Advice for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
Client's Request via email (preceded by telephone conversation at 925- 608-6683).
Thanks for your interest in our distressed navel orange tree. Here is the information you requested from our phone conversation and some photos. My 60 - 80 (?) year old orange tree has, for the three years we have lived here, regularly produced abundant crops of many hundreds of exceptionally delicious fruit each year, February - June.
In the last four weeks it has been dropping oranges at an increasing rate, by now many dozens a day, totaling over 300.
It is over two stories tall and grows in Martinez, California, in a moderate climate with hot summers and cool winters.
As you can see from the photos, the fruit is splitting, leaves are drooping, the canopy is diminishing, and a few clusters of branches have died. There is a tree nearby of the same age and size that does not appear to have any problem at all.
Our tree has not been watered regularly during the dry season, whereas the neighboring tree is surrounded by a watered lawn.
It was given a fertilization of nitrogen last year, and we wonder if this, or the lack of watering, could be the cause.
What can we do to save this magnificent tree?
MGCC Help Desk Response: Thank you for contacting the UC Master Gardener Program Help Desk with your primary issue that your orange tree's fruit splitting and also the leaves are drooping and turning over
Splitting citrus fruit is a common problem, especially with navel oranges. The following link (http://anrcatalog.ucanr.edu/pdf/8038.pdf) is a short 1-1/2 page informative UC document which describes the condition, along with suggestions for resolution.
Very briefly, fruit splitting is likely the result of stress to the tree, and is probably related to extreme fluctuations in temperature, humidity, soil moisture, and possibly fertilizer levels. The disorder is often caused by a combination of these factors rather than by a single cause.
Avoiding fluctuations in soil moisture (I suggest adding mulch under the tree canopy and consistent and ample water, especially during heat spells) as well as fertilizer levels throughout the growing season may help to minimize fruit split.
I believe the leaf drooping and turning over are also symptoms of too little water during the hot season. The dropping of leaves and resulting thinning of canopy often are the result of too little water on both fruit and ornamental trees.
I am also including some additional links which will provide information on growing healthy citrus here in Contra Costa County. In particular take a look at the 2nd link below as that will provide you with assistance on watering and fertilizing.
Please let us know if you have any additional questions!
Help Desk of the UC Master Gardener Program of Contra Costa County (EDC)
Note: 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: firstname.lastname@example.org, 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.
Cherry Tree Gardener: I am writing for help in identifying what is ailing our Japanese Fuji Cherry Tree. It is about 3 years old and had been doing very well until about a month ago. For about 2 months, we were watering it with water from our shower, but I have stopped. All of the leaves are hanging limply, but they have not yet fallen off. Thank you for your consideration and advice.
Before diagnosing your problem, could you please clarify the kind of cultural care you are providing to the tree?
1. You said that you had been watering it with water from the shower. Approximately how many gallons per week were you providing from the shower? When did you stop using the shower water?
2. How soon after you stopped using shower water did the symptoms appear?
3. Now that you have stopped using shower water, what kind of water are you providing to the tree?
4. How often are you watering now?
5. What type of watering system are you using? Drip? Spray? Soaker hose?
6. Did you fertilize the tree, or use any kind of insecticide or herbicide near the tree before seeing the symptoms?
We look forward to solving your problem.
Cherry Tree Gardener: Thanks for getting back to me. I really appreciate it. Here are responses to your questions –
1. You said that you had been watering it with water from the shower. Approximately how many gallons per week were you providing from the shower? When did you stop using the shower water? I put about 10 gallons of shower water per week. I stopped watering with shower water about 2 weeks ago.
2. How soon after you stopped using shower water did the symptoms appear? The symptoms started to appear about 4-6 weeks ago. When the symptoms appeared to be getting worse, I decided to stop watering with shower water. I thought maybe the soap in the water might be causing the symptoms.
3. Now that you have stopped using shower water, what kind of water are you providing to the tree? I water about 1-2 times per week using a hose. I give it a good watering each time, but I'm not sure how many gallons of water. If I had to guess, I'd say 3-4 gallons for each watering. The ground absorbs the water well.
4. How often are you watering now? 1-2 times per week.
5. What type of watering system are you using? Drip? Spray? Soaker hose? I just use a hose with no attachment.
6. Did you fertilize the tree, or use any kind of insecticide or herbicide near the tree before seeing the symptoms? I have not used any fertilizer, insecticides or herbicides.
Thank you again for your help. If you need any more information or pictures, please let me know.
MGCC Help Desk: Thank you for your speedy reply. We believe that your tree has not been receiving enough water through the hot part of the summer. Shower water (without harmful soaps or shampoos, see examples at http://ecologycenter.org/factsheets/greywater-cleaning-products/) is ok but appears that you will need even more water than you have usually applied. Since your tree is 3 years old, it probably has a fairly new and growing root system. During hot summer months, your tree will need a lot of water per month. The exact amount will depend upon what part of the county you live in and how big the tree is. For example, if you live in west county, say El Cerrito, and your tree at the drip line is 8 feet in diameter, it would need approximately 100 gallons during August, but if you live in Walnut Creek, your tree would need approximately 120 gallons in the same time period.
Also, the way you have been watering will deliver water only shallowly, and many of the roots will not have access to any water. The wilting is most likely a symptom of this.
We recommend that you water less often, but more deeply, to completely moisten the root zone (primarily at the drip line) down to a depth of 12 - 18 inches. If you dig into the soil with a screw driver near the drip line down to a depth of at least 12 inches, the soil should be moist but not sopping. If it is dry, you should immediately apply enough water to dampen the soil. Using a hose is fine as long as you deliver enough water. A soaker hose applied around the tree out to the drip line would be less work, and this type of slow watering helps the water go deep where it is needed. If you are able to sufficiently wet the root zone this way, watering every other week should be sufficient.
Once you have thoroughly wetted the root zone, we recommend that you also apply 3 - 4 inches of mulch or compost on top of the soil to reduce evaporation of water. Keep the compost (and water) away from the tree trunk by at least 4 inches, but otherwise spread it under the tree out to the drip line and a little beyond.
Since we believe that your tree is water stressed, it is good that you have not fertilized the tree. We recommend that you withhold fertilizer until next spring.
We believe that based upon the symptoms you provide this will take care of your problem. However, if it does not, please let us know so that we can look into other possible causes of the wilting and drying of the leaves.
Help Desk of the UC Master Gardeners of Contra Costa County
Note: The Master Gardeners 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: email@example.com, or on the web at http://ccmg.ucanr.edu/Ask_Us//span>/span>
It is tempting to pamper our plants through frequent fertilizing and watering to ensure that they grow big and lush. It understandably gives us a lot of pleasure and sense of accomplishment to see our plants thrive and bloom, or produce a bounty of fresh juicy fruit and vegetables. But, with a drought situation, now is not the time to pamper your plants. Now, is the time for tough love. Your plants might not like it much. They might become "petulant" by withholding their lushness, not flowering like before or not producing as much. But, they will survive.
Most of us unknowingly over-irrigate our plants, so its ok to reduce the water you give them. In fact, the amount of water given to plants can often be reduced by 20-40%. Most established landscape trees, shrubs, and groundcovers, regardless of the species planted, perform acceptably well with 20-40% less irrigation than they are typically given.
To reduce irrigation with the least harm to your plants, water infrequently and deeply. Do this by increasing irrigation runtimes and extending the number of days between irrigation events. I know this seems contrary to the idea that you should reduce the irrigation runtime and keep the same frequent irrigation interval, but this will work.
Schedule slightly longer irrigation runtimes so that the entire root zone of plants is rewetted at each irrigation; then gradually increase the interval between irrigation runtimes over a few weeks. This practice will allow you to save water while allowing your plants to adjust to a new watering regiment. After extending the interval between irrigations, the water budgeting or seasonal adjust feature found on many sprinkler controllers can be used to fine tune runtimes and achieve optimum water conservation.
When watering, consider the root systems of your trees, plants, shrubs and lawns:
- Tall fescue lawns normally have roots 6 to 12 inches deep
- Bermudagrass and other warm season grasses are normally at least 12 inches deep
- Trees, shrubs, and groundcovers are normally found within 12 to 24 inches of the soil surface
- Vegetables vary in depth from 6 to 48 inches (a chart that shows the root depths is linked below for you)
Adjust the runtimes in your irrigation controller every month to account for changes in the average weather conditions. This alone can reduce landscape water use by up to 10%.
It is important to gradually reduce the water over a few to several weeks so the plants can adjust to less water.
Try to irrigate during the very early morning hours (between 2:00 am and 6:00 am) because evaporation is lower and usually there is little, or no, wind to disrupt the pattern of sprinklers during these hours if you are watering lawns. In addition, water pressure is a little better for irrigation systems during this time.
To find out how deep the water is going into the soil, take a long screwdriver (or similarly shaped tool or soil probe) and probe the soil in several spots an hour or so after an irrigation. The depth that the screwdriver or tool can be easily pushed into the soil is the depth that the water has penetrated. If deeper wetting is needed to wet plant roots, then additional irrigation cycles are needed. If the soil is wet beyond plant roots, then the runtime should be reduced.
Checking the soil moisture each day during drought - or really hot, dry days - with this technique and watching the plants for signs of wilt or water stress will enable you to see how long it takes for soil to dry to the point where water must be replaced. This is the maximum interval between irrigations for the current season. Ideally, irrigation is applied just prior to the onset of plant stress, so schedule irrigation about one day shorter than the maximum interval.
Note: Established small shrubs or groundcover are those that have been in the ground for a period of one year or more. A tree or larger shrub must be in the ground for at least 3 years to be considered established.
To determine the root depth of your herbs & vegetables, go to: Herbs & Vegetables Root Depth Chart
There is some debate over what to water next after the Tree.
Ultimately, it depends on whether your focus is on food crops or on the landscape, the ease of replacement, and the expense. I value my herbs because I cook with them, and I also want a small vegetable garden to eat from this summer (food prices will be higher). So, I plan on sacrificing bedding plants and annuals in favor of my herbs, strawberries and vegetables. I'll use mulch, shade cloth and drip irrigation to get the most from the water I have available to me.
The Lesser Nobles – Shrubs.
Typically shrubs planted within the past two years will require irrigation during drought, thought not as much as newly planted shrubs. During severe drought conditions, plantings up to five or six years of age may also require supplemental water.
The Merchant Class – Perennials and Established Trees and Shrubs.
Established shrubs or trees (three years or more in the ground) can be watered deeply about once a month, especially if they are showing signs of stress. Deep, thorough irrigations from spring through summer can be enough to keep most trees and shrubs alive when water is in short supply. Many tree and shrub species will drop leaves or wilt under severe water shortage but will survive. Under-watered fruit trees probably will produce less, if any fruit, but will also survive. Once water shortages are lifted, these trees will again leaf out and produce fruit.
The Serfs – Established Lawns, Groundcovers, Containers, Bedding Plants and Annuals.
Annuals and herb plants are a lower priority because they require the most watering to keep alive and can be replaced inexpensively or can be replanted next year when adequate water is available.
P.S. Remember, The Tree is King.
It's a cruel, cruel world out there – at least it is in your garden when water usage is restricted. All those beautiful trees, plants, vegetables and lawns need watering if they are to survive. But, what gets watered? Tough choices have to be made.
Your garden is like a medieval realm of yore, complete with a King, lesser nobility, merchant class, and serfs. We all know who gets the most (the King, of course) and who gets the shaft (the serfs, alas). So, lets break it down as it applies to our gardens.
The Tree is King. The Tree is so essential to our environment. It gives shade, helps cool the air, provides a habitat for numerous birds, animals, insects and fungi, it produces food, and it filters and cleans the air. Trees should be watered first, especially newly planted trees because it takes years for a tree to mature and it is less easily replaced than a bedding plant. You also want to give top priority to any newly planted shrubs. But remember, the Tree is King.
and there's the rest. . .
For more on how to care for your trees' watering needs, see UC/ANR California Garden Web - Keeping Trees Vigorous or Keeping Landscape Plantings Alive under Drought or Water Restrictions