Aphid Alert 1999, No. 8, August 4

Summer 1999: Aphid trapping data

Results reported in this issue of Aphid Alert are total captures of winged aphids and species identifications for the following locations and sampling interval end-dates. Data for missing locations will be incorporated into this week's issue of the newsletter as the data becomes available.

Figure 1 (below). Mean number of winged green peach aphid captured per trap across all locations reported, 1998 data (blue line) and 1999 data (maroon line). These data are also available in table format (Table 1).

Figure 2 (below). Mean number of winged aphids of species known to be capable of transmitting PVY (exclusive of green peach aphid) captured per trap across all locations reported, 1998 data (blue line) and 1999 data (maroon line). These data are also available in table format (Table 1).

Summary of observations for week ending 3 August

The number of green peach aphids captured in our traps increased sharply during the past week. Numbers of this species have been consistently higher throughout 1999 than on comparable dates in 1998. Last week's green peach aphid captures were double that of the previous year on the same date. None of the green peach aphids tested to date (those captured through 27 Jul) have tested positive for PVY or PLRV, but the high numbers that are present are reason for concern. The other aphid species that are potential vectors of PVY remain at densities very comparable to what we observed in 1998. Numbers of these aphids are also increasing rapidly and can be expected to peak in the next week or two. We consider the risk of virus spread to be high at this time.