Garden phlox is a staple of many perennial gardens, but in warm, humid climates, it's highly susceptible to mildew. The flowering dogwood (Cornus florida) is prey to a wide range of insects and diseases, including borers and anthracnose. The European white birch is susceptible to the bronze birch borer.

Lilacs, garden phlox, roses, crabapples, birch and dogwoods — beloved plants sometimes host a lot of problems. In many of our favorite plant families, some members are especially insect- and disease-prone. The good news, though, is that others are not.

For garden phlox, the resistant cultivars include 'David', 'Delta Snow', Natascha', 'Robert Poore', 'Speed Limit 45' and Phlox caroliniana. Certain dogwood cultivars like 'Cherokee Princess' and 'Pluribracteata' (the double-flowered form) that show excellent resistance to anthracnose; and there's always the Kousa dogwood (Cornus kousa), which resists most of the things that plague C. florida. White-barked birches are generally susceptible to borer, particularly if they encounter stress. The much touted Betula platyphylla 'Whitespire' birch is resistant, but only if the tree has been vegetatively propagated from the original resistant strain and not grown from seed. So you if you don't want to risk tangling with the borer, you could consider the river birch (Betula nigra), which offers multicolored, exfoliating bark.