A rapid virulence assay for the Dutch elm disease fungus Ophiostoma novo‐ulmi by inoculation of apple ( Malus × domestica ‘ Golden Delicious’) fruits

Large‐scale virulence tests using trees or saplings are expensive, time‐consuming and require a considerable amount of space. The suitability of using ‘ G olden D elicious’ apples as a rapid screen for identifying O phiostoma novo‐ulmi transformants with reduced virulence was thus evaluated. When a collection of O . novo‐ulmi field isolates belonging to subspecies novo‐ulmi or americana was inoculated to apples, members of subsp. novo‐ulmi induced, on average, larger necrotic lesions than subsp. americana isolates. The size of the lesions on apples was not correlated with mycelial growth rate... Mehr ...