A: Once upon a time most cinder blocks were made from cinders that were left after coal was burned at power plants. Cinders were used as the "aggregate" that is mixed with cement to make a cinder block. Some cinder blocks are still made using fly ash from a nearby power plant but sand and gravel are more common. In any case the aggregate material is tightly surrounded by cement. It would be very difficult to dissolve the aggregate material to contaminate the soil of your raised bed.
Q: What do you think about eating the fruit from a peach tree that was planted in a septic tank field?Maria Marlowe , email
A: As long as the fruit does not directly touch the ground I would be comfortable eating it. Germs are not absorbed by the roots, so they can't be transmitted to the fruit. Perhaps you could put thick mulch on the ground under the tree or even lay a tarp there to catch fallen fruit.
Q:I'm seeing petunias with white spots on the flower petals. There are no spots on the foliage.Matt Akins, email
A: It’s probably gray mold, Botrytis cinerea, a common disease of flower petals. If a petunia flower is kept constantly moist, the mold will turn the bloom into a gunky mess. But in typical summer weather, heat dries the fungus before it can go further than the initial infection. You can prevent it by spraying with chlorothalonil (Daconil) at planting and during rainy weather.
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