Advice for the Home Gardener from the Help Desk of the UC Master Gardener Program of Contra Costa County

Help Desk:  Thank you for contacting the UC Master Gardener Program Help Desk with your concerns about your ailing Italian Cypress trees in Central County.

Italian cypress Cupressus sempervirens thrive in full sun in the dry, Mediterranean-type climate of California, but it does poorly and can become stressed and diseased in a wetter or cooler climate and if it is planted where it gets too much water or in partial shade or if it is exposed to cold winter temperatures.  As we discussed on the phone, the very wet winter last year after years of drought may not have helped your trees.

Based on what was recommended to you by a tree service, they may have been attempting to treat for root rot.  As its name implies, root rot happens when the tree's roots are too wet for extended periods, causing branches to wilt, turn yellow or brown and eventually die. A fungicide applied to the soil as directed might halt the rot.  As discussed, this may or may not help your trees.  There is more information on root rots in the included pest link below.

The irrigation requirement for Italian Cypress in at your garden in Central County is ‘Low Water', so your established trees would need no irrigation during the winter months, minimal irrigation in the Spring and Fall (no more than .5 gallons per month per tree) and 2 gallons per month total irrigation per tree in the hottest months of June – August.  With this information you can calculate how long to run your drip irrigation depending on the drip emitter output you are using.  Be careful not to overwater!

You may also want to do a close examination of your trees to help determine an appropriate course of action.  I've attached information below on various pests and diseases of cypress trees: http://ipm.ucanr.edu/PMG/GARDEN/PLANTS/cypress.html

Below are links to UC Pest Note information on several common pests of cypress that you'll want to look for:

Cypress tip miner—Argyresthia cupressella:  Browning tips may be caused by cypress tip miners, the larvae of a tiny, silvery tan moth: Argyresthia cupressella. The females lay eggs on the green tips. The eggs hatch into larvae that feed on the twig tips. http://ipm.ucanr.edu/PMG/GARDEN/PLANTS/INVERT/cyptipminer.html

Cypress canker -Seiridium cardinale:  This fungus attacks trees in the cypress family by entering through cracks in their bark and producing toxins that wreak havoc with the flow of sap, limiting the supply of water and nutrients.  The cracks in the bark could be caused by pruning cuts, boring insects, or weather damage.  The spores spread by wind and water splash. Symptoms include dieback beginning from the top of the tree or branches browning and dying throughout the canopy.  A branch can change color over a period of days. http://ipm.ucanr.edu/PMG/GARDEN/PLANTS/DISEASES/cyprcanker.html

Spider mites:  http://ipm.ucanr.edu/PMG/PESTNOTES/pn7405.html

As we discussed, your trees should be provided with the best possible cultural care: full sunlight, good drainage, moderately fertile soil, and enough moisture to prevent summer drought stress to help them resist pests and diseases.  UC does not have any specific recommendations about feeding programs for these trees, so our discussion about improving the soil around the trees with compost may be a better course of action rather than feeding with general fertilizers.

While we are unable to recommend a specific arborist in our area, we can refer you to the International Society of Arboriculture (ISA) ‘Find an Arborist' website.  This website has a search feature that allows you to find certified arborists based on where you live.   When you call, explain your situation and ask if they specialize in cypress problems. https://www.treesaregood.org/findanarborist

Please call us again if you wish to discuss more specifics.

Good luck with your trees.

Regards,

Help Desk of the UC Master Gardener Program of Contra Costa County (SLH)
Notes: Contra Costa MG's Help Desk is available almost year-round to answer your gardening questions. Except for a few holidays (e.g., last 2 weeks December), we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 2380 Bisso Lane, Concord, CA 94520. We can also be reached via telephone:  (925) 608-6683, email: ccmg@ucanr.edu, or on the web at http://ccmg.ucanr.edu/Ask_Us/. MGCC Blogs can be found at http://ccmg.edu/HortCoCo/ You can also subscribe to the Biog.

Advice for the Home Gardener from the
Help Desk of the UC Master Gardener Program
of Contra Costa County

Request: We have lived in our house for 22 years in central County. Just the past few years we have been plagued by “no-see-ums” as the weather starts to warm. They are generally gone by the time it's hot.

Of course, the no-see-ums chase us indoors during the best time of year for gardening, socializing and enjoying the out-of-doors. Last year I spent time online researching how to prevent this pesky critter. I remember reading somewhere (?) a process for treating the yard to prevent their “hatch". Unfortunately, I can't find what I read, only how to prevent bites.

Can you help me with this? We have no lawn at the house, just trees and plants surrounded mostly by bark. I thought there was something you could spray or spread on the bark ground cover.

I will appreciate any advice you can share. Thank you in advance.

CCMG Help Desk Response:  Thank you for contacting the UC Program Master Gardner Help Desk with your question concerning those pesky No-See-Ums you are battling. My childhood was spent in Vermont where these pesky flies breed in epic proportions in the summer, making life outdoors miserable. I sympathize with your frustration.

These minuscule flies are in the Ceratopogonidae family of flies commonly known as no-see-ums, also referred to as sand flies, gnats and biting midges. This family includes more than 5,000 species, distributed worldwide, with the exception being the Antarctic and the Arctic.

Like mosquitoes, No-See-Ums lay their eggs in moist areas. Both males and females consume nectar and other sweet juices for nourishment. Females, however, will also seek out a blood meal to fuel egg production. Female No-See-Ums will bite humans, pets, livestock, wild animals and birds. They breed and develop in moist wet areas. With her need for blood satisfied, the impregnated female will seek out an appropriate place to lay her eggs, which can include water-retaining hollows in trees, muddy water, wet sand, and other similar areas. About 28 days later, adult No-See-Ums emerge and the cycle begins again. No-See-Ums can be more difficult to get rid of than mosquitoes. They are smaller than mosquitoes and more agile fliers.

The research on control leans heavily to “exclusion” techniques as opposed to chemical treatment, misting and fogging. Chemical treatments have proven, in testing, to have little to no effect. If spraying or treating with chemicals is not effective there is little sense in spending your time and money in addition to adding the pollutant to your environment. While exclusion is the preferred control method you should look your property over and make sure you do not have “wet'” breeding sites.

Exclusion techniques appear to be the most effective method of control. These include wearing protective clothing, installing ultra-fine mesh screening (US 16 Standard Mesh) in-home screens and enclosing patio and porch areas with this same fine mesh screening. If you are really determined to be outside there are also pop-up tents designed with drop-down screening fine enough to block the No-See-Ums.

Topical sprays have proven to be only barely effective but might add a bit of protection while working in the garden. You could use a mosquito repellent with DEET, in addition to wearing protective clothing.

There is some information that refers to trapping as being moderately effective to highly effective, the trap tested is the CO2 mosquito trap. A home version is not too expensive and might be worth a try. No-See-Ums and mosquitos breed in the same conditions so you would be controlling any potential mosquito population as well, it might be a win-win.

The UC information on gnats was very limited. The Bug Squad from UC Davis provides some more detailed information at https://ucanr.edu/blogs/bugsquad/index.cfm?tagname=Valley%20Black%20Gnats. The best information I found was a link to research-based information from the University of Arizona. https://cals.arizona.edu/apmc/docs/No-See-Ums-IPMShort.pdf

I hope you will find some success by employing these methods. The best method may be the passage of time and the increase in temperature.

Please do not hesitate to call us with more questions …hopefully we will find some new information on the control of No-See-Ums.

Help Desk of the UC Program of Master Gardeners of Contra Costa County (BHD)

Notes: Contra Costa MG's Help Desk is available almost year-round to answer your gardening questions. Except for a few holidays (e.g., last 2 weeks December), we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 2380 Bisso Lane, Concord, CA 94520. We can also be reached via telephone:  (925) 608-6683, email: ccmg@ucanr.edu, or on the web at http://ccmg.ucanr.edu/Ask_Us/. MGCC Blogs can be found at http://ccmg.edu/HortCoCo/ You can also subscribe to the Biog.

Advice for the Home Gardener from the
Help Desk of the UC Master Gardener Program
of Contra Costa County

Subject: Grapefruit Tree vs Woodpecker

Cllient's Request: How can we keep a woodpecker(s) from making holes in the tree bark?  We don't have any insects/ants on the tree bark and we're concerned that the damage will make the tree susceptible to disease.  Thank you.

MGCC Help Desk Response: Thank you for contacting the UC Master Gardener Program Help Desk with a question about woodpeckers on your grapefruit tree. From our phone conversation this morning, I identified the culprits as sapsuckers. These drill a series of holes, usually in straight horizontal lines, in live trees so plant sap oozes out of the holes. Sapsuckers feed on the sap, as well as on any insects that become trapped in the sap. Most of the time, sapsucker holes do not cause problems for the tree. When there is continuous sapsucker activity that increases the lines of holes to a significant percentage of the tree's trunk area, it can weaken the tree and potentially kill it. 

Physical exclusion is the best way to prevent any kind of woodpecker damage. There are several methods you might see mentioned to prevent such as frightening devices or repellents, but these are not typically successful as birds quickly become accustomed to the deterrent. Covering the trunk with something that will prevent access to the tree bark is the best way to get sapsuckers to move on. Sections of lightweight sheet metal or roof flashing are fairly easy to shape around the trunk. You can get rolls of aluminum flashing at home improvement stores. Heavyweight plastic material can also be used. Use duct tape to hold it in place. You can also use wire mesh such as chicken wire, especially if it's bunched up somewhat. You will probably need to cover a great deal of the tree's bark to prevent the birds from just moving to an uncovered area. Whatever you use to cover the bark, make sure it is not too tight--you want to leave room for the tree to grow--and remove it when the birds have moved on. Depending on the size of the tree, you could also cover the entire tree with bird netting that you securely attach around the low base of the trunk to prevent all access to the tree.

Woodpeckers drill holes in trees for a variety of reasons. The largest holes are drilled for nest construction, usually in dead trees. Acorn woodpeckers drill 1/2 inch holes in which they store acorns. Smaller random holes are those made while looking for food. Woodpeckers' sharply pointed beaks and long tongues are used for extracting larvae and other insects from wood crevices. This can actually alert you to burrowing insects damaging a tree.  

This link is to more information from the University of California about managing woodpeckers: http://ipm.ucanr.edu/PMG/PESTNOTES/pn74124.html.

I hope this information is helpful. Please don't hesitate to contact us again if you have more questions.

Help Desk of the UC Master Gardener Program of Contra Costa County (SEH)

Notes: Contra Costa MG's Help Desk is available almost year-round to answer your gardening questions. Except for a few holidays (e.g., last 2 weeks December), we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 2380 Bisso Lane, Concord, CA 94520. We can also be reached via telephone:  (925) 608-6683, email: ccmg@ucanr.edu, or on the web at  http://ccmg.ucanr.edu/Ask_Us/. MGCC Blogs can be found at http://ccmg.edu/HortCoCo/ You can also subscribe to the Biog.

Advice for the Home Gardener
from the UC Master Gardener Program
of Contra Costa County

Client's Request:  Hello. We would like to plant a shade tree in our backyard in mid-County. We have a fairly shallow well… and am assuming a high water table although we don't have any wet, boggy areas. We have two semi-dwarf orange trees s that we never water and they are productive and sweet. Can you recommend links for some shade trees in these conditions .... such as Crape Myrtle, deciduous Magnolia, and Japanese Maples? Thank You.

MGCC Help Desk Response:  Thank you for contacting the UC Master Gardener Program Help Desk with a question about tree selection. You didn't say how deep your well is, but the water table is probably deep enough that it won't impact trees in your landscape. Tree roots are generally found in the top 1 to 3 feet of soil, with only some sinker roots possibly venturing deeper. Trees don't usually have tap roots past the seedling stage, but rather grow roots that extend well past the dripline (outer edge of the tree's canopy). 

If you have good drainage in your soil, any tree suited for your climate should be fine. To test your drainage, dig a hole about a foot deep. Fill it with water and allow it to drain completely. Immediately refill the hole and measure the depth of the water with a ruler. Fifteen minutes later, measure the drop in water in inches, and multiply by 4 to calculate how much water drains in an hour. Ideally, you should have 1 to 6 inches drainage per hour.

The trees you specifically asked about were Crape Myrtle, deciduous Magnolia and Japanese maple. Crape Myrtles (Lagerstroemia spp.) do well in mid-county. They need full sun and seem to appreciate our hot summers. There are many varieties to choose from. This link is to an article from the Sonoma County Master Gardeners about growing Crape Myrtles: http://sonomamg.ucanr.edu/Plant_of_the_Month/Lagerstroemia_spp_Crepe_Myrtle/.

Deciduous Magnolia may not be a good choice. According to Sunset Western Garden Book, deciduous magnolias with saucer flowers do poorly in hot and dry areas. Deciduous magnolias with star flowers seem to do better, but are very slow-growing, and the variety called Star Magnolia (Magnolia stellata) stays quite small and is usually grown as a shrub.

Japanese maples (Acer palmatum) do best in cool climates and will need partial shade and protection from hot, dry wind in the hotter areas of the County. Morning sun and afternoon shade is best. The varieties with green leaves do better with more sun exposure than the varieties with red leaves or those with lacier leaves.

You might also consider Chinese pistache (Pistacia chinesis). It is well suited for our climate and makes a good shade tree. This link is to another article from the Sonoma Master gardeners:  http://sonomamg.ucanr.edu/Plant_of_the_Month/Chinese_Pistache/.

For other ideas, this link is to a searchable database where you can select aspects you want such as shade tree, deciduous, maximum height, etc. https://selectree.calpoly.edu/about. They have good descriptions of the trees, along with photographs.

If after you perform a drainage test you find you have poor drainage (less than 1 inch per hour), contact us again and we will research those trees more suitable for a boggier area. Don't hesitate to contact us if you have any questions.

I hope this information is helpful and you find a good shade tree for your yard!

Help Desk of the UC Master Gardener Program of Contra Costa County (SEH)

Notes: Contra Costa MG's Help Desk is available almost year-round to answer your gardening questions. Except for a few holidays (e.g., last 2 weeks December), we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 2380 Bisso Lane, Concord, CA 94520. We can also be reached via telephone:  (925) 608-6683, email: ccmg@ucanr.edu, or on the web at  http://ccmg.ucanr.edu/Ask_Us/. MGCC Blogs can be found at http://ccmg.edu/HortCoCo/ You can also subscribe to the Biog.