Q.How Do I Get Rid of Whiteflies?
I have a big garden, about an acre. The flies seem to be worse on my fall crops, cabbage, broccoli, sprouts, turnips, cauliflower, etc. Vacuuming and water hoses are not an option in my case.

Certified GKH Gardening Expert
I would treat the plant with neem oil. It is effective against all of those pests and many others, but does not harm people and pets. These articles will help: https://www.gardeningknowhow.com/plant-problems/pests/insects/whitefly-control.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm