CHICAGO (CBS) — Homeowners are being told to diversify – not just by financial planners – but by a biologist who is concerned that maples could one day follow ash and American elm trees into oblivion.

As WBBM Newsradio’s John Cody reports, David Robson of the University of Illinois Extension Service says horticulturists are concerned that front and backyards across the country could be left barren if a new pest starts wiping out maples.

LISTEN: WBBM Newsradio’s John Cody reports

Robson says ash trees and red and silver maples right now constitute 30 to 50 percent of the urban forest – front yards and backyards – because they’re very pretty and fast growing.

“We tend to start growing the fastest, prettiest tree because we want instant gratification. We want instant shade,” Robson said.

But Robson says he believes ash trees may well follow the American elm into oblivion in twenty years because of the emerald ash borer. The elms were taken down by Dutch elm disease, a fungal infection.

Robson says that will leave many homes with just red or silver maples which are doing well now but could easily fall prey to another pest as did the ash and the elm. The consequence would be a lot of bare yards.

Robson says the solution is diversity. He said homeowners should see what trees their neighbors are growing, and plant something else.

He recommends slow growing oaks, hackberry trees and the Amur maple as possible replacements for ash trees when they topple, as he believes they inevitably will.

Robson will be explaining his ideas at 1 p.m. Tuesday during a teleconference to county extension offices throughout Illinois. The conference costs $5.