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.
Diagnostic samples of agronomic crops from the past two weeks have included Stemphyllium leaf spot and summer black stem on alfalfa; anthracnose, leaf streak, and leaf rust on orchardgrass; southern anthracnose on red clover; rough leaf spot and stinkbug injury on sorghum; southern rust, gray leaf spot, and northern corn leaf blight on corn; brown spot, downy mildew, Rhizoctonia root rot, sudden death syndrome, and suspected growth regulator injury on soybean; angular leaf spot, frogeye leaf spot, target spot, black shank, soreshin, and hollow stalk on tobacco.
On fruit and vegetable crops, we have diagnosed cane and leaf rust, anthracnose, and double blossom on blackberry; Sphaerulina leaf spot on raspberry; cedar-apple rust on apple; bitter rot on pear; Rhizoctonia root rot, Pythium root rot, Cercospora leaf spot, and spider mite injury on bean; anthracnose on cucumber; Pythium root rot, bacterial spot, and broad mite injury on pepper; bacterial soft rot on potato; Rhizoctonia aerial blight on Swiss chard; powdery mildew, tomato ringspot virus, Pythium cottony leak, Choanephora rot, and vine borer injury on pumpkin; bacterial spot, Septoria leaf spot, early blight, Rhizoctonia aerial blight, Fusarium wilt, southern blight, and Rhizoctonia root rot on tomato.
On landscape and turf samples, we have seen Pythium root rot, web blight and Fusarium wilt on chrysanthemum; Rhizoctonia root/stem rot and root knot nematode on New Guinea impatiens; anthracnose on lisianthus; rosette disease on rose; anthracnose and Cercospora leaf spot on hydrangea; black spot on elm; anthracnose, and Phyllosticta leaf spot on maple; bacterial leaf scorch on hackberry, sycamore and oak; Botryosphaeria canker, Stigmina needle blight, and Rhizosphaera needle cast on spruce; brown spot needle blight and Diplodia tip blight on pine; anthracnose and brown patch on fescue; Curvularia blight and large patch on bermudagrass; and Pythium root dysfunction on bentgrass.
By Julie Beale and Brenda Kennedy, Plant Disease Diagnosticians