Plant Disease Diagnostic Lab Highlights

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 summer black stem on alfalfa; common rust, southern rust, Physoderma brown spot, gray leaf spot, and northern corn leaf blight on corn; anthracnose and northern corn leaf blight on sorghum; Pythium damping off/root rot and southern blight on hemp; suspected growth regulator injury on soybean; angular leaf spot, frogeye leaf spot, target spot, black shank, soreshin, Fusarium wilt, tomato spotted wilt, alfalfa mosaic virus, and manganese toxicity on tobacco.

Figure 1:  Bacterial spot of tomato produces dark leaf spots but can also cause lesions on fruit.  Fruit lesions begin as small fleck-like spots and expand to form tan-colored, rough, slightly sunken lesions as shown here. (Photo: Julie Beale, UK)

On fruit and vegetable crops, we have diagnosed black rot on grape; coddling moth and plum curculio injury on apple; anthracnose, Cercospora leaf blight, and potyvirus on bean; powdery mildew on cucumber; bacterial leaf spot on pepper; anthracnose on pumpkin; Septoria leaf spot, early blight, bacterial spot, bacterial canker, Fusarium wilt, and ripe rot on tomato; and Fusarium wilt on watermelon.

On landscape and turf samples, we have seen Pythium and Rhizoctonia root rots on petunia; bacterial leaf spot on begonia; Rhizoctonia root rot on peony; bacterial soft rot on hosta; web blight on chrysanthemum; boxwood blight, Volutella canker and Macrophoma leaf/stem blight on boxwood; fire blight on pear; Cercospora leaf spot on honeylocust; Verticillium wilt and powdery mildew on maple; Rhizosphaera needle cast on spruce; and gray leaf spot on perennial ryegrass.

 

By Julie Beale and Brenda Kennedy, Plant Disease Diagnosticians

 

 

 

Posted in Plant Disease Diagnostic Lab