In the endoparasitic wasp Venturia canescens (Hymenoptera: Ichneumonidae) two genetically distinct lines, which differ at the VLP1 gene locus, appear to coexist sympatrically in thelytokous as well as arrhenotokous field and laboratory strains. Both lines display quite distinct morphological, physiological and behavioural variations, such as different oviposition strategies, egg numbers and gro...

Linkage maps developed from known-function genes can be valuable in the candidate gene mapping approach. A set of 121 expressed sequence tagged site (E-STS) primer pairs were tested on a framework genetic linkage map of apple (Malus x domestica Borkh.) constructed using simple sequence repeats (SSRs) and randomly amplified polymorphic DNA (RAPD) markers. These known-function gene markers, E-STS...

A range of possible substitutes for copper-based fungicides for control of apple scab (Venturia inaequalis) in organic growing were tested in laboratory and growth chamber experiments in the Danish project StopScab (2002-2004). Eighteen crude plant extracts, 19 commercial plant-based products and 6 miscellaneous compounds were tested for their ability to reduce scab symptoms on apple seedlings....

Sterol-inhibiting (SI) fungicides are widely used to manage apple scab, caused by Venturia inaequalis. However, recent observations indicate that populations of V. inaequalis in orchards in Virginia have developed resistance to myclobutanil and other SI fungicides. Little is known about the frequency and distribution of fungicide resistance in apple scab populations in Virginia. Isolates of V. ...

Ontogenic scab resistance in apple leaves and fruits is a horizontal resistance against the plant pathogen Venturia inaequalis and is expressed as a decrease in disease symptoms and incidence with the ageing of the leaves. Several studies at the biochemical level tried to unveil the nature of this resistance; however, no conclusive results were reported. We decided therefore to investigate the ...