Why are the leaves on your sunflowers getting big brown spots?

Big brown spots on sunflower leaves can be caused by several factors, including fungal infections like downy mildew or leaf spot disease. These spots may also result from environmental stress, such as inconsistent watering or nutrient deficiencies. Additionally, pest damage from insects like aphids or spider mites can lead to discoloration. It's important to assess the overall plant health and environmental conditions to determine the exact cause.