Q. My Italian cypress had spider mites, so I sprayed the
trees with an insecticide about six weeks ago. Nearby Italian cypress trees are
also full of spider mites. I was going to spray them with an insecticide until
I listened to your Desert Horticulture podcast which told me to use a miticide
instead. Which one should I use?
trees with an insecticide about six weeks ago. Nearby Italian cypress trees are
also full of spider mites. I was going to spray them with an insecticide until
I listened to your Desert Horticulture podcast which told me to use a miticide
instead. Which one should I use?
 |
| This Browning could be from spider mites, watering too often, or borers. If it occurs in the middle of summer it’s very likely spider mites. |
A. Spider mites are a hot weather insect so spraying when it’s not summer just for them doesn’t make much sense. However, spraying oils in Fall and
Winter months makes perfect sense for insects that might spend the winter on
your trees.
Winter months makes perfect sense for insects that might spend the winter on
your trees.
 |
| Horticultural oils, sometimes called dormant oil or spray oil, is the best insurance to prevent insect outbreaks like aphids, spider mites, and scale insects. |
Remember,
spraying insecticides make mite problems more likely on susceptible plants like
Italian cypress. Miticides, unlike insecticides, are less likely to cause mite
problems later. Spider mites are nearly always present on all plants they feed
on. There are lots of insects that feed on spider mites as well and keep them
in check.
spraying insecticides make mite problems more likely on susceptible plants like
Italian cypress. Miticides, unlike insecticides, are less likely to cause mite
problems later. Spider mites are nearly always present on all plants they feed
on. There are lots of insects that feed on spider mites as well and keep them
in check.
 |
| Spider mites, like their name suggests, usually leave a webbing that you can see when there is damage. |
These
predatory insects hunt down spider mites and use them for food. Think coyotes
and rabbits. Spraying traditional insecticides like Malathion, Sevin and even
organic insecticides like Neem oil or soap and water kills most insects off,
good ones as well as the bad one you wanted to control. The primary benefit of
organic sprays are its environmental safety and short life after its sprayed.
predatory insects hunt down spider mites and use them for food. Think coyotes
and rabbits. Spraying traditional insecticides like Malathion, Sevin and even
organic insecticides like Neem oil or soap and water kills most insects off,
good ones as well as the bad one you wanted to control. The primary benefit of
organic sprays are its environmental safety and short life after its sprayed.
 |
| When spider mites are active they can create a bluish green cast when they are actively feeding and often times then leaves of Italian Cypress are “dusty”. Spider mite damage always starts in the heat of the summer. |
If an
insecticide must be sprayed for some reason, watch the sprayed plants very
carefully during hot weather to see if spider mites become a problem or not.
Frequently spider mites will become a problem after spraying an insecticide
because their predators were killed. I realize sometimes you must, but spray
insecticides as a last resort.
insecticide must be sprayed for some reason, watch the sprayed plants very
carefully during hot weather to see if spider mites become a problem or not.
Frequently spider mites will become a problem after spraying an insecticide
because their predators were killed. I realize sometimes you must, but spray
insecticides as a last resort.
 |
| Close-up of the needles or foliage of Italian Cypress and spider mite damage. |
Miticides
are chosen because spider mites are more like spiders than insects and sprays
that kill insects oftentimes don’t kill spider mites. I am glad you did not use
an insecticide for mite control. It would have made the problem worse and probably
not killed the spider mites.
are chosen because spider mites are more like spiders than insects and sprays
that kill insects oftentimes don’t kill spider mites. I am glad you did not use
an insecticide for mite control. It would have made the problem worse and probably
not killed the spider mites.
Use the
University of California Integrated Pest Management websites (“Google” them by
using your favorite search engine and typing in “UCIPM” and “spider mites”).
Read these notes. They are written by entomologists who specialize in
controlling pests. After reading these notes you will be better informed than 90%
of the landscapers spraying plants.
University of California Integrated Pest Management websites (“Google” them by
using your favorite search engine and typing in “UCIPM” and “spider mites”).
Read these notes. They are written by entomologists who specialize in
controlling pests. After reading these notes you will be better informed than 90%
of the landscapers spraying plants.
The
UCIPM notes will recommend spraying oils like canola, clove and cinnamon oils
as well as horticultural oils and sulfur sprays to control spider mites. In our
hot desert environment these sprays may damage plants during the hot months. It
is cool enough in the Fall, Winter and Spring you can spray oils without damaging
most plants. Plants that may be damaged will be listed on the label.