- Author: Help Desk Team
Prune Apricot and Cherry Trees in August
If you have apricot, cherry, or related hybrid tree varieties such as aprium and pluot in your yard, plan to prune them before the end of August. This timing will help prevent infection by a deadly fungal disease called Eutypa Dieback that can kill these trees as well as grape vines.
When infected by Eutypa, branches or entire trees wilt and die suddenly, often with the leaves still attached.
Apricot tree with branch killed by Eutypa
Signs that your tree may be infected by Eutypa include darkly discolored cankers on the branches and oozing of amber colored gummy sap.
Eutypa cankers on apricot branch
Oozing Sap on Cherry Tree from Eutypa Infection
[Editorial Note: apricot photos downloaded from UC Repository. Cherry tree photocopied from UC ANR blog article by Chuck Ingels, UCCE Sacramento, https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=16014 ]
Many other varieties of trees and shrubs can become infected with the Eutypa fungus without showing disease symptoms or progressing to the dieback stage. These other tree and shrub varieties can serve as store houses for the Eutypa pathogens that could potentially spread to your grape vines and apricot, cherry, aprium and pluot trees. Trees and shrubs that can serve as reservoirs for the disease include almond, apple, blueberry, crabapple, honeysuckle, kiwi, oleander, pear, and certain native plants such as big leaf maple, California buckeye, ceanothus, and willow.
Eutypa disease is spread from an infected tree, shrub or vine to uninfected trees by splashing water from sprinklers or rain. The splashing water allows the fungal spores to enter through pruning or other wounds. Pruning vulnerable tree varieties by the end of August allows pruning wounds to heal and close before the typical start of the rainy season in Contra Costa County in late October. Also, avoid using sprinklers near recently pruned trees since water from sprinklers can also spread infections. Using these precautions will reduce the risk of infection for your trees.
Studies have shown that the Eutypa pathogens can also be spread on pruning tools that have been used to prune infected trees and shrubs. To prevent such transmission, be sure to disinfect your pruning tools before and after pruning.
To disinfect tools, soak them for thirty minutes in a 10% bleach solution (nine parts water to one part bleach). Bleach is corrosive so be sure to rinse the tools thoroughly with water after soaking. Then oil them. The bleach solution loses 50% of its effectiveness after two hours, so be sure to use a freshly mixed batch.
As an alternative to bleach, you can disinfect pruning tools with 70% isopropyl alcohol. Just spray it on your tools and it will kill any pathogens almost immediately. Alcohol is not corrosive, so you don't need to rinse it off tools.
An internet search for “how to prune apricot [or cherry, aprium or pluot] trees” will help you find videos that demonstrate good pruning techniques. Just be aware that most pruning videos are filmed when the trees are dormant. With no leaves, the branches can be more easily shown in the video to demonstrate pruning techniques. In California, you don't want to wait until the dormant season to prune these vulnerable trees because that increases the risk of an Eutypa infection. So, you'll need to adapt the pruning techniques to a tree that still has leaves.
For more information on Eutypa disease, visit this University of California IPM website: http://ipm.ucanr.edu/PMG/GARDEN/FRUIT/DISEASE/eutypadieback.html
Advice for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
Client's Request: I recently found out about your program at Todos Santos Square Farmer's Market in Concord. I spoke to one of your representatives about creating some privacy in our backyard, and he told me to consider privet because it can grow up to 40 feet high. I went to Home Depot, but they only have privet that grows to 7-8 feet. Could you please give me the name of privet that can grow up to 40 feet? Thank you!
The Glossy Privet, Ligustrum lucida, is the tallest privet; other privets grow up to 15 feet. Whilst the Glossy Privet is attractive and can grow quickly to 20-40', it also comes with significant maintenance problems. It naturalizes very easily and seedlings from the “fruit” (i.e., berries) will sprout virtually everywhere (even in groundcover). In fact, it is on the watch list of the California Invasive Plant Council (as are two other privets). Fruit drop can cause a mess unless trimmed early, and trimming will eventually prove difficult and expensive as your hedge grows taller. These issues are probably the reason that it is hard to find in stores.
Fortunately, there are several good alternatives to privets. For attractive taller hedges, you might consider:
Hop Bush, Dodonea viscosa 12-18 tall, 6-8' wide
Pacific Wax Myrtle, Myrica californica 15-30' tall and wide
Strawberry Tree, Arbutus Uneda 15-30' tall and wide
Sweet Viburnam, Viburnum awabuki 12' tall 8' wide
Pittisporum - several species
Photinia - several species
I have included suggestions above 10' tall as this height usually provides good privacy and is more manageable in terms of trimming than a 40' hedge!
When making your selection, please check these plants for temperature, soil and water needs for your location, as well as other criteria that are important to you.
If you would like to explore other options, we recommend the Sunset Western Garden Book and Plants and EBMUD's Landscapes for Summer-Dry Climates in the San Francisco Bay Area. These books have lists of plants suitable for hedges and screens, as well as plant descriptions and great photographs. Both are normally available through the Contra Costa Public Library, online, or local book stores.
Please do not hesitate to contact the Help Desk if you have further questions.
Help Desk of the UC Master Gardener Program of Contra Costa County (GHG)
Note: The UC Master Gardeners Program of Contra Costa's 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/ MGCC Blogs can be found at http://ccmg.ucanr.edu/HortCoCo/ You can also subscribe to the Blog (http://ucanr.edu/blogs/CCMGBlog/).
Advice for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
Client's Request: As we discussed on the phone this morning, I have recently installed extensive drought-resistant landscaping. I have also added wood chip mulch to prevent weeds. However, I'm concerned about how to maintain it weed-free as well as other areas in my garden. Our phone discussion covered many of the usual techniques to prevent weeds in this situation. You said that you would do some further review and possibly provide me with some more options.
UC MGCC Help Desk Response: Thank you for contacting the UC Master Gardener Program Help Desk with your questions about weed control in your new landscape.
The first option is to put down a weed fabric (not plastic) on the edges of your landscaping to control the small, sneaky weeds that appear where the wood mulch tends to be thin. Once the fabric is installed, you can cover it back up with your wood mulch. This will stop the weeds from coming up on the edges of your pathways.
Another option we didn't discuss is using a weed flamer. Flamers require no chemicals, and don't result in groundwater contamination or chemical residues on garden. One plus for weed flamers is that they are usually considered an organic gardening method. For effective weed control, you can use flamers in spring and early summer as annual and perennial weeds emerge. Killing larger, mature plants requires more heat, so save time and fuel by flaming weeds when they're still young and tender. This is a good option for larger areas that need treatment.
You can Google ‘weed flamer' for local and online suppliers as well as additional safety guidance. The idea of weed flamers isn't to burn the plants, but to quickly pass over to apply the right amount of heat to cause the water in the weed cells to boil, causing the plant to atrophy and die. Torch remaining weeds once every two to three weeks in ongoing applications or as needed until the next frost. Flaming kills annual weeds completely but does not completely eradicate the roots of perennial weeds.
If you do decide to use a flamer, be sure to keep a water supply handy, and do not get the flame near anything flammable, especially your dry wood mulch back, for safety purposes. To be safe, you may need to pull the mulch back before using the flamer or drench the mulch first with water.
Here is a link to more (and extensive) information on weed control in your garden:
http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7441.html
Please don't hesitate to give us a call if you have additional questions!
Help Desk of the UC Master Gardener Program of Contra Costa County (SLH)
Note: The UC Master Gardeners Program of Contra Costa's 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/ MGCC Blogs can be found at http://ccmg.ucanr.edu/HortCoCo/ You can also subscribe to the Blog (http://ucanr.edu/blogs/CCMGBlog/).
