This makes their stalk and head rot. Other diseases are downy mildew and rust. The most common bug to like sunflowers is a moth. It attacks the sunflower head at flowering time the larvae that feeds on the flowering part and then tunnels through the seed. Whiteflies and asphids can be a problem, too.
Birds can be a pain near harvest time.
The seeds are exposed and the large flower head acts as a perch for the birds. You can cover the sunflower heads with plastic netting. Before the flowering starts, you can also use scarecrows and play in the middle of the flowers with all your friends. Usually early fall is when harvesting begins. The sunflower heads are usually bent down.