Bleaching

No, we’re not talking about laundry additives, though bleaching in the garden can tell you loads about your plants.

​Bleaching is not the same thing as chlorosis. Chlorosis refers to leaf yellowing, though chlorotic leaves can progress to a bleached status.

Bleaching looks like it sounds. Bleached leaves and stems look as though someone poured chlorine on them. They are white and often thinner. Bleached leaves are not happy leaves.

​Bleaching can indicate several different plant problems. Most of those problems are environmental, but some are related to disease.

​Bleaching through sun and air

Pea plant infected with Fusarium wilt

The most likely culprit of bleaching is too much or too little sun, especially for seedlings and new transplants. Sunburned leaves turn white and die. Air pollution, ozone damage, PAN, and weather flecking can cause bleaching. And if you or your neighbor recently applied herbicides, localized bleaching may be from chemical overspray. Frost damage can also cause bleaching.

Bleaching through the soil

Zinc deficiencies appear as yellowing between young leaf veins and overall bleaching that does not reach leaf edges or midribs. This bleaching can also cause narrow yellow or white stripes between the veins of the upper leaves.

Bleached leaves may also be telling you the soil is low in iron. Persimmon trees, in particular, are sensitive to iron deficiencies. It may be time for one of those inexpensive, lab-based soil tests.

If your soil looks lighter than it used to, add more organic material.

Bleaching caused by disease

White mold can make leaves look bleached. Bleached leaves and stems on tomato or pea plants often indicate Fusarium wilt. If leaf tips are turning white, it may be Ascochyta leaf blight.

If your blackberries or raspberries have tiny bleached bits, it means temperatures rose suddenly and humidity levels dropped. This condition is called white drupelet. Trees with silvery or bleached leaves may have silver leaf, a potentially deadly fungal disease. And if you happen to be growing rice in Viet Nam, there is a newish bacterial infection that causes bleached leaves.

While you cannot reverse the damage done to bleached plant tissue, you can use that information to help your plants regain their health and productivity.