UC Nursery and Floriculture Alliance
University of California
UC Nursery and Floriculture Alliance

From the UC Blogosphere...

Autumn's Majesty: Tithonia

A Gulf Fritillary, Agraulis vanillae, lands on a Mexican sunflower. (Photo by Kathy Keatley Garvey)

If there's any flower that should be crowned "Autumn's Majesty," that would be the Mexican sunflower (Tithonia...

Posted on Wednesday, October 18, 2017 at 5:00 PM

Why This UC Davis Course Is Sweet

Home is where the bees are. A beekeeper at the Harry H. Laidlaw Jr. Honey Bee Facility, UC Davis. (Photo by Kathy Keatley Garvey)

"The bee hive is the ultimate home sweet home," Amina Harris, director of the UC Davis Honey and Pollination Center, ...

Posted on Tuesday, October 17, 2017 at 5:00 PM




Everything's coming up Roses!

By Jackie Woods  UCCE Master Gardener


I love roses and would like to plant a few in my landscape.  What basic information should I know before I begin this journey?   Cynthia M., Paso Robles.


Roses… a timeless symbol of love, sympathy or gratitude; an esthetically pleasing-to-the-eye flower that oftentimes produce intoxicating fragrances loved by many.  There are over a hundred species of roses and thousands of different cultivars or varieties.  Roses are easy to grow and, with a basic understanding of that they require, any garden enthusiast can be successful with growing them in their gardens.

There are many different varieties of roses.  Hybrid tea roses are a large bloom on a long stem.  (Double Delight, Mister Lincoln.)  Grandiflora are a combination of Hybrid tea and floribunda and can have one bloom per stem or cluster of blooms on a stem. (Gold Medal, Queen Elizabeth) Floribundas are shorter bushes with shorter cluster blooms but will sometimes bloom singularly. (Iceberg, Betty Boop.) Polyanthas are small bushes with clusters that are approximately one inch in diameter. (China Doll, The Gift.)  Other varieties include miniature, miniflora, tree, shrub and climbing roses.

Roses can be purchased in bare root or plant form.  Bare root roses are dormant, soil-less, leafless plants that are usually packed in moist sawdust for ease of storage and shipment.  With our mild Central Coast climate, the best time to plant roses is in early spring.   Pruning of existing rose plants should be done at the end of winter or in January- February with clean, sharp pruners. Cuts should be made ¼ inch above the bud eyes.  Throughout their growing months, prune off dead leaves, spent rose heads and sucker shoots as needed.  Feed roses in early spring and again in early summer.

If you want to know more about growing roses, please join us at the UCCE Master Gardener's Advice to Grow By workshop on Saturday, October 21, 2017 in our demonstration garden at 2156 Sierra Way, San Luis Obispo, 10:00 am to noon. Please visit our website to register at  http://ucanr.edu/sites/mgslo/. If inclement weather, please meet in the auditorium. If you would like to walk through our demonstration garden, docents will be available after the workshop until 1:00 p.m.

Posted on Monday, October 16, 2017 at 1:13 PM

The Amazing Bee-Parasite Research of Leslie Saul-Gershenz

Leslie Saul-Gershenz in the Channel Island National Park conducting a native bee survey.

Evolutionary ecologist Leslie Saul-Gershenz goes places where many have been but few have ever really seen.  Bees and...

Posted on Monday, October 16, 2017 at 11:55 AM

Meyer Lemon Problems

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

Situation: Client visited the Ask A Master Gardener (AAMG) Help Desk at a recent Wednesday morning program at MGCC's “Our Garden” asking for advice on the black spots on the fruit of his mature Meyer Lemon fruit tree. MGs on duty that morning couldn't give him a definitive answer at the time, but asked him to make some further observations about the tree and posed several questions about the health of the tree for him to answer and to send an email with his findings to the MGCC Help Desk.

Client's Response and Request: I appreciate your effort in determining the problems with my Lemon tree,
1. The tree is approximately 25 years old,
2. I bought it as a semi-standard tree. it's 18 feet tall and has a 15' canopy.
3. it's a great -year round producer of fruit.
4. The tree is located about 20' from a building, and it now gets sun all day. 
5. I recently cut down a large olive tree that partly shaded the tree and blocked a lot of early morning sun. 
6. I don't recall ever seeing spots on the rinds before, I have seen the inside of the fruit that looks darkened and not much juice before. I assumed that it was due to lack of water or fruit being old.
7. I fertilize the tree probably once a year with fertilizer spikes.
8. The bark looks fine. 
9. The spotting on the fruit is about 20% of the total, and the leaves look good. 

I'll examine the tree closer, but it's been a fantastic tree. I'll send you this now and if you need anything else from me let me know.

MGCC Help Desk Response: Thanks for coming to the UC Master Gardener Program Help Desk at Our Garden with your request for assistance with your Meyer lemon tree and fruit.  Quite a few of us have spent time researching your inquiry in the past few weeks; unfortunately, we have been unable to pinpoint a specific disease or cause in order to give you a confident diagnosis.

Here's a list of what we think could be causes for your fruit decline based on our research:

  • The change in the sun exposure is likely to have been a culprit, but we don't think that it is the only factor causing damage to the fruit.  This problem may be resolved next year after the tree has had some time to adjust to the new light exposure.
  • The high continual heat we've experienced this past summer may also have contributed to fruit decline.
  • The cold wet winter last year may have caused some of the damage to the fruit.
  • Oddly enough, actions you have taken to care for the tree may also have caused problems.  See information in the attached link below.

We found an on-line UC article that includes many photos of various types of rind damage on citrus.  There is mention in this article of many causes of fruit rind damage including: cold wet weather and frost, copper sprays, fertilizer sprays, wind damage, etc. Please take a look at this article to see if any of these causes may apply to your situation.http://ipm.ucanr.edu/IPMPROJECT/ADS/Fruit_disorders_in_citrus.pdf

We think that the best thing you can do now is to remove all the damaged fruit and give your Meyer lemon the very best cultural care you can and then you'll need to simply wait and see.  Citrus are usually very hardy in our area and we think you may see recovery and improvement by next year.

Here are some tips on giving your citrus good cultural care:

  • Citrus trees require moisture for growth and fruit production.  Apply enough water at each irrigation to wet the soil three feet deep. This requires three to six inches of water depending on the type of soil. Here is a link to information on how to water citrus: http://ipm.ucanr.edu/PMG/GARDEN/FRUIT/CULTURAL/citruswatering.html
  • A layer of organic mulch will help retain soil moisture and permits feeder roots to grow close to the surface. Mulch should not be placed close to the trunk of a mature tree.
  • Mature citrus trees are given fertilizer to maintain their growth and fruit production. Nitrogen is the chief nutrient required by citrus and should be applied each year. Smaller quantities of phosphorus and potassium are required. These nutrients are held in the soil much longer than nitrogen. Here is a link to information on how to feed/fertilize citrus: http://ipm.ucanr.edu/PMG/GARDEN/FRUIT/CULTURAL/citfertilization.html
  • Citrus may occasionally suffer from a deficiency of zinc or iron. When these nutrients are deficient, the tissue between leaf veins turns yellow, but the veins remain green, at least initially. Foliar sprays containing chelated zinc or iron can be used to correct these deficiencies. Iron deficiency can also be caused by excessively wet soil or by very alkaline soil (pH above 7).
  • Citrus is ready to harvest when the fruit has colored and is mature. Your 25 year experience should suffice to know when the fruit is ripe... i.e. dark yellow.  Fruit should be left on the tree until it attains a satisfactory "sweetness". Mature fruit should be carefully harvested. Any break in the rind will promote decay. Use sharp clippers to cut the stem close to the fruit. Fruit can be stored on the tree several weeks to several months, depending on variety, after it is mature. As you probably have experienced, fruit left on the tree too long will become overripe and can reduce the size of the following year's crop.

We hope you find this information helpful in bringing your lemon tree back to full production.  Please let us know if you have any additional questions.

Help Desk of the 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/).

Posted on Monday, October 16, 2017 at 12:12 AM

Next 5 stories | Last story

Webmaster Email: lroki@ucdavis.edu