Unusual is the usual in New Mexico, and... it looks like spring!..

Unusual flowering habit for a grapevine!...old yucca flower structure and old grapevines near Engle, NM appear somewhat 'sympatico'.

Winter wheat cover crop in row middles at the Los Lunas, ASC vineyard on Miller Road ...looks like it is greening up nicely. The cover crop has had no applied water since late October 2019. Do cover crops' benefits out weigh their costs? 

Time for bud break? and How a Bud Becomes a Bunch

What is going on with this bud? Notice anything significant? This photograph was taken today by NMSU Viticulture graduate student Ms. Jacqueline Cormier.  

Of Buds and Bunches

Adapted from: “What causes a bud to produce a bunch… or not?”  by Devin Carroll, Advanced Agricultural Services, Inc. Hanford, CA., Practical Winery and Vineyard, Nov-Dec. 2009.

This short piece, adapted from the more detailed article cited above covers some vine processes and factors that affect bud formation and fruitfulness. The original article also covers the phenomenon of plant mediated bunch necrosis or PMBN. We will not cover that here.

Fruitfulness depends on the percentage of buds on a grapevine that produce flower clusters. Flower initiation, formation, bloom and fruit set, fruit development and ripening require a two-year cycle. The developing buds contain tissues that form primordial flower clusters and require a favorable environment to flower and fruit. There are several steps to achieve a desired level of fruitfulness: flower initiation and minimal bud necrosis. Bud necrosis is caused when the vine “decides” that to carry the bud to fruitfulness is not worth the metabolic costs. It takes more energy than the vine can afford and the bud is aborted. In this case, secondary buds within the compound bud will grow and allow the vine to survive but not bear fruit, or bear much less fruit. Injury to the vine can also cause bud necrosis…pathogens, heat, water stress or frost can damage or kill a bud. Bud mites, can infest buds and move from old to new buds during the early weeks after bud break and multiply from there. Hundreds of these mites can inhabit one bud and damage the inflorescence (flower cluster).

Inflorescence initiation

Grape flowers and fruit clusters are borne on new shoots that come from dormant buds.  Each dormant bud is formed at each node and leaf axil on a shoot the previous season and is actually a compound bud that contains three separate buds. The primary bud within the compound bud, for most Vitis vinifera varieties, under most growing conditions, will produce 1 to 3 clusters with 2 clusters being typical. However, this shoot may remain vegetative on young vines and the number of inflorescences is also variety dependent. For instance, Chambourcin (a hybrid) and Petit Verdot (Vitis vinifera) often have more than two clusters per shoot. The secondary bud can have a fruit cluster but not always, and the third bud typically produces vegetative growth (shoots and leaves) only. Regardless of flower clusters, each simple bud contains a 6-12 node shoot that is compressed and complete with primordial leaves, flower clusters (if present) and tendrils. This complete shoot is within each bud. Compound buds develop from the base of the shoot towards to the shoot tip. This process takes from two to three months beginning as soon as the node appears in the spring. After formation, the bud stops growing and becomes dormant until it breaks and grows the following spring. Grapevines do not form terminal buds as many temperate zone fruit crops do. The shoot tip will die back in the winter to a fully ripened (lignified) portion of the shoot that has a mature dormant bud. Cluster initiation for next year begins in midsummer and are fully formed within the dormant bud by the end of the growing season. Final development of the flowers occurs as the shoot emerges the following spring. The flowers are fully formed by bloom time when the shoots are about 18-24 inches long. Grapes generally flower late… about 4 to 5 weeks after bud break, later than most tree fruit crops. Grapes are wind pollinated for the most part and warm, sunny conditions at bloom favor fruit set. Note that the most fruitful buds are located at bud number 4 to 10 on the cane. Thus, when spur pruning (leaving only the number 1 to 4 buds) some degree of fruitfulness or total possible crop is sacrificed. If spur pruning, the buds left on spurs are formed before bloom. These represent next year’s entire crop. If canes are used, some crop will come from buds closer to the shoot tip, and they are exposed to environmental conditions that existed later than the buds near the base of the shoot.

It is possible for two buds to form at the same node. This phenomenon is common in Pinot Noir, and has been observed in Cabernet Sauvignon, Syrah, Merlot and Chardonnay. Because these are fairly widely planted varieties, this double bud phenomenon may be due to more reporting, rather than actually something more common to these varieties in particular.

The rachis (specialized stem bearing flowers and fruit) forms branches before the bud goes dormant, but the flowers themselves are formed after winter, at bud break. Therefore, environmental conditions just after bud break influence the final number of flowers. But cluster size contingent on rachis branching is determined by conditions in the prior year.

A non-specific tissue called an “anlage” gives rise to either an inflorescence (flower cluster) or a tendril. The inflorescence can be seen within a bud ten nodes from the shoot tip when the bud is dissected and viewed with a microscope. The vine’s decision to form flower clusters comes much earlier and is correlated with temperature especially in the buds about three nodes from the shoot tip. Therefore, both vine physiology and temperatures the shoot is exposed to in the first weeks following bud break play a role in vine fruitfulness.

Several factors impact flower cluster formation: temperature (hot and cold), light and shading, carbohydrate reserves, water, nitrogen, mineral deficiencies, and plant growth hormones.

Temperatures held at 68^oF immediately following bud break on Muscat grapes greatly reduced the number of flower clusters. Similarly, at temperatures > 95^o F, flower cluster numbers were greatly reduced. However, cold temperatures are likely the most common cause for low fruitfulness in a given variety the following year because temperatures in that range are more common in the spring.

Solar radiation (light) and favorable temperature are two critical climatic factors. Shade can reduce fruitfulness, but shading due to canopy is not the usual case early in the season when leaves are small or not yet emerged. Thus, cloudy, cool days as the shoot emerges and grows in spring can reduce bud fruitfulness. The amount of light falling on a shoot’s leaves is correlated to the number of flower clusters eventually formed in the buds of that shoot. Accumulated light rather than just peak intensity is the important aspect. A short day-length or several hours or days of cloudiness can reduce bud fruitfulness.        

Stored carbohydrates influence the formation of flower clusters in young buds. Carbohydrates in roots, trunk cordons, canes and spurs were stored the year before the buds were differentiated. Thus, growing conditions and vine strength two years ago strongly influence the current year’s fruitfulness. Overall, buds are a weak sink for carbohydrates compared to actively growing shoot tips. Rapid shoot growth will draw carbohydrates from the buds and shading on such vigorously growing vines also reduces fruitfulness.

Excess water will reduce the number of flower clusters on a vine…while water deficit does not. Overwatering and excess growth that promotes canopy shading likely draws carbohydrates away from buds and lowers their fruitfulness.  

Mineral deficiencies that include potassium and phosphorus can reduce bud fruitfulness. Low phosphorous detected around the time of bud break can be linked to cold soil temperatures that prevents uptake by roots despite the mineral being present in the soil. In the case of most New Mexico soils with elevated pH (above 7), phosphorous can be in short supply due to reduced availability. Potassium and phosphorus can be added to the vine via foliar sprays. This should be done shortly after bud break to increase fruitfulness in the first several buds.

Plant growth regulator compounds or hormones, gibberellic acid (GA) and cytokinins interact to regulate inflorescences in grapevines. Early on, GA can favor analage formation that give rise to inflorescences, but that same GA decreases inflorescences by favoring tendril formation. Cytokinins, on the other hand can favor inflorescences over tendrils. Although some kelp-based sprays have been reported to contain cytokinins…it is not clear if such cytokinins are the correct types for grapes.

Resources for pest management and spraying...

Oregon State University and Extension has put together some powerful resources for pest management and spraying in vineyards. I noted that several of you mentioned powdery mildew and how to approach spraying in general at the NM Wine Conference in Las Cruces earlier this week. Below are some resources from Oregon State...check them out. Not all will be applicable, but I am confident that a good bit of it will be very practical and immediately useful at your respective vineyards.

Extension Resources

Preparing your pest management program for 2020

Use the following resources when developing your pest management spray programs:

• Pest Management Guide for Wine Grapes in Oregon
• Plant Disease Management Handbook
• Insect Management Handbook
• Weed Management Handbook
• Pesticide Safety
• Effective Vineyard Spraying

Sheep in the Vineyard

To view the video click on the link below

Check out this interesting and captivating video of sheep in the Tablas Creek Vineyard near Paso Robles, California.

Tablas Creek Winery Sheep in the Vineyard



I visited Tablas Creek winery that makes excellent, Rhone influenced wines near Paso Robles, CA in 2018. Recently, my wife Kelly and I had the opportunity to attend a tasting of Tablas Creek wines right here in NM near Taos. At this event, the wines were introduced and poured by Tablas Creek, Senior Assistant Winemaker, Chelsea Franchi. All wines impressed, but I was most intrigued by the Grenache Blanc.
Since I am working with and researching the use of cover crops for New Mexico vineyards with NMSU graduate student Jacqueline Cormier, I am constantly looking for different ways to manage the covers. I have heard about the use of sheep for years...but recently ran across some information on integrating sheep into the vineyard. Mr. Ian Consoli of Tablas Creek sent this video on sheep at Tablas Creek Vineyard. Not sure it would work here in New Mexico, where most row middles are bare ground, but it is interesting and would certainly be intriguing to give it a try.



Also, check out this scientific paper on sheep in the vineyard published in: Agronomy for Sustainable Development

Ecological and economic benefits of integrating sheep into viticulture production

Photos of pruning...The before, the after and the Ugly...and weighing dormant pruning weights...sort of

Some further observations and takes on pruning

In the two photos immediately below one can see the same vine before and after pruning to the single high-wire training system. The idea is to leave two horizontal semi-permanent cordons with long spurs (4-5 buds) evenly spaced along each cordon. The previous cordons were removed and "new" cordons were tied down. Notice the horizontal "new" cordons are still technically canes that have been tied down. Over time, these will develop into semi-permanent cordons, from which spurs will arise and be pruned annually.

"The Before", un-pruned French-American hybrid vine at Los Lunas ASC

"The After", pruned French-American hybrid vine at Los Lunas, ASC

The next three photos depict the fact of grapevine anatomy. Unlike many perennial, temperate zone fruit crops (apple and peach) grapevines have no terminal bud. 

Grapevine cane with viable dormant buds. In the spring, new growth will arise from each of these buds. Each of these new shoots could have from 1-4 clusters of grapes. Later in the summer, these shoots will lignify (turn brown and form weathered bark) and will have newly formed buds for the subsequent season...and as Kurt Vonnegut  might say..."...and so it goes.."

In this photo, the end of the cane simply 'sloughed' off. The cane ends without a terminal bud. Also, notice the withered and desiccated appearance of this cane. It is not viable at this juncture and should be removed when the vine is pruned.

Finally, when making cuts that are larger than a dime...take time and inspect the exposed cut end. It should appear a slightly creamy green in color. That indicates it is likely free of infection from wood-rotting organisms.

The cut end of a cordon or small trunk. Notice the creamy, green color...it is indicative of healthy wood, likely free of wood rotting pathogens.

Which wood rotting disease is this? I cannot tell you. The organism would have to be isolated and identified by a pathologist or someone that has experience with these organisms. But the expression and result is similar within the grapevine...the discolored interior wood that is not functional and the compromised growth of spurs and canes that are associated with the diseased wood.  There are many wood rotting diseases...Botryosphaerria, Eutypa, Esca....to name a few. 

Link to scientific article on botryosphaeria dieback in grapevines and how to treat it surgically and how to dress the wounds

Finally, check out the photo below...the workers at the NMSU experimental vineyard at Fabian Garcia ASC in Las Cruces, are weighing pruning wood recently cut from the adjacent vines. The amount of one-year wood that was pruned from each vine will dictate how many buds/vine to leave to produce next year's crop.

Pruning Philosophy Spring 2020

GRAPE PRUNING                         New Mexico State University                       Winter 2019 - Spring 2020

Gill Giese, Extension Viticulture Specialist           ggiese@nmsu.edu                 

            Pruning is arguably the most important cultural practice a grape grower performs. Pruning has a dwarfing (pruned vines are physically smaller) and invigorating (the vigor of remaining growing points is increased) effect on the vine. When wood is removed, the roots that previously supported the top growth will have an abundance of hormones and carbohydrate reserves. The roots will also have an increased water and mineral absorbance capacity relative to the remaining top growth. This increased capacity or ‘excess supply’ stimulates the remaining shoots to grow and expand at a rapid rate. The rate of growth over time is referred to as “vigor”. Vigor is not the total amount of growth, or overall vine/plant size. To summarize thus far: the above ground portion of pruned vines are physically smaller and the remaining shoots grow more rapidly (increased vigor) compared to shoots on an unpruned vine.

A term often confused with vigor is “vine capacity”. Vine capacity relates to vine size, and is a separate concept. Capacity is the total amount of fruit/crop a given vine can support to a desired degree of maturity. Vine productivity and sustainability depends on vine capacity: first, for the vine’s physiological requirements and second, for the economic viability of the vineyard enterprise. At pruning, the following is determined: type, position and number of buds that will produce fruit. Bud number, that impacts crop load, is set at pruning and can impact berry composition i.e. fruit ‘quality’. Thus, pruning plays a crucial role in vine health and productivity.   

            Purpose of pruning: achieve the desired amount and quality of fruit over a number of years.

1.      Set the appropriate fruit load to the size/capacity of each vine

2.      Shape and train the vine, integrating the vine to a given trellis system. Direct vine growth into a well-spaced canopy that allows air, sunlight and spray materials into the canopy, to contact the foliage and fruit at the optimum time and degree during the growing season. Within this goal, one should keep in mind not just the current upcoming fruiting season but subsequent seasons. Ideally, this multiple year outlook informs how you shape or set-up the vine for the long term.

Balanced vine growth begins with pruning: How many buds to leave?

1.      Weigh pruned, one-year old wood. Leave 30 buds for the first lb. removed and 10 buds for every lb. thereafter. This is called the 30+10 formula, and is applied to Concord and other American varieties. Another formula, leaves 20 buds per 1 lb. of wood removed and is the ‘formula’ for many vinifera or European wine grapes. These ‘formulas’ provide a starting place and are not definitive…they are an aid to matching pruned wood with the fruit crop. Balanced pruning is a technique that uses: cane weight (one-year old wood), node counting and a pruning ‘formula’ for estimating vine capacity. Dr. Nelson Shaulis of Cornell University developed this technique in the middle of the 20^th century. It assumes the selection of well-exposed canes with fruitful buds. Each pruning formula, or nodes per pound of canes, is driven by growth and fruiting characteristics of the variety. Vine capacity varies between trellis/training systems and between adjoining vines in a row. The intent of balanced pruning and/or a ‘formula’, is to avoid over or under-pruning vines of differing capacity. Balanced pruning is the first step in achieving the annual desired quality level with maintained or improved vine capacity for the following year’s crop (Coombe and Dry, 1992).

Example bud number formulas:

Variety                                    Formula

Cabernet Sauvignon    20+20                          Concord                      30+10

Cabernet Franc            20+20                          Niagara                        40+10

Chardonnay                20+20

Riesling                       20+20

Seyval                           5+10

Vidal                           15+10

Other Hybrids             20+10

2.      Leaf area: fruit ratio, a measure of a vine’s capacity:

The leaf area to fruit ratio is defined as: Pn (photosynthetically active) leaf area measured in square centimeters (cm²) to mass, measured in grams (g). This ratio depends on the trellis system used. The vertical shoot positioned (VSP) trellis generates a leaf area:fruit ratio of about 0.8 to 1.2 m² leaf area per kg fruit or about 10 cm² of leaf area per 2g of fruit, or about 5-6 mature leaves per each medium sized cluster (Figure 1). Divided canopies can be a bit more efficient, where 0.5 to 0.8 m²/kg are needed to mature fruit (Kliewer and Dokoozlian, 2005). Efficiency here is defined as the least amount of leaf area that is required to mature a given amount of fruit.  

Figure 1. The relationship of leaf area to crop weight. Examples of three trellis systems: A1 = vertical, B1 = lyre and C1 = Geneva double curtain, (Kliewer and Dokoozlian, 2005).

3.      If vines have 3.5 lbs. of prunings/vine, one should leave about 42 buds as a default, 6 buds/ft., or 2-3 spurs per foot. What if one must choose between total number of buds/vine and achieving the desired number of shoots per foot? In this case, the number of buds per foot takes precedence over the total number of buds per vine. Avoid a shoot density per foot that results in a dense and congested canopy, that leads to increased disease pressure and poor light exposure of fruit clusters.

4.      Wood:fruit ratio should be approximately 5-6 lbs. of fruit per 1 lb. of wood removed.

Factors that impact pruning…or, pruning depends on:

1.      Climate: Is your climate continental or maritime? If continental (BTW: all of New Mexico has a continental climate), there is an increased chance of winter and/or frost injury due to wide swings in night and day temperatures and no dampening effect from large bodies of water. In this case consider:

-          Leaving more buds at pruning time and shoot and crop thin later in the season

-          Prune late, to delay budburst and aid avoidance of frost injury in the spring

-          “kicker canes” are ‘extra’ canes left on the vine, that can enter budburst relatively late. Kicker canes can be used to replace spur borne buds killed by frost. Kicker canes are typically replaced each year and help dissipate excess vine vigor or be positioned to serve as a replacement trunk if needed.   

2.      Soil Fertility:
      -   deep soil = vigorous growth, prune light (leave many buds) to increase rate
          of early shoot growth
      -   poor soil = prune severely (leave few buds) to stimulate vigor in remaining
          buds

3.    Variety: pay attention to number of: bunches/shoot, flowers/cluster, berry weight,
                      and bud position
            -   some varieties have sterile basal buds, example: Nebbiolo, some have many
                basal buds that will not be counted at pruning time that can burst and grow
                later leading to a congested canopy.  

-   apical dominance? Phenomenon most evident in the spring, where the buds
    at cane tips   
    break bud first, and subsequently, buds located closer to cordon or trunk will
    burst.
    One can use this to advantage by leaving longer spurs and after the apical
    buds reach
    bud burst, they are pruned off …this will delay budbreak in remaining buds
    and could help avoid a late frost.

 4.   Economic: winter pruning most economical way to control crop, but is least
                          precise method of crop control
            -   cluster, fruit and shoot thinning during the growing season costs more, but is
                 more precise compared to winter or dormant pruning

Pruning Procedures

                        1.  Timing:

-          Early prune to finish pruning by budburst, this may be dictated by size of vineyard and number of pruners available. Pruning can be done after budburst, but the risk of bud damage is greater because the process can damage of knock off the tender growing buds.

-          Early pruning = early bud break, growth advancement can persist through harvest

-          Double pruning = making two passes through the vineyard.

o   First pass, make rough cuts and remove bulk of the prunings from the trellis

o   Second pass, adjust bud numbers to desired number/vine prior to bud break

-          Delayed pruning, cutting off wood as budburst approaches, development of remaining buds will be delayed

o   The delay can persist through harvest

o   Delayed pruning can reduce Eutypa, Esca and other wood rotting diseases.

      
Figure 2. Left: a cross section of a cordon infected with fungal wood rotting disease, evident in the discoloration. Right: end cut cordon revealing fungal wood rotting infection.

2.   Pruning Degree: 

-          Balanced pruning: number of buds retained based on weight of wood removed at annual dormant pruning

o   SEVERE                < 20 buds left on the vine

o   MODERATE        20 to 70 buds left on vine

o   LIGHT                  > 75 buds left on the vine 

            3.  Cane Selection Criteria:
                        -  varietal color: light brown Vitis vinifera varieties, with brown coloration to
                            the cane tip

                        -  1 cm (3/8 inch) in diameter desired, strive for cane uniformity

                        -  moderate internode length, about 3-4 inches

                        -  round buds instead of flat buds
                        -  canes of different length and diameter, should retain different number of
                            buds
                        -  age or location

4. Vine Age: different training goals for different age vines

-     young vines – establishment of framework based on trunk arrangement

-     mature – framework and buds type placement within your trellis system

Pruning affects most vineyard activities and vine growth parameters such as: crop yield, winter hardiness, insect and disease management and ultimately berry composition and resultant juice and wine quality (Chapman et al. 2004). Although pruning can become intuitive once you have practiced a bit, a winegrower with an eye towards the bottom line should maintain good records to supplement and support her pruning decisions.

REFERENCES

1.      Chapman, D.M., Matthews, M.A., and J.X. Guinard. 2004. Sensory Attributes of Cabernet Sauvignon Wines Made from Vines with Different Crop Yields. Am. J. Enol. Vitic. 55: 325-334.

2.      Coombe, B.G., and P.R. Dry. 1992. Viticulture Volume 2, Practices. Winetitles. Adelaide, Australia

3.      Fisher, H.K. 1999. Factors Affecting Successful Vine Growth, Yield and Quality., Wine Industry Workshop, Geneva NY

4.      Howell, G.S. 2001. Sustainable Grape Productivity and the Growth-Yield Relationship:  A Review.  Am.J. Enol. Vitic. 52:3 165-174.

5.      Kliewer, W. M. and N. Dokoozlian. 2005. Leaf Area/Crop Weight Ratios of Grapevines: Influence on Fruit Composition and Wine Quality. Am. J. Enol. Vitic. 56:170-181.

6.      Pool, R.M. 2004. Vineyard Balance- What Is It?  Can It Be Achieved? Acta.Hort. 640, ISHS p 285-302.

7.      Winkler, A.J., Cook, J.A., Kliewer, W.M., and L.A. Lider. 1974. General Viticulture. University of California Press, Berkeley.

Installation of 'Access" tubes to accomodate frequency domain reflectometry probe in order to measure volumetric soil moisture at Fabian Garcia ASC by Jacque Cormier, NMSU Viticuture PhD graduate student

1.21.2020 

This week at the Fabian Garcia ASC vineyard in Las Cruces the access tubes are being installed into the cover cropped and bare soil 'control' plots of the Malbec block. Tim, one of our student workers uses a mallet and metal rod to drive the fiberglass tube into the 100-centimeter deep hole made by an auger. A consistent and tight (no air spaces or gaps) soil to tube contact installation is critical. Once installed, these tubes will accommodate a banded probe, frequency domain reflectometry (FDR) probe that can detect soil volumetric water content at 6 different depths. These moisture readings will help researchers (us) better understand the relationship between different vineyard cover crops and soil moisture throughout the seasons, and how any differences in soil moisture affect vine performance.

Installation of access tube with aluminum rod that is
    placed inside of the tube and then driven to depth with
mallet to place the tube at the correct depth.

Components used to install the 'access' tubes

1.17.2020
Over the next two weeks the vineyards at NMSU's Fabian Garcia Agriculture Science Center will be dormant pruned. Dormant pruning maintains the vines within a manageable size from year to year, making it easier for the field crew to access the fruit and manage the inter-row cover crops. Here at Fabian Garcia we spur prune the predominately vertical shoot positioned (VSP) trained vines. Later in the spring, after bud break, we will thin new shoots to a specific count per foot (usually 3-4 per foot of cordon) to keep the research vines consistent and to maintain 'vine balance' (leaf to fruit ratio). The dormant wood is bundled per vine and weighed in the Malbec block, being used in the cover crop study.

Weighing dormant pruning wood and Tim (recording the weights on his phone (background with black jacket and baseball cap) @ NMSU Fabian Garcia ASC, January 2020