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)

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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)

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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

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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?

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.

Brown Rot on Apricot Fruit
Photo by William W. Coates, courtesy UC Statewide IPM Program

Monolinia survives from the previous season as velvety, grey or tan tufts of spores. After rains are over, these tiny spores remain on host blossoms, peduncles (stalk where flower attach), and twigs. They, along with mummified fruit remaining on the tree or on the ground, are the sources (inoculum) for blossom infection. This inoculum can germinate in 2-4 hours and spread to blossoms by air current, rain splash and insects. If flowers are not wet from rain or irrigation, very little blossom blight will develop. Monolinia can also affect green fruit in early summer, and as most rot develops during the month before harvest, fruit is most susceptible to brown rot as it ripens. Fruit rot can develop while fruit is on the tree or post harvest while it is in storage. You can minimize post harvest brown spot by chilling harvested apricots destined for home consumption.

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)

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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/)

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

Client's Request:  I've managed to grow an apricot tree from seed. It's now big enough that it has produced a few apricots in prior years. However, it hasn't produced any fruit now for several years. What is preventing fruiting and what can I do to get fruit?

Help Desk Response:  Thank you for contacting the UC Master Gardener Program Help Desk. Congratulations on growing an apricot tree from a seed! I understand that you would like to know why your tree has not produced fruit for several years and what you might do to get fruit.

The apricot tree's lack of fruit production could be due to flower or young fruit damage from weather; it could be due to reduced pollination, also potentially affected by weather; it could be due to tree damage caused by a pest or pests, or it could be a nutrition issue for the tree.

Weather
Fruit trees form their flower buds in the fall. Lack of rain or high winds can damage buds before they blossom. Spring rains or late-spring frosts can also damage or kill buds and blossoms. Apricots in general perform best in climates with dry spring weather. This year we had both late frosts and spring rains in parts of the County. Last year we also had significant spring rains, and prior to that several dry years in succession. So, weather could certainly have had a negative impact on the fruit production of your apricot tree for the past several years.

Reduced Pollination
Pollination issues could also have played a role. Fruit production depends on pollination, which is the transfer of pollen from the male part (anther) of a flower to the female part (pistil) of the same or another flower usually of the same species. Apricots are self-fruitful, meaning that they may be pollinated by pollen from another flower on the same tree, or in the case of apricots, by pollen from the same flower. The transfer of pollen from one variety to a different variety of the same type of tree is called cross- pollination. Although not required, cross-pollination does improve the number of fruit that form on apricots. Pollinators, such as bees, are usually responsible for apricot pollination.

This link to a Penn State University extension website
https://extension.psu.edu/pollination-requirements-for-various-fruits-and-nuts
identifies several factors can affect pollination:
Temperatures below 55-60°F reduce bee activity
Windy and rainy weather can slow bee activity
Presence of other flowers -- the fruit plants generally are poor nectar producers and bees will naturally seek out the best nectar producing flowers
Most insecticides will reduce bee activity -- therefore do not spray them during bloom

Pests affecting apricot trees
Apricots are susceptible to a variety of pests, listed at this link:
http://ipm.ucanr.edu/PMG/GARDEN/FRUIT/apricots.html
These include sucking and boring insects and other invertebrates, and bacterial and fungus diseases. If, after reading the descriptions, you suspect that you have any of these issues, there are controls suggested at the same link and sub-links. 

Cultural care
The best prevention is good cultural care. Maintaining a good fertilization program can keep your tree vigorous and help prevent infections. Adequate irrigation will help as well.
http://homeorchard.ucanr.edu/Fruits_&_Nuts/Apricot_Prunus_armeniaca_L/
http://ipm.ucanr.edu/PMG/GARDEN/FRUIT/CULTURAL/apricotfert.html
http://homeorchard.ucanr.edu/The_Big_Picture/Irrigation/

With respect to pruning your tree, apricot trees should be pruned in late summer, since they are susceptible to a fungus infection if pruned during wet weather. Because of this, they should be pruned in August -- after fruit production is complete, and early enough to allow time for pruning wounds to close prior to the beginning of winter rains. Information on pruning apricots can be found at this link.
http://ipm.ucanr.edu/PMG/GARDEN/FRUIT/CULTURAL/apripruning.html

I hope that this information is helpful. If you have any questions about the material in these links, or anything else, please contact us again. 

Good luck with your tree!

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

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Note: The  UC Master Gardeners Program of Contra Costa's Help Desk is available year-round to answer our 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, although we will be moving this spring. We will notify you if/when that occurs. 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/)