Dead Arm question.
Not the wine, the Eutypa version! What causes it, and how best to deal with it? I could of course look it up but who needs to be resourceful when you have the DJ's?!
Thanks in advance.
Kristoff
Hi Kris,
Eutypa is present in many vineyards- of all ages.
All wine grape varieties are susceptible to Eutypa Dieback along
with many other plants including Almonds, pome fruit trees and willows.
All can be a source of disease.
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| Eutypa dieback of grapevine caused by Eutypa lata. Courtesy G. Munkvold |
Eutypa is caused by the fungus Eutypa lata. The fungus produces
ascospores on old infected wood and is spread by rain splash traveling
on the wind.
The spores are able to travel large distances and can infect fresh,
unprotected wounds, such as those left by pruning cuts. Spores are
produced all year but can only infect fresh cuts during wet weather.
Treating exposed trunk wounds with particular fungicides or physical
paint based barriers will prevent Eutypa dieback infection and is a
recommended practice where cuts greater than 20 mm are needed. Click
here for information on wound protection - http://www.sardi.sa.gov.au/pdfserve/hort/hort_crops/grapes/eutypa_trunk_disease/eu_pruningwound_fung.pdf
Once a vine is infected with Eutypa the only method currently
available to growers to eradicate the fungus, is to remove infected
tissue using remedial surgery. There are two main approaches to remedial
surgery.
i) Cutting off the trunk at least 10 cm below any signs of obvious infection and training up a watershoot or grafting.
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| Remedial surgery - (c) SARDI |
ii) Training a healthy shoot from the base of the trunk and removing
the infected trunk once the new shoot begins cropping. Click here for
more tips on remedial surgery.
Once inside the vine the fungus slowly grows spreading over a period
of years along cordons and down to the trunk. Eutypa moves along the
vines water-plumbing (the xylem).
Eutypa dieback causes characteristic stunted shoots, most obvious in
spring, small bunches and in cross-section, a wedge of discoloured dead
wood. It contributes to the decline of vineyards by reducing growth
and yield. Bunches are smaller from a Eutypa infected vine, compared to
healthy vines. Eventually Eutypa will kill vines.
Eutypa infection can be prevented by avoiding pruning cuts during
wet weather. Pruning cuts made in early winter remain susceptible to the
disease for some weeks, while those made in early spring heal much
quicker.
If possible delay pruning until August for high risk blocks or those already showing signs of the disease - http://www.sardi.sa.gov.au/pages/hort/hort_crops/grapes/eutypa_trunk_disease/eutypapage1.htm
Comments
I bought an old vineyard with some 80 year old bush vine grenache. Half of the vines are dead or missing and I think half of the remaining ones have the symptoms of Eutypa. I want to do my best and try to save as many old vines as possible, and here is my question:
I read a lot about rejuvenating an old vineyard and some authors recommend to cut the trunk almost to the ground so the root system will send some new shoots close to the cut.
Is this really possible, would the vines produce new growth from the old trunk?
Any suggestions are more than welcome.
Thanks
Stan
Vinifera is basically a weed its harder to kill than you think.
Having said that it would be risky to cut at ground level.
If they are 80 years old the root system will be massive which will help.
Before you get the chainsaw out get someone in the know to assess the yard and get a plan together. Most old vineyards like yours just aren't viable.
But if your thing is making Old Vine Grenache then it might be doable.
Personally rather than risk a failure with the few remaining vines I'd start by training a water shoot up (maybe 2)from near ground level, you might have to do a hard prune of the head to encourage this.
When you've got some viable shoots then cut the head off the next year. The following year (year 3) the stump will go nuts with new shoots with any luck.
Of course I'm assuming the Eutypa is removed if you do get to the cutting stage.
Following that I already organised for two experienced people to come and have a look at the vines.
Cheers
Stan