Saturday, January 29, 2011

Downy Mildew - UPDATE 29/1/2011

In the Adelaide Hills - Downy Mildew oilspots continue to stay alive and in some cases are increasing in size and damaging berry stems causing fruit to dry out (below).

Donwy mildew has 'burnt' off part of this bunch as it has developed.
In all regions - We can see fresh oilspots from the Secondary Infection on the 13th and 14th of January. These new Downy Oilspots are of a small size and are beginning to turn red. Favourable weather including heavy dews in the Adelaide Hills have cause some advanced Downy Mildew infections to form a mosaic pattern on leaves (below).

Downy Mildew secondary infection spread. Note the mosaic pattern.
Secondary infection conditions are quite different to primary infections and can occur outside of a 10:10:24. For a secondary infection to occur there must be existing oilspots in the vineyard or located nearby. Unfortunately this season a high percentage of vineyards have been spreading Downy Mildew into those around them.

2010/2011 Downy Mildew Summary.

1) 10:10:24 Primary Event – 30th October - This was confirmed by the finding of Oilspots from this 10:10:24 Event in mid-November.

2) & 3) Two Downy Mildew Secondary Events (Warm, Wet Nights) 12th and 14th of November.

4) One Downy Mildew Secondary Event (Warm, Wet Night) - 24th of November.

5) One Downy Mildew Secondary Event (Warm, Wet Night)- 7th of December.

6) Two Downy Mildew Secondary Events (Warm, Wet Nights) - 13th and 14th of January.

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