- 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
Fertilizing Fruit Trees and Information on Chill Hours"
Advice for the Home Gardener from the
Help Desk of the UC Master Gardeners of
Contra Costa County
Home Gardener Request: We're finally jumping into fully caring for our mini-orchard here in Mid-County. Could you please point us to a good reference book for that task... Also, we are getting acquainted with chill hours for growing and/or buying various fruit trees, especially for apple, plum and pear trees. Where can we find local info on chill hours?
CCMG Help Desk Response: Thanks for calling the UC Master Gardener Program Help Desk this morning with your questions about what and how to feed your apple, plum and pear trees and year to date chill hours for your area.
After some further thought, I'd like to suggest that you may want to complete a soil test of your orchard to see what your soil may be lacking before fertilizing your trees this spring as that will drive what and how much to feed.
I found that the UC Home Orchard: Growing Your Own Deciduous Fruit and Nut Trees book supports soil testing before adding potentially unnecessary fertilizers to your soil:
Although deciduous fruit trees require many nutrients for tree growth and fruit production, those grown in backyard settings in typical sandy loam to clay loam soils with proper irrigation rarely need to be fertilized. Nutrient deficiencies, when encountered, are generally limited to nitrogen, potassium, iron, and zinc, and on rare occasions, boron. Unless your soil has a known nutrient deficiency, regular applications of fertilizer usually are not necessary in a mature orchard.
Below is a link to a list of soil testing companies for you to choose from. When you contact one of the labs, they will give you instructions on how to take the sample and prepare it for shipping. Some of the labs listed also have helpful information on how to interpret the results including the amounts of necessary additives your soil needs. Soil testing companies: https://ucanr.edu/sites/ccmg/files/51308.pdf
Below is a link to information from the UC California Backyard Orchard website. It includes information on common elements for normal growth and amounts to feed by age of the tree rather than size: http://homeorchard.ucanr.edu/The_Big_Picture/Fertilization/
The links below include helpful seasonal information for growing fruit trees:
Apples & Pears: Calendar of Operations for Home Gardeners: http://homeorchard.ucdavis.edu/7258.pdf
Plums: Calendar of Operations for Home Gardeners: http://homeorchard.ucdavis.edu/7262.pdf
And finally, here is the link I used to find current information on chill hours in Contra Costa County. I selected the El Cerrito Weather Station for a chill hour to date and historical information:
https://ucanr.edu/chillcalc/?controller=station&action=reportresults&STATION=213
You may want to consider purchasing The UC Home Orchard: Growing Your Own Deciduous Fruit and Nut Trees book as it was developed especially for backyard orchardists, rare fruit growers, and small-scale growers. It is available through various online booksellers and through the UCANR Catalog: https://anrcatalog.ucanr.edu/
I hope you find this information helpful. Please let us know if you have any additional questions.
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.
Client's Request: I'm a trapper in the Ag Department. We have been looking for plum bud gall mites in the county. I recently came across this plum tree with a huge growth or gall, it's 8" long and 7" wide on the underside of a branch, the tree is around 15 years old. Homeowner wants to know what it is and what should be done about it. The tree is in Pittsburg. Any ideas?
MGCC Help Desk Response: Thank you for contacting the UC Master Gardener Program Help Desk with your question about a very large gall on this 15 year old plum tree in Pittsburg.
I believe this is a gall caused by the bacterium Agrobacterium tumefaciens commonly referred to as crown gall mite or possibly Plum Bud Gall Mite (Acalitus phloeocoptes (Nalepa)). Crown gall, as its name implies, typically appears at the crown of a plant, where the trunk enters the soil but it also can infect the main trunk and side branches. Plum trees are among a long list of plants commonly infected by crown gall including many popular home garden fruit trees (pluots, etc.).
The surface of crown galls and wood underneath is the same color as healthy bark and wood. However, when cut with a knife, crown galls are softer than normal wood and lack the typical pattern of annual growth rings. Galls can be tiny and smooth on young plants but usually are rough and sometimes massive on older trees.
Crown gall appears to have a relatively minor effect on most older plants which is the situation you found. Since this tree is 15 years old and the gall appears to encompass a major part of the main branch I would suggest leaving it be. If the distal portion of the branch starts to decline then the branch can be removed back towards the trunk thereby removing the gall.
Without further inspection of the gall here in our office, another possibility is the Plum Bud Gall Mite (Acalitus phloeocoptes (Nalepa)) which are well described in the Santa Clara County UCCE link below.
Following is a link to a UC Integrated Pest Management website that explains crown gall http://ipm.ucanr.edu/PMG/GARDEN/PLANTS/DISEASES/crowngall.html
and here is a Santa Clara County UCCE link to Plum Bud Gall Mite:
http://mgsantaclara.ucanr.edu/files/300211.pdf
We could give a more conclusive response if you would bring a sample to our offices during our office hours described at the bottom of this response.
I hope your homeowner will be relieved. Good luck.
Help Desk of the UC Master Gardener Program of Contra Costa County (EDC)
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 Home Gardeners from the Help Desk of the
UC Master Gardener Program of Contra Costa County
Client's Request: We live in the south County currently and are moving 10 miles north into the center of the County in April 2020. We currently have tree roses that we planted 4years back and lots of fruits trees that we planted 10 years back. How can we move roses and fruit trees to our new home. Fruit trees that we are mainly looking to move are pluots, plums, pears, grapes, persimmon, pomegranates, apple and a few citrus plants. Would appreciate all your information on if and how to make the move for my favorite plants without giving them a shock.
Help Desk Response: Thank you for contacting the UC Master Gardener Program Help Desk for information about moving several trees to your new home. Unfortunately, you can't move trees without causing them stress and while it is possible to successfully move a plant from one location to another, moving established fruit trees like yours, is very difficult and usually not advised. Unless the tree is uniquely special, buying new trees for the new location makes a lot more sense.
Here's a link to an article by Clemson University Cooperative Extension giving detailed instructions about moving established trees. I think you will find it helpful if you decide to try to move your trees despite the difficulty. They recommend pruning the tree roots in the fall and then moving the tree before bud break next year. The most important thing is to get as much of the root ball as possible and go at least a foot deep. The new hole should be 50 percent wider than the root ball and about the same depth. You do not need to amend the soil.
Moving the rose trees will probably be much easier as they are quite resilient and it may be possible to move them at any time if done correctly. Here's another link to an article called "Myths About Transplanting Roses" which won an award from the Northern California, Nevada and Hawaii Rose Society. You may find this helpful since it gives good instructions on how to transplant a rose during the growing season. In short, they advise to give the rose as much water as possible the day before transplanting, get as much of the root ball as possible and minimize the time out of the ground.
Good luck and please let us know if we can be of further assistance.
Help Desk of the UC Master Gardener Program of Contra Costa County (TDT)
Note: 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.ignore.edu/HortCoCo/ You can also subscribe to the Blog
Advice for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
Apricot Tree Showing Signs of Brown Rot
by Chantal Guillemin , Master Gardener
Request: My Royal (Blenheim) apricot tree usually produces delicious fruit, but this year almost all had brown discoloration. Globs of golden sap ooze out in many places along branches and the ends of some branches have brown, withered leaves and dead flowers. What kind of disease is affecting my apricot tree? What can I do about it?
Photo by Jack Kelly Clark, courtesy UC Statewide IPM Program
Response: Thanks for contacting the Help Desk of the UC Master Gardener Program of Contra Costa County about the problems with the brown spots appearing on your apricot fruit.
Expanding dark brown, firm, circular spots on apricots are symptomatic of a very common and serious disease of stone fruit called brown rot. The exudation (oozing) of sticky droplets of gum (sap) from the base of dead flowers and the bark of infected twigs is further indication that Monolinia spp., the brown rot fungus, is present on your apricot tree. Brown rot can also infect other stone fruit such as almond, peach, plum, cherry, nectarine and quince (a pome fruit).
The first symptom of brown rot is the browning and withering of blossoms. These infected blossoms cling to twigs for months. Cankers, which are sunken brown areas, may develop around twigs at the base of infected flowers, causing leaves at tips of twigs to become dark brown and shrivel up.
Photo by William W. Coates, courtesy UC Statewide IPM Program
Gardeners in Contra Costa County can practice the following sanitation measures to decrease the spread of brown rot fungal disease: frequent checking of stone fruit trees for signs of brown rot, timely and appropriate pruning, furrow or drip irrigating versus overhead sprinklers, and planting disease tolerant varieties.
Inspect your apricot and other stone fruit trees nearby often for symptoms of brown rot. Do this during the bloom period, as fruit turn green, and when they begin to ripen. Consider harvesting fruit before it is ripe but once it is soft will lessen the risk of brown rot. After harvest, remove all fruit left on trees or destroy them because they are potential overwintering sites for brown rot. Ensuring that gardening sanitation tasks are performed on a regular basis will go a long way to minimizing the development of spores from mummified fruit hidden beneath weeds and debris on the ground.
As for apricot trees, pruning should never be done during winter dormancy. That's our wet season, and atmospheric moisture carries airborne spores and pathogens. Apricot and cherry trees are particularly susceptible to Eutypa dieback, a disease which causes whole branches to wither away. Do not inflict pruning wounds on apricot trees at this time. Pruning diseased twigs and dead blossoms still clinging to branches of apricot trees should be done after leaves drop but before the first fall rains.
Other stone fruit require the same removal of infected plant tissue but this can be done as soon as these are detected. Burn, bury or bag all diseased branches and leaves. Destruction of these affected parts and the removal of mummies from the tree and from beneath the tree prevents the buildup of brown rot inoculum. This applies to flowering cherry, plum and quince as well. Do not put diseased plant parts in compost. Remove broken or diseased branches. Prune trees from the time they are planted to allow good ventilation in the canopy.
Avoid wetting blossoms, foliage, and fruit during irrigation by using furrow or drip irrigation. As far as prunes are concerned, drying them immediately after harvest kills the brown rot fungus.
Some plant varieties are known to be least susceptible to brown rot. Apricot cultivars Tilton, Harcot, and Harglow are touted to have some brown rot resistance. Royal, Blenheim, Perfection, and Derby Roal are most susceptible to this fungal infection.
If left unmonitored, brown rot fungal infection of apricots and other stone fruit can thwart homeowner's plans for a harvest of healthy fruit. Familiarization with brown rot symptoms and taking action to remove sources of brown rot spores can alleviate the problem of brown rot fungal infection on apricots and other stone fruit.
For additional information, you can also consult:
UCANR publication 7259, Apricots: Calendar of Operations for Home Gardeners;
UCANR publication Pests in Garden and Landscapes – Brown Rot Monilinia spp.;
UCANR publication 3332, Pests of the Garden and Small Farm, pp 144-145;
UCANR publication 3382, California Master Gardener Handbook Chapter 16
UCANR publication 3311, Postharvest Technology of Horticultural Crops;
UCANR publication 3345, Diseases of Temperate Zone Tree Fruit and Nut Crops;
UCANR publication 3485, The Home Orchard
Those not available as free download UC publications are often available at your local branch library or by mail order from UCANR.
Please do not hesitate to contact the MGCC'S Help Desk if you have further questions and/or need recommendations.
Help Desk of the UC Master Gardener Program of Contra Costa County (CCG)
Note: The UC Master Gardeners Program of Contra Costa'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.ucanr.edu/HortCoCo/ You can also subscribe to the Blog (http://ucanr.edu/blogs/CCMGBlog/)
