Seasonal variation in Blueberry scorch virus concentration in highbush blueberry and implications for disease monitoring and management

Seasonal variation in relative Blueberry scorch virus (BlScV) concentration was determined for three infected highbush blueberry, Vaccinium corymbosum, cultivars in a commercial field in southwestern British Columbia, Canada. Relative virus concentration per g of infected blueberry flower clusters and leaf terminal tissue varied during the season with significant cultivar-by-time interactions. Flower clusters had the highest BlScV concentration per g of tissue and could be collected in early May for disease surveys. Timing of leaf sample collection for BlScV surveys, transmission studies and virus purification should be based on studies of temporal variation in BlScV concentration for the principal cultivars in a production area.Les variations saisonnières dans la concentration relative du virus de la brunissure nécrotique du bleuet (Blueberry scorch virus; BlScV) ont été déterminées pour trois cultivars infectés du bleuetier géant, Vaccinium corymbosum, dans un champ commercial du sud-ouest de la Colombie-Britannique, Canada. La concentration relative du virus par g de grappes de fleurs et de tissu terminal de feuille infectés a varié au cours de la saison, avec des interactions significatives entre les cultivars et le temps. Les grappes de fleurs avaient la plus haute concentration du virus par g de tissu et pouvaient être cueillies au début de mai pour évaluer la maladie. Le moment choisi pour la collecte des échantillons de feuille pour l’étude du BlScV, les études de transmission et le traitement du virus devrait se fonder sur des études de variation temporelle dans la concentration du BlScV pour les principaux cultivars d’une zone de production

Biological control of the two-spotted spider mite in raspberries with the predator mite, Phytoseiulus persimilis

Phytoseiuius persimilis was released to control the two-spotted spider mite, Tetranychus urticae, in field raspberries at Agassiz, B.C. The mite predators became established and responded numerically to the prey in the treatment plots. For a period of 8 weeks after release, the numbers of T. urticae were consistently lower in the treatment plots than in the controls. Differences in numbers of T. urticae between the treatments and the controls were significant on two dates.Key words: Tetranychus urticae; Phytoseiulus persimilis; Rubus idaeus; biological control; Fraser Valle