Plant Disease Diagnostic Lab Highlights

The following plant disease highlights have been compiled from samples submitted to the University of Kentucky Plant Disease Diagnostic Laboratories since the start of 2019.

Diagnostic samples of agronomic crops have included Sclerotinia crown and stem rot on alfalfa; Pythium root rot, Rhizoctonia stem and root rot, Fusarium root rot, and hemp russet mite infestation on hemp.

On fruit, vegetable, and herb crops, we have diagnosed winter injury on raspberry; Pythium root rot and genetic abnormalities on tomato; injury from high soluble salts on pepper and tomato; and Phytophthora root rot on lavender.

On ornamentals, we have diagnosed cold injury and phosphorus deficiency on lobelia; Florida fern caterpillar on Boston fern; anthracnose and Rhizoctonia root rot on leucanthemum; boxwood blight (Figures 1 & 2), boxwood leaf miner, and Volutella canker on boxwood; Botryosphaeria canker on dogwood; elongate hemlock scale and Phomopsis dieback on hemlock; Dothistroma needle blight on pine and spruce; and Rhizosphaera needle cast on spruce.

Figure 1  It’s back!  So far in 2019, we have confirmed boxwood blight on landscape samples well before the growing season begins, similar to the early months of 2018.  Be on the lookout for symptoms of lower canopy defoliation. (Photo: Julie Beale, UK)

Figure 2.  Black streaking on stems infected with the boxwood blight pathogen.  For boxwood blight management information, refer to UK Extension fact sheet PPFS-OR-W-20 (Photo: Julie Beale, UK)


Julie Beale and Brenda Kennedy, Plant Disease Diagnosticians




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