Preventing Poppy Diseases

The poppy is known for its lovely large, bright red flowers that beautify any garden. Some of the flowers can extend up to 6 inches in diameter. The flowers usually bloom from mid-spring through to summer. Poppy seeds are edible and make a delicious and nutritious snack. They are rich in calcium and contain healthy fatty acids.

Plant poppies in well-drained soil and full sun areas. Although easily grown, there are some diseases that pose a threat to poppies. It is helpful to know control measures you can take in preventing poppy diseases.

Bacterial Blight

Bacterial blight consists of spots saturated with water. These manifest on the flowers, foliage and stems and also on the pods of seeds. Much of the foliage is shed off eventually resulting in death of the plant.

You should destroy old plants as well as any affected plant parts. Avoid using the same soil for planting poppies, but if you must, you should steam pasteurize the soil. Practice crop rotation and be careful to gather seeds only from healthy plants.

Downy Mildew

Downy mildew frequently appears on poppy seedlings. Pale spots will appear on the leaves of older plants. A mold that is white or gray in color usually covers these spots. The mildew causes the stems of the plant to become distorted and hinders flowers from developing. The plant eventually collapses although the mildew causing parasite often remains in the poppy seeds.

You can control downy mildew by spraying repeatedly with a copper fungicide. Destroy all infected plants as early as possible to contain spreading of the disease. Be careful to gather seeds only from plants that are free from the disease.

Powdery Mildew

Powdery mildew is a fungal growth that attacks the leaves. It begins as tiny white powdery spots and gradually appears as a white coating and resembles dust that has gathered on the leaves. It develops during high humidity periods and results in stunted growth of the plants. Leaves turn yellow and drop off prematurely.

Use a fungicide to control this disease. Gather and destroy all fallen leaves.


Oedema is caused when the roots absorb water at a much faster rate than can be used by the plant. Water pressure builds up in the leaves, resulting in enlarged leaves with small swollen blisters. The blisters gradually harden into brown wart-like structures. When severely infested, the warts extend to the flowers and stems of the plant. Eventually, the leaves become yellow and drop off. Plant growth ceases. Oedema usually occurs when winter is drawing to a close and the humidity is high, and in locations with warm, moist soil. 

Avoid over-watering during the winter. It is best to keep the poppies slightly dry. Avoid high humidity. Keep the humidity below 70 percent especially in the winter. This will reduce the amount of water available to the plants. Make sure the plants are not overcrowded. You can space them apart to improve on air circulation and reduce humidity.