Since my October posting the weather conditions have been such that one has been playing catch up.

Late October:  Above average rain ensured conditions were favourable for fungal diseases.  It was difficult finding a window of opportunity to apply sprays.  Many vineyards in the region were caught badly with severe outbreaks of Downy Mildew.  No evidence of anything here in the Gherardi vineyard, thank goodness!

November:  Wet, cool conditions prevailed right through the month providing conditions ideal for further fungal disease pressure.  These conditions were not conducive to good flowering and fruit set.  There have been many reports of “hen & chicken” in varieties which in all my years the likes of which I have never seen e.g. Sauvignon Blanc, Semillon and Cabernet Sauvignon.

December: Eventually the weather patterns changed and summer finally arrived.  More reports of issues with mildew  from around the region.  In my opinion spray programs and/or timing were the issue and more attention needs to be paid if spring weather like this becomes the norm.

Plans were put in place for further grafting of some Merlot over to Viognier, however we were waiting for warmer weather to facilitate the success rate.  I had already prepared the vines and at the insistence of my winemaker (Jurg Muggli) we thought we would knock over the 1,500 vines in 3 - 4 days!!!  It proved slower than we thought.

New Swiss grafting technique:

It is worth highlighting the features of the method.

• Bud wood is taken in winter and stored in a fridge.  I usually wrap in moiste paper and keep in a sealed plastic bag.
• “Rootstock Vines” are pruned hard to encourage strong water shoots from anywhere below the cordon wire.
• About a week before grafting enough scion material is removed from the fridge and soaked in water to encourage bud swell.  Even if some green leaf has appeared, this is OK.

• Contrary to most grafting methods hard wood is placed into a green shoot via a ‘V’ notch. 

• The join is then wrapped tightly ensuring it is airtight to allow good callusing of the graft union.

• After about 3 to 4 weeks, if the graft is successfull, the bud begins to push.

• I usually leave the tape on until next pruning, ensuring that the graft union has hardened sufficiently.

There is a lot of work keeping the top growth of the “rootstock vine” under control.  Once the graft has made about 10cm of growth, the top growth can be removed, string attached ready for training the new shoot.

We wait to see the overall results.  Keep you posted over the coming weeks.

Vineman

Technorati Tags: downy mildew, grafting, scion, rootstock

This entry was posted on Sunday, January 11th, 2009 at 2:28 pm and is filed under Vineman Tips, Gherardi Vineyard, viticulture, Season Predictions. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.