Advice for the Home Gardener from the Contra Costa Master Gardeners' Help Desk

Client's Questions and Concerns
Client called with “huge problem with birch trees". She left her email address, but also asked for someone to call and help her with some advice. Called several times but couldn't leave a message since her voicemail box was full. Sent her an email with some of the “usual” problems with birch trees and asked her to contact us if she needed more information. (Note:  Although this advice didn't come to satisfactory conclusions, CCMG Help Desk thought it would be beneficial to remind gardeners of the value and care of their trees, especially the oft-planted and vulnerable birch trees, and the need for prioritizing tree care especially during the drought. You can replace and restore many shrubs and perennials in several years and at moderate costs; replacing trees can be expensive when you include value to the property and costs of removal, and can take many years.)

Response and Advice from the CCMG Help Desk
Thank you for calling Master Gardeners with your birch tree problem. However, in order to help you, we will need some more information and either samples or photos of the tree.

I did try calling you, but your voicemail box is full so I could not leave a message. If you would like to call us or e-mail with details such as: where do you live; where are the trees planted; how old are the trees; your irrigation routine; and any recent changes in their vicinity. With this information, we can start trying to identify what may be the problem with your birch trees.

In the meantime, I have included information which might be helpful adapted from an article from a Solano County Master Gardener blog:

• Most likely your birch tree is a European white birch (Betula pendula), native to northern Europe with its cooler climes and plenty of rainfall to sustain the trees. They grow magnificently there, and to their full potential, much larger than any you'll likely see in Contra Costa County.
• In Contra Costa County, especially the central and eastern areas, the life span of a birch tree is approximately 25 years due to heat and lack of rainfall. Decline will often show in branch dieback or leaf drop. During drought, birch trees – which need consistent and deep irrigation – will show signs of stress such as dead branches. Or depending upon the tree's age and care, those dead branches may just be signs of old age and a steady decline.
• Many homeowners with birch don't realize how stressed birch trees can get in drought periods. The natural habitat of birch trees is the forest, where they grow alongside creeks and streams.
• Birch are often planted in lawns and home owners forget that when they stop or reduce irrigating their lawns that birch will often be put in stress unless additional water is provided.
  • If your tree is in a lawn, remove the grass from around the trunk out to the drip line and replace it with a layer of fine bark mulch, chopped red cedar bark or aged compost. A bender board around the perimeter of the mulch will prevent the mulch from working into the lawn.
• To determine the actual soil moisture “feeding” your birch, you can push a long screwdriver into the soil, working outward from the trunk to the drip line under the leaves. If the screwdriver does not easily penetrate the soil, then the tree must be irrigated.
  • One method of supplemental tree irrigation is to lay several lengths of soaker hoses, working outward from the trunk to the perimeter of the tree under the drip line. Attach a garden hose to the soaker hose and let the water drip for several hours until the screwdriver will easily slip into the soil. You can find a rmuch more duable and automated version of this watering system at http://ccuh.ucdavis.edu/public/drought/tree-ring-irrigation-contraption-tric-1/tree-ring-irrigation-contraption-tric
• The birch root system is also extremely sensitive to fertilizers and herbicides, including weed and feed products as well as mechanical damage, for example string trimmers.
• 

  Bronze Birch Borer holes
  photo: Vacavilletreeservice.com
  When birches get stressed during even our “usual” Northern California summer droughts, borers can move in. This problem is often exacerbated by reduced irrigation during our current long-term drought. The bronze birch borer, Agrilus anxius, is the main culprit. Apparently there is quite a large local population of the borers. Intensive insecticide applications may keep them at bay. Check the University of California Statewide Integrated Pest Management website for more information on preventive measures: http://www.ipm.ucdavis.edu/PMG/GARDEN/PLANTS/birch.html.
  If you go to this link and in the right columns scroll down to 'birch borers', you might find clues to what is ailing your tree bug-wise. However, it is important to positively identify the cause before any measures are taken to manage the problem, so we look forward to hearing from you again.

 With a little TLC, you should be able to coax a few more years out of your birch.

 Contra Costa Master Gardeners' Help Desk

---

Note: The Contra Costa Master Gardener Help Desk is available year-round to answer your gardening questions.  Except for a few holidays, we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 75 Santa Barbara Road, 2d Floor, Pleasant Hill, CA  94523. We can also be reached via telephone:  (925) 646-6586, email: ccmg@ucanr.edu, or on the web at http://ccmg.ucanr.edu/Ask_Us/

Advice for the Home Gardener from the Contra Costa Master Gardeners Help Desk

Client's Problem & Questions:

Client called and MG volunteer discussed her gopher problems… and that she didn't want to kill the gophers, possibly using cinch traps. Discussed the information on the UC Pest Note on gopher management and the various “home remedies” readily found on the web and that basically they were “snake oil”. For a “permanent” solution only exclusion, baiting, fumigation or trapping will work. Most gardeners usually end up using exclusion and/or trapping …or getting a gopher service. 

CCMG Help Desk Response
Following up on our phone conversation earlier today, you will find below the information we discussed and/or promised on the phone. I did some additional research and have included wht I found as well below. In one instance, I came across a research paper regarding gopher management in California almond orchards. The almond orchard research showed that trapping plus additional fumigation had the highest efficacy. The reason that these two methods were combined was because the research showed that as the gophers become trap shy, the additional fumigation targeted the gophers that the traps missed. I believe the lesson learned from that research it that it will probably take more than one “solution” to get effective control of your gopher population.

In your case, because you are trying to protect your vegetable patch, and your hesitation to “trap and kill” the gophers, exclusion is most likely going to be the best, most effective method. You mentioned that this was a project you might take on next spring. Here is some information on gopher wire to line your raised beds or bury around your in-ground vegetable beds. Gopher wire is specifically designed for gopher exclusion. Look for a wire mesh measuring no more than 3/4” square or diagonally. The reason for the 3/4" spacing is the holes must be small enough to keep young gophers out. This size is determined by a young gopher's shoulder girth at the weaned age of about 8 weeks. The mesh should be 20 gauge wire (thick enough to resist the chewing of gophers). Really high quality mesh will be “double galvanized” which gives it a much longer life when buried in the ground. You must either bury the wire mesh at least 2 feet deep with some surface wire barrier showing as well when encirciling in-ground plantings. For raised beds you would line the bottom and some of the side walls (see Pest Note below).

You also mentioned that you were putting in a cover crop of clover. In my research I found information about clovers and gophers that would be helpful to you. Gophers are attracted to most clovers, especially crimson clover, which is a popular cover crop. Try substituting sour clover from the family Melilotus indica. Sour clover is high in coumarin, the original source of the blood thinner Coumadin. Gophers avoid ingesting sour clover, possibly because the coumarin adversely affects their blood chemistry. Sour clover also fixes nitrogen, reseeds easily, and has flowers that attract bees. Several plants are often called sour clover, including oxalis (gophers love oxalis), so be sure to get Melilotus indica.

If you should decide to trap and are going to use a cinch trap, be sure to buy the best quality you can afford. Cheaper models may not work at best, and will maim the animal at worst. One method I read for disposal was to release the gopher from the cinch trap back into the gopher hole and bury the gopher in place, there seems to be some evidence that there is some deterrent effect to this method and has the added benefit of (maybe) adding nutrients to the soil as it decomposes. As we discussed on the phone if you use this method do a web search on setting cinch traps and get familiar with the method before you begin.
(e.g., https://www.youtube.com/watch?v=Xz2GplXB-9s).

The link below is the UC Davis IPM link to information on gopher management. It is comprehensive and will help you understand all the pros and cons of the various management options.
http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7433.html#MANAGEMENT

Thanks for contacting us with your garden question, if we can be of further assistance please call us again. 

Contra Costa Master Gardeners Help Desk

---

Note: The Contra Costa Master Gardener Help Desk is available year-round to answer your gardening questions.  Except for a few holidays, we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 75 Santa Barbara Road, 2d Floor, Pleasant Hill, CA  94523. We can also be reached via telephone:  (925) 646-6586, email: ccmg@ucanr.edu, or on the web at http://ccmg.ucanr.edu/Ask_Us/

 

Advice for the Home Gardener from the Contra Costa Master Gardeners Help Desk

Client's Question and Concerns:
I'm trying to control gophers and squirrels on my property. I am worried that owls might harm my cat. Could you please let me know if this is cause for worry? If not, could you please send me some information.

CCMG Help Desk Response:

Thank you for contacting the Master Gardener help desk.

Rodents, especially voles, rats and gophers, are barn owls' favorite foods. They do a pretty good job of reducing the population of these unwanted pests. Barn owls are cavity nesters and will nest in artificial boxes. They are fairly tolerant of human activity and will nest quite close to houses, making them ideal predators for the rodents that plague our gardens. Barn owls are mostly white or light tan; their call is a loud screech.

Great horned owls do not use nest boxes, preferring large open nests. They, too, eat rodents, but will also take larger animals such as skunks. Great horned owls are larger than barn owls and are brown; their call is the stereotypicalHoo-h'HOO-hoo-hoo. Here is a link to the Hungry Owl Project in Marin County where you will find lots of information about owls: http://www.hungryowl.org/ 

Great Horned Owl
(Bubo-virginianus)
photo: owlpages.com

Barn owls are not a danger to an outdoor house cat, but certainly great horned owls are (skunks are about the same size as many house cats). If you have ever heard the great horned owl call in your neighborhood, you probably have them at least occasionally. They have pretty large territories.

To protect your cat, it's really best to keep it indoors, especially at night. There are lots of dangers outside besides great horned owls. Here's a link to American Bird Conservancy's Cats Indoors program that will give you lots of information about how to make an outdoor cat a happy indoor cat: http://www.abcbirds.org/abcprograms/policy/cats/index.html 

Gophers are a common problem for many of us in Contra Costa. These burrowing animals eat plants, sometimes causing a great deal of damage. Here's a link to information about controlling gophers: http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7433.html

Not knowing if your squirrel problems are from tree or ground squirrels, I'm including links for information about controlling both species: 
tree squirrels:  http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74122.html and
ground squirrels:  http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7438.html 

Please don't hesitate to let us know if you have further questions.

Contra Costa Master Gardeners Help Desk

---

Note: The Contra Costa Master Gardener Help Desk is available year-round to answer your gardening questions.  Except for a few holidays, we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 75 Santa Barbara Road, 2d Floor, Pleasant Hill, CA  94523. We can also be reached via telephone:  (925) 646-6586, email: ccmg@ucanr.edu, and on the web at http://ccmg.ucanr.edu/Ask_Us/

Advice for the Home Gardener from the Contra Costa Master Gardener Help Desk

Client's Questions and Requests
Client called and discussed about his need for more information about pruning his numerous backyard fruit trees. He lives in central county. CCMG Help Desk followed up with an email on advice about pruning his fruit trees.

CCMG Help Desk Response and Advice:
Thank you for calling the Master Gardener help desk this morning. It was nice to speak with you. It was also great to get a new recipe for cooking fava beans!

You have a wide variety of wonderful fruit trees in your yard, many of them not commonly planted in this area. You asked about pruning them. Basically, the idea behind pruning is to control size for easier care in maintaining and picking fruit (taller trees do not bear more fruit!); increase strength – develop strong limb structure; distribute sunlight evenly throughout tree; regulate fruit bearing – removes excess fruitwood; renew fruitwood – to continue strong buds and flowers; and to remove undesirable wood- dead, broken, and crossing branches. 

University of California and its Cooperative Extension provides a wealth of information, most of it free through their catalog (http://ucanr.edu/Publications_524/)which you can order from (see also link on CCMG home page (http://ccmg.ucanr.edu/), column left). You can also find extensive UCCE information published on the web. Here is a link to a great publication that describes fruit tree pruning and includes diagrams to help you figure out how to prune your own trees: http://homeorchard.ucdavis.edu/8057.pdf.

You mentioned that some of your trees were getting large-here's a link to an article about pruning overgrown fruit trees: http://homeorchard.ucdavis.edu/8058.pdf. Both of these have enough basic information to cover all your deciduous trees, but for the less-common varieties, I'll give you some hopefully useful hints and tips below, as well as links to more information about each one.

Citrus
Prune citrus in late spring or summer to shape trees, only to remove twiggy growth, dead wood and weak branches, or any crossing, broken or shaded branches from the interior. Wait until May to prune out any frost-damaged wood, as it may revive. Here is a link to Citrus for the Home Garden in Contra Costa County: http://ucanr.edu/blogs/slomggarden/blogfiles/4260.pdf. You'll find lots of information specific to growing citrus here. Here is another link that covers diseases and disorders of citrus fruit: http://www.ipm.ucdavis.edu/PMG/C107/m107bpfruitdis.html. You'll see that brown rot is common in citrus—this causes the soft dark decay that develops in citrus and occurs mostly on the bottom side of fruit and happens mostly to fruit lower on the tree (closer to the soil). The dark spots on your Mandarins is possibly from a bacterial infection.

Quince

Quince
photo: simplyrecipes.com

Trim quince trees annually in late fall or in winter, when the tree is dormant and before the new growth appears. Flowers and fruit form on new growth, so do not prune after growth starts in spring. Remove all branches that grow inward toward the center of the tree and those that grow at an angle significantly more or less than 45 degrees from the supporting branches to keep the interior of the tree open for air circulation and light penetration. Prune out all branches that cross other branches. Prune quince tree branches at the point where they emerge from supporting branches, leaving about one-quarter to one-half inch intact to preserve the growth collar next to the supporting branches. 

Codling moths (common on apples, pears and other fruit) can be a problem for quince. They can be difficult to manage, especially if the population has been allowed to build up over a season or two. It is much easier to keep moth numbers low from the start than to suppress a well-established population. In trees with low levels, codling moth often can be kept to tolerable levels by using a combination of nonchemical management methods; however, it is important to begin implementing these measures early in the season. Sanitation should be the first step in any codling moth control program. Every week or two, beginning about six to eight weeks after bloom, check fruit on trees for signs of damage. Remove and destroy any infested fruit showing the frass-filled holes. It also is important to clean up dropped fruit as soon as possible after they fall, because dropped fruit can have larvae in them. Removing infested fruit from the tree and promptly pick up dropped fruit from the ground is most critical in May and June but should continue throughout the season.

Excellent control can be achieved by enclosing young fruit in bags right on the tree to protect them from the codling moth. This is the only nonchemical control method that is effective enough to be used alone and in higher population situations. However, it is quite time consuming to apply the bags, so this method is most manageable on smaller trees with fewer fruit. You can bag all the fruit on the tree or just as many fruit as you think you will need. Keep in mind that unbagged fruit are likely to serve as a host and increase the pest population, so it would be prudent to employ sanitation to keep the population in check.

Here is a link to information about codling moths from the University of California: http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7412.html that goes into detail about controlling these pests.

Pomegranates
photo: mixwellness.com

Pomegranates

Prune in late winter after danger from winter freezes, but before the tree blooms in spring. To keep the interior of the tree open during the growing season, prune in summer as needed. Light annual pruning of established trees encourages fruit production; pomegranates tend not to require heavy pruning if maintained regularly. Remove dead and damaged wood during late winter and remove sprouts and suckers as they appear. Heavy pruning will reduce the crop.

Apricots
photo: freepik.com

Apricot
As I mentioned on the phone, apricots should be pruned during the summer in late August because of a fungus that infects trees during the cool and wet season. Remove shoots from the center of the tree and cut out interfering limbs and dead and diseased wood. Here is a link to information about pruning apricots: 

http://www.ipm.ucdavis.edu/PMG/GARDEN/FRUIT/CULTURAL/apripruning.html.

Figs
Fig trees are productive with or without heavy pruning. It is essential only during the initial years. Since the crop is borne on terminals of previous year's wood, once the tree form is established, avoid heavy winter pruning, which causes loss of the following year's crop. It is better to prune immediately after the main crop is harvested, or with late-ripening cultivars, summer prune half the branches and prune the remainder the following summer. If radical pruning is done, whitewash the entire tree. Here is a link to information from California Rare Fruit Growers (CRFG): http://www.crfg.org/pubs/ff/fig.html.

Mulberry

Mulberry
photo: dreamstime.com

o special pruning techniques are needed after the branches have been trained to a sturdy framework, except to remove dead or overcrowded wood. A mulberry tree can be kept to a tidy form by developing a set of main branches, and then pruning laterals to 6 leaves in July in order to develop spurs near the main branches. It is not advisable to prune the trees heavily since the plant is inclined to bleed at the cuts. Cuts of more than two inches in diameter generally do not heal and should be avoided at all cost. The bleeding will be less severe if the tree is pruned while it is dormant. Here is a link from CRFG: http://www.crfg.org/pubs/ff/mulberry.html.

Jujubes

Jujube dried
photo: inlandempirecsa.com

Unpruned trees produce as well as trees that have been pruned. Extensive winter pruning, however, will keep the plants in better health and produce more easily obtainable fruit. A link from CRFG: http://www.crfg.org/pubs/ff/jujube.html.

Persimmon
lt: fuyul & rt:hachiya
photo: dreamstime.com

Persimmons
Prune persimmon trees to develop a strong framework of main branches while the tree is young. Otherwise the fruit, which is borne at the tips of the branches, may be too heavy and cause breakage. A regular program of removal of some new growth and heading others each year will improve structure and reduce alternate bearing. An open vase system is probably best. Even though the trees grow well on their own, persimmons can be pruned heavily as a hedge, as a screen, or to control size. They even make a nice espalier. Cut young trees back to 1/2 high (or about 3 feet) at the time of planting. Here is information from CRFG: http://www.crfg.org/pubs/ff/persimmon.html and from UC that includes information on pests and diseases of persimmons: http://www.ipm.ucdavis.edu/PMG/GARDEN/PLANTS/persimmon.html.

*****

Since so many of your trees are not typically grown in our area, one of your best resources is the California Rare Fruit Growers. Their website is http://www.crfg.org/, the local chapter is the Golden Gate chapter (http://www.crfg.org/chapters/golden_gate/index.htm). The Golden Gate Chapter of CRFG conducts meetings throughout the northern San Francisco Bay Area, usually in the odd-numbered months on the second Saturday of the month. Meetings almost always include speakers, tastings, a raffle of unusual plants and the chance to talk to people who live in your area and who share your interests. You would probably find someone who could advise you further on pruning techniques at one of their meetings. In addition, CRFG holds a Scion Exchange in January that you might want to attend. In the past when I've attended, they had classes on pruning of the various fruit trees that you have, let alone the opportunity to get scions that you might want to graft onto your trees (scions are usually free… $5 charge for non-members at the door). Information on the CRFG's Scion Exchange can be found at http://www.crfg.org/chapters/golden_gate/scionex.htm. I have always enjoyed the Exchanges when I attended.

I hope this gives you a start on pruning your backyard orchard. Please let us know if you have more questions.

Contra Costa Master Gardeners Help Desk

---

Note: The Contra Costa Master Gardener Help Desk is available year-round to answer your gardening questions.  Except for a few holidays, we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 75 Santa Barbara Road, 2d Floor, Pleasant Hill, CA  94523. We can also be reached via telephone:  (925) 646-6586, email: ccmg@ucanr.edu, or on the web at http://ccmg.ucanr.edu/Ask_Us/