What's New
What’s New
October 2026
Watch for Boxwood Blight this Fall
Sudden defoliation of boxwood bushes Black lesions on boxwood leaves and stems
Boxwood blight is a destructive disease that attacks leaves and stems of boxwood, which causes significant defoliation. The Plant Disease Information Office has received numerous boxwood samples infected with boxwood blight. Periods of warm and wet weather conditions during this summer favored the disease development. The disease causes dark brown to black lesions on leaves and stems, and a severe infection can result in sudden defoliation. For more information of this disease, please read the linked fact sheet. Boxwood Blight (pdf) and Boxwood Blight Identification Guide (pdf). If boxwood blight is suspected, samples may be sent to our office by following the linked Sample Submission Guidelines.
July 2026
What's Wrong with My Lilacs?
Fungal leaf spot of lilac has been favored by warm and wet summer weather conditions this year, which results in small brown spots, blight, and premature defoliation. Fungicide applications may help to prevent the disease by reducing new infections, but wouldn't eradicat them. So, good sanitary and cultural practices are critical to effectively manage the disease. For general information of fungal leaf spot diseases and strategies for their manament, please read the fact sheet Leaf Spot Diseases of Ornamental Trees and Shrubs (pdf).
New Fact Sheets Published Online
Link to Bacterial Leaf Spot of Herbaceous Ornamentals (pdf)
Link to Foliar Nematodes of Herbaceous Ornamentals (pdf)
May 2026
What's Going on My Cedar Trees?
The orange structure in the photo is cedar-apple rust fungus. Several species of Gymnosporangium can cause rust diseases on cedar trees. For more informaiton of Gymnosporangium rust diseases, please read the fact sheet Gymnosporangium Rusts: Common Cedar Rust Diseases (pdf).
April 2026
Two New Fact Sheets Published Online
Link to Cherry Leaf Spot fact sheet (pdf)
Link to Rose Downy Mildew fact sheet (pdf)
March 2026
What Happend to My Lawn
Gray snow mold is a common fungal disease in late winter especially after prolonged snow cover. Symptoms appear when snow melts, which including gray or bleached grass blades and reddish brown fungal structure on infected leaves. Linked please find a fact sheet Gray Snow Mold of Turfgrass in Home Lawns (pdf). For correct disease diagnoses, please send us samples by following the Sample Submission Guidelines.