The following plant disease highlights have been compiled from samples submitted to the University of Kentucky Plant Disease Diagnostic Laboratories from June 1 to June 30, 2020.
Diagnostic samples of agronomic crops have included Rhizoctonia damping off, Lepto leaf spot, and iron deficiency on alfalfa; leaf streak on orchardgrass; Pythium and Rhizoctonia root rots, magnesium deficiency, compaction/shallow planting, genetic anomalies, and thrips injury on corn; Rhizoctonia root rot and compaction on wheat; Rhizoctonia root rot, Phytophthora rot/stem rot, and potassium deficiency on soybean; Pythium root rot, thrips injury, and compaction on hemp; Pythium root rot, black shank, soreshin, target spot, and frogeye leaf spot on tobacco.
On fruit, vegetable, and herb crops, we have diagnosed Phytophthora root/crown rot on blueberry; Phompsis leaf blight, common leaf spot, and slime mold on strawberry; anthracnose on grape; cane blight on raspberry; fire blight, Botryosphaeria canker, cedar-apple rust, and frogeye leaf spot on apple; leaf curl on peach; black knot on plum; Rhizoctonia root rot on bean; white mold on cabbage; wireworm injury on sweet corn; Septoria leaf spot on cowpea; bacterial wilt on cucumber; Pythium root rot on pepper; bacterial blackleg on potato; web blight and spider mite injury on spinach; Cercospora leaf blight and angular leaf spot on squash; Pythium and Rhizoctonia root rots, bacterial canker, blossom end rot, leaf mold, early blight, timber rot, southern blight, and tomato spotted wilt on tomato; Pythium root rot on watermelon; suspected growth regulator exposure on various vegetable crops; bacterial blight on basil; and powdery mildew on hops.
On ornamentals and turf, we have diagnosed Pythium and Rhizoctonia root rots on begonia, calibrachoa, impatiens, and petunia; anthracnose on daylily; web blight on Ficus; Volutella blight on pachysandra; bacterial blight on poppy; Phoma dieback on vinca; powdery mildew and scale insect on euonymus; boxwood blight, Volutella canker, Macrophoma leaf blight, and leaf miner injury on boxwood; Cercospora leaf spot on hydrangea; sawfly injury on rose; leaf spot (Blumeriella) and bacterial spot on cherry; spot anthracnose on dogwood; anthracnose, leaf blister, and Phomopsis dieback on maple; anthracnose, leaf blister, and jumping oak gall on oak; scab on willow; Botryosphaeria dieback and Phytophthora root/crown rot on arborvitae; Botryosphaeria and Phomopsis canker/dieback on chamaecyparis; Leptographium root rot on pine; Rhizosphaera needlecast and Dothistroma needle blight on spruce; freeze/frost injury on various landscape species; take-all and Pythium root dysfunction on bentgrass; large patch on bermudagrass; southern blight on bluegrass; brown patch and red thread on fescue.
By Julie Beale and Brenda Kennedy, Plant Disease Diagnosticians