Inspect Poinsettia Cuttings
Friday, 09 July 2010 11:17
Carefully inspect incoming poinsettia cuttings (by each batch, and variety) to insure that they are free of insects and diseases and are of the quality you expect.
Look for whitefly egg, nymphs and pupae on the underside of the leaves, especially the oldest bottom three leaves where most of the whitefly may be found. If possible, randomly inspect from 10 to 30% of the cuttings. Inspect each shipment and cultivar separately. Record which shipment or cultivar has whitefly and which stage is present.
Whitefly eggs and nymphs are very small, so a 10x handlens or hands free optivisor is helpful. Patches of dried spray residue or dried latex might be confused with dusty appearance once sees near the whitefly eggs.
Don’t assume that if you don’t see whitefly adults emerging from the shipping containers, that you are free of whitefly. Adults are less likely to be observed compared to the more sedentary stages.
Record which shipments and varieties may need follow-up treatments. For information on chemical control of whiteflies, including the highly resistant Q Biotype of the siverleaf whitefly see "The Best Guess" pesticide program for the Q whitefly on poinsettia. Scroll down to get to the recommendations and for links to more information.
If you are using biological control of whiteflies, see the pest message posted on Friday, June 25th.
In addition to whitefly, look for fungus gnat larvae and signs of their feeding damage (blunt root tips). Roots should be white and healthy with no signs of root rot disease.
Look for any angular leaf spots with a yellow halo, that may be indicate of a bacterial leaf disease. Bacterial leaf diseases spread rapidly under warm, wet conditions. See an example of a bacterial leaf spot disease on poinsettia.
Fact Sheets: Managing Whiteflies in Greenhouses University of Connecticut
Managing Fungus Gnats and Shoreflies in the Greenhouse University of Connecticut
Photo: Fungus gnat vs Shorefly adults on sticky card
Leanne Pundt, University of Connecticut and Tina Smith, University of Massachusetts
