Q: I just bought a cherry tree and found it has red shiny spots on most of its leaf stems. I sprayed with a fungicide but see no result, those spots look permanent. Are they OK? Is there some treatment I should do?

A: Scale insects are commonly found on stems and young branches of fruit trees. Mild infestations are usually not a problem. If the tree looks otherwise healthy, I would take a “wait and see” approach. Keep an eye out for the presence of honeydew (a sticky substance exuded by scales and aphids) and ant activity.

Scales are similar to aphids in that they have a symbiotic relationship with ants. They suck the juice out of a plant and poop out sticky honeydew, which is almost pure sugar. Ants harvest the honeydew and, in return, protect the aphids/scales from predators. If you can exclude ants from an infested plant, many predatory insects will take care of the pests.

Scale is also a favorite target of parasitic wasps. If you have a good-quality magnifying glass, you may spot some holes or hollowed out scales still stuck to your tree. Parasitic wasps are tiny and harmless to humans, but they can keep scale populations under control in their own, brutal way.

If your tree is showing signs of distress, such as leaf yellowing, and has an out-of-control scale problem, application of horticultural oil should control them. Horticultural oil is very specific to scale and aphids, and shouldn’t harm beneficial insects. Always follow package directions and precautions!

Gardening resources

Q: We have been having trouble growing large container plants near our pool deck. The pots are very big – 26 inches tall and 28 inches wide. They are heavy glazed pottery and they have drainage holes at the bottom. Everything we’ve tried to grow has died. There were mushrooms growing in one of the pots.

A: Most of the large, heavy, glazed pottery containers have a single drainage hole at the bottom. This hole is usually 1 to 1-and-a-half inches in diameter and should be adequate for drainage purposes. The problem is that since the pot is so big and heavy, water cannot escape freely from the bottom of the container if it is sitting on a hard surface like a pool deck.

The container should be elevated (even a little) so that excess water can drain away. You can buy little feet specifically made for this purpose, or you can use 2 bricks to elevate the pot a few inches.

This can result in dirt leaking out of the bottom of the pot. If this becomes a problem, you can remove the plant and potting soil and place a piece of shade cloth or window screen in the bottom of the pot and replace the soil and plant.