Advice from the Help Desk of the
UC Master Gardener Program of Contra Costa
Client: I have 5 different varieties of nectarine and peach trees in my Central CCC backyard. I treat the trees in late winter for peach leaf curl using an organic - approved spray. That works great.
What do you think the problem is? What is the cure? I prefer to use organic methods.
Advice from the MGCC's Help Desk: Thanks for contacting the MGCC Program's Help Desk. From your description, the problem with your nectarine fruit appears to be caused by the “brown rot fungus”, monilinia fruiticola. Peaches can be attacked by Brown Rot as well.
Brown rot fungus is tough and can survive over the winter:
- in infected twigs
- inside dead blighted blossoms that remain on the tree
- dry mummified fruit that has been left on the tree from the previous year
- dry mummified fruit left on the ground from the previous year
Brown rot infection and disease development can take place over a wide temperature range and flowers can be infected from the time buds open until petals fall. Water must be present on the flower surface for infection to occur. Spores produced on the tree parts described above in spring are carried through the air by wind and splashing water to infect flowers of the new year's crop.
Appropriate applications of fungicide is the usual preventive measure to prevent brown rot, especially if you've had it occur before. However, fungicides can only prevent brown rot; they will not cure brown rot so timely application is important. Organic fungicides do not appear to be readily available for home gardeners. Recommended applications of copper-containing fungicides or synthetic fungicides such as myclobutanil at pink bud stage - just before the buds open can help avoid serious fruit losses. Rainy periods will require more spray. Additional applications when fruit starts to color may be needed if rainy weather persists. Do not apply copper compounds after bloom.
More specific information can be found by following the links below:
Good luck this year with your nectarines. Hopefully, pruning, sanitation, cultural care, and a timely application of a fungicide will minimize brown rot.
Please let us know if you have any further questions we can help you with, and thank you for contacting our program!
Help Desk of the UC Master Gardener Program of Contra Costa (JMA)
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: 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 (//ucanr.edu/blogs/CCMGBlog/).