Published on 30/09/2021
And this spring what they are finding is plenty of disease, whether it is net blotch on barley or stripe rust and speckled leaf blotch on wheat. Bayer staff know from experience that three key factors are key for effective disease control: Go early, Go hard and Go on time.
Clearly this spring it is very important to go early with disease already evident. The first fungicides are going to have to start without delay, at growth stage (GS) 31-32 in barley and GS32 in wheat.
For paddocks where disease is evident a GS30 application needs to be part of the fungicide programme.
The first fungicide needs to be very robust. It is always important to start fungicide programmes with strong, effective fungicides and to use full label rates. Getting on top of disease early makes it much easier to control or the rest of the season.
Paying attention to the spray interval is very important for successful disease control. Ensure an interval of 25-28 days between your GS32 and GS39 applications and 21-25 days between GS39 and GS60-65 applications.
Every year Bayer conducts fungicide trials to understand the performance of its fungicides under NZ conditions.
In spring 2020 Bayer conducted four wheat trials, one in the lower South Island, two in Canterbury and one in Southland.
The geographical spread was particularly valuable last year because although disease levels in Canterbury and Southland were low to moderate, in the lower North Island heavy and consistent rain resulted in intense pressure from speckled leaf blotch and leaf rust.
Whatever the disease pressure, control by VIMOY iblon + Prosaro applied at GS39 proved to be outstanding, giving excellent disease control which led to impressive green leaf longevity.
But as is the normal practice in NZ, VIMOY iblon + Prosaro at GS39 was followed up with a GS65 fungicide application of either Prosaro + Amistar or CALEY iblon.
By doing this, disease control and greenleaf longevity were further increased and impressive yield increases resulted.
In the case of the GS39 VIMOY iblon + Prosaro and GS65 Prosaro + Amistar programme, the yield increase was 2.5 t per ha, giving a profit of $660 per ha. For the GS39 VIMOY iblon + Prosaro and GS65 CALEY iblon programme, the yield in-crease was $3.1 t per ha, giving a profit of $850 per ha.
All of the fungicide treatments tested are mixtures of fungicides with different modes of action so they provide a sound fungicide stewardship option to delay the development of fungicide resistance.
While extremely pleased with the performance of VIMOY iblon + Prosaro and CALEY iblon the Bayer team were not surprised. In Bayer trials in NZ these fungicides have always performed exceptionally well.
Words: Neil Waddingham, customer marketing manager, Bayer Crop Science