Advice for Home Gardeners from the Help Desk of the
UC Master Gardener Program of Contra Costa County
Help Desk Response: Thanks for contacting the UC Master Gardener Help Desk about the problem you are observing on your nectarine tree.
Your nectarine tree is showing the classic symptoms of a fungal disease commonly called "peach leaf curl". It is a common problem for both peaches and nectarines, particularly in years when we have abundant rains as has now occurred this year. The fungal spores that spread the disease can be spread through splashing water and rain.
As you may already have noticed, typically the affected leaves turn yellow or brown and can remain on the tree or may fall off; they are replaced by a second set of leaves that develop more normally unless wet weather continues. Most often the disease will not show up on the developing fruit, but occasionally it does affect fruit, causing corky areas to develop on the fruit surface. Those fruits are still okay to eat—just cut away the affected area.
Unfortunately, there is nothing you can do now to stop the disease on your tree. The typical management approach for controlling peach leaf curl is to use a fungicide in the late fall or early winter months when the tree is dormant. The use of fungicides when the tree is dormant can control the development of the spores that usually survive the hot summer months on the surface of the tree bark. Those spores are reactivated by winter rains and attack the leaves when they emerge in the spring. You should plan now to consider applying such a fungicide in early December, particularly if we are having frequent rains. Just try to schedule the fungicide spraying for a time when you expect to have several successive days of dry weather so that the fungicide can work and not be washed off the tree. You can learn more about peach leaf curl and the use of fungicides to control it at this University of California website: http://ipm.ucanr.edu/PMG/PESTNOTES/pn7426.html
Since fungal spores may also be present on the fallen leaves, it is a good idea to pick up all fallen leaves. Don't put them in your compost pile unless you have a pile that regularly achieves and maintains high temperatures. If your compost piles doesn't have those high temperatures on a regular basis, you can dispose of the leaves in a green bin that goes to a waste company's compost area. Fortunately, those sites typically have compost piles that achieve the high temperatures needed to kill fungal spores.
If you have not yet fertilized your tree, this would be a good time to feed. Just be careful not to use too much fertilizer. It would be better to use less now and re-apply some additional fertilizer is about a month or six weeks. Here's a link to more information on peach tree care: http://homeorchard.ucanr.edu/Fruits_&_Nuts/Peach/ which also applies to nectarine trees.
We hope that this information is helpful. You're welcome to contact us again if you have other questions.
Help Desk of the UC Master Gardener Program of Contra Costa County (TKL)
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.ucanr.edu/HortCoCo/ You can also subscribe to the Blog.
Advice for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
Client's Request (via phone message) Last year my apple tree was seriously impacted by codling moths. I understand that there are routines timed to the hatching of the moth that a home gardener can follow to minimize, maybe even eliminate, damage to the apples. Can you advise me on those routines.
MG Help Desk Response: Thank you for your call to the UC Master Gardener Program Help Desk. Your message indicated you are looking for information on the hatching timing for codling moths in your area.
In cooler areas (e.g., west Contra Costa County), look for first stings in early to mid-May and stings from a second generation mid-July to mid-August. In warmer areas (inland Contra Costa County) start looking for first stings by mid-April. Inland, there may be as many as 3 generations hatching through the summer, all requiring treatment.
To use the calculator, you will need to know the date of when moths are found in your traps and sunset temperatures have reached 62 degrees. This date is known as the biofix date. When asked to select a UC CIMIS weather station, choose the one of five in Contra Costa County that is closest to you. That will produce a chart with expected degree days for the time period you specified and recommendations for degree-day accumulations for each spraying.
For more information on codling moths and their control, see this UC document: http://ipm.ucanr.edu/PMG/PESTNOTES/pn7412.html. For a calendar of gardening operations for apples: http://homeorchard.ucanr.edu/Fruits_&_Nuts/Apple/.
Please let us know if you have further questions.
Help Desk of the UC Master Gardener Program of Contra Costa County (SEH)
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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: email@example.com, 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 Gardener from the
Contra Costa Master Gardeners' Help Desk
Description of Client's Problem:
Here's the advice that the Master Gardener Help Desk gave the client.
It appears that the problem is Pear Blossom Blast (Pseudomonas syringae) not Fire Blight as we originally thought.
Blossom blast and die back is caused by a bacterial infection and very difficult to treat. Infected buds fail to open, dry out and die. Leaves may be spotted. Flower petals and stems may also be affected, and fruit cluster bases can turn brown or black. Occasionally, fruiting spurs may be killed. Cankers may develop in twigs and branches.
Symptoms of this disease, especially on flowers, may closely resemble fire blight. However, blast infections seldom extend more than 1"-2" into a spur. Bacterial ooze, which is common with fire blight, is not present with Pear Blossom Blast and none could be seen on your samples or pictures. Frost and cold injury promote infection (we did have some pretty cold spells this year). Warm, dry weather inhibits this disease.
Selecting non-chemical management options should be your first choice:
- Avoid wounding plants. (weed wacker too close, branches rubbing, etc.)
- Prevent frost injury when possible. Plant hardy varieties in protected locations.
- Provide proper culture to minimize succulent shoot growth and to reduce injuries.
- Prune out and destroy infected tissues as soon as they are noticed. Make cuts at least 6" below infected areas and sterilize pruning tools between cuts.
Bacterial Blossom Blast is difficult to control. Monitor temperatures and protect against frost, which may help prevent infection. In areas where Blossom Blast is common, copper sprays labeled for this use may be applied in the fall or dormant season, but the efficacy of these treatments is questionable.
Some additional information on Pear Blossom Blast can be found on the UC IPM web site at:
Editor's Note: Each month the CCMG Help Desk's Quality Assurance Team selects responses to county residents' Help Desk questions that produced informative responses that are either unique or unusual, or provided updated information that would be informative to all gardeners, or are of general interest, especially of seasonal concerns. We are highlighting these responses in the HortCOCO blog so all interested Master Gardeners and the public may utilize the information.
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. We can also be reached via telephone: (925) 646-6586, email: firstname.lastname@example.org, and we are on the web at http://ccmg.ucanr.edu/