Tuesday, November 9, 2010

Red alert for the Riverland - Downy Mildew Status as of 5pm 9/11/2010

RED ALERT


Primary Event and multiple secondary events have caused a Downy Mildew outbreak to begin. Rain is expected to be suitable for further Downy Mildew secondary events, warm wet nights, on Saturday and Sunday.

Our sources in the Riverland have taken these photos showing what to look out for;

Downy mildew on flowers.
Downy mildew on a leaf.











Left - Downy Mildew on inflorescences after an overnight bag test.  
Right & Below - Downy Mildew spread on leaves.

Downy mildew on the front side of a chardonnay leaf
Get professional advice - Now!

Downy Mildew is a rare disease and as such needs specialist advice specific for your situation.

With vines rapidly growing - there will be a much shorter period of effective cover. Shorten the intervals and don't assume that just because sprays went on that you have avoided infection.

Be skeptical of rain fastness with over 25mm of rain. If over this amount of rain occurs it is likely to wash off most of your protection.

If in any doubt - and primary infection (10:10:24) and/or a secondary infection (warm, wet, night) is confirmed - spray with metalaxyl rather than relying on the action of protectants. This is especially relevant with patches that will suffer fungal attack from subsequent secondary infections at / close to flowering.

You cannot kill oilspots once they are visible. You can only control their spread.

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Unless effective action is taken now, yield loss is likely in the Riverland this season as inflorescences are vulnerable to infection at this stage of the season, Capfall, EL 19-25.

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