Week 12 (Sept. 2 - 6th)

The day has finally come! Harvest season has begun! The much anticipated harvest was kicked off this week with the picking of MN 1259. It is a very early ripener, so we will have to wait a few more weeks to pick he next variety, but the five lugs which we picked from 7 or 8 vines was a successful opener to the season. 

Across the board acid levels are dropping, while sugar levels rise as we progress into late summer. Due to this, I am tempted daily by the luscious, hanging fruit, as this is the first time that they are actually palatable. I find myself mindlessly plucking a berry and popping it into my mouth every few vines, but this isn't always a rewarding act. Within seconds I either pucker, cringe and spit or smile and enjoy the sweet, flavorful fruit. Most varieties by now look ready to pick, but only a few in actuality have reached their desired, full potential. I guess I'll just have to wait to experience the best that the vines can offer! 

In the field we cut each cluster, pick out the bad fruit and shot berries, and then carefully lay them into these yellow lugs. We then transport them to the winery, record their weights by vine, randomly select 50 berries and record their total weight. 

Next we press the fruit. We use this mini bladder press, which is filled with water from a hose. We allow the rubber bladder inside to reach 25 psi (or around 2 bar), release the water, mix up the pomace with our hands, and then do it again. Three presses effectively squeezes out all the juice while retaining the stems, skins and seeds inside. 

Green and orange horn worms like this are becoming problematic in the newly planted vineyards. They are stripping the leaves from the young vines at a rapid rate. We use an integrated form of pest management to control this problem (we squish them). 

We spent the tail end of the week preparing for Saturday, our open house fall tour. We invited close to one hundred local residents and growers so that they could learn about grape growing and breeding, taste grapes, and tour our vineyards. Peter, Raina, and I spent Thursday and Friday collecting three clusters from 75 varieties. The grapes ranged from table grapes to V. vinifera wine grapes to MN wine grapes. It was fun to be able to compare different varieties side-by-side and determine their intricacies in sugars, acids, textures and flavors. I was also able to network a little and meet local grape fanatics like me!

Week 11 (Aug. 26th - 30th)

We spent a few days touching up the nursery this week so that Peter can more easily evaluate the progress of the young vines. The nursery floor was covered with a mat of purslane, a weedy succulent, but this was not necessarily a bad thing. Due it its density, the purslane helped retained soil moisture and out competed other more difficult-to-control weeds from spreading. We tilled the aisles, hoed around the the plants, and then tilled the aisles again. Afterwards we had to carefully inspect the drip tape for leaks since our hoes were pretty sharp. 

New shoots, whether they on a spur or young vines like this, are hardening off now that the days are getting shorter. In doing this the vine is sealing itself off to the environment that surrounds it while forming a periderm that will be able to withstand the winter. Since vascular flow is gravity assisted, shoots that are pointing upwards are hardening off much faster than their downward facing counterparts. Due to this, a VSP training system is one of the most effective for cold hardiness.

Some varieties, such as many vinifera, are poor at depositing and maintaining appropriate levels of callose in their vascular system during the winter months. Therefore, water may begin to flow into the trunk during warm days and then freeze once the temperature drops back below freezing at night. This causes trunks to split, such as in the photo above, and the plant to die. Growers need to carefully judge how much fruit they allow each vine to bear during the growing season, which will determine how stressed on resources the vine is going into the process of hardening off. Also, if possible, they need to allow the vine time to stabilize and prepare itself for winter after harvest and before the first frost. It's a tricky to be able to judge what to do when in order to maximize winter hardiness in cold-climate grapes.  

Black rot is still affecting some grapes. At first I thought this was merely sunburn, but then I realized that sunburn is more widespread over exposed clusters, while this discoloration on select berries. Temperatures over 95F inhibit evapotranspiration, which helps cool the plant, and intense sun lyses enzymes in the pulp of the berry, which is effectively a small greenhouse. Below is a photo of what sunburn looks like.

In order to prevent sunburn one needs to be selective in their leaf-thinning. Without the leaves to shade the clusters, the berries heat up too much. This causes them to raisin and fall off.

Week 10 (Aug. 19 - 23rd)

These are Frontenac Noir and Frontenac Gris vines side-by-side. Frontenac, just like Pinot, is prone to yielding bud mutations every now and then. This means that maybe one out of every million buds will have a mutation in one, or multiple, genes which control color. These buds form into shoots normally, however they produce fruit that is distinguishable from the rest of the shoots on the vine. If noticed, a cutting can be taken of the mutant and propagated vegetatively. In some cases Frontenac has been known to mutate from Noir to Gris, as well as Blanc, and then even back to Noir. This last part is exciting since the bud that mutates back may have fruit with unique chemistry from the original.

This unusual leaf pattern is caused by the application of 2,4-D (a common broad-leaf herbicide) to lawns, golfcourses and soybean/corn fields. The volatile chemical drifts into the vineyard and very low concentrations, however it is still potent enough to disrupt the formation of the vascular system in new growth. Therefore, you can track when the herbicide was applied based on which leaves along the shoot are affected. We say the mutated leaves look "fish tail-y" 

In each block of our vineyards we have also installed "Bird Gard", or as I prefer to call them squawks boxes, in order to further deter birds from entering. Every 15 min they emit bird distress calls from five or six different birds. There is debate on whether or not they are effective, but at least the neighbors can enjoy the squawks all day long!

Many table (or eating) grape varieties are hitting veraison at this point in time...

... due to this fact, we have installed an electric fence around he table grape block to keep out the raccoons. We have also set up six live traps, which we bait with tuna, in order to trap them if they're around.

I found this downy mildew-covered tendril and couldn't resist taking an artsy photo. The spores of downy mildew (and  other fungi) are retained in old tendrils and rachis that overwinter on the plants and cling to the trellises. Therefore, if one is to grow grapes organically, particularly without using fungicides, then they must make sure to remove all left-over scraps in order to prevent future fungal outbreaks. 

Week 9 (Aug. 12 -16th)

Grape berries grow at different rates during the growing season. Cell division is complete within a few weeks after fertilization, but cell expansion continues throughout the entire season. The process is represented by a sigmoidal curve, meaning that cell expansion begins rapidly, has a "lag period", and then finishes rapidly. During the lag period the plant focuses all of it's energy and resources to the development of root and shoots. Once these are established, the pipework and solar panels (or power and glory), the plant transitions to devoting all of its resources to expanding and ripening the fruit until harvest.

This further illustrates what is going on with the vine during the growing season. Notice how anthocyanin levels increase  after the lag phase. Anythocyanin makes the grapes red and sugar makes the berries sweet, however flavor compounds don't start accumulating until the berry has begun to shrink in size at the very end of the growing season. This is why growing grapes is tricky in northern climates. Early frosts sometimes determine when a grower must harvest even though grape quality (for wine flavor) isn't to its prime yet.

During this dry spell we need to water young vines with the "water wagon" on a weekly basis. Since they have yet to develop fruit, young vines devote all their energy to vegetative growth. This means that their roots and shoots are constantly expanding, so they need constant water supply. We don't want to over-water young vines, however, as this would encourage their roots to remain shallow in the soil. Shallow roots make vines more susceptible to drought and winter damage.

We are now constantly netting vines as they ripen their fruit. For the high cordon trellis systems like this we drape the net over the top, where on the VSP trellis systems we connect the top of the net to the fruiting wire. For both systems we cinch the bottom up and twist-tie it closed.

Check out the damage that occurs when the birds get to the grapes before we're able to net.

I was fortunate enough to cap off the week by volunteering at the fifth annual Cold-Climate International Wine Competition at the U of M. I spent the day opening bottles, pouring glasses, and carting around full and empty flights of wine to and from the judges. It was an exciting day, as us volunteers were able to sample the wines once the competition was complete. Not only that, we were allowed to bring home the "back-up" bottles of each non-medal-winning wine :)