Watch for whitefly in fall greenhouse crops. The following is a short article on the subject.
Monitor poinsettia and other greenhouse crops closely for the different stages of whitefly. Avoid letting weeds grow under the benches which serve as epicenters for whitefly populations. If you treated poinsettias 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. Be sure to continue closely monitoring lower leaves which would have expanded before the systemic was applied. Check pesticides labels to see whether they note “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’. When applying pesticides late in the season to poinsettias, it is best to try out a spray on a few plants before treating the whole crop. Other materials that work well include Azatin, Aria, Endeavor, Enstar, Flagship, Judo, Marathon, Pedestal, and Talus.
Reprinted from the October 30, 2009 edition of the Greenhouse TPM/IPM Bi-Weekly Report University of Maryland Cooperative Extension Central Maryland Research and Education Center http://www.ipmnet.umd.edu/09Oct30G.pdf