When it rains, it pours, and when it pours... we get Botrytis!

Thursday, September 27, 2012

Hi Folks,

The heavy rains we've been experiencing over the past few weeks have NOT been a welcome sight for grape growers... with such an early season and so many people close to harvest, this extra moisture is not what we needed.  I've been hearing reports of alot of splitting berries (especially in the Seyval and the Vinifera varieties).  If you maintained a good protectant spray program throughout the season and had good coverage before the clusters started to fill in, you will probably be better off than if you had not!  However in years like this where it was SO dry and so little disease pressure all along it's easy to get complacent and skip the odd spray here and there.  I think this fall is a harsh reminder of why those protectant sprays are so important - we never know what the weather is going to be like a week or two down the road, so best to be prepared for it.

There is no replacement for a good protectant program and it's hard to play 'catch up' after the fact but in conversations with Drs. Rick Delbridge and Paul Hildebrand, the best 'eradicants' are Switch or Pristine... however if you have a full blown infection they are not going to cure it... just hopefully keep them from getting worse if these wet conditions persist.  That said though, you need to watch PHI's for products as we are so close to harvest...Pristine has a 14day PHI and Switch a 7day PHI... Elevate, Scala and Vanguard are all excellent protectant materials but will not 'cure' the problem once the disease has become established.

You can check out all the products registered for Botrytis on my blog post below from earlier this year entitled 'Let's Talk about Botrytis'.

I thought I would share this article from Wayne Wilcox at Cornell entitled Understanding and Controlling Botrytis. 

For the wineries, I found an interesting article on Mark Cheins Penn State Wine Grape Growing website:  Fermenting with Botrytis 101

And finally we've been getting some questions about KMS (Potassium metabisulfite) and potential for inhibiting botrytis... I found this research article out of South Australia that suggests it has little effect on botrytis sporulation.  You can read the full article here.   

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