Plant Health Problems
See Perennials for a detailed discussion of problems that may occur and are common to most herbaceous ornamentals.
Diseases caused by Bacteria:
Bacterial blight, Xanthomonas papavericola.
Infection first appears as water-soaked areas which soon become black and are often surrounded by a translucent ring. A bacterial exudate or ooze may occasionally be found in the spots. Spots may develop on leaves, stems, buds, flowers, and seed pods. When stems are girdled, plants collapse and die.
Control strategies are aimed at prevention. However, removing and roguing of diseased plants or plant parts is critical. Any equipment or tools that come in contact with diseased plants should be disinfested with 10% household bleach, 70% alcohol, or one of the commercially available compounds. It is also important to avoid overhead irrigation since these bacteria are easily spread in splashing water. Crop rotation is also effective since planting in clean soil gives best control. Starting with clean seed or healthy transplants is helpful.
The bean aphid and the green peach aphid commonly infest poppy. Among the compounds registered for control of this pest in Connecticut are acephate or insecticidal soap used as foliar sprays. Imidacloprid may be applied to the soil for systemic uptake by the roots. Consult the label for dosage rates and safety precautions.