- Author: Ed Perry
- Editor: Anne Schellman
The peach leaf curl fungus is spread by tiny spores which are produced on infected leaves and blown about by wind. As leaves begin to emerge in the spring, the spores are washed onto them, and infection begins. If the weather remains cool and wet, young leaves will be continually infected. Throughout the winter, while the tree is dormant, the spores lie exposed on limbs, twigs and buds. It is during this period that the disease can be controlled with fungicide sprays. In the dry, hot weather of late spring and early summer, the disease stops spreading.
Spraying now during the dormant season helps prevent peach leaf curl in spring. Several products are generally effective in controlling peach leaf curl and are readily available at nurseries and garden stores. These include products containing basic copper sulfate. Make sure to do a thorough job of covering every bit of the tree with the spray.
Ed Perry is the emeritus Environmental Horticultural Advisor for University of California Cooperative Extension (UCCE) in Stanislaus County where he worked for over 30 years.
- Author: Anne Schellman
Why spray for peach leaf curl disease?
Right now, the fungus that causes leaf curl is present on your trees. Once spring arrives, its spores “move” via water droplets splashed onto developing leaves. When the environment is right, these spores invade newly developing leaves, growing in between leaf cells and causing distortion of cells.
Symptoms of peach leaf curl disease include puckering leaves that curl and turn a reddish color. Often the entire first set of leaves may drop off. When new leaves begin to grow, these leaves are also infested. Twigs and shoots distort and often die. Fruit is rarely affected. However, left untreated, nectarine and peach trees begin to decline and fruit production is substantially reduced.
Often when gardeners see symptoms of leaf curl disease on their tree, they are tempted to pull off the affected leaves, thinking this will help. Unfortunately, there is little to do at this point to control the disease.
Prevention
Using Pesticides
Insects, diseases, and weeds are pests, and products used to kill them are called pesticides. Whether a product is organic or not, it can still have an impact on you and/or the environment, so be sure to follow the directions on the product label regarding personal protection, correct mixing, and application. When spraying, make sure to coat the tree until the product is dripping off. Come spring, your peach and nectarine tree trees should leaf out and grow vigorously, followed by a healthy crop of fruit.
Learn more about peach leaf curl by visiting the UC IPM website and reading their Quick Tips on it at http://ipm.ucanr.edu/QT/peachleafcurlcard.html For more detailed information about this disease, read the Pest Notes at http://ipm.ucanr.edu/PMG/PESTNOTES/pn7426.html
Coming Soon
Bare root fruit trees are arriving in nurseries and garden centers. If you are thinking about planting fruit trees but aren't sure what to plant, how to plant, and how to care for them, you'll want to attend our online Bare Root Fruit Tree Planting and Pruning Class on January 25, 2022. More details coming next week.
If you have fruit trees that produce a lot of small fruit, you may be missing an important step in growing fruit trees called "thinning." Next month we'll publish an article on how and when to thin fruit from Ed Perry, retired UCCE Stanislaus County Emeritus Horticulture Advisor.
Anne Schellman is the UCCE Stanislaus County Master Gardener Program Coordinator.
- Author: UC IPM
Peach leaf curl is a disease that affects peach and nectarine trees. Although you may not see symptoms right now in the dormant season in California, it's time to think about treatment, especially if your tree had the disease last year.
Symptoms of this fungal disease include distortion, thickening, and reddening of foliage as trees leaf out in the spring. As weather warms, damaged leaves that die and fall off trees are replaced with new, usually healthy leaves. However, after several years without treatment, peach leaf curl will cause tree decline and reduced fruit production.
Avoid peach leaf curl by growing varieties resistant to the disease. For nonresistant peach and nectarine trees, consider spraying with preventive fungicides in the dormant season just before or as buds swell.
See the UC IPM publication Pest Notes: Peach Leaf Curl for more information about the disease and management options. Always read and carefully follow all precautions and safety recommendations given on the pesticide label.
- Author: Anne E Schellman
You've probably read a lot lately in the news about West Nile virus and Zika virus. In mid-June, the first human case of West Nile virus in Stanislaus County was diagnosed. This past week, mosquitoes that can carry the Zika virus were found in our county.
Why do mosquitoes bite?
It may surprise you to learn that mosquitoes get most of their food from flower nectar. However, female mosquitoes need a blood meal to produce eggs. If she bites someone while carrying a virus, it can infect that person.
What is the difference between West Nile virus and Zika virus?
West Nile virus is carried by Culex tarsalis or the Western encephalitis mosquito. This species is most active just after sunset. It feeds on birds and other mammals, including humans.
Eighty percent of people infected with West Nile virus do not show symptoms. The other twenty percent may have mild symptoms including fever, headache, body aches, nausea, vomiting, and sometimes swollen lymph glands or a skin rash. One in 150 people infected will develop a neurological illness that may result in death.
Zika virus is transmitted by several species of Aedes mosquitoes. These mosquitoes bite people during the day. Women infected with Zika during pregnancy may have an infant born with microcephaly and other severe brain defects.
Although this mosquito has been found in Stanislaus County, the virus has not been found in California. Aedes mosquitoes can only transmit Zika if they carry the virus.
How can I protect myself and my family?
Stay tuned tomorrow for part II of this blog post, with helpful tips for prevention and protection from mosquitoes.
Resources:
University of California Agriculture and Natural Resources. UC IPM Pest Notes: Mosquitoes. Taken from http://ipm.ucanr.edu/PMG/PESTNOTES/pn7451.html on August 5, 2019.
Vector Disease Control International. Culex tarsalis-the Western Encephalitis mosquito. Taken from http://www.vdci.net/blog/mosquito-of-the-month-culex-tarsalis-western-encephalitis-mosquito on August 5, 2019.
California Department of Public Health. Zika: What Californians Need to Know. Taken from https://www.cdph.ca.gov/Programs/CID/DCDC/Pages/Zika.aspx on August 5, 2019.
