Forecasting barley yellow dwarf virus in autumn-sown cereals in 1998

Abstract

Aphid vectors of barley yellow dwarf virus (BYDV) were sampled from three 7.5 m high suction traps in Canterbury from April to October 1998. Aphid numbers were very high (up to 193 aphids per trap per week) in April and May and medium to low (0 to 44 aphids per trap per week) from June to September. A BYDV forecast based solely on numbers of aphids caught in traps (aphid flights), or primary infestation, accurately predicted high virus incidence for wheat sown before mid-May. However, an exceptionally mild winter encouraging the secondary spread of aphids within crops was implicated in the high level of BYDV found in wheat crops sown after mid-May that was not predicted by aphid flights. A measure of secondary aphid infestation and virus infection may need to be included in future BYDV forecasts.

Farmer survey of yellow dwarf viruses in autumnsown cereals in Canterbury

“…A significant relationship between numbers of aphids trapped in June and July and the proportion of crops with levels of YDV was established by Farrell & Stufkens (1992). In general, this relationship has continued to hold with warmer winters probably contributing to greater virus incidence in recent years (Teulon et al 1999a;2001). A successful application, co-ordinated by the Foundation for Arable Research (FAR) in association with Crop & Food Research, was made by a farmers' group (Canterbury Arable Research Groups) to the Agricultural and Marketing Research and Development Trust (AGMARDT) to fund an expanded aphid monitoring-virus forecasting programme for three years (1998)(1999)(2000).…”

“…Barley, wheat and oats are the major cereal crops in New Zealand, with the greatest proportion of these crops grown in Canterbury. All these cereals are susceptible to yellow dwarf viruses (YDV) (barley yellow dwarf and cereal yellow dwarf) (Mayo & D'Arcy 1999), which are a major source of cereal crop loss in New Zealand (Teulon et al 1999a). Yellow dwarf viruses impose an estimated cost of $3.7 million per year in Canterbury (Bicknell & Greer 1999).…”

“…Lowe (1967) recommended that winter wheat should be sown after 1 June to avoid infection by late-autumn flights of the aphid vectors, and Farrell & Stufkens (1992) concluded that the late sowing of cereal crops in Canterbury (after 15 May) contributed to low levels of YDV infection in most years between 1983 and 1991. Knowledge of aphid flight activity after crop emergence can be used to decide on the need for insecticide spray applications to control vectors and to reduce YDV infections in crops (Farrell & Stufkens 1989;Teulon et al 1999a).…”

An ensemble model for predicting Rhopalosiphum padi abundance

“…In Canterbury, New Zealand, as in other parts of the world, BYDV is transmitted by at least six species of aphids, the most important of which is R. padi (Farrell & Stufkens, 1992;Teulon et al, 1999). In the Canterbury region, R. padi typically has two distinct flight peaks.…”

“…In the Canterbury region, R. padi typically has two distinct flight peaks. The first occurs in autumn when primary infection of BYDV takes place in autumn-winter sown crops, and the second occurs in late spring (Teulon et al, 1999). Historically, virus management was centered on late sown crops, so that plants emerge from the ground after the aphid flight period.…”