All entries for Friday 06 March 2015

First forecasts for 2015!

The long run of aphid data from the Rothamsted suction-trap network, combined with the long run of weather data available from the Met Office and others, makes it possible to establish relationships between weather and the timing of the start of aphid flights and aphid abundance in spring and early summer. The best predictor is the mean temperature in January and February, and confidence is greatest for those aphid species which pass the winter in the active stages rather than as eggs, including Peach–potato aphid (Myzus persicae) and Potato aphid (Macrosiphum euphorbiae). This is because active stages are susceptible to low winter temperatures but can take advantage of warm conditions, whereas eggs are very cold hardy and in diapause, so don’t respond to warm conditions in mid-winter. Although Cabbage aphid (Brevicoryne brassicae) overwinters mainly in the active stages it flies later and is more difficult to predict.

The temperature in January and February was close to average at all sites, the greatest difference from average being at Starcross, where it was 1^oC above average. Thus the timing and early-season abundance of aphids is expected to be around average.

You can find the predictions for each of the three pest species at each suction trap site here: ahdb_potato_and_brassica_forecasts_2015.pdf.

Rosemary Collier : 06 Mar 2015 20:55 |  Comments (0) |  Close comments |  Report a problem