VINE TALK: Valuable lessons on disease control
By Dave Antrobus, Solutions Development Lead
The extreme weather conditions of the 2016/17 vintage will be one for the record books for sure! Across Australia, we’ve experienced unprecedented conditions from summer rain and heat waves in the east, to a cool summer interspersed by unseasonal deluges of rain in the west. I was reminded of just how extreme these conditions have been when I saw on the news a Swan Valley viticulturist paddling down the rows between his vines in a canoe. I felt disappointed for him, and many others in similar circumstances, to see all his good work ruined by elements beyond his control.
Thankfully, these intensities have not impacted as heavily on all growers, although weather conditions have created high risk scenarios for the big three foliar and fruit diseases: downy mildew, powdery mildew and botrytis.
As the season comes to an end, we are now well placed to assess what disease management strategies worked – and what didn’t – in these extreme conditions.
The large volume of rain meant preventative programs based on contact sprays were really tested and, given the conditions, persistence of contact fungicides on plant surfaces was a key factor. Good surfactant technology maximises the ability of the active ingredient to stick to the waxy cuticle of the leaf, resisting wash-off effects of rain and other degenerative effects of wind, sunlight and humidity.
It’s worth investing in well-researched superior contact products that have a history of proven performance. It’s preferable to use multi-site contact fungicides as the foundation of your disease management as these fungicides are considered a much lower risk to developing resistance and their use takes the pressure off the higher risk fungicides.
Furthermore, this season has highlighted to me just how important it is to protect your crop during flowering and berry development. It’s a critical time in crop growth. Strategic use of more robust sprays will pay big dividends and in this respect I have received a great deal of positive feedback about REVUS®.
REVUS as a superior protectant against downy mildew that not only binds quickly to the waxy cuticle of the leaf, but also moves through the leaf surface to be locked in, making it completely rainfast. The primary benefit is a rainfast preventative strategy against downy mildew that doesn’t get washed off and lasts longer than more traditional protectant products.
The feedback I’ve received has been that growers using more robust systemic sprays during flowering and early berry development have had greater success against both downy and powdery mildew. Growers that locked in a spray at the two key timings of 80% capfall and EL29 for botrytis control have also seen the benefits with clean crops.