Many of the ground-nesting bees are very specific in the flowers they visit and are not generalists like honey bees. They do not swarm like honey bees and are not social. They are important pollinators and should be left to forage unless the nest is in the wrong site. In the spring dull, olive-green spots with a velvety texture develop on either side of the leaves. These more or less circular spots with a fringed border can range in size from pinpoints to D2 inch or more in diameter.
Secondary infections produce spots that are irregular and are found along the veins.
The first defense against scab is planting resistant cultivars. If needed, protectant fungicides such as captan, Cleary's 3336, Banner Maxx or Immunox should be applied when the new growth begins, often adequate control can be achieved with several sprays applied at bloom and repeated 7-10 days later. I have received several samples already of dead branches from a variety of landscape ornamentals that have what appears to be Botryosphaeria canker. I talk about this disease often, but it will be common this season following last year's very dry late summer and fall. Sunken, dark areas often occur in the area between the healthy and diseased plant part.