Pruning Part One (Pre-pruning)

Pre-pruning may be considered as an approach to help control total pruning costs, allow for some disease management by waiting until disease risk is lowest and frost protection by delaying the onset of bud break in the spring.


Mechanized pruning considerations could include electronic and pneumatic (hand shears) or tractor mounted implements used to finish or pre-prune a vineyard block.

This above unit has rubber tracks that allow for operation in semi-wet soil conditions.  Rubber reduces the risk of soil compaction during months that typically include wet conditions.  Walsh will preprune 400 +/- acres every year. 

This above unit has rubber tracks that allow for operation in semi-wet soil conditions.  Rubber reduces the risk of soil compaction during months that typically include wet conditions.  Walsh will preprune 400 +/- acres every year. 


Before Prepruning


After Prepruning


General Concepts in Prepruning Include:


  • Common measures of optimal pre-pruning length are: 12-15 inches (30-40cm), Length 6-8 internodes

  • Reasons for pre-pruning vary: there is some thought of controlling costs, disease and frost control (up to 2 weeks) by allowing for a later finish pruning pass. If vine disease impact is reduced, the effective life of a vineyard may be extended.

  • A grower may choose to pre-prune mechanically or by hand. If by machine, field conditions for access, possible compaction, cost of equipment & R&M are to be considered.

  • Pre-pruning is generally applied to Cordon and not Cane pruned blocks.

  • If mechanized pre-pruning, consider the buildup of debris in the vine row which may eventually lead to pest and disease control issues(See mulching action in the video below.)

  • There may be vineyard infrastructure (negative) impact from cut wires, broken posts and stakes that will need repair following a mechanized pre-prune pass.

  • Some trellis systems and vineyard row spacing will allow for hand pre-pruning only.

  • Typically a pre-pruning machine on the north coast will prune one row at a time. Timing may become an issue depending on the condition of the equipment and skill of the operator.
  • Narrow Vineyard Avenue width and hillsides (<15-17%) will limit the use of a pre-pruner.

  • When incorporating early season pre-pruning as a management strategy, later Season (finished) pruning is possible. This may allow a grower to use less (hand) labor by giving workers additional time to finish a vineyard.

  • Worker safety is always an issue around mechanized operations however hand labor pruning presents additional challenges with workers comp around the strenuous and costly activity of hand pruning.

Contact Walsh if you would like professional advice on quality mechanization of your vineyard:

    Useful Links:



    So It Rained, Now What

    On September 21st, 2013 Napa/Sonoma experienced a much greater total amount of rainfall than the meteorologists were projecting. Originally the reports were for up to 0.10" for the entire event.  Surprisingly, the area experienced up to 1.0" of rain. 


    During the early morning of September 21st, we had the first rainfall hit between 1:00am and 3:00am in the morning. This rain was minimal and we expect most of this moisture did not penetrate vine canopies.

    The mid-morning of September 21st, it rained again around 8:00am.  This rain was also minimal and we saw a rewetting of the ground and canopies.  It was still insignificant rainfall totals in most areas.

    In the late-morning between 9:00am-12:00pm we had heavy down-pouring rain.  The clusters were soaked and ground was muddy.  Totals seen from the Sonoma Valley and Napa Valley were 0.5"-1.0" of rain.  

    Shortly after the last rain fell in the late morning on September 21st, we had sun and wind come into the area.  Clusters were dry by  Saturday @ 5:00pm as long as they were not in low lying areas (or otherwise wind protected areas).  24 hour cluster wetness was avoided for most areas.


    Chardonnay and Zinfandel blocks are the most sensitive to rot pressure.  Maximum control over rot is achieved through canopy management, with the best results occurring when the canopies are leafed wide open before the event.  In highly sensitive areas, Walsh leafed heavily before the rain. 

    Another approach is to spray botrytis materials that prevent rot.  Walsh clients elected to do this in only the most sensitive areas.  This effect is measurable, but not nearly as effective as opening the canopies.


    (1) Most clusters did dry out by 5pm Saturday, before the critical 24 hour wetness, that can trigger the Botrytis life cycle.

    (2) Phenology records indicate we are 120-130 days after bloom.  Many blocks still have 10-25 days left to get fully ripe.  As a result, grapes still have healthy protective skins, making them less susceptible to rot.

    (3) The September 21st rain was our first significant moisture of the harvest season.

    (4) Walsh does not expect rampant Botrytis activity in area vineyards.  We will continue to monitor the situation with winemakers.


    Click the link for a good research paper on botrytis control that supports our discussion on leafing to control botrytis.

    As of Sunday, NOAA projecting high winds and fire danger by the end of the week.  This will dry out any rot and likely lead to a greatly increased rate of ripening.

    Napa & Sonoma Harvest Update

    A&nbsp;Stem Jack&nbsp;(w/ Berry)&nbsp;Sorted by a&nbsp;Walsh Mobile&nbsp;Optical Sorter

    A Stem Jack (w/ Berry) Sorted by a Walsh Mobile Optical Sorter

    Walsh clients are  currently 40% complete with their 2013 harvest.   Work is being done in Stags Leap, Rutherford, Carneros, Russian River, Alexander Valley, and the Sonoma Valley.  Yields are above average (~+20%) in most varietals and in most regions.  Walsh average client yields as of 9/16/13:

    Sav Blanc 7.0 tons/acre

    Chard 4.5 tons/Acre

    Pinot 4.5 Tons/Acre

    Cab Sav 3.8 Tons/Acre

    By Pick Type Mix:

    48% Hand/52% Machine

    The September heat wave produced many raisins (dehydrated fruit), which will definitely lower yields for most of the remaining blocks.  In many cases, Walsh clients are utilizing mobile sorting systems to eliminate these potentially "jammy", "cooked", "baked" or otherwise "unfocused" flavors from their black grapes. By comparison in 2012, we did not experience much of any dehydration, which lead to the record size crop.

    Walsh has learned it is much less expensive to remove sunburn and/or dehydrated fruit with high speed optical sorting equipment, when compared to thinning whole clusters in the field.  Thinning in the field entails labor costs and growers lose a high percentage of good quality fruit in the process. 

    Winemakers often ask if they can keep "dimpled fruit" and "sort out the raisins".  Most clients have found that making this distinction is possible with optical sorting equipment.  But as good as the sorting equipment works, they are not perfect, and it is better to avoid sun related fruit problems with traditional canopy management.

    Stand out differences this year are more "pips" and "jacks with grapes still attached".   The presence of jacks can impart negative green and/or herbal flavors in the wine. We have attached an example picture of a "jack with grapes still attached".  We are seeing more jacks in the fruit fruit this year.

    Right now the weather is fantastic, with temps in the mid-to-high 80's and partly cloudy.  The picking has slowed some as the weather has cooled.

    Learn More About Walsh. 

    Walsh is a leading service provider at harvest of:

    Night Hand Harvesting

    Machine Harvesters with On-Board Berry-Sorting

    Harvest Logistics/Planning

    Harvest Lab Analysis

    Grape Hauling

    Mobile Optical Sorting     


    Start: Field Optical Berry Sorting

    Harvesting berry-by-berry with high tech tools has begun in Napa.  These tools harvest the fruit and remove MOG (materials other than grapes) to such a high precision that even the most labor intensive alternatives cannot match the quality of fruit delivered to the winery. 

    The team responsible for harvesting the fruit works to calibrate the sorter to winemaker specifications.

    Blending New Technologies for Quality 

    Hanna CS 16 2012-10-18.jpg

    Free Run Whites "In Field"

    Free run white harvesting is an exclusive Walsh offering for early season white wine harvesting with our modern harvesters. This equipment separates the juice in the field and preserves the harvest.  Specialized false bottom trailers imported from France ( by Pellenc America) allow us to minimize oxidation and phenolic extraction, both important considerations for quality production. 


    Selectiv Harvest Chardonnay

    This picture was taken moments ago in the Carneros region of the Napa Valley. Some wineries are embracing high quality mechanization of  harvest, approaches that respect the quality of the process and the fruit. 

    Often Dry Ice and KMBS are used to further protect the harvest.  When the conditions are correct, results in Chardonnay can be excellent.   See photo from tonight's pick.