Vintage 2017 The Fungal Trifecta Powdery Downey and Botrytis

The coming vintage, 2017, is shaping up to be a vintage from hell. The coming vintage, 2017, is shaping up to be a vintage from hell, which the industry so desperately needs. Do not despair, help is at hand – careful management can produce a crop of tasty sound grapes ready for any winemaker Critical management is to prevent fruit damage and keep enough working leaves to ripen and properly flavour that fruit.

Temple Bruer 2011 Photo M Bruer To get undelayed ripeness, and correct varietal flavour, we need five or the equivalent of five mature leaves past the last bunch on a cane. Preventing fruit damage is about getting appropriate certified organic chemical and or biological protection early enough to be effective. Timing can be critical, especially with Downey and Botrytis. Leaf protection is usually less of a drama, although all three can progress at bushfire speed in the correct conditions. Observation is very important and you have to be prepared to commit the time to do this.

This spray needs a minimum of six hours of bright sunlight to work Powdery mildew, usually the most serious, easy to control early with a vegetable oil and bicarb. This spray needs a minimum of six hours of bright sunlight to work

For this fungicide the ratio of the two chemicals is vital here with 3ml of oil for every 4g of bicarb. Temple Bruer 2001. Photo P.Crisp

Micrograph showing the powdery mildew conidia Temple Bruer 2001. Photo P.Crisp

This spray needs a minimum of six hours of bright sunlight to work and therefore must be sprayed in the morning of a bright sunny day with spraying finishing six hours before sunset. Temple Bruer 2001. Photo P.Crisp

Unlike sulphur there is no minimum temperature that governs its efficacy. Temple Bruer 2001. Photo P.Crisp

This will eradicate powdery on flag shoots – something that no systemic spray will. This fungi grows on the surface of the leaf and is easy to kill. It is important to note that sulphur is incompatible with vegetable oil. Temple Bruer 2001. Photo P.Crisp

It lives inside the vine tissue Downey mildew, can be very serious with rain events seven to ten days apart It lives inside the vine tissue

This fungus is vulnerable when it emerges from the leaf prior to sporing. Temple Bruer 2001. Photo P.Crisp

Oil and bicarb will kill it at this stage, you only have eight to twelve hours before sporing commences – observation is critical. A binocular microscope is useful here. Always add Bordeaux mixture to this mix, 1.25gl-1 as some spores may have formed and be dispersed. Temple Bruer 2001. Photo P.Crisp

Botrytis cinerea – more usually known as bunch rot. Very serious with rain around harvest. Can go from 3% to 100% infection in seven days.

Best control is with another fungus – Tricoderma – 2 sprays needed, Coloniser at 20% capfall and Antagoniser at 80% capfall. Temple Bruer 2011. Photo M Bruer

Care needs to be taken with Antagoniser, immune compromised people should be kept well away from it. Some soft soaps can work post infection but by then the horse has bolted. Temple Bruer 2011. Photo M Bruer