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/).
/span>/span>Adcive for the Home Gardener From the Help Desk of the
UC Master Gardener Program of Contra Costa County
My questions are around best practices for fruit production. Should I fertilize the plant, and if so, with what and when? Should it have lots of water, little water, or none? Any advice will be welcomed
MGCC Help Desk Response: hank you for your inquiry to the UC Master Gardener Help Desk about how to get more fruit on your pomegranate bush.
There are a number of possible reasons why your bush is not producing more fruit:
- Pomegranates are self-pollinating, but do you have adequate pollinators in your garden? Growing a variety of flowering herbs and other plants that attract bees and hummingbirds can encourage their presence in your garden and enhance the ability of the pomegranate to self-pollinate. Also, planting another pomegranate bush may help.
- Is your bush getting at least 6 hours of bright sunlight a day? Shading of the bush by other trees, fences or buildings may reduce fruit production.
- Do you have the right cultivar for your area? Some cultivars are ornamental only. Here is a link to suggested cultivars: http://homeorchard.ucdavis.edu/plant_pomegranate.pdf
- Is your bush getting enough water or too much water? Although pomegranates are drought tolerant, they do require irrigation. Good drainage is important in order to prevent root rot. Mulch will help to retain moisture.
- Do you fertilize your bush? Fertilizing your shrub in March and July will help with fruit production. Excessive nitrogen should be avoided.
- Have you pruned your bush too severely? Do you remove suckers that grow from the root area? The suckers drain energy from the plant.
- Netting the bush can help to discourage squirrels from taking the fruit. The fruits ripen in 6-7 months and should be cut from the branch and not pulled off--to prevent damage to the plant.
- Since you mentioned that the bush drops its flowers in the spring, there is most likely some cause for the flowers dropping at that time as well. Besides wind and/or frost, the flower drop could be moisture stress because of the lack of rain earlier. (Not an issue this year!) Checking the moisture level of your soil at flowering time would be beneficial. Using a soil probe to check the moisture or just digging down 6 to 12 inches and checking how moist the soil is by hand are the best methods. The following website will explain how to check moisture content by look and feel. http://www.cdpr.ca.gov/docs/county/training/inspprcd/handouts/soil_moist_feel_test.pdf
- Mulching your tree will also help with moisture issues. Placing 2 to 4 inches of mulch throughout the root zone of your tree is appropriate, but also provide 12" of clearance around the trunk.
Here are some links that provide more information about growing pomegranates that may be helpful:
http://www.crfg.org/pubs/ff/pomegranate.html
http://homeorchard.ucanr.edu/Fruits_&_Nuts/Pomegranate/
http://ipm.ucanr.edu/PMG/GARDEN/PLANTS/pomegranate.html
These links will give you more specific information about the questions listed above.
I hope this information is helpful and let us know if you have any further questions. Good luck!
Help Desk of the UC Master Gardener Program of Contra Costa County (EKP)
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/).
/span>Client's Question: I apparently missed a recent program at MGCC's Our Garden on “Summer Fruit Tree Pruning”. Summer fruit tree pruning is a new concept to me. Can you please provide me with more information?
Help Desk Response: Thank you for contacting the UC Master Gardener Program Help Desk with your question about summer fruit tree pruning. Sorry, you missed the Our Garden program on this subject. I hear it was excellent.
In July and August, you can prune out excessively vigorous shoots that shade lower fruiting branches. Use thinning cuts (removing a branch entirely) rather than heading a branch (by cutting off a portion of it) so that you don't stimulate even more growth. You can also train young branches by bending and staking them to grow in the desired direction.
Cherries and Apricots are also typically pruned during the summer before the rain starts (hopefully)--rather than winter--to avoid a branch dieback disease called Eutypa, which can infect wounds made during wet weather.
Wait for winter dormant pruning to remove other crowded or unwanted branches. I have attached a link to a great MGCC article about fruit tree pruning which includes more links to calendars of fruit tree maintenance throughout the year: http://ccmg.ucanr.edu/files/77175.pdf.
Good luck with your summer pruning. Please do not hesitate to contact us again with your questions.
Help Desk of the Master Gardener Program of Contra Costa County (JLW)
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 from the Help Desk of the
UC Master Gardener Program of Contra Costa County
Client: Hello, I live in Contra Costa County and am basically a newborn to the gardening world. I want to grow fruit trees in my home "orchard". I have a “big” question: What fruits will grow well where I live and how do I grow them?
I hope that this information is helpful. Good luck on your “orchard”.
Help Desk of the UC Master Gardener Program of Contra Costa County
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/).
Client's Situation and Question: My rhubarb tends to die back in the summer much earlier than I think it should or expect. I know that the soils where it is planted are marginal and I haven't fertilized the rhubarb. I do give it regular water. What is causing the early summer die back? and how can I improve the health, vigor, and survival of my rhubarb?
UC MGCC Program's Help Desk Response: We believe that the rhubarb's early die back may be due to a combination of lack of fertility and Contra Costa County's hot summer temperatures. Rhubarb plants do best if fertilized regularly. If you want to grow organically, you can use a six-inch layer of good compost around the base of the plant. The compost will provide a continuous nutrient source that may last for several months. Rhubarb also responds well to manure, but be sure that it has been well composted since applying fresh manure will burn the plant. You can purchase composted manure at a nursery or home supply store. It can be mixed into the compost before you put it around the plant.
Another contributing cause of the summer die back could be hot summer temperatures. Die back is a common response to temperatures that are too high. Although rhubarb likes plenty of sun, providing some shade on hot summer afternoons may help.
Hope this info helps your rhubarb thrive. It's a great perennial vegetable to have in your garden—does well in desserts but can also be used in savory dishes.
UC Master Gardener Program of Contra Costa's Help Desk (TKL)
Editor: Although this response is written for Contra Costa County gardeners, thanks go to the UC Master Gardeners of Sonoma County for input.
Don't miss our 2016 Great Tomato Plant Sale:
@ http://ccmg.ucanr.edu/EdibleGardening/GreatTomatoPlantSale/
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 at http://ucanr.edu/blogs/CCMGBlog/.