Advice for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
Client's Request: I have a Crape Myrtle bush/tree that is about 15 years old. The last 4 to 5 years it starts out with new growth in the spring with nice green leaves. Then in about this time of year, the older leaves turn a yellow/orange color and start to drop off and continue to fall off till winter. I continue to get new sucker growth at the base of the tree, which I cut off. I do not see any indication of mold, fungus, or insects on or under the leaves. I do not spray the tree with any insecticide. I have several Petunias planted around the base of the tree, which get watered every other day for about 10 minutes during the warm summer months. I live on the Delta so the water table here is 2 to 3 ft below the surface. I don't know if I'm watering too much or not enough. I do not fertilize the tree, but I do plant the Petunias in potting soil which has slow release fertilizer in it. I also prune the tree every year in January. I have attached 4 pictures for you to look at.
My questions?
1. What is causing the leaves to turn yellow/orange and then fall off?…
2. Is the tree getting too much water or not enough?
3. Should I be fertilizing, if so, what should I use?
4. Are their insects or something else I'm not seeing that is causing the problem?
Will appreciate any advice you can give me.
UC MGCC Help Desk Response: Thank you for contacting the UC Master Gardener Program Help Desk. Your pictures were very helpful. I also appreciate that our phone call in addition to your email as it allowed me to ask questions for additional information.
Your primary issue is… "What is causing your crape myrtle leaves to change color and fall prematurely/"
The questions posed in your email are as follows:
- What is causing the leaves to turn yellow/orange and then fall off?
- Is the tree getting too much water or not enough?
- Should I be fertilizing, if so, what should I use?
- Are their insects or something else I'm not seeing that is causing the problem?
First, we do note that the Town of Discovery Bay (a Delta community) lists Crape Myrtle on its Suggested Plant List for Discovery Bay Residents. We cannot confirm how that recommendation was made but perhaps contacting Town officials would provide their latest guidance and experience.
Following is a link to the University of California Integrated Pest Management website where it presents information of common problems associated with crape myrtle. http://ipm.ucanr.edu/PMG/GARDEN/PLANTS/crapemyrtle.html……
One of those common problems is water management – either too much or too little. Recognize that too little water or too much water can cause nearly identical above ground symptoms to a plant. Following is a link to that discussion. http://ipm.ucanr.edu/PMG/GARDEN/ENVIRON/poorwater.html
I believe your situation is due to too little water. I base this on our discussion of your current watering protocols which essentially is shallow watering that takes place for the petunias near the trunk of the tree.
The following link will take you to a web site of the Vacaville Tree Foundation which will reinforce our discussion on tree watering. It will provide an illustration as well as information on how to water a tree – where in relation to the canopy, how deep and how often. As we discussed, as a tree grows its roots extend beyond the canopy and water applications need to also extend outward. This information is from Vacaville but I believe the environmental conditions are similar to your residence, Discovery Bay. Crape myrtle is a low water use plant and per this site should be watered monthly during the hot season to a depth of 18-24 inches per irrigation. http://www.phytosphere.com/vtf/treewater.htm
You mentioned that in your area you have a high water table. My concern with the above watering recommendations is I do not know exactly how high the water table is in your area – and I was unable to find that information. If it is so high that water is consistently available within the 18-24 inches then too little water is not your problem and conversely too much water may be your issue. You probably should check into exactly what your situation is. You can dig a hole out at the edge of the tree canopy and what you find should tell you the answer.
With regards to fertilizing – It does not appear that your situation is due to a nutrient deficiency. From your picture the leaves do not appear to be affected by a shortage of nitrogen or iron – the two most common shortages. UC does not recommend the regular fertilization of landscape trees. If you choose to fertilize I suggest that you wait until the watering situation – too much or too little - is resolved. If it turns out to be too little water then right after you irrigate, you can fertilize. Make your fertilizer application according to label instructions and if it is a soil application make it to the same area that is being irrigated – in and around the canopy. The Following is a UC IPM link to cultural tips, including fertilizing for trees and woody plants. http://ipm.ucanr.edu/PMG/GARDEN/culturalmenu.html
You also have questioned whether this situation may be the result of insects. Nothing that I see on your tree or heard from you would suggest insects as your problem – good news!
It was wonderful talking to you. If you have any additional questions, please feel free to contact us again.
Editor's Note: Pictures were intended to be attached, but software wouldn't let them be displayed appropriately before editor went nuts. Check back in a few days and maybe software will let me "fix" them.
Help Desk of the UC Master Gardener Program of Contra Costa County (EDC)
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, 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/)
Advice for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
MGCC Help Desk Response: Thank you for contacting the UC Master Gardener Program Help Desk with your question about no fruit but lots of flowers on your tomato plants
There could be several reasons for lack of fruiting in tomatoes:
-- Night temperatures too low, below 55ºF (12.8ºC);
-- Daytime temperatures too high, above 90ºF (32.2ºC).
The plants will produce when temperatures become favorable. Note, though, that heirloom tomatoes can be fussier about temperatures than most hybrid tomatoes and in some areas can wait until late summer or early fall to start setting fruit.
-- Excess nitrogen fertilizer. Lots of healthy green leaves and stem growth, but few flowers or fruit.
-- Too much shade – you need a minimum of six hours of sun to produce fruit.
-- Lack of pollination. While tomatoes are self-fertile, the conditions mentioned above will inhibit pollination.
-- Plants set out too early in spring. -- We recommend planting tomato seedlings the first of May; often earlier planting of seedlings will be inhibited by cold temps and they will just “sulk”; consistent warmer weather and nights should get them growing
Recommendations:
-- Choose varieties adapted to your climate zone,
-- Plant tomatoes in full sun,
-- Keep soil evenly moist,
-- Avoid excessive nitrogen fertilizer, and
-- Tapping on blossom stems 3 times a week at midday when flowers are open may improve pollination and help set fruit.
Here is a comprehensive UC link about tomato culture, pests, diseases, and environmental disorders: http://ipm.ucanr.edu/PMG/GARDEN/VEGES/tomato.html
We hope this information helps! Let us know if you have any additional questions.
Help Desk of the UC 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, 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/)
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?
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)
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/)
Advice for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
MGCC's Help Desk Response: Thank you for contacting the UC Master Gardener Program Help Desk with a question about your elm tree. Thanks also for sending good photos of the leaves, and especially of the insect. The insect is an elm leaf beetle, and it chews small round holes in elm leaves. A heavy infestation of the beetles can actually defoliate a tree, and multiple years of this will weaken the tree and cause its decline.
Managing elm leaf beetles will require an integrated program that includes good cultural care, conservation of natural enemies, regular monitoring, and possibly insecticides and bark banding by a licensed tree care company.
Cultural care: Elm trees are native to areas with summer rainfall, so you will need to give them adequate irrigation during our dry months. Pruning should be done just to remove dead branches. Avoid unnecessary pruning.
Preserving natural predators: Predators of elm leaf beetles include earwigs, lacewing larvae, some ground beetles and several others. To preserve these in your landscape, minimize pesticide application on surrounding areas and use less-persistent products, or apply pesticides in a band on the trunk (this will kill larvae when they crawl down the tree to pupate, thus reducing next year's problem). Bark banding, while it can be effective, may require application by a licensed pest control operator because the chemicals are not available for home use. Short-lived contact sprays of oils such as Neem oil or horticultural oil, or Spinosad can work, but only if the tree can be thoroughly sprayed, which is unlikely in a tree as large as yours.
Systemic insecticides can also be used for control of elm leaf beetles. These are applied to one area of the tree (bark, roots, etc.) and are moved to other parts of the tree (leaves). These pesticides when injected into the tree, or into the soil, minimize environmental contamination. Because elms flower before leaves come out, and are wind pollinated, the risk of harming beneficial pollinator insects is low when using a systemic insecticide on elms.
This link will take you to more information about elm leaf beetles: http://ipm.ucanr.edu/PMG/PESTNOTES/pn7403.html.
There are other things that can cause problems for elm trees. The dead and dying branches at the top of the tree may be from a lack of water, but could be from a disease such as verticillium wilt which typically shows with dying branches at the top of the tree. Keeping your tree happy with adequate irrigation is probably the best thing you can do. For more information on elm tree pests and diseases see: http://ipm.ucanr.edu/PMG/GARDEN/PLANTS/elm.html.
I don't know specifically how large your tree is (e.g., width), but it can take up to 200 gallons of water a week appropriately applied to keep a large elm healthy. Elms are listed as needing moderate water (in a range of very low to high). To calculate how much water you should be applying each month, go to this website: http://www.waterwonk.us/how-much/ where you can input the size of the tree (and that is how wide do the branches spread tip-to-tip) and the month. It will calculate the amount of water needed for optimal care.
Please let us know if you have more questions.
Good luck!
Help Desk of the UC Master Gardener Program of Contra Costa County (SEH)
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/)
Help for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
MGCC Help Desk Response (via email): Thank you for calling the UC Master Gardener Program Help Desk with questions about your roses with (probably) Black Spot (Diplocarpon rosae) and/or Powdery Mildew [Podosphaera (previously Sphaerotheca) pannosa var. rosae].
Without the roses in-hand or recent photos, we can't be sure that the problem is appropriately identified. However, both of these diseases are common rose problem this time of the year and can be confirmed by pictures in the linked references below.
Both of these are fungal diseases. Both may be the result of the uneven weather we have been having with rain and warmth and cool weather all at almost the same time.
As we previously discussed, the initial treatments for the two are somewhat contradictory. Black Spot results from water sitting on the leaves. To avoid Black Spot, the leaves should be kept as dry as possible with no more than seven hours of moisture on the leaves. Powdery Mildew can be treated by washing off the leaves. The compromise would be to wash the leaves off during a warm period (say by 10am) to ensure that the water evaporates quickly. Also make sure that any fallen leaves are cleaned up from below the plants and disposed of into your garbage not into your compost. See the Pest Note link following : “Powdery Mildew on Ornamentals” for more details on management. http://ipm.ucanr.edu/PMG/PESTNOTES/pn7463.html.
Thank you for contacting Master Gardeners with your questions. Please do not hesitate to call again.
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 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/)
