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.