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.
Recent diagnostic samples of agronomic crops have included magnesium and zinc deficiency symptoms on corn; spring black stem on alfalfa; leaf streak on orchardgrass; Pythium root rot, black root rot, angular leaf spot, black shank, soreshin, Fusarium wilt, tomato spotted wilt, alfalfa mosaic virus, temporary phosphorus deficiency, and transplant shock on tobacco.
On fruit and vegetable crops, we have diagnosed Botryosphaeria canker, Phomopsis canker, anthracnose fruit rot, blueberry mosaic, and tobacco ringspot virus on blueberry; cane blight, spur blight, and cane borer injury on blackberry; anthracnose and black rot on grape; cedar-apple rust, frogeye leaf spot and fire blight on apple; bacterial leaf spot on peach; Phyllosticta leaf spot on pawpaw; Fusarium crown rot on asparagus; bacterial wilt on cucumber; thrips injury on garlic; purple blotch on onion; bacterial leaf spot, Pythium and Rhizcotonia root rots on pepper; blackleg on potato; powdery mildew on pea; bacterial canker, Pythium root rot, timber rot, Septoria leaf spot, tomato spotted wilt, leaf mold, and chemical injury on tomato; bacterial crown rot on rhubarb; anthracnose and gummy stem blight on watermelon.
On landscape and turf samples, we have seen Phoma dieback on vinca; Pythium and Rhizoctonia root rots on catharanthus; Pythium root rot on petunia; Rhizoctonia root rot on coneflower; powdery mildew on peony; Volutella canker/dieback on boxwood; Armillaria root rot on hydrangea; rosette on rose; Phomopsis twig blight on juniper; Phyllosticta needle blight on cryptomeria; Botryosphaeria dieback on Leyland cypress; Phloeospora leaf spot on mulberry; scab and cedar-apple rust on crabapple; powdery mildew on dogwood; anthracnose and Phyllosticta leaf spot on maple; anthracnose, Botryosphaeria dieback, and Actinopelte leaf spot on oak; Rhizosphaera and Stigmina needle cast/blight on spruce; red thread and anthracnose on fescue.
By Julie Beale and Brenda Kennedy, Plant Disease Diagnosticians