Wilting Sunflowers

Water Amounts

• A lack of water causes plants to wilt. Sunflowers tolerate droughts better than many plants, but too little water over long periods of time will cause them to wilt. Iowa State University recommends watering young sunflowers regularly to help them establish a strong root system. To check whether plants need water, poke a finger in the soil and water them if it feels dry 1 inch beneath the surface. Too much water can also result in rotting plant roots and wilting. Plant sunflowers in soil with good drainage and do not water them when the soil is already wet.

Sclerotinia Wilt

• Sclerotinia wilt causes sunflowers to wilt and produce fewer seeds and less oil. Other symptoms of this fungal disease include cankers around the base of sunflower plants, rotting roots and bleached lower stems. Plants infected with this disease sometimes blow over in strong winds and may eventually die. Fungal spores in the soil cause sclerotinia wilt. After this disease attacks sunflowers, gardeners cannot recover damaged plants. To prevent problems with sclerotonia wilt, do not plant sunflowers in fields where other crops used to have this disease. North Dakota State University also recommends buying certified sunflower seeds, because nurseries try not to sell infected seeds.

Sclerotinia Stalk Rot

• Sclerotinia stalk rot infects the stalk of sunflowers with the same fungal spores that infect plants with sclerotinia wilt. Unlike sclerotinia wilt, sunflowers become infected with this disease through spores in the air, rather than spores in the soil. It often infects plants through a wound cause by insects or weather damage. This disease causes sunflowers to wilt and creates a rotting spot somewhere along the plant stalk. The weakened point in the stalk may bend or break. Sclerotinia stalk rot requires moisture on the surface of the plants to infect them. Prevent this disease by watering sunflowers at their bases rather than spraying water all over entire plants. Avoid planting new sunflowers near existing infected sunflowers, because the infection can spread through the wind.

Sclerotinia Head Rot

• Sclerotinia head rot disease happens when the sclerotinia fungus spreads with the wind and infects the tops of sunflower plants. This disease causes the flowers to wilt and look ragged and bleached out. Sunflowers with sclerotinia head rot also have small black spots on them where they start rotting. To prevent this disease, keep healthy plants away from infected plants. Also avoid excessive moisture on the heads of sunflower plants by irrigating them only at their bases.