Is it Ozone Damage?

Ozone damaged leaf

Before you go out in the field to look for ozone damage to milkweed, and when you double check your leaf samples back in class, remember to review the classic ozone injury symptoms.

Ozone injury is always:

on the upper leaf surface only

interveinal (between the veins not across the veins)

black in color

distinct with sharp edges

most pronounced on the older and middle-aged leaves

Ozone injury will never:

have haloes

rub or wash off

And, don't forget that most leaves will have multiple types of damage and that most damage is caused by insects, diseases, nutrient problems or heat stress, rather than ozone.

Okay, now that you've reviewed the classic ozone injury symptoms, follow this slide show and view different milkweed leaves. Can you tell if it's ozone injury?

Begin the slide show or >>

See the list of slides >>