Greenhouse - Whiteflies in Poinsettias

Whiteflies can be late season problem in poinsettias in some greenhouses. The following is an article on the subject from the University of Maryland.

Late Season Whitefly Control

Most greenhouses are reporting very low whitefly activity this fall but there are a few exceptions. Some people let the weeds grow under the benches which served as epicenters for whitefly populations. If you treated with imidacloprid (Marathon) or dinotefuran (Safari) as soil drenches after pinching then you should have pretty good control of whitefly on the foliage that expanded after the application. John Speaker is noting that if whiteflies are present in a greenhouse the adults are having the most success establishing populations on the lower foliage where the systemic did not move into the foliage that was already expanded before a systemic insecticide was applied to the substrate.

Many of the poinsettia varieties are showing bract color so foliar insecticide applications get tricky at this point. Most of the pesticides will state on the label “do not apply when bracts are in color”. In past years we have observed that Abamectin (Avid), pyridaben (Sanmite), chlorfenapyr (Pylon), acetamiprid (TriStar) and dinotefuran (Safari) applied as foliar sprays in bract stage without causing any noticeable damage on poinsettia varieties such as ‘Freedom’, ‘Prestige’ and ‘Monet’. If you try late season whitefly control try out a spray on a few plants before treating the whole crop.


Article and picture from the November 7, 2008 edition of the Greenhouse TPM/IPM Weekly Report from the University of Maryland Cooperative Extension, Central Maryland Research and Education Center