Springtime planting is almost here but don't rush to plant seeds until the soil has warmed up! Planting seeds too soon, when the soil is cold and wet, risks losing them to damping-off, a disease caused by fungi and oomycetes in the soil. Learn more about this common disease in the newly updated Pest Notes: Damping-off Diseases in the Garden written by UC IPM Director Dr. Jim Farrar and UCCE emeritus advisor Ed Perry. They cover the biology of the pathogens, identification of the disease, and how to prevent damping-off when growing transplants or seeding directly into the ground.
- Author: Ed Perry
For many in California, the backyard orange or grapefruit tree is almost a member of the family, and any negative change in its appearance elicits concern. One such change in appearance is leaf yellowing and drop that often occurs during the winter in citrus. Citrus leaves can remain on the tree for as long as three years depending on tree vigor, but disease, inadequate or excessive nitrogen fertility, excessive salt or born in the soil, poor irrigation practices, freezing temperatures, pest pressures and low light levels significantly reduce leaf longevity. Excessive leaf drop during the growing season is more likely to indicate a serious problem than leaf drop during the winter. Winter leaf drop normally reflects nothing more than a momentary swing in the natural balance between the natural elimination of old senescing leaves and their replacement.
Reduce winter water applications to citrus trees that have defoliated or that have a significantly thinning canopy. Trees like this require little, if any, supplemental irrigation. Even a mature tree with a full leaf canopy will require less than 10% of the water that it would require during the summer.
The best indicator of tree health for a defoliating citrus tree during the winter will be how well it produces the first flush of new growth in the spring. A decision to keep or remove a citrus tree based on tree health should not be made during the winter. Even trees that lose most of their leaves during winter are capable of replacing leaf canopies with the spring flush of growth, usually with little loss in fruit production. Trees that do not produce a vigorous flush in early spring may have a more serious problem. March is an excellent month to begin applying fertilizer to encourage new leaf growth and fruit production and to help keep an old friend of the farm or family backyard around for years to come.
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: Ed Perry
Fruit color is a poor indication of ripeness, because many fruits have fully colored rinds a long time before they can be eaten.
Don't expect citrus fruits to increase in sweetness or ripen more fully once you've picked them, as do peaches and some other fruits. When picked at any stage of maturity, citrus fruit does not change after picking, except that it may decay or slowly dry out.
When you're picking citrus fruit that you plan to store for awhile, be careful not to bruise or break the skin. Fruits that are cut or scratched during harvesting will rot fairly quickly in storage. Citrus fruits with perfectly sound skin are fairly decay proof, and will last in cool, moist storage for several weeks (38 to 48 degrees F, 85 to 95 percent relative humidity). Under dry conditions at room temperature, fruits develop off flavors and shrivel within a week to 10 days.
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: 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: Belinda J. Messenger-Sikes
Because mistletoes can damage trees, you may decide to do something about mistletoes infesting your trees. The first step is to find out whether you're dealing with broadleaf or dwarf mistletoe. Mistletoes differ in their life cycles, the damage they cause and management methods. UC Cooperative Extension Advisors Igor Lacan (San Mateo and San Francisco Counties), Steven Swain (Marin County) and Ed Perry (Stanislaus County, retired) have updated and expanded Pest Notes: Mistletoes. It includes more about identification of broadleaf and dwarf mistletoe, the latest information about where specific mistletoes grow in California, as well as details about how dwarf mistletoe infest trees and under what circumstances. The publication has management options for both types of mistletoes, information on community-based mistletoe management, a new section about the ecological benefits of broadleaf mistletoes, and new references.
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