What Are the Brown Spots on the End of Leaves on Sunflowers?

Rust

• Rust appears as cinnamon colored spots on leaves, and these spots may contain brownish blisters as well. The blisters have orange or rust colored spores inside. Rust usually begins on the undersides of leaves and spreads to the top.

Leaf Spots

• Leaf spots are irregularly shaped patches of brown that appear on leaves. These can vary in size, frequency and even the shade of brown. Most likely to occur first on the tops of leaf surfaces, these brown spots become more apparent during hot, humid weather.

Control Methods

• Rust can overwinter in plant debris, so removal of dead matter should be accomplished in late fall. Removing diseased leaves quickly and placing them in a plastic bag to avoid spreading spores is one way to stop the spread of leaf spot. Adequate spacing between plants provides good air circulation and helps reduce the impact of either disease.