Yellow and pink leaves on Vitis labrusca...what is going on?

Vitis labrusca with yellowing leaves on its shoot tips. 

Weed control in a desert vineyard

    The following photos were taken at Santa Ana Pueblo vineyard June 23, 2020. All rows in the block were treated with the pre-emergence herbicide Chateau (flumioxazin), that has some post application activity on very small weeds (< 2 inches). This application occurred in early spring, timed to coincide just prior to some predicted rainfall. Rain is required to move the material into the soil where germinating weed seeds are located. The applications, at the labelled rate of 2-6 qts/acre were tank mixed with the adjuvant: "GROUNDED" that is available from Gemplers. After some timely rains...predicted prior to the application, the weed control was excellent. Again, the rainfall within a couple days of application are crucial for the material to be effective. Notice the difference in weed control evident in the side by side rows. The row on the left, with tumbleweeds Russian thistle (Kali tragus) present, was 'missed' by the applicator and thus received no herbicide treatment. The adjacent row on the right, was treated with the flumioxazin herbicide. The weed control is visually evident and obvious...as you can see by the lack of the Russian thistle in the treated rows...on the right hand side in the photos. 

Lack of weed control evident in left hand row, Russian thistle present. This photo was taken about two months after the herbicide flumioxazin was applied in the vine rows...with the row on the left having been skipped or 'missed'. The treated row, on the right, is relatively free of weeds including Russian thistle.

Same two rows shown from a slightly different perspective. One can see some weeds in the right hand row (treated row)...but few to no Russian thistle. 

Vines in Recovery and Rehabilitation

June 17, 2020: A sequence of photos from Santa Ana Vineyard north of Bernalillo. Starting from the top...the photo was taken looking north between two rows of Pinot Meunier. Notice the vigorous and crowded vegetative shoot growth? In the next photo one can see a single vine as we move closer towards the canopy. The third photo reveals the reason why there is so much vegetative growth...and finally, the fourth photo is a close-up within the a single vine's canopy. Notice the dead spur that was left at pruning? I was intended to give rise to two shoots, one from each of the "count buds" that the pruners left for this season. But, as we know...after those shoots budded out and began to grow, a late frost occurred, in mid-April that killed them. All that remains of them is the dead spur...but at the base of the spur, notice that there is about 4 non-count buds that have burst and are giving rise to shoots. One of these shoots appears to bearing fruit. So...the vines will have a crop after all. But it will likely be smaller and ripen later relative to a 'normal' crop that would have been borne on the primary shoots. 

Looking west, between two rows of Pinot Meunier, on June 17, 2020, following a late freeze that killed nearly all new growth in mid-April. The vines appear very vigorous due to a proliferation of secondary and latent buds that are growing after the primary ones were killed. 

Closer in to the canopy of a single vine of Pinot Meunier. Very vigorous, it is  likely that sunlight does not penetrate uniformly and not many fruit clusters are visible from this vantage point. 

Pushing shoots aside and looking within the canopy of the previous photo, notice all the secondary shoots arising from a common point near the base of the dead spur? 

Shoot congestion explained....notice the remnants of the dead bud in the foreground on the spur and the  numerous secondary shoots growing from the base of the spur in the background? These secondary and in some cases, tertiary shoots are growing in response to the death of the primary shoots. Some of these shoots have leaves...but typically, not the 12-15 full size, mature leaves required to fully ripen a fruit cluster.

The cold snap of October 2019

The October 2019 Cold Snap 

The winter damage evident this spring that is manifesting itself now in New Mexico vineyards, especially those in the northern 1/2 and eastern 1/3 of the state, may have ocurred last fall. Most growers I have talked with remark on the sudden swing, from moderate temperatures to temperatures well below freezing in the latter half of October 2019. Take a look at some temperatures recorded at four New Mexico sites: Farmington, Los Lunas, Portales, and Las Cruces. Note the temperature or diurnal swing in temperatures on October 31st at each of the sites. Portales recorded a low of 11 degrees on that date, after a high of nearly 60 degrees Fahrenheit.

Crop Estimation

CROP ESTIMATION

Adapted from: Crop estimation and crop thinning, by Dr. Tony Wolf, Virginia Tech

 

A.    Why perform a crop estimate?

1.    Avoid over-cropping. What is over-cropping?

-       retaining more crop than the vines can support to the desired degree of maturity by the desired time frame. This maturity is measured by: Brix, pH, TA, color, flavor and aroma

 

Figure 1.Chambourcin shoot with three clusters. Given that 12-14 leaves are needed to ripen one medium size cluster, this shoot is ‘over-cropped’. The shoot’s leaf area will not support and ripen the amount of fruit present. 

 

-       ** in other words, a heavier crop delays maturity …to the point that the crop never ripens given the amount of time before the first fall frost.

2.    Determine how much crop to remove to reach a target crop level (if currently above target)

3.    Realize available crop for sale/use in your winery, schedule labor, equipment and supplies

B.     Requirements:

1.    Record of previous harvests and lag-phase average cluster weights, if lag-phase used

2.    Accurate count of sampling unit per acre (or missing units per acre)

-       Units: bearing vines per acre or ‘panels’ of canopy per acre, if non-uniform vine spacing. ‘panel’ = row distance between two consecutive line posts

3.    Accurate count of clusters per sampling unit

C.    Source of variability:
             Components of yield is divided into two major pools:

1.    Components set in previous year, or at dormant pruning, determines clusters per acre: 

                                               i.     vines per acre

                                              ii.     nodes retained per vine

                                             iii.     shoots per node

                                             iv.     clusters per shoot (fruitfulness)

2.    Components determined in current season, determine average cluster weight: 

                                               i.     flowers per cluster

                                              ii.     berries per flower (percent set)

                                             iii.     berry weight

All components shown above are variable, which collectively reduces crop estimate accuracy. 

For example:

Vines per acre:Attrition due to disease, predation, mechanical damage, water stress, 

First step: accurate count of bearing units per acre. Calculate % missing “units” (vine- or panel-basis) and deduct this % from crop estimate, assuming 100% vine stand or trellis-fill.

Nodes per vine:  Varies dependent on pruning uniformity and from variety-to-variety, depending on crop expectation; for example, Seyval (hybrid) often has no count nodes retained, and Cabernet Sauvignon typically has 3 to 4 nodes per foot of cordon.

 

Shoots per node:  Varietal difference: Seyval> 1 shoot/node, bud necrosis or winter injury can = <1 shoot per node. GDC (Geneva Double Curtain) training has led to >1 shoot per node (due to enhanced light environment) 

 

Clusters per shoot:Varietal differences, cane vs. spur pruning, light and temperature regime of developing buds in previous season, bud necrosis and previous season’s crop level, all affect this variable.

 

Berry weight:  Affected by fruit set and degree of crop thinning, i.e., crop thinning increases size of remaining berries, and is strongly affected by moisture conditions (rain or irrigation) after fruit set.

·       Aim to thin crop in the 2-week period before veraison to limit berry size compensation

·       Thin earlier if you need to stimulate vine size and vigor

 

 

 

 

 

D.    Working equation:

Tons/acre = 1/2000 lbs. X vines/acre X clusters/vine X average cluster wt. (lbs.)

Average cluster weightcan vary significantly, and will likely be major source of variation of error in accurately predicting yield. Note actual numbers below from a vineyard of 

the hybrid, Vidal.

 

Vines/acre            clusters/vine (2013-2017)      average cluster wt. (lb.)     tons/acre

691 (9’ x 7’)           29 – 48 (avg. = 38)                0.49                                         6.43

691 (9’ x 7’)           29 – 48 (avg. = 38)                0.58(~ 15% greater)                7.61

 

E.     Improving the working equation:

Crop prediction model improved by using anhistorical, average lag-phase cluster weight,plus the current season lag-phase cluster weightto adjust the predicted harvest cluster weight:

 

Predicted yield = (vines/acre) X (clusters/vine) X (S/Ax H)

where: S= lag-phase cluster weight for current season 

A= historical, average lag-phase cluster weight (several years’ data)

            H= historical, average harvest cluster weight (several years’ data)

Recommend a destructive sampling of allclusters from 5 to 15 vines per block, to arrive at mid-season cluster weights. To sample otherwise, will introduce bias – you will tend to sample only the largest clusters of the vine. Sample early July, about 45 to 50 days post bloom – be consistent each year. 

 

Be aware of extremes of precipitation after lag-phase that can skew results

Alternatively (less precise); use multiplier pre-harvest to predict harvest cluster weight. Start of lag-phase

 

 

 

What constitutes an acceptable crop level? 
Tons per acre is too broadly affected by 
plant density and subsequent missing vines. 
Targeting 1.0 to 2.0 pounds of crop per foot 
canopy is a generally acceptable, albeit 
somewhat broad benchmark. 

 

Example: consider Cabernet Sauvignon vines

Planted 9’ x 5’, thus, 968 vines/acre. If 
cropped at 1.5 lb. /foot of canopy 
(VSP trained), = 1.5 lb. x 5’ x 968 vines/acre =
 7,260 lbs. (3.63 tons/acre). 
A reduction in fruit maturity

(less color density) is common when this 
crop level is exceeded. White fruited 
varieties @ 2.0 lbs. /foot, OK; 
use the lower end for high quality red

wine potential.

Figure 1.Diagram showing relative size and color of berries at 1- day 

intervals after  flowering, passing through major developmental events (rounded boxes). Also shown are the periods when compounds accumulate, the Brix and an indication of the rate of inflow of xylem and phloem vascular saps into the berry. 

                                                            Illustration by Jordan Keutreumanidis. Winetitles.

 

Complications and considerations:

1.    Drought / excess moisture

2.    ^oBrix is not a good indicator of crop level, especially with large vines that are not balanced. There is example of Cabernet Sauvignon vineyard at a 9 tons/acre crop, that did not differ from 4.5 tons/acre crop vineyard…with respect to soluble solids accumulation rate or values at harvest. BUT… what was difference in color density? Remember that consumers ‘drink with their eyes’…color is important. 

 

When is best time to thin crop?

1.    Early (within 30 days of fruit set) result in increased berry size – potential for > ROTS

2.    Less compensation (berry size increase) occurs if crop thinned near veraison

3.    Less benefit to remaining crop after veraison

4.    “green thinning” = preferential removal of clusters that exhibit delayed color formation at onset of veraison – tends to mechanically reduce variability of maturity at harvest

5.    Timing is not as critical with large vines, as it is with small vines

 

 

 

 

 

 

 

 

Table 1. Average cluster weight data for selected varieties 
grown at the AHS Jr AREC in Winchester, VA

Variety	Ave. cluster wt. (lbs)
Cabernet Franc	0.38
Cabernet Sauvignon #8	0.28
Chardonnay #4	0.41
Chardonnay #95	0.32
Chardonnay # 96	0.30
Chardonel	0.43
Mourvedre	0.61
Petit Manseng	0.22
Petit Verdot	0.24
Syrah	0.40
Tannat	0.58
Traminette	0.32
Vidal	0.49
Viognier	0.41

 

 

 

 

 

 

Table 2.Selected average cluster weight data from Winchester vineyard.

Year	Ave. cluster weight (lbs) at harvest
	Chardonnay #4	Cabernet Sauvignon #8	Vidal
1991	0.35	0.23	0.19
1992	0.49	0.31	0.38
1993	0.47	0.32	0.36
1994	0.33	0.22	0.41
1995	0.52	0.28	0.42
1996	0.32	0.31	0.34
1997	0.45	0.29	0.42
1998	0.41	0.27	0.49
Mean	0.42	0.28	0.38

 

 

 

   Table 3.Percent (%) increase of average berry weight of Cabernet Sauvignon and Chardonnay, in North Carolina.

vine yard*	variety	avg. berry wt. -  July 1	avg. berry wt.-  July 8	% increase	avg. berry wt. –  July 15	% increase	avg. berry wt. –  July 21	% increase	avg. berry wt. –  July 28	% increase	% increase July  1 to 28
BW	Cab Sau	0.309	0.484	56.6%	0.666	37.6%	0.740	11.1%	0.779	5.2%	152%
RP	Cab Sau	0.466	0.712	52.9%	0.754	5.9%	0.936	24.2%	0.958	2.3%	106%
SCC	Cab Sau	0.437	0.716	63.7%	0.807	12.7%	0.846	4.8%	0.840	-0.7%	92%
BW	Chard	0.518	0.671	29.6%	0.754	12.4%	0.922	22.3%	0.960	4.1%	85%
RP	Chard	0.754	0.920	21.9%	1.046	13.7%	1.183	13.1%	1.239	4.7%	64%
SCC	Chard	0.595	0.748	25.7%	0.883	18.0%	0.910	3.1%	0.983	8.0%	65%

* Vineyards in Surry Co., NC., within a ~15-mile radius. All clones of Cabernet Sauvignon
 were likelydifferent. The Chardonnay clones at RP and SCC (Surry Community College) were likely
the same clone: Dijon clone 96.

 

Table 4.Percent (%) increase of average berry weight and final berry weight of Cabernet Sauvignon and Chardonnay, in North Carolina.

vine yard*	variety	avg. berry weight - harvest	% overall increase, July 1 to harvest	50% of avg. berry weight - harvest	50% weight date	GDD (growing degree days, 50o F)	harvest date
Black Wolf	Cab Sau	1.194	286%	0.597	07/12/05	1514.8	10/19/2005
Round Peak	Cab Sau	1.659	256%	0.830	07/17/05	1680.4	10/20/2005
SCC	Cab Sau	1.464	235%	0.732	07/09/05	1554.6	10/10/2005
Black Wolf	Chard	1.682	225%	0.841	07/18/05	1663.4	9/21/2005
Round Peak	Chard	1.855	146%	0.928	07/08/05	1455.1	9/14/2005
SCC	Chard	1.617	172%	0.808	07/11/05	1606.7	9/13/2005

* Vineyards were all in Surry Co., NC., within a ~15-mile radius. All clones of Cabernet Sauvignon were likelydifferent. The Chardonnay clones at Round Peak and SCC (Surry Community College) were likelythe same clone (Dijon clone 96)

 

 

CROP YIELD ESTIMATION: (adapted from article by Oregon State University’s Steve Price)

            In the late 1980’s, Pinot Noir production in Oregon was expanding. Being able to estimate the final crop amount early in the season would be an economic advantage to grape growers and winery owners. The Oregon climate (especially the Willamette Valley) is often cool and cloudy during fruit initiation and bloom. These conditions affect clusters formed per vine, flowers per cluster and berries per cluster and vary from year to year. This variability directly impacts the amount of harvestable crop in a given year. 

            . 

The system uses 

1.    Bearing vines per block

2.    Clusters per vine

3.    Cluster weight at the lag phase of berry growth 

4.    Cluster weight at harvest 

This information is used to make 2 crop estimates per year: one at pre-bloom, and the second at pre-veraison.

-- Vines per Block

            The vine is the basic vineyard unit. An accurate count of vines per block is needed to use yield/vine or clusters/vine in an crop estimate. Remember that young vines come into production at slightly different times and in older blocks, vines succumb to disease such as crown gall, nematodes, tractor ‘blight’ or possibly phylloxera. Vine counts are simple …in a rectangular block multiply the number of vines/row by the number of rows. In an irregular block, a row by row count is required. After you know the total number of vines, you can count missing or non-productive vines each year and subtract that number from the total to arrive at producing vines per block.
 

Figure 2.Xarello variety at modified E-L stage 12, with pre-bloom clusters, easily visible. NMSU viticulture, experimental vineyard at Fabian Garcia, Agriculture Science Center, Las Cruces, NM

 

--Cluster per Vine

            Nodes per vine changes yearly and is determined by vine size and pruning severity. Shoots/node is determined by pruning and weather during bud initiation the previous year. Clusters/shoot depends on weather in the year prior to cropping. Clusters are visible and easily counted about 2 weeks before bloom (see Figure 2). Not all vines in a block have to be counted, although all clusters on the selected sample vines should be counted. The number of sample vines per block depends on how uniform the block is. Where vines are the same size and age, and pruned to the same bud count, about 4% need to be sampled. This percentage holds for small blocks up to about 3 acres in size. In non-uniform blocks with variable vine size and vine age the percentage counted needs be increased. A vine count of 30% was required in one trial with non-uniform vines. 

--Cluster Weights at Lag Phase

            Cluster weights are the most difficult component of the crop estimation process to predict, partly because they are sensitive to the environment right up to harvest. The lag-phase occurs about mid-way between bloom and harvest, when berry growth rate slows temporarily. It is generally associated with lignification or hardening of the seed coat.  Flowers per cluster, berries per flower or fruit set and seeds per berry (which greatly affects berry weight) all have been determined by this stage, and their effects can be measured by a sample cluster weight. This sample weight correlates well with final cluster weight. Simply, large clusters at lag-phase = large clusters at harvest and small clusters at 

lag-phase, are small at harvest. A random sample of 200-400 clusters/block is usually adequate. This total weight, divided by the number of clusters = average cluster weight. There is no need to weigh individual clusters. Timing of mid lag-phase sampling is more difficult (refer to Tables 3 and 4 above) as it takes some trial and error to determine the mid-point of lag-phase. 

Typically, it is accepted that the mid-point occurs about 55 days after first bloom. In the Oregon work, mid-point lag-phase coincided with 75% hard seed tips. This “hard seed tip” determination is done by passing a sharp knife through the grape berry. If the knife pushes the seed, instead of slicing through it, then the berry is said to be at ‘hard tip’ or ‘hard seed’ stage, or mid-lag phase. The Oregon study used Pinot Noir. Chardonnay and Sauvignon Blanc show cluster weight variability due to differences in bud fertility. Merlot and Gewurztraminer have differences in fruit set that impact cluster weight. Obviously, seed hardening test cannot be used with seedless table grapes, and this is where a certain  number of days past bloom would be used.                                                    

 

 

--Cluster Weight at Harvest

            Cluster weights at harvest are a key part of yield prediction, and it is crucial that cluster weights be determined each year to provide a record for crop estimation in future years. The long-term record establishes the between cluster size variation and yield variation. The information can be used with early season predictions and with lag-phase sample to predict this year’s harvest cluster weight. To record cluster weights at harvest, it Is easier to sample out of harvest bins as fruit is received at the crush pad. However, a sample randomlycollected directly from the vines correlates better with the lag-phase sample, and is likely closer to the true cluster weight than is a bin sample. In the bin, it is difficult to tell partial from complete clusters. Only about 200-400 clusters collected directly from the vines are needed to determine an accurate representation of average harvest cluster weight.

 

--Predicting Yield

            The grower will need the following information: vines/block, clusters/vine, lag-phase cluster weight, and harvest cluster weight to generate an effective yield prediction. The first prediction uses vine counts and estimates of clusters/vine, just before bloom. Vines/block are multiplied by cluster/vine to estimate clusters/block. Then harvest cluster weight is multiplied by clusters/block for an initial estimate of tons/block.  

            This first estimate can be revised after the lag-phase cluster sample is taken (~ 55 days after full bloom …or mid lag phase as you determine it). This sample is compared to average lag-phase cluster weight to estimate harvest cluster weight. For example, if the lag-phase sample is 20% larger then the average lag-phase cluster weight, the harvest clusters are estimated to be 20% larger than average harvest cluster weight. This revised cluster weight is then multiplied by clusters /block for an estimate of tons/block. These two predictions can be put in formula form as shown below:

 

 

First prediction: V x C x H – estimated yield

V = vines/block, C = cluster/vine, H = average cluster harvest weight

Second prediction: V x C (S/A x H) = estimated yield 
where S = lag phase cluster weight, A = average lag phase cluster weight

 

This formula assumes that cluster weight will always increase the from lag-phase to harvest. This won’t always happen…take a look at what we found in North Carolina when we tracked berry weight development over the course of the season in Chardonnay and Cabernet Sauvignon (Tables 3 and 4). 

            Final cluster weight is influenced by environmental effects on berry size. During the final part of the season growers should be aware and adjust estimate accordingly. A hot dry season will reduce berry sizes, so crop estimates should be reduced. Conversely, late rains can increase berry size and increase crop estimates. Bird damage, heat and sunburn that shrivel berries, botrytis and animal predation or disease can affect cluster size and yield. So, no estimate is final …until the crop is in. 

            .

--Conclusion

Growers need a record of harvest cluster weights and lag-phase cluster weights in order to apply these formulas and generate a crop estimate. The better the data (records)… the better the estimate. Accuracy depends on long-term records and how weather/climate and your practices affect yield variation. The systems summarized above worked well with Pinot noir in the Willamette Valley of Oregon and with certain varieties in Virginia. 

Accurate crop estimation is still very much a work in progress in New Mexico, but the concepts and the procedures explained here are sound. Overall, crop estimation is meant to reduce confusion and streamline processes and work in the vineyard and winery. This season…I will be collecting average cluster weights from cooperating growers. I plan to share the results at the annual NM Wine Educational Conference tentatively scheduled to be held at Santa Fe in 2021. If you would like to work with me to develop records of harvest cluster weights in 2020, please contact me:

 

 

 

Gill Giese, Extension Viticulture Specialist

ggiese@ nmsu.edu 

 

505 865-7340