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 week have included anthracnose and summer black stem on alfalfa; anthracnose and leaf streak on orchardgrass; common rust, southern rust, Physoderma brown spot, gray leaf spot, and northern corn leaf blight on corn; take-all on wheat; brown spot and suspected growth regulator injury on soybean; angular leaf spot, frogeye leaf spot, target spot, black shank, soreshin, and tomato spotted wilt on tobacco.
On fruit and vegetable crops, we have diagnosed white rot and plum curculio injury on apple; brown rot on peach; Cercospora leaf spot on cherry; downy mildew on cucumber; vine borer injury on pumpkin and squash; Rhizoctonia root/stem rot on potato; Septoria leaf spot, early blight, bacterial spot, powdery mildew, Pythium root rot, southern blight, and ripe rot on tomato; powdery mildew on turnip; anthracnose, gummy stem blight, and Fusarium wilt on watermelon.
On landscape and turf samples, we have seen bacterial soft rot on hosta; bacterial leaf spot on hydrangea; web blight and Fusarium wilt on chrysanthemum; thread blight on crabapple; Cercospora leaf spot on ninebark; leaf blister on oak; Dothistroma and Stigmina needle blights and Rhizosphaera needle cast on spruce; and brown patch on fescue.
By Julie Beale and Brenda Kennedy, Plant Disease Diagnosticians