The following plant disease highlights from the University of Kentucky Plant Disease Diagnostic Laboratories represent recent sample submissions from field crops, fruit, vegetables, and ornamentals.
Diseases diagnosed on agronomic crops during the past week have included gray leaf spot, Diplodia leaf streak, southern rust, Fusarium stem rot, bacterial stalk rot, and Northern leaf blight on corn; Rhizoctonia crown rot, Rhizoctonia web blight, summer black stem, and anthracnose on alfalfa; leaf streak on orchardgrass; powdery mildew, Cercospora leaf spot, and powdery mildew on red clover; gray leaf spot on millet; Phytophthora and Rhizoctonia root rots on soybean; and angular leaf spot, black shank, soreshin, frenching, potassium deficiency, and target spot on tobacco.
On fruit and vegetable samples, we have diagnosed black rot on grape; cane and leaf rust and cane blight on blackberry; Phoma leaf spot, cedar-apple rust, and frogeye leaf spot on apple; scab, bacterial spot, and brown rot on peach; southern blight on pepper; bacterial spot, early blight, Septoria leaf spot, Southern blight, Rhizoctonia root rot, and Fusarium wilt on tomato; bacterial soft rot on garlic; and Pythium root rot on potato. Numerous cucurbit diseases were also diagnosed, including: Alternaria leaf blight on cucumber; angular leaf spot on pumpkin and squash; anthracnose on watermelon; Cercospora leaf spot on cucumber, pumpkin, and squash; downy mildew on squash; gummy stem blight on pumpkin and watermelon; and powdery mildew on squash.
Ornamental and turf samples included Pythium root rot and Cercospora leaf spot on chrysanthemum; Rhizoctonia root/stem rot on phlox and snapdragon; Cercospora leaf spot on statice; Pythium and Rhizoctonia root rot on black eyed Susan; powdery mildew on viburnum; Macrophoma leaf and twig blight on boxwood; spot anthracnose on linden; anthracnose on oak; Rhizosphaera and Stigmina needle diseases on spruce; anthracnose on dogwood; Mycosphaerella leaf spot on ash; brown patch on fescue; Pythium root dysfunction on bentgrass, and Pythium blight on fescue.
By Sara Long, Plant Disease Diagnostic Lab Assistant; and Julie Beale and Brenda Kennedy, Plant Disease Diagnosticians