The following plant disease highlights have been compiled from samples submitted to the University of Kentucky Plant Disease Diagnostic Laboratories from September 1-17, 2019.
Diagnostic samples of agronomic crops have included summer black stem/leaf spot and anthracnose on alfalfa; Diplodia leaf streak and southern rust on corn; Pythium root rot, Cercospora leaf spot, Septoria leaf spot, Bipolaris-like leaf spot, downy mildew, russet mite, spider mite, soil compaction, and mechanical and rodent injuries on hemp; Cercospora leaf blight, target spot, sudden death syndrome, soybean cyst nematode, soybean stem borer, and charcoal rot on soybean; black shank, hollow stalk, and frogeye leaf spot on tobacco.
On fruit and vegetable crops, we have diagnosed Phytophthora crown rot on blueberry; Botrytis blight and rednecked cane borer on blackberry; downy mildew, Pseudocercospora leaf blight, and bitter rot on grape; plum curculio injury and sooty blotch/flyspeck on apple; bitter rot on quince; anthracnose, Cercospora leaf spot, and downy mildew on cucumber; Pythium and Rhizoctonia root rots on pepper; black rot, Alternaria leaf spot, and bacterial soft rot on kohlrabi; anthracnose and powdery mildew on pumpkin; zucchini yellow mosaic virus, angular leaf spot, and powdery mildew on squash; bacterial spot, Septoria leaf spot, early blight, leaf mold, and ripe rot on tomato; gummy stem blight and downy mildew on watermelon.
On ornamentals and turf, we have diagnosed aster yellows on coneflower; Septoria leaf spot on sunflower; Pythium root rot on petunia; Pythium root rot, web blight (Rhizoctonia), Cercospora leaf spot, European pepper moth injury, and Fusarium wilt on chrysanthemum; Volutella canker and boxwood blight on boxwood; Cercospora leaf spot on euonymus and hydrangea; Phytophthora root/crown rot on arborvitae and rhododendron; powdery mildew on dogwood; elm yellows on elm; Phyllosticta leaf spot, anthracnose (Monostichella), and tar spot on maple; anthracnose, Actinopelte leaf spot, and bacterial leaf scorch on oak; bacterial leaf scorch on sycamore; anthracnose and Pythium root dysfunction on bentgrass.
By Julie Beale and Brenda Kennedy, Plant Disease Diagnosticians