May 5, 1993
Dothistroma needle blight is caused by the fungus Mycosphaerella pini. Common hosts include Austrian, ponderosa, and mugo pines.
The forsythias were spectacular this spring in Iowa. Many of the shrubs were completely covered with bright, yellow flowers. Unfortunately, this is not always the case. Many of the forsythia varieties that have been widely planted in past years, such as 'Lynwood Gold' and 'Spring Glory', don't reliably bloom in Iowa. (They usually bloom well once every 4 to 5 years.) Their flower buds are killed by low winter temperatures. These varieties bloomed well this spring because of the relatively mild winter.
Several disease and insect pests on apples have appeared or are about to appear. A checklist:
If there is still a spot in your flower or vegetable garden for something new, one of the 1993 introductions may fit the bill.
Quince rust is caused by the fungus Gymnosporangium claviceps. The quince rust fungus requires two hosts, both a juniper or cedar and a pomaceous host, to complete its disease cycle. Pomaceous hosts include hawthorn, serviceberry, flowering quince, mountain ash, cotoneaster, pear, and susceptible apple varieties.
On pomaceous hosts symptoms are most common on fruits, but also occur on twigs, buds, and leaves. Infected fruit are often misshapen and have sunken lesions near the blossom end. The fungus causes swellings or distortions on twigs and petioles.