Leafhoppers and bienniel bearing
I have read that leafhopper damage does not significantly affect productivity of fruit trees but I'm beginning to doubt if this is true for trees grown with a very low spray program- especially certain varieties that are highly susceptible to significant infestation.
Here, Euro plums hardly grow during the summer months because of stunting when the white potato leafhoppers move in. It is interesting that J. plums are much less affected and are much more reliable croppers.
Apple varieties that are most susceptible to LH damage also seem to tend to be bienniel, such as Cox Orange and T. King.
Maybe this is all a coincidence, but I'm wondering if any of you have experience that would seem to support the conclusion that LHs can be a real problem in the orchard beyond just damaging and killing grafts and stunting the growth of establishing trees.
Leafhoppers, like aphids, mine for protean and pull a lot of carbohydrate out of the tree in ratio to their small size so they do more than just damage leaves and growing shoots. They also directly rob trees of a lot of energy.