Agreed on sooty blotch, the dark sunken spot with the black center doesn't look like scab to me (at least not the way I normally see it present) It does look just like a type of rot we often get on our honeycrisps during wet years; but that normally shows up much later in the season....close to harvest. I don't know the name for it, but generally the apples are still harvestable and we just cut out that section. It usually has well defined edges and a narrowing cone of mushy rotten apple extending down from the surface. My experience with bitter pit is a tan "corky" area under the dimple in the skin, and a Spartan says it gets worse during storage.

Very possible that the little black fellows are aphids. If so, they suck plant sap and will weaken the plant. Rub them off, or use direct hits of insecticidal soap, diluted according to label directions. In both cases, repeat as needed. I'm not able to see enough detail to suggest what the white might be.

Thank you, Silica. I will contact the local Extension service. Meanwhile I found this on Citrus Black Spot: https://www.aphis.usda.gov/aphis/ourfocus/planthealth/plant-pest-and-disease-programs/pests-and-diseases/citrus/citrus-black-spot/citrus-black-spot . The description of the spots does not quite match what I am seeing and fortunately the fruit has not been affected. My lemon tree started as a volunteer. Its parents may have been commercial citrus cultivars but it grew from a seed spread by the wind or wildlife. I wasn't sure what it was when it first appeared in my garden but it was too close to a rosebush so I put it in a small pot. That was about 10 years ago. I have 2 other store-bought lemon trees but they are more than 40 feet away and so far neither has spotted leaves.

I am in the San Francisco Bay. Neem oil can be used after pruning in January and before the bush leaving out - this is called the dormant spray. After that I maintain a regular spraying schedule when the roses are leaving out, usually once every 2 weeks, but different rose growers spray at different intervals depending on the disease pressure in your area. It is too late when you see fungal disease on the leaves, even though some of the fungicides are labelled as "curative". It is best to just remove those sick leaves to slow down the disease from spreading to the entire bush. It is best not to spray Neem oil when the temperature is hot outside. Otherwise the leaves may be damaged. Another dormant spray people use is copper fungicide. Also better time to spray is in the early morning.