Some people hear ‘fungal resistant’ and think that means all they need to do is plant the vine, prune it and then collect the fruit at harvest.

As I spend much of my time working outside of the UK, quite a lot of my contact with people there comes to me in the form of letters.

I recently received a letter from a friend in which lay a comment…”Some people hear ‘fungal resistant’ and think that means all they need to do is plant the vine, prune it and then collect the fruit at harvest…”

This got me thinking as I felt a bit uncomfortable with this, and perhaps I might be able to offer some insight around this matter to help people gain a broader understanding around the subject.

‘Resistant’ as applied to some vines of fairly recent crossings, is best to be considered as only being half true.

Whilst a recently released new variety might very well hold a mix of genetic information from its diverse parentage offering a form of resistance, this does not always last forever.

Consider that this resistance could be termed as a ‘barrier’ within the vine, and this inhibits the actions of an attacking mildew, please be aware that this ‘barrier’ is fixed in place. As such it cannot vary or change.

We are familiar with how our own complex bodies build forms of ‘anti-bodies’ resulting from infections, or inoculations. These can greatly assist in resisting future waves of infection that move through our population. Certainly we are more aware of matters around this after the years of Covid-19.

The vine with but a ‘fixed barrier’, (my words,) is thus compromised in its ability to fend off new variants of mildew.

As the mildew reproduces, (which it does with many new generations every few years,) there is a very real possibility that a mutation might be created. 

Supposing that this mutation allows it to break through a resistant vines defences… very quickly that new mildew will multiply, and soon it will infect all such vines that it encounters unless they have been adequately covered in a fungicide spray.

I am aware that this sounds like an absurd situation, the resistant vine that is not resistant but the fact is that the vine is resistant up to the time when a stronger mildew arrives in the vineyard.

Mutations in new populations of mildew are inevitable, at some time, however you might get lucky and get away with offering no protecting chemical cover, and for some years, but not forever.

It is for this reason that it is often advised that recently released resistant vines are given strategically timed sprays, say first leaf, 80% flowering, and just prior to bunch closure. This is normally considerably less spraying than with V. vinifera, certainly in warmer European areas and in risky regions of periodic heavy thunderstorms, but it can be enough.

The truth of the matter now, is that many such older, and supposed resistant varieties, are simply past their resistant life.

They might very well have other attractive attributes, a good crop, early ripening etc, and for this they can still be grown to good advantage. Here it helps to spray in future years of growth much the same as for a V. vinifera variety.

There are some varieties that whilst being older do yet carry on with some robust resistance. This might be more apparent for particular varieties, and in particular regions.

I believe strongly in being ever vigilant always looking for early signs of infection no matter what variety you are growing.

This ‘scouting’ or seeking out early days of infection can be very important, I sometimes feel people neglect to show enough effort to doing these searching vineyard walks, (around sundown/evenings are often the best times for leaf observations.)

Botrytis operates a little differently, and for which there is no resistance as such, by some internal barrier type mechanism.

There are many things that breeders look out for whilst running field trials for new varieties. For grape clusters, much of the forms better equipped to fend away Botrytis simply hold a few physical benefits.

Loose cluster, where I include ventilation between the individual berries, but also a canopy in which heavy clusters do not lie directly over another lower cluster (often trapping a leaf in between.)

Individual berries with a thicker skin perhaps, or maybe a better coating, a form of a waxy layer over the berries skin. 

Looser clustered varieties in some regions appear to not harbour so many damaging or detrimental insects within the mass of rather protective little floret or berry stalks. This being compared to other types of a more tight, cylindrical nature. Some of these cylindrical types can also ‘self pull off’ individual berries as they all swell up at veraison, and thus leave an open wound in berries on some clusters and from which infections arise.

Where to from here? This is a question that is almost answered for us as breeders have been working on a series of ‘next generation’ vines.

The idea being to breed into a vine multiple layers of resistance, and also for each of the possible major forms of fungal resistance.

This is where the smart money is operating in modern breeding, where there are now many new varieties awaiting field trials, and micro vinifications, etc.

It is a complex matter, and after which the vines have to show that they produce acceptable wine, (or perhaps your interest is in table grapes, and why not?).

Fungal infections further south in the warmer climates can be explosive in the right conditions, as compared to the benign climate of cooler regions. However there are many truly capable resistances being successfully bred into new varieties, and with no GMO type toad genes being spliced into place here.

There are known multiple resistant vines being bred which are then crossed with more tasty varieties, and out of which their offspring can be tested by genetic marking.

If the offspring carry many ‘layers’ or barriers from which it is considered extremely unlikely for infection to find a way through, then these vines are a truer long term prospect to be resistant, and are given field trials.

An interesting aspect that arises from some of this work, stemming from the nature of some of these complex genetic influences, is that occasionally it is found that a vine is unusually early ripening.  It is these vines that are of particular interest me.

Whilst much of the above might sound a little odd to people who do not move in the circles of new vine developments, there is a lot more to aspects of modern viticulture than often gets talked about.

A bit strong to call this a time for a revolution, but it carries some of the most significant changes for the wine industry, since the introduction of phylloxera… and then rootstocks and grafting was learnt and put to use.

It all happens in a vine nursery, so much more dynamic than simple grape processing by wineries!

I’m pleased to conclude by letting you know that new varieties here in Germany, are now giving rise to new styles of wine being released, and sometimes it feels like it occurs weekly.

Yesterday I came across in a supermarket a Kloster Eberbach Muscaris/Hibernal, for just shy of 10 Euro (which is a good price here).

Big company, highly regarded, lots of bio credentials, a vast history as well as a great future, and with close to 500 acres.

New varieties that are not so dependant on chemical applications are here now, and are here to stay.

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