Skip to main content
APS Plant Health 2025 Main banner
Icon Legend
This session is not in your schedule.
This session is in your schedule. Click again to remove it.

POSTERS: Nematology II

P-432 - Beauty and the beast: dahlia's battle against lesion nematodes

Tuesday, August 5, 2025
10:15 AM - 11:00 AM HST
Location: Exhibit Hall 3
Abstract Text:

Dahlia (Dahlia variabilis L.), a native species of Mexico and a key member of the Asteraceae family, is a highly valued and economically important ornamental plant widely used in floral arrangements, bouquets, and event decorations. Dahlia tubers from multiple flower producer and home gardener stakeholders were submitted to the Penn State Plant Disease Clinic and Nematode Diagnostic Lab, exhibiting diseased symptoms, including a bark-like texture with longitudinal grooves and scarring of the tuber skin. In severe cases, the tuber surface developed a granular texture. Brown lesions beneath the skin were observed on all symptomatic tubers, leading to rotting during storage. Root lesion nematodes were extracted from the affected tubers, ranging from 5 to over 70 nematodes per gram of skin peel. Morphological and molecular analyses identified the nematode as Pratylenchus pseudocoffeae. Molecular identification was confirmed using the internal transcribed spacer (ITS) and the D2D3 region of the 28S large subunit ribosomal DNA markers. To our knowledge, this is the first report of P. pseudocoffeae in Pennsylvania and the first documented occurrence on dahlia. Dahlias are a significant component of the U.S. cut flower industry, which has seen substantial growth in recent years. Therefore, recognizing new pathogens of this plant can provide relevant information for nematode control by producers.