Here's what the Ad Hoc Whitefly Taskforce says:
1. Scout. Inspect your crops at least weekly.
2. Exclude or isolate. If at all possible, try to exclude whiteflies from your growing facility with screening material, and if possible, isolate the facility so that workers have to enter through an anteroom.
3. Practice good sanitation.
4. Inspect incoming shipments and isolate if necessary. All of the major propagators are cooperating in this program, so you should not be receiving undue numbers of whiteflies. Because zero tolerance is not the goal for anyone, you may see a whitefly or two when your shipments arrive. That’s normal, and means that your propagator (or rooting station) is probably following good management practices.
5. Watch your neighbors' fields.
6. Study and implement the "Management Program For Whiteflies On Propagated Ornamentals" recommended by the Task Force. It’s available here.
7. If you have control problems, contact your propagator, your local extension agent or university expert. Follow our “Whitefly Management Program,” and get your whiteflies biotyped.