- 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.
The adult beetles are small (1/8 inch), slender, black beetles with dull yellow wing bands. The larvae are white, short-legged grubs. They are especially attracted to overripe, broken, fermenting, and dried fruits, and are common in orchards, drying sheds, and on fruit trays. The adults lay their eggs on ripe and rotting fruits of all types. They may also infest grapes before they have been completely dried and made into raisins. Fig varieties that have large "eyes" (openings at the blossom ends of fruits) are most affected; fig varieties such as 'Mission' and 'Tina' have small eyes, and are less infested by the beetles.
A complete life cycle of the dried fruit beetle may vary from a minimum of 15 days in the summer to several months in the winter. In winter, both adults and larvae survive in decaying cull fruit of any kind. The pupae generally overwinter in the soil.
Sanitation is the best way of controlling dried fruit beetles. Eliminate potential breeding sites by harvesting ripe fruit promptly and picking up fallen fruit as soon as possible. Keep cull fruit in tight garbage cans or garbage bags until disposed of. If you dry fruit, you should thoroughly clean your drying trays after each use.
You may want to try trapping to reduce dried fruit beetle infestations. To do this, place several overripe peaches in a bucket, then coat the insides of the bucket with 90-weight oil, Tanglefoot, or a similar sticky material. Once the buckets are hanging in the tree, the fermenting peaches attract the beetles, and they become trapped in the sticky material. This method will give you partial control only.
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
Citrus trees grow best in loam or sandy loam soil, but you can grow them in most soils that have good drainage. If your soil drains poorly, you might try planting in a raised bed or on a mound. Plant your trees in an area that receives full sun, and allow enough room for the tree's mature size. I don't recommend planting in a lawn area because it's difficult to irrigate both the citrus and the lawn correctly. Also, the grass tends to absorb many of the nutrients needed by the tree.
Dig the planting hole just deep enough to plant the tree at the same level that it was in the nursery. The diameter of the hole should be about 6 inches larger than the root ball. If the hole is too deep, the tree will settle too much after planting. Trees that settle too deep are likely to be killed by crown rot, a fungus disease that frequently develops where the soil covers the bark of the tree.
You can place balled and burlap-wrapped trees in the planting holes without removing the cloth sacking that covers the roots. Plant them a little higher than they were in the nursery, allowing about 3 inches for settling. Try to have the uppermost roots branch out at about ground level after the trees have settled.
Do not put any fertilizer in the hole when planting your tree because it may damage the roots. It's safer to apply fertilizer to the surface of the soil after you've planted. If you use manure, use it lightly because roots may be damaged by salts which manures contain.
Citrus trees do very poorly in dry soil, so be sure to pay close attention to irrigation, especially during the first summer.
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.