Response of local and scab-resistant cultivars to woolly apple aphid.

摘要

In-plant resistance is a key tool in the development of sustainable strategies of pest control. Germplasm in the form of 28 local apple cultivars and ten commercial cultivars carrying the Vf gene for resistance to apple scab Venturia inaequalis was evaluated for the response to woolly apple aphid (WAA) Eriosoma lanigerum in the greenhouse. The response of Malus floribunda 821 was also assessed. Five plants of each cultivar were infested in July 2006 and 2007 with aphids previously reared from field populations. Aphid infestation was evaluated weekly on a scale from 0 to 4. After leaf fall, damage to the woody tissue of the plants caused by the galls was evaluated on a scale from 0 to 3. There was a significant correlation between the results from 2006 and 2007. Two months after the infestation, all the cultivars except M. floribunda 821 and the resistant reference cultivar 'Geneva', sustained aphid populations. While all cultivars were considered susceptible to WAA, there was a gradient among cultivars in both infestation and damage. However, there was no significant correlation between infestation and damage. Comparing these findings with previous results of our group, there was no correlation between cultivar susceptibility to the woolly and the rosy apple aphids.