whitefly on kale

[Barb]

White fly is a perennial problem on my calvelo Nero kale.  How do commercial organic growers manage to avoid it?  You don’t see clouds of whitefly on the kale in the veg boxes.  Guy Watson commented on this week’s Countryfile:  growing in small fields surrounded by hedgerows attracted predators to deal with pest problems.  I interplant veg with herbs,flowers and fruit on my allotment aiming for year round biodiversity but so far haven’t found a predator that actually enjoys eating them.  Could it be that some varieties of kale are less prone to whitefly than Nero?