The disease occurs in woodlots and forests, home landscapes, and urban plantings. Distribution and Host Range Ash yellows has been reported only in North America. Ash yellows has also been found in two southwestern locations. Ash yellows MLOs have not been detected in naturally infected plants other than ash and lilac. Symptoms of ash yellows vary with ash species.
White ash sustains permanent and often rapid decline in tree growth.
Slow twig growth and short internodes can cause foliage to appear tufted at tips of twigs and the crown to appear more transparent than normal. Subnormal leaf size and light green leaf color, upturned leaf margins, and premature fall coloration are common. Eventually a progressive dieback of branches begins and witches -brooms may develop at the trunk base. Witches -brooms are clusters of upright spindly shoots. Vertical cracks and cankers are common on the trunk near the ground.