white sticks and brown bud tips on dahlias
My dahlias are developing brown apical leaves (usually much worse than show in the pics as I remove the leaves) -- and on the surface of the older leaves are these short white flattened sticks about 1 x 4 mm. They appear to be a plant fragment. What causes this? I do have what I think is a brown potato leaf hopper that I occasionally see on the leaves (last picture), and a large ornamental potato about 6 feet away. The Dahlias have slightly rumpled leaves but not the white mottling associated with viruses. I am wondering if the white sticks are a clue as to the cause of the browning and eaten leaves around the flower bud tips. If it is not caused by a bug, could it be caused by a Phytoplasma? (since it infects potatoes) -- and if it is this, does this disease infect the bulbs so all must be destroyed to get rid of the bacterium?
Not sure I can add much more. Agree the white sticks are nothing to be worried about. If leaf hoppers then they would be moving when disturbed. Since you are removing symptomatic leaves as they appear we can not help you with what it might be. It could be viral as the symptoms can be quite varied depending on the virus, the cultivar of dahlia and the environment.
The plant is still producing beautiful flowers -- so I won't destroy it. But note the damaged leaf to the left. I have included additional pics of the insects on the dahlia as well. One is the leaf hopper -- the other is a white spider that forms nest in the Dahlia leaves. Would like to know if they are damaging.
Spiders are generally not a problem unless they are of the small type called mites. Since you have large, lovely flowers and nice foliage I would stop worrying and enjoy the blooms.