Poinsettia White Flies Problems by Dr. Claudio Pasian Horticulture and Crop Science Department The Ohio State University By the time you read this, your poinsettias will be gone but it is important to remember this advice for next year. Make a photocopy of this note and put it in a place where you or your growers will find it when growing the 2001 poinsettia crop. Several Candian growers reported white fly problems despite the fact they applied the commonly used product imidacloprid (Marathon). Growers in Ohio and other states had similar experiences. Important: this product must be used as preventative and NOT as a curative. This means that if the product is applied when the white fly population is very high, you probably will have real difficulty controlling the problem. In their efforts to combat white flies, some growers delay the application of Marathon until the last phase of the crop (when regular pesticides cannot be applied because of bracts). In order to avoid problems with this strategy, growers should control whiteflies by spraying insecticides early on.