Silvering can be a symptom of disease, environmental stress, insect feeding, or mineral deficiencies, similar to bronzing.
Silvering is not the same thing as chlorosis. Chlorosis refers to leaves becoming a paler green over time, usually due to insufficient nitrogen, eventually turning yellow. Chlorosis can ultimately lead to silvering, but silvering generally describes how some leaves become white rather than yellow. There are several causes for silvering.
Diseases that cause silvering
Silvering may occur in mosaics, a collection of viral diseases. Leaf silvering is also a symptom of, wait for it, silver leaf. Silver leaf is a fungal disease of apple, cherry, and pear. Fruit silvering refers to whitened areas under the skin of peppers or tomatoes. The Phytophthora oomycete causes fruit silvering, avocado root rot, buckeye rot, and potato blight.
Environmental stresses that cause silvering
Drought and temperature extremes can cause silvering. Chemical overspray and pollution can also cause leaves to turn silver, especially among tomatoes and peppers. Also known as chimera or head silvering, environmental stress can turn leaves grayish-green and small. You may also see blisters on the leaves and pale streaks on the stems. When this occurs, flowers are usually sterile. Any fruit that grows will have grayish-green streaking and be less flavorful. If you see white patches on fruit, it is probably sunscald.
Silvering due to insect feeding
Sap-sucking insects can cause leaf silvering. The most common causes of leaf stippling or silvering include feeding by:
Silvering due to nutrient deficiency
Potassium deficiencies can cause leaf silvering. In this case, you will see upward leaf curling. Manganese deficiencies can cause leaf silvering, premature leaf drop, smaller-than-normal leaves and seeds, and weak roots and stems. An inexpensive lab-based soil test can help determine if this is the problem.
Silver in the garden isn’t always a bad thing. Silver plants can add a nice color contrast to potted plants and landscapes. These plants usually prefer full sun. They often get their silver appearance from a coating of white trichomes that look like fur. Most white and silver plants are ornamentals, but there are some edible silver plants:
You can grow a surprising amount of food in your own yard. Ask me how!
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