Sun Scald

By Shelby Biasini

Have you noticed the upper leaves of your corn plants browning and dying? This could be the result of Sun Scald.

Causes

Most commonly caused by abiotic factors and sometimes from bacterial and fungal organisms in vegetables. Most likely to see this from the eastern to western states when it gets hot out with clear skies and direct sunlight.

How does it happen?

With the dry season we are having, we are more likely to see Sun Scald on plant leaves when temperatures are higher up in the 90s with a lot of wind on clear days. The crop leaf temperature can rise to critical levels where the plant cells are damaged and leaves a scalded appearance.

Symptoms

When upper leaves are exposed to sun, they become the most susceptible to Sun Scald. It can occur at or around 80F+ degree days to corn, soybeans, and vegetables. Leaves typically turn a rusty brown color on the underside of the leaves and shadows where the sun could not reach portions of the leaf.

Results

Once sun Scald occurs, it can create an entryway for fungi, bacteria, and pests, and eventually lead to rapid tissue death of the plant. Be aware that Sun Scald is very similar to Cercospora, which affects the topside of the soybean leaf and becomes a leathery brown color. If you see Sun Scald in your corn fields, make sure to keep an eye out for any possible disease or insect pressure.