The following plant disease highlights have been compiled from samples diagnosed in the University of Kentucky Plant Disease Diagnostic Laboratory from May 29 to June 18, 2024.
Diagnoses on agronomic crop samples have included Pythium and Rhizoctonia seedling root rots, thrips feeding, magnesium deficiency, suspected herbicide injury, and shallow planting on corn; Rhizoctonia root and crown rot on alfalfa; brown stripe and anthracnose on orchardgrass; Phytophthora root and stem rot on soybean; bacterial black rot on canola; Pythium and Rhizoctonia root rots, Fusarium wilt, tomato spotted wilt, and transplant stress on tobacco.
On fruit, herb, and vegetable samples, diagnoses have included black root rot complex on strawberry; Phytophthora root and crown rot on blackberry, raspberry, and blueberry; frogeye leaf spot, bitter rot, fire blight, rosy apple aphid, codling moth, and plum curcurlio injuries on apple; cherry leaf spot (Blumeriella) on cherry; brown rot and scab on peach; web blight on lemon balm; Rhizoctonia root rot on mint; bacterial brown spot, Rhizoctonia stem rot, and thrips injury on bean; black rot on cabbage; bacterial wilt and Alternaria blight on cantaloupe; target spot, cucumber beetle feeding, and spider mite injury on cucumber; spider mite injury on eggplant; anthracnose and blue mold rot (Penicillium) on garlic; downy mildew and Stemphyllium blight on onion; Rhizoctonia root rot, Pythium pod blight, and Rhizoctonia web blight on pea; Phytophthora crown rot on rhubarb; tomato spotted wilt on pepper; bacterial spot, early blight, Septoria leaf spot, Botrytis fruit rot, Rhizoctonia stem and root rot, root knot nematode, tomato spotted wilt, blossom end rot, and whitefly infestation on tomato. Symptoms suggestive of chemical injury/growth regulator exposure were observed on many vegetable and ornamental plants.
On herbaceous ornamentals and turf, diagnoses have included Pythium and Rhizoctonia root rots and mealybug on buttercup; Phoma leaf spot on heliotrope; Septoria leaf spot on Japanese indigo; rust on mallow; plant bug injury on peony; Cercospora leaf spot on zinnia; red thread on bluegrass; brown patch on tall fescue; Curvularia blight and melting out on perennial ryegrass.
On woody plants, diagnoses have included Pestalotiopsis needle blight on arborvitae and juniper; anthracnose and ash flower gall on ash; boxwood blight, Volutella canker, Macrophoma dieback, and boxwood psyllid on boxwood; powdery mildew and spot anthracnose on dogwood; bacterial spot on hydrangea; anthracnose, leaf blister, Botyrosphaeria canker, potato leafhopper burn, various insect and mite galls, and gloomy scale on maple; Armillaria root rot on oak; brown spot needle blight on pine; Botrytis blight, thrips, and rose slug injury on rose; spider mite injury on spruce; and tuliptree scale on tulip tree.
By Julie Beale, Plant Disease Diagnostician/Director, and Sara Long, Plant Disease Diagnostic Assistant
Kentucky Pest News 