Advice for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
Help Desk Request: I'm delighted you're available to help diagnose garden problems! Below are four pictures of a grape leaf problem. I have four old vines - Flame and Thompson seedless - that grow against a south-facing solid fence. The vines are close enough that they are co-mingled across the fence. The problem currently is located in one area of the vines and was not visually noticeable three weeks ago. All the vines are vigorous and seem healthy except for the affected leaves. I have cut most of the leaves and vines that are visibly distressed and placed them in my green waste bin. In the 15+ years I've had the grapes I have never had this problem; however, this year I was VERY, VERY late in pruning back the vines, and did not complete the pruning until the new vines had grown a couple feet long. Perhaps the evil villain over-wintered because of my tardy pruning?
Any idea what the problem is - fungus, bug or insect critter, bacteria? I have not seen anything crawling on either side of the leaves. And, what is your recommended approach and treatment? Thanks in advance for your help!
Submitted Representative Images of Affected Grape Leaves (below)
MGCC Help Desk Response: Thank you for contacting the UC Master Gardener Help Desk with your issue of ‘bumps and holes' on your grape leaves.
Thank you for the pictures and note that the blister is on the top of the leaf and the bottom shows fuzzy white. We were able to diagnose simply from the damage itself. The bumps are the result of mites – specifically grape erineum mites. The good news here is that even though the mites infest the leaves, no management is necessary as they rarely lead to any crop losses.
Erinium mites are wormlike, light yellowish white and microscope so you really would need magnification to see the actual mites themselves.
Young leaves show bright pinkish or reddish swellings on upper surfaces. Corresponding areas on lower surfaces are concave and densely lined with a felty mass of plant hairs
The mites overwinter under outer bud scales and move to unfolding leaves in spring. They associate in small groups to feed on lower leaf surfaces; the result is production of masses of enlarged leaf hairs inside a blisterlike area on the leaf. On the undersides of the leaves, beneath the swellings, are concave, densely lined, felty masses of oversized leaf hairs in which the mite populations develop. As the population increases, some move to new areas or to other leaves. From mid-August to leaf drop, there is a movement back to the overwintering site underneath the bud scales.
You indicated that this is new to you and that you were a bit late pruning. I cannot explain for sure why this year and not prior years and I cannot be sure the late pruning added to this situation.
Following is a link to a UC Pest Management website on the subject but it does not really add to the information I have provided above. http://ipm.ucanr.edu/PMG/GARDEN/FRUIT/PESTS/grerineummte.html
Good luck and enjoy those grapes, and do not hesitate to contact us again with garden problems.
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: 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 Biog.
Wisteria Vein Mosaic Virus
Advice from the Help Desk of the
UC Master Gardener Program of
Contra Costa County
Client's Question: This spring I planted 4 wisteria vines around our pergola and they've grown well but now two plants have bumpy leaves and one has brown curl at the end of a few leaves. I worked the soil well and added compost before planting. Any ideas? Thank you.
Help Desk Response: Thank you for contacting the UC Master Gardener Program Help Desk regarding your wisteria plants. Your photos are very helpful in showing the damage you mentioned. You mentioned that one plant has a few leaves with brown tips and curling, and 2 plants have “bumpy” leaves.
On those “bumpy” leaves, I see some yellow patches, and my research leads me to believe it is Wisteria Vein Mosaic virus. This virus affects a wide variety of horticultural and vegetable crops — roses, beans, tobacco, tomatoes, potatoes, cucumbers and peppers — This Mosaic is a viral disease found throughout the United States.
The virus is transmitted mechanically and by grafting. Cuttings or divisions from infected plants will carry the virus. It can be introduced into landscapes on new plants that were infected during their production. Other wisteria can become infected if it comes into contact with infected sap from a plant with the virus. For example, using the same tool for infected and non-infected plant without disinfecting in between use. Mosaic virus over winters on perennial plants and is spread by insects that feed on them. Aphids, leafhoppers, whiteflies and cucumber beetles are common garden pests that can transmit this disease. Soil, seed, starter pots and containers can be infected and pass the virus to the plant.
Once a plant becomes infected with the virus, it usually remains infected throughout its life.
Aside from discoloring foliage and distorted leaves, the virus does not seriously harm wisteria or significantly reduce the vigor of infected plants. There is no cure or treatment, and generally none is needed if the plant's cultural needs are met and it is otherwise healthy.
Here are a few precautions to take:
- Do NOT save seed from infected crops.
- The virus can be spread through human activity, tools and equipment. Frequently wash your hands and disinfect garden tools, stakes, ties, pots, greenhouse benches, etc.
- Avoid working in the garden during damp conditions (viruses are easily spread when plants are wet).
Here is a reference link from UC on the virus. Take a look at the photo attached to the article, it looks very similar to your photos. http://ipm.ucanr.edu/PMG/GARDEN/PLANTS/DISEASES/wisteriavirus.html
If you are interested, here is an article describing first report of Wisteria vein mosaic virus in Wisteria sinensis in the United States of America. https://www.plantmanagementnetwork.org/pub/php/brief/2008/wisteria/
Plant virus symptoms look similar to many nutrient deficiencies. The following conditions will also cause the brown tips and curling leaves that you see:
- Too much fertilizer/salt in the soil.
- Soil too wet and/or poor drainage.
- Other nutritional deficiencies.
You mentioned that you planted 4 plants and only one has brown tips. Take a look to see if that plant receives more sun than the others which might explain the brown tips.
Here is a reference on how to manage pests in wisteria. I recommend reading the articles under Environmental Disorders (on the right side of the screen), and there is also information on good cultural practices. http://ipm.ucanr.edu/PMG/GARDEN/PLANTS/wisteria.html
It is difficult to say whether the Mosaic virus is the cause of both the “bumpy” leaves and the brown tips and curling leaves or they are also caused by cultural practices (e.g. excess fertilization/salt, overwatering).
Since your plants are new and only planted in the spring, it is possible that the plants were already infected with the virus when you bought them. You might want to talk to the nursery and see if they would replace them.
I hope this information is helpful in managing your wisteria. I have a wisteria myself and it is such a joy to see the flowers in the spring. Please do not hesitate to contact us if you have further questions.
Help Desk of the UC Master Gardener Program of Contra Costa County (BY)
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: 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 Biog.
Advice for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
MGCC Help Desk Request: What's going on with my persimmon tree? I worked a bunch of compost into the soil around it in the spring and mulched with leaves. But it looks like it needs nutrients. What should I give it? This is its third year since planting. Thanks
Persimmons are generally disease free, but the black spots showing on some of the leaves look like fungal spots. I can't tell from the photo what type of fungus, but there are several that can occasionally affect persimmons. A wet spring, such as we have had, may exacerbate this, as can overhead watering, so you should make sure any nearby sprinklers do not hit the tree. UC does not recommend any treatment other than good cultural care. Removing any fallen leaves also will help. http://ipm.ucanr.edu/PMG/GARDEN/PLANTS/DISEASES/leafspotdis.html.
As long as the spotted leaves are green, I think it would be best to leave them on the tree, as the foliage looks a little sparse - those leaves are still making food for the tree. Now we have hotter and dry weather, leaf spot fungi will be less active.
As you mention, the tree does look like it could use a little help. Persimmons don't generally need a lot of fertilizer, but yours may benefit from a balanced fertilizer for fruit trees (follow package directions ). Make sure the mulch does not cover the bottom of the trunk just above the roots - this area should be clear so that air can get to the roots. When adding compost to the tree you do not need to work it into the soil, which may risk damaging the roots. Worms and other soil creatures will take care of incorporating the compost. Persimmons don't need as much water as some other fruit trees, however, a young tree needs regular irrigation until established, and will do better later on with continued irrigation. The soil should not be overly wet, but do not let it dry out.
The following links give more information about caring for persimmons.
http://www.crfg.org/pubs/ff/persimmon.html
and
http://sonomamg.ucanr.edu/The_Kitchen_Garden/FRUITS/Persimmon/
I hope this information will help your tree to do better, and if you have any further questions, please do not hesitate to contact us.
Help Desk of the UC Master Gardener Program of Contra Costa County (SMW)
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: 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 Biog.
Help for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
Help Desk Request: I've just moved into my first house, and I would like to grow a moderate-sized vegetable garden in the back of the property. However, the prior owner did not maintain the area I'm considering and it is heavily infested with weeds. I would like to remove the weeds. I'm considering the use of Glyphosate for weed elimination and maintenance. What would Master Gardeners recommend?
Help Desk Response: Thank you for contacting Master Gardeners of Contra Costa County Help Desk. Your request is quite active in the public eye these days in California. The use of weed controls such as Glyphosate are regulated both by the Federal and the State Government. Master Gardeners isn't a regulatory agency, but one area we provide information on to home gardeners is the use of herbicides. We get that information from the University of California's Agriculture and Natural Resources (UCANR) on the use and effects of herbicides like Glyphosate. Under that structure, MGCC recommends the use of Integrated Pest Management procedures to effectively reduce and/or minimize the use of herbicides such as the legal use of Glyphosate.
UCANR has as of April 2019 updated their response to "Why UCANR provides scientific information and guidance on the use of Glyphosate in California". You can find this 2 page document attached as well as on the web.
It is obvious from the ongoing news that many will not agree with that guidance but it is based on science, best practices, and legal requirements for this herbicide that has been in public use since 1974.
If you have further questions, please do not hesitate to contact us. ... And always follow the directions for use...
Help Desk of the UC Master Gardener Program of Contra Costa County (SIM)
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: 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 Biog.
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MGCC Help Desk Response: Thank you for contacting the Help Desk of the UC Master Gardener Program of Contra Costa County. Based on the photo you provided, it is likely that your rose are infected by Powdery mildew (Podosphaera pannosa). This fairly common fungi produces mycelia and spores on leaves and shoots, and sometimes on flowers. It looks like a gray (older infections) or white (newer infections) powder on both sides of the leaves, differentiating from Downy mildew, which tends to appear only on the underside of the leaves.
Powdery mildews spread with windblown spores. They do not need water to germinate and die when wet for an extended period. They like moderate daytime temperatures (60-80 degrees F), cold nights and shady and low light conditions. UC Agriculture and Natural Resources (UCANR) recommends a number of measures to control infestations but once a plant has extensive infections it is usually too late to control and prevent damage to the plant. It is hard to determine from the photo how badly infected your rose is, but the following recommended measures may be helpful in managing it.
- Prune during the dormant season to increase air circulation and light penetration. Trim or remove adjacent plants to avoid crowding.
- Remove infected plant parts to reduce spore production. This should be done when the plant is wet and the spores can't generate.
- Irrigate using an overhead sprinkler in the morning when the spores would otherwise be released.
- Some infections may require fungicides, these usually only prevent new infections and may need to be applied repeatedly when conditions favor disease development. Use less toxic pesticide products wherever possible and carefully follow instructions on proper use, storage and disposal to reduce adverse impacts to other species and the environment. Mild to moderate infections can be treated with horticultural oil or plant-based oils, such as neem oil. Do not apply in bright sunshine or when outside temperatures are 90 degrees or more as it may burn or otherwise damage the plant and some beneficial insects. Also, read instructions carefully on preventing harm to bees.
- Disease prevention can also be effective with the application of sulfur products, especially ready-to-use soap like surfactants. These are not effective once the disease has appeared.
If your plant is substantially infected, consider removing it and growing a more resistant cultivar and species. Some examples are Meidiland shrub roses, Rosa rugosa, glossy-leafed hybrid teas, grandifloras, that are trademarked as Care-free, Knock Out, and Home Run. Plant in a sunny location and provide ample adjacent open space for air circulation.
For additional information please see this link to UCANR Integrated Pest Management Program Pest Notes: http://ipm.ucanr.edu/PMG/PESTNOTES/pn7463.html
We hope this information is useful. Feel free to contact us again if you have any further questions.
Help Desk of the UC Master Gardener Program of Contra Costa County (NHP)
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: 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 Biog.
