Q. Francisco, just to start, what does your routine look like during the harvest? Do you have a typical day?

A. Well, it's mainly vineyard work although it's true we also have quite a lot to do in the cellar. Especially at the beginning of the harvest when we have all the tanks and equipment to clean. But most of the time is spent visiting all of the valleys where we grow grapes. We set off early each morning to visit the different plots and come back to the winery at about five in the afternoon to do all the cellar work (trying the fermenting wines, decide macerations times, rackings, etc) and follow fermentation. We might work in the winery until late at night. Perhaps midnight. It depends. At the peak of the harvest we really are working hard. We'll finish at one thirty in the morning and back in at six. It's a very exhausting time.

But, you don't realise how tired you are at the time. And you see this in the workers too. There are very few sick days or people asking for time off. Until right after the vintage. Then everyone gets ill.

Q. And what decisions have to be taken day to day?

A. In the vineyards it's seeing how the different lots are ripening. Each vineyard is divided into different lots and we just go out and try them. Usually we have in our hands the 'vigour maps' that we took [using aerial photography] in January. We contrast the picture of the vineyard we have in the photograph with the reality. Once we have tasted the grapes we then have to decide what to pick. It's not a matter of sugar levels – we have no problem with that in Chile. It's mainly to do with skin ripeness or the acidity in the grapes. But, this is the key part of the harvest. I work through every lot by tasting.

Q. So just talk us through the various people involved. Who does what?

A. You know as Chief Winemaker I can't do all the lots every day. So in fact I have eight winemakers and they check and then prioritise the various tasks. Two of them (the more experienced ones) help me following the lots following in the vineyard. They'll call me and say 'no, don't worry, this lot still has two weeks to go' or 'we need to think about harvesting this. It's getting ripe'. When it's close to ripeness I can go.

But because we have fruit across 1000ha (hectares) in different sites it can take along time. You can easily do 600 to 800km a day in the peak of the harvest getting around the different lots, even when you have all the work prioritized like this.

Even when we have all this information I still have a challenge. I've got a sheet with the kilos of grapes to be harvested and the priorities and we send all the information to the viticulturalists who then have their picking programme. Between us we decide on whether to use bins or cases or refrigerated trucks. For instance, for the Icon wines we use small 15kg cases and refrigerated trucks. For the reserve wines we use the small cases in open trucks and then for the varietal wines we use 400kg bins.

We must remember the winery has a maximum capacity of cases that it can work with. It can only accept 30 tonnes a day through its sorting tables. And we're working twenty-four hours a day. Now if I send less I have 12 people doing nothing for hours at the sorting tables, but if I send more then the grapes are sitting around and we can't do that. So it's quite a lot of logistics.

Q. What sort of help do you and your team have to make those decisions? Has technology changed the way harvest decisions are made?

A. Our 'vigour maps' are one of the tools we use. They are aerial photographs of the different vineyards taken in January. Usually vine vigour is related to canopy growth [of leaves and shoots] and so the clusters in more vigorous areas have more leaf cover. So these will tend to be greener tasting and ripen later than the less vigorous lots. Now you have to verify that by taste. But then this is just one tool. Technology changes lots of things. For instance, going back to the sorting tables, these improve the quality of the grapes and therefore the wine.

Q. Errazuriz has done a great deal of work using precision viticulture – how does that affect the way you harvest the grapes?

A. Again, in precision viticulture, vigour maps are only one tool. To really know your vineyards you will have a broad variety of tools. Aerial maps, soil maps and so on. And you can build up a picture of how much water to use, for instance. And that will have an impact on the yield of grapes that you have from each vine. Or other inputs in the vineyard. As you build up you start to have images of the costs of different lots and how economic they are, the quality of grapes, the environmental impact and so on.

Q. And what part does tradition play? Do people still rely on any folk wisdom handed down through the generations when harvesting?

A. I guess we do. We use both technology and tradition. You cannot really replace tradition because in the end I still go and check everything myself. Because when you take photographs in January that's just one reality that might change. Also for me, even with all the chemical analysis of grapes – sugar, acidity, phenols -you still have to try the grapes. You need to be in the field to know when they are ready.

And it depends on the variety. In Sauvignon Blanc we're looking for intensity and freshness and a certain level of acidity. But we don't really need to pay as much attention to the skins and the phenols. But with the reds it's mainly a question of the skins, tannins and colour! I look to see if the seeds are brown – that's a good indicator of ripeness. The pulp. Is that green or transparent-brown? And then of course different varieties behave in very different ways. For instance the feeling in your mouth, between the leathery character of Merlot skins and the brighter, softer character of Cabernet Sauvignon.

Q. I know that Sauvignon Blanc is particularly interesting to harvest – how critical are harvest decisions when you are dealing with Sauvignon?

A. It's a very sensitive variety. Very tricky. Chardonnay is much more forgiving. We're looking for a grassy, fresh style. When you're looking for the right time to harvest it, blink and you... well, you don't have a wine that's awful. But it will be less fresh. It's probably one of the varieties where you have to be most careful.

Q. And how does that process compare with other white varieties like Chardonnay?

A. Well, usually a portion of Chardonnay goes into oak, especially for the Reserva wines. So you can always make up for a later harvest by putting less of the wine in oak. Or you might use less malo-lactic fermentation to keep freshness in the wine. If you like there are more tools you can use in the winery to help you.

Q. So what is it about Sauvignon Blanc that makes harvest time so critical to the eventual quality of the wine?

A. When you lose acidity... you lose acidity. And this is a wine that's all about freshness and bright flavours. You can't make that up in the winery.

Q. Talk us through this particular vintage – what challenges has it thrown up?

A. Up until now, the weather has been good this year. We had some rain in February although that didn't affect us adversely. The whites are really healthy as March was quite warm. (Although not today. It's pretty dull and cloudy today here. But there's no real risk of rain.) The yield is lower than last year but then the harvest is more concentrated than in 2006. By this I mean we are harvesting everything quicker, as everything is coming ripe together.

We're still picking Chardonnay, Merlot is already done and we'll finish Cabernet by the end of April. In some ways 2007 is more typical than 2005 and 2006 were. We're not going to be waiting too long into April and May. It's faster and getting pretty busy just now. It's a good vintage though, better than 2006.

Q. Just to give people a sense of what's going on, during this period, can you describe a choice you might make now that would have a really noticeable effect on the wine in our glass when it arrives here in the UK?

A. Well, we deal with that question all the time, because you have a market style in your mind. Also you have to be in touch with what people want. When you are in touch with what the customer likes, you can decide the way you want to go. For instance, there's a big difference between the UK and US style, and then there's always the style you like as a winemaker. So you are starting to think about issues like whether the wines will need to have oak, how much ripeness you are looking for, and the style of tannins in reds and then of course how that will influence the alcohol levels. Interestingly, in the US people look for soft tannins and are very forgiving of the high alcohol you get from leaving grapes on the vine to ripen the tannins. But in the UK, the British are much less forgiving and like wines with less alcohol. You really do have to be thinking about all sort of thing all the time to produce wines everyone will like!

Q. It's obviously quite an intense time for everyone. How do you deal with the workload and stresses of such an important time of year?

A. In a way, people who decide to become winemakers choose this way of life. It's very hard and there are no short cuts. I have university friends who decided that the pressure of harvest was just too much. They went into teaching, or research, or the analytical side of wine.

But maybe those of us who stay must be a little...masochistic? We seem to thrive on the stress. Because after the harvest, of course, one has the stresses of fermentation! Will we have a stuck fermentation for example? What will we do? But I guess people do it because they love it. You get tired, of course! Especially in the mornings when you have to get up and you're really tired from the night before. But yes, I think that for all of us in the winery... you see people happily doing this. I think it's true. I think we are all probably slightly masochistic.

Q. Obviously this is just one part of the harvest and the winemaking process. What thoughts are going through your mind now regarding the rest of the harvest and work coming up?

A. Well, today, as Head Winemaker I have other responsibilities. I've a great team on site, but I also have visitors to receive. For instance, in half an hour I'm to meet our Japanese importers and we'll talk and then have lunch together. Just half an hour ago I had a video conference with our office in Santiago, discussing quality control issues. Not just harvest issues, but throughout the entire winery. So there's much more to do than just the harvest!

Sometimes I miss being an Assistant Winemaker, and harvest time makes my job much harder with all these other responsibilities. Even so, I still have to try the grapes and wines. So tonight I'll set off the vineyards and work there until around 6.00pm, and then come back to the winery to work late. My wife is French though, so she goes to France each year for the harvest with our young daughter. It's easier really. That way I'm not worrying about coming home or ignoring her. We know that this is the best way – so I can concentrate on the harvest work.

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