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Grape Production in Short Season Regions: DMACC Midwest Viticulture Blog Timely information and ideas on growing grapes in a short season region

Grape Production in Short Season Regions: DMACC Midwest Viticulture Blog
Timely information and ideas on growing grapes in a short season region.

Grapes on Vines
June 10
Seasonal Issues in the Vineyard 2011
November 23
Realistic Grape Production

If I look at a cross section of the average grape grower in the Upper Midwest, a large portion of them do not come from a commercial horticultural background.  While that has its strengths, it also poses some concerns.

For grape and wine production to have a permanent place in the nontraditional grape growing regions, it needs to be profitable.  If I look at some of the growers in our region, if they factor in even a small cost for their labor, I would expect that many would not see a sustainable profit.  While some write off grape production as a ‘labor of love’, and you should only do it if you enjoy it, we need to be more efficient. 

The general trend for grape prices in our region is that in many cases there are decreases.  This hasn’t occurred in every state to the same degree.  Vineyards are a long term investment, so if one compares the shifting of row crop acreage between corn, soybeans, wheat, etc, much of that solves some of the supply and demand concerns in a short time.  Since a large portion of the cost of a vineyard is the actual first 3 years of establishment, we can’t expect a yearly ebb and flow of numbers of acres like we do in row crops, so if supply is catching up with demand, prices may take a hit.

While some try and silence these ideas, I think we need to face what might come.  In some cases the prices of different grape cultivars will be affected differently. 

One suggestion I have made to some growers that have an over planted cultivar or a cultivar that is decreasing in price is too not to suddenly jump out of it and replant.  Most of the cost of the vineyard is already been put up and so changing cultivars only adds to that.

If you have a cultivar that might only be selling for $XXX, figure out how you can grow it profitably for that price.  You may or may not be able to.  Before assuming you can’t, look at some practices you may be implementing that may not be cost effective.

When I communicate with growers or perspective grape growers I am often surprised at some of the practices that they are told they need to do, or practices they think are extremely important.

Here are a few practices that I question whether or not they are cost effective to do.  If you do them don’t get offended, but question if the benefit outweighs the time involved, because that is the true question.  We can micro manage too, but it doesn’t mean it will always lead to more profit or better fruit quality.

A couple weeks ago I had a question about raking of grapevine leaves in the fall and then shortly after that I came across a recommendation posted online from a grower that stated this was important.  While some diseases can overwinter on fallen leaves, I can’t see how taking the time to rake and remove them from the vineyard will lead to an economic benefit for growers using standard pest management. 

The same goes for removing all canes after pruning.  I am fully aware that they can harbor diseases, but taking the time to pull out every cane is not effective.  I have seen some growers with pretty slick ways of removing canes to a point where they can do it efficiently, but in most cases it will not lead to more profit.  I recommend going through the vineyard with a flail type mower to shred the canes, leaves, etc after pruning.  It will assist in them breaking down more quickly which will lead to less harboring of disease.  Keep in mind it is impossible to have a completely sanitary vineyard.

Mowing and skirting are two practices that make a vineyard look neat and tidy, but I question their cost effectiveness to the extent that some are using them.  We do need weed control in vineyards, but I have seen no evidence to show that mowing a vineyard twice a week to look like a manicured residential lawn will lead to better vine health and fruit quality.  The same goes for skirting vines.

While everyone has their own approach to grape production I think we need to question every practice we implement.  Its good business, and it’s good for the vineyard because then you have more time to focus on the practices that truly make a difference.  We need to be careful we aren’t making an acre a full time job.

November 15
The Year After: Scenario 2

During my first year in graduation school at Michigan State, the juice grape vineyards had an extremely low yield due to a very wet, cool bloom period.  Our plots yielded less than a ton/acre.  The following season we were ready to have plots that had a commercial level of fruit on them, however the plots received damage from a late spring frost when the shoots were about 2” long. 

At that point we were uncertain how well the plots would yield, but much to the surprise of many, the plots had a full yield.  The reason for this was that the secondary buds were extremely fruitful and had as much crop on them as the primaries normally did.  The reason for this was the vines had a low yield in the previous year and were able to allocate a lot of resources to the buds.  These vines had been canopy managed in the previous year of low yields and were pruned by people experienced with determining which canes were superior.  In this situation if the primary buds had not been frosted off, there would have been a bumper crop and if the season was long enough, the vines would have been able to ripen that bumper crop.  Since the primary buds had been frosted, a normal cropping level was still achieved.

So the question is, which scenario will you encounter?  It’s hard to say.  If you performed proper canopy management in the low yield years and there was no winter damage, I would say you are more likely to be in scenario 2.  However, I suspect more growers might be in scenario 1.  In this situation consider leaving extra buds, but make sure to consider early shoot thinning after you can see how fruitful the shoots are, not when the shoots have gotten too large.  This year, leaving high quality canes in less than ideal positions, instead of inferior canes in ideal positions, can also be an option to increase the chances of having a normal crop.  Hopefully these practices will not be required in the subsequent growing seasons.

November 05
The year after: scenario 1
A number of vineyards in the Upper Midwest were plagued with low yields this year.  A couple of factors contributed to this.  One of those factors was cold winter temperatures that killed off the primary buds which are more fruitful than the other buds.  In some areas yields were also limited by the disease infestations from the wet growing season which caused berries to drop.

In many parts of the Upper Midwest, yields were largely limited by the late spring freeze event that occurred in many places around Mother’s Day.  At that point, in many areas, the buds had broken and active shoots growth had started, leaving the vines prone to freeze injury.

Late frosts usually induce low yields due to the shoots from the primary buds being killed off.  Under cropped vines often respond by producing more foliage than normal.  This large amount of vegetative growth can be a challenge.

There are two main scenarios that can happen the season following a year of very low yields, however, they are very different to manage.  I have seen both scenarios happen and you can’t always predict which you will fall into.  Hopefully the following information can give you some guidelines to follow.

Scenario 1:
In the past couple of years a few growers in my region have had low yields due to a frost and then the following year were again disappointed by low yields.  This all goes back to that large amount of vegetative growth.  

The buds that we leave when pruning training systems with cordons are usually the 3-6 buds at the base of the cane, near where the fruit usually is.  In years with low yields often that excessive growth can cause a lot of shade in that fruiting zone.  Sometimes in years of low yields growers do not put forth the canopy management efforts seen in years of high yields since they see lower profits.  This can cause problems because the buds we prune to are differentiating in the summer (around July, depending on your location and growing season). This differentiation determines how fruitful and how cold hardy the buds can get.  The more sun exposure, the more cold hardy and clusters will increase in both numbers of flowers and numbers of clusters.  Shade has a negative impact on those attributes.

In these cases the first step to managing the vines is to avoid that excessive shade from happening by implementing some canopy management early in the season.  I am not suggesting photogenic vines are required, but some canopy management may be. 
If you are dealing with the aftermath of shade, you need to be more careful at pruning as compared to previous years.  Care must be taken to prune the best canes, canes that show signs of being well exposed such as having a dark color, short internodes, etc.  In some cases these canes will not be in the best positions on the vines since the cordon area often gets shaded when no canopy management is performed.  To get sufficient yield, you may need to retain more of these canes that were in the sun, but may not be in the best positions.   While this may not lead to the perfect vine structure, hopefully it will be temporary and next year you can prune to canes that are in better positions. 
Alternatively some growers leave longer spurs since often the spots on the canes farther away from the cordons are better exposed.  This does leave extra buds, which can lead to more shade, however, if a grower is diligent in shoot thinning, once the shoots are 6” long you can easily see which have clusters and which do not, this allows correction for the extra number of buds, but gives insurance for having sufficient crop.

Too often in situations of the ‘year after’ people prune as normal.  In these situations the canes that are in the ideal position on the vine, are the ones that had been shaded and not the ones that are fruitful and cold hardy.  This leads to low yields for a second year.  Recognizing superior quality canes is key to recovery. 
In the last few years I have seen many Edelweiss vineyards that have run into the situation explained above since they are difficult to shoot position during the growing season.  Low yields caused by frost have been followed by a year of low yields caused by pruning to inferior canes.

We'll address the second scenario in the next posting.
May 05
Seasonal Issues in the Vineyard: Free Summer Online Sessions from DMACC

For seasonal updates and some question and answer time, we will be using the website www.wiziq.com as a forum.  Through this site we will be offering 1hr sessions at 9 pm CT on the 2nd and 4th Monday of the month beginning in May and ending in August. 

 

This online forum allows up to date access to information, while not having to leave your home.  To get into the sessions you just need to click on the link listed for that particular date and time.  When the session begins you will be prompted for a screen name to be used.  I suggest you use your first name, initial of your last name and your general location (example: Randall V, Central IA).  If you are unable to attend the sessions while they are running live, you will be able to view the recording in the following days by going to that same link.

 

The way we will run the sessions is that I will start out with ~20 minutes explaining what I have been seeing in the vineyards lately.  The remaining time will be for questions and discussion.  If you have questions you would like addressed in the session, one option is that you can email them to me before hand and I’ll try and address them during the session. 

During the question time you will also be able to ask questions live if you are logged into the session.  To do that there are 2 options, you can type them in or if you have a computer microphone, you can be given access to ask them verbally.  Make sure that you have the volume turned on your computer to be able to hear the sessions. 

 

I hope that we are able to utilize this tool.  We will be focusing on issues regarding the cultivars grown in short season regions like the Upper Midwest.  We may have a few glitches starting out, but feel free to participate.  In the first session we’ll go over the basics of how the program works.

Schedule 

Seasonal Issues in the Vineyard: Monday, May 10, 9pm

http://www.wiziq.com/online-class/310739-seasonal-issues-in-the-vineyard-may-10-9pm

 

Seasonal Issues in the Vineyard: Monday, May 24, 9pm

http://www.wiziq.com/online-class/310741-seasonal-issues-in-the-vineyard-monday-may-24-9pm

 

Seasonal Issues in the Vineyard: Monday, June 14, 9pm

http://www.wiziq.com/online-class/310742-seasonal-issues-in-the-vineyard-monday-june-14-9pm

 

Seasonal Issues in the Vineyard: Monday, June 28, 9pm

http://www.wiziq.com/online-class/310743-seasonal-issues-in-the-vineyard-monday-june-28-9pm

 

Seasonal Issues in the Vineyard: Monday, July 12, 9pm

http://www.wiziq.com/online-class/310745-seasonal-issues-in-the-vineyard-monday-july-12-9pm

 

Seasonal Issues in the Vineyard: Monday, July 26, 9pm

http://www.wiziq.com/online-class/310747-seasonal-issues-in-the-vineyard-monday-july-26-9pm

 

Seasonal Issues in the Vineyard: Monday, August 9, 9pm

http://www.wiziq.com/online-class/310750-seasonal-issues-in-the-vineyard-monday-august-9-9pm

 

Seasonal Issues in the Vineyard: Monday, August 23, 9pm

http://www.wiziq.com/online-class/310751-seasonal-issues-in-the-vineyard-monday-august-23-9pm

May 05
Shoot Thinning: Count versus Non-count Shoots

In a lot of the viticulture guidelines and literature about shoot thinning we differentiate between count and non-count shoots.  Before we get into why this matters, let’s differentiate them. 

Count shoots are the shoots that arise from a node that we counted at pruning time.  So if we left 50 buds, the 50 shoots that in theory arise from them are considered count shoots.  Non-count shoots are shoots that come from places that we did not count at pruning.

The photo below shows the count shoots coming off of canes and the non-count coming off of older wood.

Typically it is thought that these non-count shoots have inferior quality fruit than count shoots.  For this reason they are often thinned off unless they are growing in blind spots where renewal is needed. 

There has not been a lot of work done with the differences in the fruit from count and non-count shoots.  The only published work I found was by Wolpert, Howell and Mansfield in 1985 with Vidal (Am. J. Enol. Vitic., Vol. 34, No. 2, 1983).  In this study they defined count shoots as those originating more than about a inch from the base of a cane and non-count as anything else.

What they found was that count shoots had about 60% larger clusters, ~5% higher soluble solids and a ~10% lower TA.  This is generally what we might expect.  The question remains is it the origin that determines the differences in ripening, or is it when they begin to grow? 

If we look in the above photo we can see that the lower right non-count shoot looks to be very similar to the count shoots in age.  However, the lower non-count shoot in the center of the photo is quite a bit behind in development.  It makes sense that the latter would be behind in ripening compared to the count shoots, but what about the non-count that is the same age as the count?  I don’t know, but my tendency is to put the emphasis on the age of the shoot (or when it started growing) rather than where it originates. 

Quite often we do have a lot of non-count shoots that start growing later than count shoots.  And in some cases these non-count shoots are very fruitful and can contribute a lot to the yield (see chart from Cornell Grape Pages ‘Training Systems’ by Bob Poole).

While I would tend to think non count shoots don’t hurt fruit quality a lot if they started to grow at the same time as count shoots, in most cases if they grow much later, not thinning off the fruit or the non-count shoots can be very detrimental to fruit quality (see photo below).  Keep this in mind when shoot thinning.

 

May 04
Shoot Thinning: Count and Non-count Shoots

In a lot of the viticulture guidelines and literature about shoot thinning we differentiate between count and non-count shoots.  Before we get into why this matters, let’s differentiate them. 

Count shoots are the shoots that arise from a node that we counted at pruning time.  So if we left 50 buds, the 50 shoots that in theory arise from them are considered count shoots.  Non-count shoots are shoots that come from places that we did not count at pruning.

The photo below shows the count shoots coming off of canes and the non-count coming off of older wood.

 

Typically it is thought that these non-count shoots have inferior quality fruit than count shoots.  For this reason they are often thinned off unless they are growing in blind spots where renewal is needed. 

There has not been a lot of work done with the differences in the fruit from count and non-count shoots.  The only published work I found was by Wolpert, Howell and Mansfield in 1985 with the cultivar Vidal (Am. J. Enol. Vitic., Vol. 34, No. 2, 1983).  In this study they defined count shoots as those originating more than about a inch from the base of a cane and non-count as anything else.

What they found was that count shoots had about 60% larger clusters, ~5% higher solids and a ~10% lower TA.  This is generally what we expect.  The question remains is it the origin that determines the differences in ripening, or is it when they begin to grow? 

If we look in the above photo we can see that the lower right non-count shoot looks to be very similar to the count shoots in age.  However, the lower non-count shoots in the center of the photo is quite a bit behind in development.  It makes sense that the latter would be behind in ripening compared to the count shoots, but what about the non-count that is the same age as the count?  I don’t know, but my tendency is to put the emphasis on the age of the shoot (or when it started growing) rather than where it originates.  A lot of times we do have a lot of non-count shoots that start growing later than count.  And in some cases these non-count shoots are very fruitful and can contribute a lot to the yield (see chart from Cornell Grape Pages ‘Training Systems’ by Bob Poole).

 

While I would tend to think non count shoots don’t hurt fruit quality a lot if they started to grow at the same time as count shoots, in most cases if they grow much later, not thinning off the fruit or the shoots can be very detrimental to fruit quality.  Keep this in mind when shoot thinning

 

 

 

April 02
Grafting Mature Vines

At the most recent Iowa Wine Growers Association Conference one of the more interesting topics in the viticulture session was one given on grafting mature vines.  There was enough interest that we are considering trying to have a follow up workshop late this spring.  If you are interested in potentially attending a workshop like this late May, please send me an email (rjvos@dmacc.edu).

As a young and growing industry, we are experiencing some ‘growing pains’ for several reasons.   There is starting to be more of a disconnection between the cultivars that wineries want and what are in the vineyards.  Everyone has different opinions on how this started and we won’t get into that here, but the reality is that it exists and so now we have to deal with it.

Figure 1: The vines are mature, productive, vigorous, there is a good trellis and they're paid for.  So what's the problem?  They're the wrong cultivar! 



Some growers are starting to rip out those cultivars and replant in the existing vineyard.  It’s not necessarily a bad approach since the trellis and so forth is the most expensive part of the investment, but many of these vines were mature enough to starting producing profitable yields, and now that they have been planted, it’s another 3 years until first crop.  Until this point I have been hesitant to explore top working (grafting) these vines.  Based on a lot of the information out there, the graft unions can be somewhat cold tender and in some regions are covered every year, however, for the most part, that is done with the cold tender vinifera.

The reasons for top working vines are a bit different than for planting grafted vines to begin with.  In general we top work vines only because we want to switch cultivars.  In general when using grafted vines at planning, it’s because the cultivar you want to bear fruit is susceptible to pests in the soil (phylloxera, nematodes, viruses), its low in vigor and you want to increase the vigor, or you have a unique soil situation that a rootstock is more adapted to. 

A key point is that if you are having trouble getting vigorous vines of a cultivar in your vineyard, top working those vines will not solve all your problems since you still have the root system of the previous cultivar.  In this case top working vines would not be helpful.

At the conference we had a grape grower/breeder/wine maker from NE who has been grafting cold hardy hybrids onto mature vines for quite some time with few issues of the unions succumbing to winters.  He has had a high percentage of grafts taking as well.  This was something that was helpful for me to learn and reinforced some of my thoughts.  A lot of growers in our region are now looking at this as a way to convert vineyards with mature healthy vines of a less desirable cultivar over to produce fruit from a cultivar in demand with only a year of lag time, as compared to 3-4 years lag time from a re-plant situation.

We are going to trial some grafting in a few locations this season and will follow the progression over the next few years.  Hopefully we will keep you posted on the results.

March 26
The Disconnect Between Vineyard and Wineries:  Grape Cultivars

The last couple of years grape growers, in some of the non-traditional grape growing regions such as Iowa, have come across a new situation.  In years past, there has been a shortage of grapes and now supply has caught up with demand and in some cases has exceeded it.

While it is getting increasingly difficult to sell some grape cultivars, some are still in demand.  In the past, in our region, there was not a real price discrimination between different grape cultivars, I see this becoming an increasing part of reality for grape growers in all regions, as it should be.

A common question I get in our region of the Upper Midwest is why some grape cultivars should be worth more than others.  If we look at other regions, there is a large price gap between grape cultivars (see Finger Lakes NY prices).  In regions such as MI, NY, PA, etc, the industry is quite diverse, ranging from the juice grapes like Concord and Niagara; hybrids like Chambourcin, Seyval, Traminette; and the traditional vinifera cultivars.  What you see in these regions are large price differences, in some cases nearly 10X the difference between the lows and the highs.

In these regions they have adapted management for each type of grape.  Juice grape cultivars can be grown with a lower cost of production than wine grapes due to their high yields, fewer pesticide applications, mechanization, lower canopy management requirements and predictable yield every year.  While I am not suggesting that these large price differences will become part of the industry in the Upper Midwest, I think the reality is that some will come and should come. 

As growers we need to identify which are the most profitable grape cultivars.  In many cases that I see, the ones that are the highest price per ton are not the most profitable.  Just as an example for here, I’ll use Vignoles.  If you have high quality fruit you can likely sell it at a good price, however, we are on the fringes of its hardiness, so the last few years bud damage has been extensive and yields low, even in a good year it is not the most productive cultivar.  The clusters of Vignoles are also prone to rotting from various pathogens, making an aggressive pest management program essential to getting it fully ripe.  All this costs money and increases risk.  Other cultivars we grow in the region have high yields, are easy to manage the canopy, and are quite disease resistant.  It’s likely as grape supplies get higher in some regions there will be more price discrimination.

February 19
Marquette:  early, mid & late.  What time of harvest was best?

This past fall I taught a course on how to manage mature vineyards.  In that course, we focus a lot on pruning, canopy management, crop load management, and vineyard economics.  In this particular section of the course, it was comprised of roughly 1/3 of students interested only in grape production and 2/3 of students who were more interested in wine production, or were looking to get involved with both grape and wine production.


During harvest, we collected fruit samples at 3 different times of harvest, roughly 2 weeks apart.  So, we had a range of about a month between the first and last samples.  From these samples I froze a portion of the juice for tasting later, and small batches of wine were made from the rest of the samples in Ames.  Last week we looked at LaCrescent and in general the students liked the middle harvest.

 

The students were given 3 different juice samples (early, middle and last harvest) and the wine made from the fruit picked at those harvest times.  The students were first asked to select the sample they liked the best.  After the preference was identified they had try to determine which harvest they came from.

 

Typically the advice given out on red grape cultivars, especially in short season areas of the Midwest, is to let them hang on the vine as long as you can.  In some cases this is an attempt to drop the high TA commonly found in some of our cultivars or to reduce the herbaceous flavors that some of the hybrid red grape cultivars can often have.


After some debate, most of the students selected the early harvest as the one that had both the highest quality juice and wine.  The term was that it was the ‘most ripe’.  Once again the question brings out the disconnect in what is ripe.  Is it the level of maturity or is it the matching of the proper flavors, sugar, acidity, etc. with the product being made from the grapes?

 

After selecting which had the highest quality, the assumption from what we are told with reds in our regions is to ‘let them hang’ and so the highest quality was assumed to be the latest harvest.  When pressed to decide which was the order of harvest, those that determined the harvest order based on the degree of sweetness and acidity got the correct harvest order, even though initially they assumed that the ‘best’ one was the latest harvest.  Once again preconceived notions may have influenced all our choices.  The most interesting comment that one of the students that works in enology made about the ‘best’ sample, which was the earliest harvest, was that it had more complex flavors.  Since I am not a wine expert I can’t speak much to that, but the student assumed that as the fruit for reds hangs longer it gets more complex, but in this case they did not perceive that.

 

So what about the numbers?  The early, mid, and late harvests had a brix of roughly 20.5, 23 and 23.5 respectively, and a pH roughly of 3.3, 3.4, and 3.5.  If you looked at the fruit samples, the early harvest was taken a bit later than I would have liked and by the time the late harvest came around the berries were showing some shriveling.  So it might be that by shifting the harvests all a week earlier might have given a better glimpse of a range of the commercial harvest dates.

 

I was surprised to see the results.  Once again, this was by no means a scientific study, and I can’t say that this trend will be the same every year.  I do think that some of the red hybrids could have improvement in quality based on spending more time on harvest timing decisions.  A few years ago I saw producers harvesting too early and I think there may have been an overreaction to that with some cultivars.  I don’t have much experience with Marquette, but I would use St.Croix as an example in that I think delaying a harvest too late can reduce the fruit quality.  For one, the berries on St.Croix seem to decide overnight that they want to fall off the clusters the next day, but also from the limiting tasting that I have had, it also seems to develop negative flavor traits by harvesting too late as well.

 

I don’t claim to have all the answers, but with all the work throughout the growing season put into quality fruit production, I am shocked at the lack of effort put into determining when to harvest grapes.  All the work put into the growing season can be diminished by improper harvest timing.

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