From the UC Blogosphere...

C'mon In, the Pollen's Fine!

It's a cold spell. As temperatures dip throughout much of California, and honey bees snuggle inside their hives, it's...

A pollen-covered honey bee heading toward Bacopa. (Photo by Kathy Keatley Garvey)

A pollen-covered honey bee heading toward Bacopa. (Photo by Kathy Keatley Garvey)

C'mon in, the pollen's fine! A honey bee reaching for pollen.(Photo by Kathy Keatley Garvey)

C'mon in, the pollen's fine! A honey bee reaching for pollen. (Photo by Kathy Keatley Garvey)

The 'Gold' That an Apple Tree Yielded

Thar's gold in them thar apple trees. Gold? When a rotten apple tree was cut down last week on private property in Davis,...

A male Valley carpenter bee (right) peers from a hole. A female (all females are solid black) occupies the hole next to him.

A male Valley carpenter bee (right) peers from a hole. A female (all females are solid black) occupies the hole next to him.

A cluster of male Valley carpenter bees.

A cluster of male Valley carpenter bees.

Extension apiculturist (emeritus) Eric Mussen holds a handful of male Valley carpenter bees.

Extension apiculturist (emeritus) Eric Mussen holds a handful of male Valley carpenter bees.

This male Valley carpenter bee backed into its drilled hole to keep warm.

This male Valley carpenter bee backed into its drilled hole to keep warm.

Rain helps rangeland trees and grasses begin recovery

There is good news and bad news related to the California drought and foothill rangeland. In San Luis Obispo County, the drought has taken a toll on majestic oak trees, said a story in the San Luis Obispo Tribune.

“Water stress renders oak trees more likely to express early leaf browning and to be more susceptible to damage from native and introduced tree pests and diseases,” said Bill Tietje, UC Cooperative Extension natural resources specialist. “One or more of these (drought years) could be the last straw for an already stressed tree.”

Recent rain has helped, but trees on shallow soil or on warm, south-facing hillsides are especially vulnerable.

“We are getting many reports of trees that are on the way out or are dead,” Tietje said. “The drought is certainly weakening many trees, and those that are old or have oak worm are dying.”

The Tribune reported that stressed valley oaks have a tendency to drop limbs or for the whole tree to drop, according to a report by Mary Bianchi, UCCE advisor and director in San Luis Obispo County. This happens because the tree closes its pores to conserve water while its roots continue to soak up what water they can.

“This causes water to build up in the trunk and limbs,” Bianchi wrote. “Apparently, the extra weight can cause limbs and maybe the whole tree to break, by some reports as though the tree exploded.”

Rangeland grasses are greening the foothills

The grassy surface of rangeland is faring better, reported the Modesto Bee. Abundant rain in December brought new growth to rangeland that has suffered badly in three years of drought.

“This December has been great for growing grass, lots of moisture and warm temperatures,” said an email from Theresa Becchetti, a UCCE livestock and natural resources advisor in Stanislaus County. “I'm not counting any chickens before they hatch, though.”

Pruning the Backyard Fruit Trees This Winter?

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: //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
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

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
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
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

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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/

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