The stripe rust epidemic in 2003 resulted in the infection of a number of wheat crops of various varieties in the Parkes area. The decision to spray or not to spray was a difficult one given the timing of infection and the severe drought conditions experienced at the time.

Objectives

The aim of this demonstration was to determine if an economic result was seen after spraying of an H45 crop for stripe rust.

METHODS

Location: Goobang Valley

Cooperator: Allan Forbes

Rainfall 2002:

TRIAL DETAILS:

2003: H45 sown with 100kg MAP

2002: Canola sown with 250kg Single superphosphate and 50kg MAP

The H45 crop was sprayed with Tilt at 250ml/ha with 70L water on the 20 September 2003. The crop was at ear emergence and the stripe rust was still in hotspots across the paddock (<5% infection level). Although on minimal soil moisture, the crop looked like it could yield at 3t/ha or more and so the decision to spray was made. A section in the corner of the paddock was left untreated. Two 30m strips were harvested from the untreated and the treated areas.

Results and Discussion

There was no significant difference between the yield of the sprayed and unsprayed sections. This result indicates that there was an economic advantage to not spraying, in this trial.

The stripe rust damage tended to occur in patches across the paddock and within the sampled areas. The crop was badly hit by frost and moisture stress in September and October which resulted in lower than estimated yields. These issues, which are seasonal effects, mean that the information from this trial is greatly affected by the season in 2003. 2003 was not a typical year in the Parkes area, so the results from this trial should not be used until more work is carried out in more typical seasons.

More work on this subject is expected to be carried out in 2004.

Acknowledgments

Allan Forbes (Cooperator), Dubbo CEU unit, Central West Farming Systems