Advice from the Help Desk of the
UC Master Gardener Program of Contra Costa County
MGCC Help Desk Request:I am located in Central County. I am having issues with my lemon tree. I have attached some photos. I was hoping you could give me some advice.
I have never sprayed pesticides. I am hoping for a more organic solution to the issues. I know it might not be possible.
I have not fertilized it this year. It is on our sprinkler system so it gets water daily. Some of the leafs have spiderweb looking substance under the leafs. Some leafs are yellow. I have also noticed the spikes are very large. Thank you so much for your help.
MGCC Help Desk Response: Thank you for contacting UC Master Gardener Program with your lemon tree questions and for sending the photos. The symptoms you are seeing could be the result of various minor problems that occur on citrus. The curled leaves show signs of citrus leaf miner. Citrus leaf miners are moth larvae that create shallow tunnels in young leaves. They can distort the leaves but are generally not harmful to the tree. You are probably seeing the end result of leaf miner damage that was done previously. For more information on citrus leaf miners, see: http://ipm.ucanr.edu/PMG/PESTNOTES/pn74137.html.
We are not sure about the spiderweb type substance. It could be from an insect, e.g., whiteflies, but if so you should also find sticky areas on the leaves. Also, any pictures of the insect would be helpful. It is also possible that there are spiders on your tree. If that is the case, I would not worry. If you want the spider identified, see if you can get a photo and we will try to identify it.
The fruits look like they may have been damaged by the thorns which you indicated are very large. That would happen if the fruits were rubbing against the thorns. Is that possible? If not, another possibility would be herbicide damage. Is it possible that herbicides were used anywhere near the citrus tree? Even your neighbors? Make sure you remove the damaged fruits from the tree before we have any more rain. The damaged areas provide an opening for fungi and other diseases to get into the tree. Also, large thorns might indicate that the branch is a juvenile branch or is coming from below the graft, the "bump" near the bottom of the trunk. If from below the graft, you should consider removing that branch as it probably will not produce edible fruit.
The spots on the leaves may be from a fungus. The fungus may be the result of the watering, especially if the sprinkler system is putting water on the leaves. Make sure that the sprinkler is set low and also make sure that the sprinklers are not dampening the tree trunk. Wet tree trunks can lead to root or crown rot from fungus growing around the roots and crown (where the roots and trunk meet). Root and crown rots are serious diseases that are difficult to treat and can ultimately kill the tree.
The daily sprinkling may also be causing other problems for the overall health of your tree. Daily watering might not be supplying the citrus with enough water. Citrus, like most trees, do best with less frequent, and deep watering to promote stronger roots. To give you an example of how infrequent the watering should be, watering in the heat of summer should be done about every seven to ten days. This would be for citrus planted in the ground and with several inches of mulch under the tree out to drip line. In a pot you would need more frequent watering as they dry out faster. If other plants on your irrigation system need frequent watering, you should consider setting up a separate irrigation system on a different timer for the lemon. For more information on watering citrus, see: http://ipm.ucanr.edu/PMG/GARDEN/FRUIT/CULTURAL/citruswatering.html.
You mentioned that you had not fertilized the tree this year. Yellow leaves are a common sign of a lack of nitrogen. Citrus trees require regular fertilization, especially with nitrogen. The fertilizer should be applied in January or February (prior to bloom) with a second application in May and perhaps a third in June. This link has more information on fertilizing citrus: http://ipm.ucanr.edu/PMG/GARDEN/FRUIT/CULTURAL/citfertilization.html.
Finally, I thought that you might be interested in this general write-up on growing citrus in Contra Costa County: http://ucanr.edu/blogs/slomggarden/blogfiles/4260.pdf
Please let us know if you have any remaining questions. You are also welcome to bring plant samples into our office if you want more information. We are open Monday to Thursday, 9am to 12 noon.
Good luck with your lemon tree..
Help Desk of the UC Master Gardener Program of Contra Costa County (ECS)
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
Help Desk Response: Thank you for contacting the Help Desk with your questions and concerns about your Bush Anemone plant with yellowing leaves.
Once established, this is a very hardy low-water-use plant, but even these varieties need extra water usually for the first several years while becoming established. However, yellow leaves can be a symptom or either under or over-watering. You mentioned that there is only one one-gallon dripper for 40 minutes a week, which would give the plant less than one gallon a week. Even for a young drought-resistant plant, this may not be enough, especially since it was planted this spring spring and in sandy soil. Also, one drip emitter would only be watering one side of the root ball. You can check on the moisture in the root area by carefully digging down beside the plant with a trowel or your hand, to feel for moisture, or if you have a soil moisture meter that can also be used. When you water, you want to wet the whole of the root ball and then let it dry out between waterings. If you want to continue to use drip, a circle of inline emitter hose around the plant or at least 2 emitters on opposite sides of the root ball would provide more even moisture than a single emitter.
http://ucanr.edu/sites/scmg/ Plant_of_the_Month/ Carpenteria_californica/.
The paragraph on Cultivation provides some good advice on getting your Bush Anemone back in good health and watering appropriately for the first several years. (The pictures in this blog post were also copied from the Sonoma County Master Gardener article in the link.)
I hope this is helpful, and that your plant will do well.
Follow-up response from the client: Thanks so much for this information. I have mostly drought tolerant plants but I always find that first year or two a big question mark. I have a newish lavendar that seems to be thriving with no water at all - and then this which seems to need more. And I love this plant when grown, so I don't want to lose it! I'll give it more water until the rains (hopefully) begin.
Help Desk of the UC Master Gardener Program of Contra Costa County (SMW)
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/).
From the Help Desk of the Master Gardeners of Contra Costa County
Client's Questions and Requests: (Originally from a phone call to the MGCC Help Desk...) I'm a new resident of central Contra Costa County having bought a house in Walnut Creek. The house and garden are probably 30-40 plus years old and mostly mature. There is a grove of 30-40 foot Redwood trees that look like they are doing o.k. and many other mature garden plants. We intend to do some remodeling on the house and garden which will include some new planting, but the redwood trees will remain in place for privacy and shade. In our replanting of parts of the garden we would like to utilize drought tolerant plants. We also have a creek adjacent to our property that we wish to protect with minimal disturbance. Do you have some guidance for us to consider as we rethink our garden.
As we discussed previously, We'd be reluctant to recommend planting redwood trees in central or east CCC (and with some reservations in west CCC). However, with your existing mature trees, the goal is to maintain their health and promote longevity. The links provided below provide information for redwood tree care and irrigation. You mentioned that the trees are very large and that they appear to be in good condition, so it is likely that after four years of drought they have been getting water from somewhere - maybe the nearby creek provides a high water table. However, even if we get rain this winter, drought conditions are likely to continue, and you may want to plan for future irrigation.
Although some mature trees can often survive one season with only one or two deep waterings during the spring and summer, several years without enough water can result in severe drought stress and even death. Drought-stressed trees can also be more prone to damage from diseases and insects as well as the effects of increased salts in the soil from lack of ample irrigation. Salts in the soil may also increase depending on the salinity of the irrigation water provided (such as may be the case with recycled water).
Here are some great articles about redwood cultivation in California that you may find helpful in deciding how to best approach improving and/or maintaining tree health:
- http://ccmg.ucdavis.edu/files/103008.pdf
- http://www.ipm.ucdavis.edu/PMG/GARDEN/PLANTS/redwood.html
- http://ucanr.org/sites/mgslo/newsletters/Trees42617.pdf
- http://www.ufei.org/files/pubs/Redwoods.pdf
The article in the link below addresses a new technique (TRIC) by UC horticulturists designed to water landscape trees by the home owner maximizing the use of water and insuring that water is reaching the drip line of the tree: http://ccuh.ucdavis.edu/public/drought/tree-ring-irrigation-contraption-tric-1/tree-ring-irrigation-contraption-tric. While TRIC system provides an effective optimal and automated solution, if the cost appears prohibitive, UC has now designed a simpler solution for less cost, but it requires more home owner attention and management (see RSIC).
You also asked about finding an arborist to inspect the health of your trees - the International Society of Arboriculture has a web tool to assist you in finding qualified members (i.e.,Certified Arborists) in your area: http://www.treesaregood.org/findanarborist/arboristsearch.aspx. You may want to consider a consulting arborist first as well as friends or neighbors for recommendations.
Finally, here is the link to the UC Davis Arboretum's list of good drought resistant plants for our area: http://arboretum.ucdavis.edu/arboretum_all_stars.aspx. We also have a lot more information on this subject should you need it.
Thank you for contacting Master Gardeners. I hope you will enjoy your new home, and if you have further questions please feel free to contact us again.
Help Desk of the Master Gardeners of Contra Costa County
Note: The UC 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: 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.
/span>Advice for the Home Gardener from the Contra Costa Master Gardeners' Help Desk
Client's Questions and Concerns
Client called with “huge problem with birch trees". She left her email address, but also asked for someone to call and help her with some advice. Called several times but couldn't leave a message since her voicemail box was full. Sent her an email with some of the “usual” problems with birch trees and asked her to contact us if she needed more information. (Note: Although this advice didn't come to satisfactory conclusions, CCMG Help Desk thought it would be beneficial to remind gardeners of the value and care of their trees, especially the oft-planted and vulnerable birch trees, and the need for prioritizing tree care especially during the drought. You can replace and restore many shrubs and perennials in several years and at moderate costs; replacing trees can be expensive when you include value to the property and costs of removal, and can take many years.)
Response and Advice from the CCMG Help Desk
Thank you for calling Master Gardeners with your birch tree problem. However, in order to help you, we will need some more information and either samples or photos of the tree.
In the meantime, I have included information which might be helpful adapted from an article from a Solano County Master Gardener blog:
- Most likely your birch tree is a European white birch (Betula pendula), native to northern Europe with its cooler climes and plenty of rainfall to sustain the trees. They grow magnificently there, and to their full potential, much larger than any you'll likely see in Contra Costa County.
- In Contra Costa County, especially the central and eastern areas, the life span of a birch tree is approximately 25 years due to heat and lack of rainfall. Decline will often show in branch dieback or leaf drop. During drought, birch trees – which need consistent and deep irrigation – will show signs of stress such as dead branches. Or depending upon the tree's age and care, those dead branches may just be signs of old age and a steady decline.
- Many homeowners with birch don't realize how stressed birch trees can get in drought periods. The natural habitat of birch trees is the forest, where they grow alongside creeks and streams.
- Birch are often planted in lawns and home owners forget that when they stop or reduce irrigating their lawns that birch will often be put in stress unless additional water is provided.
- If your tree is in a lawn, remove the grass from around the trunk out to the drip line and replace it with a layer of fine bark mulch, chopped red cedar bark or aged compost. A bender board around the perimeter of the mulch will prevent the mulch from working into the lawn.
- To determine the actual soil moisture “feeding” your birch, you can push a long screwdriver into the soil, working outward from the trunk to the drip line under the leaves. If the screwdriver does not easily penetrate the soil, then the tree must be irrigated.
- One method of supplemental tree irrigation is to lay several lengths of soaker hoses, working outward from the trunk to the perimeter of the tree under the drip line. Attach a garden hose to the soaker hose and let the water drip for several hours until the screwdriver will easily slip into the soil. You can find a rmuch more duable and automated version of this watering system at http://ccuh.ucdavis.edu/public/drought/tree-ring-irrigation-contraption-tric-1/tree-ring-irrigation-contraption-tric
- The birch root system is also extremely sensitive to fertilizers and herbicides, including weed and feed products as well as mechanical damage, for example string trimmers.
- When birches get stressed during even our “usual” Northern California summer droughts, borers can move in. This problem is often exacerbated by reduced irrigation during our current long-term drought. The bronze birch borer, Agrilus anxius, is the main culprit. Apparently there is quite a large local population of the borers. Intensive insecticide applications may keep them at bay. Check the University of California Statewide Integrated Pest Management website for more information on preventive measures: http://www.ipm.ucdavis.edu/PMG/GARDEN/PLANTS/birch.html.
If you go to this link and in the right columns scroll down to 'birch borers', you might find clues to what is ailing your tree bug-wise. However, it is important to positively identify the cause before any measures are taken to manage the problem, so we look forward to hearing from you again.
With a little TLC, you should be able to coax a few more years out of your birch.
Contra Costa Master Gardeners' Help Desk
Note: The Contra Costa Master Gardener 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/
/span>/span>Help for the Home Gardener from the
Contra Costa Master Gardeners' Help Desk
I am trying to get good information and advice about water-wise irrigation controllers that operate in conjunction with rain and temperature gauges for my small, mixed-plant residential garden.
Master Gardeners' Help Desk Response:
Smart Controllers (commonly referred to as ET controllers, weather-based irrigation controllers, smart sprinkler controllers, and water smart irrigation controllers) are a new generation of irrigation controllers that utilize prevailing weather conditions, current and historic evapotranspiration rates, soil moisture levels, and other relevant factors to adapt water applications to meet the actual needs of plants. These controllers will help you to apply the appropriate amount of water in response to your particular plant and soil conditions, often resulting in water conservation. Through optimum water application, overwatering can be avoided, reducing the incidence of soil-borne diseases, and resulting in healthier plants.
Information Sources: While many of the more complex, remote/central controllers are designed for commercial use, there are many which are suitable and affordable for the home landscape. The University of California Center for Landscape and Urban Horticulture website explains the fundamentals of Smart Controllers. This UC site, titled "Is a Smart Controller for You?" might also be of use to you.
Local Information Sources: Each manufacturer has online information regarding their company's controllers. Most major companies such as Irritrol, Rainbird, Toro, and Hunter make Smart Controllers appropriate for home garden use. While we cannot recommend one manufacturer over another, you might go to a local irrigation supply company or nursery and ask for recommendations which take into account the number of stations and specific needs of your irrigation system.
Rebate Programs: You might also want to check into rebate programs sponsored by the local water districts for installing water conserving irrigation systems and controllers. The East Bay Municipal Utility District has a rebate program for qualifying irrigation controllers. The Contra Costa Water District has a similar rebate program.
Good luck in your quest to find the appropriate controller for your garden! It's great that you are considering a Smart Controller, as water conservation is very important in our Mediterranean climate. Please let us know if you have any additional questions.
Contra Costa Master Gardeners' Help Desk
Editor's Note: The CCMG Help Desk is available year-round to answer your gardening questions. Except for a few holidays, we're open every week, Monday through Thursday from 9:00 am to Noon at 75 Santa Barbara Road, 2d Floor, Pleasant Hill, CA 94523. (map) We can also be reached via telephone: (925) 646-6586, email: ccmg@ucanr.edu, and we are on the web at http://ccmg.ucanr.edu/. "Ask a Master Gardener" help tables are also present at many Farmers Markets as well as at the CCMG's "Our Garden" programs (map). See the CCMG web page for details/locations.