Italian Cypress Brown and What To Do About Them

Italian cypress can turn brown for several reasons; how its watered, the type of soil its planted in, spider mites during summer months and borers…yes, borers.

Italian cypress

Italian cypress is a tree native to Mediterranean climates along the northern coastal areas of Africa, the Middle East, Greece, Turkey, Montenegro, and southern Europe. This plant grows in climates that are cool and wet in the winter and hot and dry in the summer. In the US the describes the coastal areas of southern California. It is NOT a desert plant…but it will grow there.

Selections of the tree chosen for landscapes can grow to 60 feet tall and 4 to 8 feet wide. It is propagated easily from seed but varieties like ‘Glauca’ are propagated by hardwood cuttings taken in late winter or early spring. These varieties were selected for some outstanding traits that could be marketed to residential and commercial landscapes.

This is a big tree. It should not be used around single story homes or commercial buildings. Its scale is for much larger residences, resorts or commercial buildings. But many homeowners select them because they are evergreen and can provide some visual privacy, not good for noise abatement.

Italian cypress can turn brown. The main reasons are the watering practices and soil type, spider mite feeding damage and borers. What? Borers? You heard it here first.

Soil

The soil it is planted into MUST drain water or it will die. Root rot is a common problem with this tree if it is planted in soils that have lots of clay or don’t drain water. Make sure your soil drains!

Irrigation and Root Rot

This tree came from climates with cool wet winters and hot dry summers so don’t water too often! Put it on a valve that waters palms, fruit trees, other landscape trees and shrubs but not with lawns, flower beds or vegetable beds. It will not like it if it is watered with the same frequency as cacti and native desert trees like palo verde and mesquite unless they are watered too often!

Italian cypress with drooping branches is a sign it is getting too much water. Either it is watered too often or the soil is not draining water fast enough.

Enough water should be applied each time to wet the soil to at least two to two and one half feet deep. The amount to apply varies because of the soil so you will have to play around with the number and size of the emitters. But when you apply water, it should wet the area under the canopy out to the ends of the branches. Normally I will tell people AT LEAST half the area but these trees are narrow and upright so water the entire area.

Spider Mites

Early stages of spider mite infestation and browning.

Spider mites are always there on Italian cypress. Count on it. They become a problem when it is hot, during the summer months, and the natural mites and insects that pursue and eat them are eliminated or interfered with. This can happen right a few days or weeks after an insect spray was applied or they get dusty. The insecticide kills off the good guys so spider mite populations explode in numbers.  Or dust on the leaves and branches run interference with the good guys and block them from finding the spider mites. This is like a slow leak and their numbers don’t explode like after an insecticide application but their numbers go out of control more slowly.

Mite damage is not always accompanied by webbing but it can be a hint they might be there. Use the paper test to make sure.

Some mites don’t spin webs.It can be an indicator they are there but don.t rely on it 100%. Use the paper test instead. Hold a white 81/2 x 11 piece of paper near the brown area and slap the browning branch against it a few times. Don’t pick a branch that’s been dead for awhile but one that is browning or recently died. Pick one with webbing in it if you want to check it. After slapping the white paper hold it still and look for little crawlies on the paper the size of this period “.” Very small. Are the small dots moving on the paper? Do they smear on the paper if you brush your fingers against the paper? If those “periods” are moving, they smear and your plant is turning brown, it has spider mites.

What To Do About Spider Mites?

Wash the tree from dust after dust storms. You may need a power washer. Don’t plant them near dirt roads that allow vehicles to kick up the dirt and make them dusty.

This horticultural oil can be used to control spider mites when weather is cooler.

Use insecticides as a last resort. Don’t apply insecticides as insurance unless there is a good reason for the application. If mites become a problem, you may need to use a miticide, not an insecticide.

I use the University of California Integrated Pest Management  websites for recommendations on borer control.
http://ipm.ucanr.edu/PMG/PESTNOTES/pn7405.html

http://ipm.ucanr.edu/TOOLS/PNAI/pnaicompare.php?pn=7405&x=79&y=21

http://ipm.ucanr.edu/QT/spidermitescard.html

Most of the insecticide recommendations are oils (e.g. Rosemary oil, Cinnamon oil, Clove oil, etc.) and should not be applied until weather cools in the fall or spring.

Borers

Borers were never reported to be a problem with Italian cypress. So I didn’t suspect borers until a few years ago when it was reported to me by a homeowner. I didn’t think it was true until he sent me pictures and confirmed it. They are a problem with other cypress so it makes sense.

Borer damage in Italian cypress

What To Do About Borers?

If borers are confirmed to be a problem use the insecticide imidacloprid as the active ingredient as a soil drench. This insecticide has been implicated in colony collapse of honeybees and its use has been banned in several countries but not currently the US. Avoid applications in spring when the treated plant may flower and attract honeybees. Apply it after it has finished flowering in mid to late spring.

Pruning

These trees can be pruned with a “flat “top” by removing the pointed top just below the height wanted. This helps reduce its height but it will grow wider than if it were left alone.

Avoid pruning these trees by shearing with a hedge shears. If “floppy” branches are a problem use a hand pruners and cut the offending branch well inside the tree canopy and hide the cut.

These Italian cypress are sheared twice a year whether they need it or not

Avoid wrapping the tree with plastic green nursery tape f branches are “flopping”. Instead, control “floppiness” through less frequent watering.