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.

Diseases diagnosed on agronomic crops during the past week have included spring black stem/leaf spot and Lepto leaf spot on alfalfa; and Pythium root rot on tobacco transplants.

On fruit and vegetable samples, we have diagnosed anthracnose fruit rot, common leaf spot, and Phomopsis leaf blight on strawberry; anthracnose on grape; cedar-apple rust, fire blight, frogeye leaf spot, and plum curculio injury on apple; black root rot (Thielaviopsis) on bean; Pythium root rot on potato; leaf mold (Fulvia), timber rot (Sclerotinia), and Fusarium wilt on tomato; and gummy stem blight and Pythium root rot on watermelon.

Figure 1. Dogwood powdery mildew produces visible white mycelium and spores and causes leaf distortion if infection occurs early in the growing season. Recent hot, humid weather is ideal for development of powdery mildew. (Photo: Tom Miller, Extension Agent, Ballard County, Kentucky)

Figure 1. Dogwood powdery mildew produces visible white mycelium and spores and causes leaf distortion if infection occurs early in the growing season. Recent hot, humid weather is ideal for development of powdery mildew. (Photo: Tom Miller, Extension Agent, Ballard County, Kentucky)

Ornamental samples included Pythium and Rhizoctonia root rots on petunia; anthracnose on clematis; Botrytis blight on annual vinca; cottony camellia scale on holly; Volutella blight on boxwood; rust, fungal canker (Nectria), and rose sawfly feeding injury on rose; powdery mildew on dogwood (Figure 1) and serviceberry; anthracnose on ash, sycamore, elm, and maple; Cytospora canker on willow; and Seiridium canker on Leyland cypress.

 

By Julie Beale and Brenda Kennedy, Plant Disease Diagnosticians

 

Posted in Plant Disease Diagnostic Lab