Apple scab and cider

[David Pickering]

This current cider apple season for my district has been a particularly wet one with consequent increased apple scab (‘black spot’, Venturia ineaqualis) infections. Making the best of this I have come up with a ranking of the English and French cider cultivars we have in Australia as regards their susceptibility to scab.

http://www.cideroz.com/cider-apples-black-spot/ 

Infection seems to be generally thought of as of little consequence and a preliminary on-line search would seem to confirm this - see two references below. Has anyone come across more specific references concerning the affect - if any - that scab infection might have on fermentation and subsequent aspects of cider production?

https://bsppjournals.onlinelibrary.wiley.com/doi/full/10.1111/ppa.12492 

The last paragraph of the discussion does give the idea that apples infected with the scab fungus would give no problems in cider production.

Differentiation in populations of the apple scab fungus Venturia inaequalis on cultivars in a mixed orchard remain over time

 

 

 

 

This study demonstrated that differentiation between V. inaequalis populations on different cultivars did not decrease over time in mixed orchards, indicating that a super race, if present, has not become common. This agrees with inoculation studies of isolates from the mixed orchard and other monoculture orchards (Barbara et al., 2008). Therefore, it may be concluded that mixed apple orchards could be a feasible component of an integrated management scheme. Although the reductions of 10–30% in scab are modest, it is likely that mixed cultivar orchards are beneficial in managing other pests and diseases too (Parisi et al., 2013). Implementation is particularly suited for cider and juicing apples, because cosmetic damage is unimportant and disease management need not be as stringent as for dessert apples.

The Pacific Northwest extension publication on ‘hard cider’ and orchards:

http://cesonoma.ucanr.edu/files/209991.pdf 

Page 24: Whether you have an existing orchard of dessert apple varieties and use the culls to make cider or are growing apples specifically for cider, the key point to remember is that apples used for premium cider must have good internal quality; that is, they must be fully ripe and free of rot and other damage. External blemishes such as mildew, russet, or mild apple scab lesions are of little consequence in cider production. A key to ensuring good quality fruit for cider making is to harvest only fruit that is fully ripe. Trees that have too high a fruit load, or leaves that are unhealthy (somewhat yellowed or diseased) can have poor internal fruit quality. See the sections on thinning and pest management (pp. 32 and 33, respectively) for more information regarding these issues. 

Page 33:  If you manage an orchard solely for cider production, a good pest control program is important. However, some pest issues can be tolerated at low levels. For example, external blemishes such as mildew, russet, or mild apple scab lesions are of little importance so long as internal fruit quality is good.

Cheers - David

David Pickering - "Linden Lea" 681 Huntley Road, ORANGE NSW 2800 Australia

http://www.cideroz.com/
http://www.cideraustralia.org.au/

[Claude Jolicoeur]

Hi David,

Here in Quebec, there is high scab pressure, and sensitive varieties may some years be very badly covered by lesions. I have seen fully black golf-ball sized apples...

I agree that light scab will not affect the juice/cider in any way. But for heavily scabbed apples, I find the yield is reduced while the concentration of the juice is increased. It seems the scab fungus reduces the content of water in the apple, thus the juice has higher sugar and acidity. This may in fact increase the quality of the cider, albeit reduce the quantity...

Claude

[Eric Tyira]

An orchardist/cidermaker I know talks a lot about the trees having to “fight” to stay healthy.  Part of that ends up as increased sugar and tannin.  

Perhaps the sugar level increases as a percent of liquid volume only because the water content is reduced?  I’d be curious if reduced juice in the fruit is a cause or effect.  Does the tree do this on purpose to fight the disease (much like our bodies increase in temperature to fight viruses) or does the scab cause the fruit to not be able to take up water?

Separately but related, a permaculture guy I know talked about higher sugar levels in the fruit as a result of scab.  This aligns with what Claude has observed.  

Back to the cidermaker, he mentioned the old timers would check the leaves for sugar levels and then spray sugar or molasses water to boost the sugar levels in the leaves, presumably to fight disease(?).  The question is whether this is healthy like eating an apple (to you humans) or just a sugar high like eating a piece of candy. 

No matter, I think everyone would or should agree that healthy soil is tops to give the trees a fighting chance. 

Eric

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[Andrew Lea]

On 01/04/2021 10:58, David Pickering wrote:

>
> Infection seems to be generally thought of as of little consequence and
> a preliminary on-line search would seem to confirm this - see two
> references below. Has anyone come across more specific references
> concerning the affect - if any - that scab infection might have on
> fermentation and subsequent aspects of cider production?

Here is the UK perspective from Liz Copas, our most respected cider
orchardist. One is from an article she wrote in 1985 (in Cider and juice
Apples: Growing and Processing) and the other from 2011 (in the Cider
Apple Growers Guide). See attached PDFs

I think there is rarely enough scab in modern commercial production to
significantly affect juice yield or other quality aspects. There is
anecdotal evidence for scabbed dessert apple fruits being slightly more
flavoursome than their unaffected controls, but whether this is due to
water loss or increased synthesis of secondary metabolites due to
environmental stress, it is hard to say.

Andrew


--
near Oxford, UK
Wittenham Hill Cider Portal
www.cider.org.uk
www.amazon.co.uk/Craft-Cider-Making-Andrew-Lea/dp/1785000152

[DICK KIRK]

If you like it the way it is, just drink happily. If you want slightly drier & more alc, either add slight amt of yeast nutrients and/ or small amount of yeast, to further the fermentation.

Dick

On Apr 9, 2021, at 5:55 AM, Len Nicholas <lennich...@gmail.com> wrote:

Hi Andrew

I have some naturally sweet cider this year as I have racked frequently and the cider has now stopped fermentation at 4.6% ABV. To protect the cider should I sulphate the juice as I've always had cider in the past over 6% ABV so not had to bother. Thanks in advance.

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