Managing smoke in the vineyard

How can I reduce smoke in my vineyard from controlled burns?

Whilst bushfires are largely out of our control, it’s well worth investing time in working with your local fire and natural resource management agencies and grower groups to collaborate on when, where and how controlled burns (for fire risk reduction) are carried out during the growing season. Stubble burns are generally low risk but open communication with district councils and cereal farmers can reduce any concerns.

• Fact sheet – Protocols for vineyard managers to minimise smoke taint from prescribed burns
• Fact sheet – Protocols for fire managers to minimise smoke taint from prescribed burns
• Fact sheet – Stubble burns

How can I protect my grapes from smoke before a fire?

Unfortunately, you can’t. Smoke ‘taint’ gets into grapes through their skins. There aren’t yet products available to spray onto the surface of fruit that have been proven to reduce or prevent smoke taint.

I can smell smoke – now what?

The good news is, that even if you can smell or see smoke in your vineyard, it doesn’t necessarily mean that your grapes have been affected. 

The likelihood and extent of smoke damage will depend on a number of factors. The most important are listed below:

Stage of fruit and leaf development –

Intensity of the fire – smoke from a large amount of freshly burnt vegetation is most likely to cause smoke taint. The longer it lingers, the greater the possible impact.

Proximity to fire – vineyards close to the fire are more likely to be impacted. 

Weather conditions – conditions like wind direction also affect how much smoke is exposed to grapes.

Grape variety – some varieties appear to more readily take up smoke than others. For example, thicker-skinned grapes like Chardonnay and Shiraz are less susceptible to damage, while Pinot Noir’s delicate skins do little to protect the fruit. You can’t assume that a poor result from testing from one variety in your vineyard will apply to all. To further complicate matters, grapes naturally contain low levels of smoke compounds and these levels vary from one variety to another.

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How bad is the damage? Grape testing options

Before you can make any decisions about what to do with your fruit, you need to know if (and how badly) the grapes have been affected. This may vary across different areas of your vineyard. 

Currently, the only option is for grape samples taken 2–3 weeks before your scheduled harvest date to be tested.

Grapes, juice and wine can all be tested for the level of smoke taint. Laboratories can test grapes and juice and provide advice on the likely effect on the wine made from them. Alternatively, the laboratory (or the winery) can make a small batch of wine from the exposed grapes to assess the likelihood of any damage in the final product. Assessment is made using analytical testing and/or tasting. 

If and how the grapes can be processed into something saleable, will depend on the level of smoke taint, the grape variety and any magic the winemaker can work back at the winery.  

Taking and preparing pre-vintage grape samples for testing 

How you sample, test and transport grape samples may vary, depending on the Phylloxera Management Zone your vineyard is located in, as well as the testing laboratory you choose.

However, to give you a general idea of what to expect if this is your first smoke analysis request, here are some generic guidelines:

• Test no more than 2–3 weeks before your planned harvest date.
• Plan your sampling date around opening times for collection points or laboratories and courier services to ensure freshness.
• Take grape samples early in the morning, before it gets hot and vines are stressed.
• Take approximately 30 random bunches from across the whole vineyard. No more than one bunch per vine.
• Keep different grape varieties separate.
• Keep samples cool.
• Consider keeping different blocks and vineyards separate.

After collecting all your samples:

• Pull about half the grapes off each bunch and mix them thoroughly in a large container.
• Take about 500g of grapes from the mix and double-bag them into two labelled zip-lock bags.
• Put in the freezer for at least 24 hours before packing on cold packs and sending to the laboratory.
• The labels on both bags should include the grower’s name and address, variety and block details.

Where do I get my grapes tested?

There is currently only ONE commercial laboratory that offers smoke compound and taint testing. Fortunately, there are multiple drop-off points across the regions.

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Smoke affected grapes - How to make the most of a bad situation

Harvest — but minimise smoke taint

If you have decided to keep the smoke-affected fruit for processing, there are some harvesting techniques you can use that may reduce the transfer of smoke taint-producing compounds to the grape juice. Whilst these suggestions work best when applied in combination, it is unlikely that anything you change during harvesting or in the winery will totally eliminate smoke taint in badly affected grapes.

Adding new techniques or technology to your usual routines may also add additional costs: you’ll need to estimate these and weigh them up against any benefits you hope to achieve by including them.

• Exclude leaves and stalks — they also absorb chemicals from smoke. Anything you can do to keep Material Other than Grape (MOG) away from the grapes and juice, the better.
• Consider how and when to harvest your fruit

When smoke hits your vineyard, smoke molecules are taken in through the surface of the grapes. The vine responds by attaching sugars to the smoke molecules, and the bound ‘smoky flavours’ end up mainly in the grape skins.

• Machine harvest quickly — it is now thought that you may typically have a 48-hour ‘window’ before the vine starts attaching the sugars to the volatile smoke molecules and locking in the smoky flavours. Consequently, if your vines are ripe enough to harvest when the smoke hits, taking them off the vine quickly (by machine) may be useful in reducing smoke taint in the juice.
• Hand-picking — reduces grape splitting and juice contact with smoke particles on skins and MOG.
• Process as quickly as possible — to reduce skin-to-juice contact.
• Keep your fruit cool — to slow down smoke-related reactions in the grapes.

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Cut your losses and dump your grapes

If you have decided that the smoke taint in your grapes is bad enough to make harvesting unviable, then there are things you can do to get the most out of your vines next season.

• Good news — smoke taint will not carry over in your vines to next season’s fruit.
• Take unwanted fruit off your vines early. Whilst there are pros and cons depending on your circumstances, removing smoke-tainted fruit with a mechanical harvester (at higher-than-usual ground speeds) is likely to be the most cost-effective choice. This is because:
  • Leaving grapes on the vine until winter pruning increases disease risk in the following season (and the associated treatment costs and possible fruit quality downgrades).
  • Rotting grapes attract biting insects and can gum up your pruning equipment the following winter, making routine pruning (mechanical or hand) more difficult and costly.
  • Removing fruit early will reduce the water needed by your vines during the growing season.
•  Standard canopy management such as wire-lifting or trimming need not be done, as long as the canopy doesn’t get in the way of machinery still in use.

Tip:

Develop good relationships with buyers in the bigger wineries with the capacity to blend. Have conversations during the year with other potential buyers of your fruit in case your expected purchaser rejects it.

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What to do with your unwanted fruit

There are pros and cons for each of the options listed below (including the costs of harvesting, transport or cultivating) and you will need to assess against your own business circumstances.

• You can drop grapes straight onto the ground from the harvester into the midrow or under-vine, where they can be:
  • Left to rot or cultivated into your soil to improve soil health, or 
  • Grazed by livestock such as sheep. 
• Alternatively, you may be able to go some way to offsetting your harvesting costs by selling grapes to:
  • livestock producers as a high-energy feed supplement (conditions apply)
  • a distiller for spirit production

Note – some distillers will use smoke-affected grapes to manufacture base spirit for gins, fortified wines or industrial use. Whether they will pay for them and how much, will depend on the distiller. Getting to know your local distillers and finding out early in the season if and in what condition they will accept any fruit, may be helpful if you need their support at short notice.

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Looking ahead — how to maximise next season’s harvest

Removing damaged fruit is just one step towards making sure vines are in the best possible shape to bounce back and deliver a decent yield next season. 

The care provided to your vines after fruit has been removed will affect next season’s budburst, vine growth and yield. Vine canopies and leaves need to be kept healthy by:

• Irrigating — keep water up to your vines to avoid stressing them.
• Pest and disease control — continue to monitor your vines and roll out your usual control methods right up to leaf fall.
• Autumn feeding — give your vines an extra lift after the growing season with a dose of nitrogen, phosphorous and potassium fertiliser.

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Frequently asked questions

Take care of yourself

Walking into a vineyard after a fire has been through can be confronting. Physical and emotional exhaustion from fighting the fire will make matters worse.

A calmer, clearer head will help you see a way forward. Talk to your friends and colleagues, and if you’re not sure where to turn next please reach out for professional support.

• Lifeline 13 11 14
• Beyond Blue 1300 224 636
• SANE Australia 1800 187 263