The following plant disease highlights have been compiled from samples submitted to the University of Kentucky Plant Disease Diagnostic Laboratories from July 30 – August 20, 2019.
Diagnostic samples of agronomic crops have included common rust, southern rust, Diplodia leaf streak, gray leaf spot, and northern corn leaf blight on corn; leaf streak and anthracnose on orchardgrass; northern corn leaf blight on sorghum; summer black stem/leaf spot and anthracnose on alfalfa; Pythium and Rhizoctonia root rots, Cercospora, Septoria, and Bipolaris-like leaf spots, cannabis aphid, spider mite, russet mite, web blight (Rhizctonia), and southern blight on hemp; target spot, brown spot, frogeye leaf spot, stem canker, and sudden death syndrome on soybean; angular leaf spot, frogeye, target spot, black shank, soreshin, Fusarium wilt, hollow stalk, and manganese toxicity on tobacco.
On fruit, herb, and vegetable crops, we have diagnosed Phytophthora crown rot on blueberry; cherry leaf spot (Blumeriella) on plum and cherry; cedar-apple rust, frogeye leaf spot, plum curculio, and sooty blotch/flyspeck on apple; fire blight on pear; scab on pecan; brown rot on peach; downy mildew on basil; Cercospora leaf spot, common bacterial blight, and spider mite injury on bean; Cercospora leaf spot and powdery mildew on cucumber; bacterial spot and Fusarium root rot on pepper; root knot nematode on potato; Phytophthora and Fusarium crown rots, and bacterial soft rot on pumpkin; anthracnose, powdery mildew, and Phytophthora crown rot on squash; Septoria leaf spot, early blight; ripe rot, and buckeye rot on tomato.
On ornamentals and turf, we have diagnosed southern blight on ajuga; Pythium root rot on bugloss; Rhizoctonia stem/root rot on aster; Pythium root rot, web blight (Rhizoctonia), and Fusarium wilt on chrysanthemum; Rhizoctonia stem/root rot and black root rot on phlox; powdery mildew on sedum; Phoma blight on vinca; web blight/thread blight on euonymus and cherry; Volutella canker and Macrophoma dieback on boxwood; Phytophthora blight on rhododendron; Phomopsis dieback on Japanese tree lilac; scab and frogeye leaf spot on crabapple; spot anthracnose, Septoria leaf spot, and Phyllosticta leaf spot on dogwood; Cercospora leaf spot on honeylocust, sweetgum, viburnum, and willow; Phylloticta leaf spot, anthracnose, and Verticillium wilt on maple; anthracnose on oak; elongate hemlock scale on fir; Rhizosphaera needle cast and spider mite injury on spruce; anthracnose, take-all patch, Pythium root dysfunction, and black layer on bentgrass; and brown patch on fescue.
By Julie Beale and Brenda Kennedy, Plant Disease Diagnosticians