who are “good guys” that spin webs
and hang out in plants. These spiders can be beneficial.
Mite attacks to plants may come
after the application of a hard pesticide. Bad mites are always present on
plants but their numbers are controlled by predatory insects and even “good
mites”. So, applying a hard pesticide to control borers, for instance, could
lead to an outbreak of spider mites because the predatory “good guys” were
killed.
after the application of a hard pesticide. Bad mites are always present on
plants but their numbers are controlled by predatory insects and even “good
mites”. So, applying a hard pesticide to control borers, for instance, could
lead to an outbreak of spider mites because the predatory “good guys” were
killed.
What
can you do? Confirm that spider mites are the problem. Use a white paper test.
Shake or slap an infested branch on a white piece of paper or paper plate.
Closely look at the white surface for tiny dots, the size of a period, crawling
along the paper.
can you do? Confirm that spider mites are the problem. Use a white paper test.
Shake or slap an infested branch on a white piece of paper or paper plate.
Closely look at the white surface for tiny dots, the size of a period, crawling
along the paper.
Smear
them with your fingers if you aren’t sure. If you see lots of them, along with
plant damage that I described, you have confirmed mite damage.
them with your fingers if you aren’t sure. If you see lots of them, along with
plant damage that I described, you have confirmed mite damage.
Multiple
applications of soap and water sprays do a good job getting small outbreaks
under control. Hosing the leaves of plants monthly, or after a dust storm,
removes dust from the leaf surface which can increase spider mite populations.
applications of soap and water sprays do a good job getting small outbreaks
under control. Hosing the leaves of plants monthly, or after a dust storm,
removes dust from the leaf surface which can increase spider mite populations.
Severe
infestations of spider mites may require a pesticide application. Whenever
spider mites were problem during the year, be sure to apply two dormant oil
sprays during the winter months.
infestations of spider mites may require a pesticide application. Whenever
spider mites were problem during the year, be sure to apply two dormant oil
sprays during the winter months.