Comparison of Botrytis cinerea airborne inoculum progress curves from raspberry, strawberry and grape plantings

Airborne Botrytis cinerea conidia concentration was monitored using a new qPCR assay in strawberry, raspberry and grape plantings in 2010, 2011 and 2012. Airborne inoculum progress curves (IPCs) were constructed and analysed using the maximum ACC (Yₘₐₓ), ACC during the flowering period (Yf), and area under the IPC (AUIPCₛₜd) and descriptors derived from fitting growth models. The structure of IPCs was examined by conducting multivariate principal component analyses. The dimensionality of the data was reduced to two principal components (PCs) accounting for 86·12% of the variation. All descriptors derived from growth models were associated with PC1 and descriptors derived directly from the data were associated with PC2. Based on principal component analysis, the structure of the IPCs varied with the crop, with AUIPCₛₜd values of 28·18, 42·79 and 155·83 and Yf values of 53·58, 20·14 and 142·54 conidia m⁻³ h⁻¹ in raspberry, strawberry and grape, respectively. Time to 50% of the maximum inoculum concentration was lower in raspberry and strawberry than in grape. The IPCs monitored in raspberry were characterized by narrow ranges for mean absolute rate (0·012–0·016) and AUIPCₛₜd (16·80–48·85), the IPCs monitored in strawberry were characterized by wide ranges for mean absolute rate (0·031–0·080) and AUIPCₛₜd (12·31–98·39), and the IPCs monitored in grape crops were characterized by a lower mean absolute rate (0·006–0·012) and a higher AUIPCₛₜd (50·95–335·14).