With fall quickly approaching, you’re likely busy with poinsettia production and looking for ways to keep your crops pest free. Because poinsettias are highly susceptible to a variety of diseases and insects, such as Botrytis and whiteflies, implementing appropriate cultural practices will help to keep your poinsettia crops healthy through the end of production.

Implement cultural practices in your operation to ward off three key threats:

Botrytis:

Botrytis is the most common disease that affects ornamental plants. Initial infections appear as water-soaked spots on foliage and flowers which turns into gray mold once the disease is established.  To reduce the threat of Botrytis:

• Provide a clean, dry growing environment
• Scout frequently. Look out for symptoms including small, light brown spots on flowers, V-shaped, tan-brown lesions on foliage and plant wilting
• Irrigate early in the day to reduce how long leaves are wet
• Provide good plant spacing and horizontal air flow
• Keep humidity low by heating and venting
• Immediately remove wounded and diseased plants as well as dead flowers and leaves to limit spore production and spread

Whiteflies:

Whiteflies are common pests in nurseries and greenhouses with multiple species in the U.S. These pests use their piercing-sucking mouthparts to extract plant sap, affecting the overall vigor of plants. To curb whitefly populations:

• Maintain weed-free production areas. Since whiteflies feed on numerous hosts, weeds are potential sites of contamination
• Inspect new shipments of plants for mature whiteflies and nymphs
• Use screens in greenhouses to help exclude populations
• Scout regularly. Check the underside of leaves with a hand lens for egg and nymph populations. Monitor for adults with yellow sticky cards

Whiteflies and nymph damage resulting in black sooty mold on poinsettia leaf.

2017 - Vero Beach Research Center, FL

Powdery Mildew:

Powdery mildew fungi form white, talcum-like spots called “colonies” on leaves, stems, flowers and the bracts of poinsettias. If uncontrolled, the fungus increases in size and number to cover the plant’s surface. Leaves begin to turn yellow, then brown, before eventually dropping. Take steps to prevent powdery mildew infections by:

• Providing a clean, dry growing environment
• Checking incoming plants for disease
• Removing diseased plants immediately to limit spore production and spread
• Scouting fully expanded leaves weekly, particularly in the lower to mid-canopy where air movement may be limited
• Implementing overhead irrigation, which may reduce the spread of powdery mildew as it washes the spores off plants

Regularly implementing cultural practices is an essential part of maintaining crop health at your operation. However, cultural practices alone may not be enough to protect poinsettias from these common threats. Review our Poinsettia Agronomic Program, which provides guidance for leveraging the strengths and modes of action of different products so they provide maximum benefit when you need it most. Plus, our agronomic program has built-in resistance management to help preserve pest management technologies for years to come.

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