When landscape plants develop yellow leaves during the growing season, the cause often is high pH soils, making iron unavailable.

But this year some parts of the central United States have received so much rain that soggy soils are keeping plants from taking up the nutrients they need to maintain a healthy green color, said Ward Upham, horticulturist with Kansas State University Research and Extension.

"Fortunately, the chlorosis caused by wet soils will correct itself when those soils dry out. In other words, the plants will regain their color after more normal summer weather returns," Upham said.

If drier weather doesn't prove to be the solution, however, gardeners can check with their county's Research and Extension office to learn more about iron chlorosis. Or, they can check Upham's discussion of the subject on the Web (http://www.oznet.ksu.edu/news/sty/2004/yellow_leaves040204.htm).

High pH soils tend to be most common in areas of low rainfall with soils derived from limestone rocks, he said.