March 2016 Issue of Wines & Vines

A Conversation with Markus Bokisch

Influential Lodi grower discusses irrigation, weed control and mechanization

by Laurie Daniel
Markus Bokisch photo.jpg
Markus Bokisch

Markus Bokisch, owner of the vineyard-management company Bokisch Ranches in Lodi, Calif., isn’t the area’s largest grower. He is, however, considered one of its most influential.

Bokisch Ranches farms about 2,250 acres in various parts of the Lodi American Viticultural Area and surrounding regions. About 150 acres are Bokisch’s own vineyards: Terra Alta and Tizona in the Clements Hills sub-AVA, and Las Cerezas in the Mokelumne River AVA. Bokisch and his wife, Liz, are also partners in several other vineyards totaling 1,100 acres. He manages the rest of the acreage for other owners. Although Bokisch sells to some large wine producers, his grapes also go to small, high-end wineries such as Turley, Forlorn Hope, Neyers and Mark Herold Wines.

Bokisch grew up in Southern California and spent summers in the Catalonia region of northeastern Spain, where his mother was born. That’s also where he first developed an interest in wine. He went on to graduate from the University of California, Davis, in 1989 with a degree in plant pathology and international ag development.

He immediately went to work for Joseph Phelps Vineyards as a viticulturist, and it was while looking for Rhone grape varieties during his tenure at the St. Helena, Calif.-based producer that he encountered Lodi. After three years at Phelps, Bokisch spent a year in the vineyards of Catalonia. When he returned, he was determined to plant his own vineyard and found himself drawn to Lodi. In 1995, the Bokisches bought the property that would become Terra Alta. The following year, they started Bokisch Ranches.

Bokisch is perhaps best known for Iberian grape varieties. He farms about 175 acres of Iberian grapes and sells them to at least 30 wineries. He also specializes in wines made from those grapes at his winery, Bokisch Vineyards.

Q: Water management has been a huge topic in recent years in California. What sort of technology are you using to reduce water use in the vineyards you manage?

Markus Bokisch: We have been fortunate in Lodi because the drought has not had a large impact here. Well-water levels have not dropped in a similar fashion to what has been reported in parts of the Central Valley or Coast Range. Yet we live in a semi-arid savanna, and water efficiency should always be a top priority.

In the past, we used two basic methods for determining our water usage: visual inspection and tensiometers (a device for measuring soil tension). Visually inspecting the vines for signs of water stress in key indicator areas will always be the final determinant of how much we irrigate. Tensiometers have served as a good aid to support our visual conclusions. The problem with both these techniques is that they lack precision, which can lead to significant over-use of our water resource.

Our next refinement in irrigation strategies involves the use of Ranch Systems’ remote weather stations, which we plan to install this winter. These stations will include a main hub in the vineyard, with a modem that reports back to our computers and/or smartphones. The weather stations monitor real-time temperature, humidity, dew point, rainfall, wind speed and direction, and UV radiation. In addition, they control several irrigation valves while measuring water pressure and flow at the pump and water flow behind each of the valves. Many variables including evapotranspiration will be used to determine our weekly irrigation schedules. The remote valve control will save labor and allow us to verify that systems are working properly at all times. The powdery mildew index will be used to guide the timing of spray cycles. Temperature sensors scattered throughout the block will be able to trigger alerts for frost control and heat mitigation.



    Bokisch Ranches manages about 30 acres of old Zinfandel vines, and those vineyards present some viticultural challenges.

    “These vines pre-date the concept of vineyard mechanization and do not bend their will to its adoption,” Markus Bokisch says. “Almost everything has to be done by hand.…Fortunately, due to a total lack of wires and a lower planting density, most labor-related tasks are cheaper than in modern, conventional vineyards.” Plus, the prices paid for old-vine Zinfandel fruit are higher.

    In December 2013, Bokisch says, a lot of old-vine Zinfandel in Lodi was hit by a prolonged freeze. “Due to the drought, the vines were starved for water and were not sufficiently hardened to endure the cold. Many vines died or lost many spur positions,” he says.

    “We decided to install subsurface drip irrigation down every row to supplement the soil profile in the fall to prevent winter freeze damage. The system also served to irrigate the vines in late summer, prior to harvest. We also installed surface irrigation and placed emitters in the areas where vines had perished during the freeze.”

    Spraying is also a challenge, Bokisch notes. Because Zinfandel is susceptible to mite infestations, he tries not to use sulfur dust, which can exacerbate the mite damage and use fungicide sprays. But because of the spacing of the vineyards, he’s able to use only a small, 4-foot-wide sprayer. He leases a Venturi Air three-point sprayer from his neighbor and also uses it for vineyards with high-density plantings.

Q: You farm organic vineyards as well as vineyards that are certified sustainable under the Lodi Rules for Sustainable Winegrowing. What equipment and techniques are you using for managing weeds?

Bokisch: Our involvement in the Lodi Rules (sustainable certification program) has had an impact on what types of herbicides we use and how we rotate their use in the vineyard.

In our organically certified vineyards, all of the blocks are located in gravelly or cobbley clay loams along the base of the Sierra Foothills. While there seem to be more organically registered herbicides that are becoming available to the market every year, they are all contact herbicides that are mostly effective only when the weeds have just emerged and are smaller than the circumference of a quarter. Berm cultivation is still required.

We currently utilize a Kimco berm cultivator with rotating tines that automatically churns the soil in the berms. Its automated sensor triggers the cultivator to retract around an oncoming vine. This system can be used twice, followed by a discing to fill in the soil that has been pushed into the row. We find that it takes five to six passes to effectively control weeds in one season with cultivation. This is true whether you use a cultivator like ours or a weed knife. A weed knife seems to require less horsepower, therefore less diesel, and can be driven almost twice as fast, from 2 mph to almost 4 mph.

It costs us approximately $50 per acre per pass for our berm cultivator, and it costs us $22 per pass for our disc. Assuming four passes per season with the cultivator and two with the disc, we are paying $244 per acre to control our berm weeds. This figure does not take into account the hours of weed trimming directly around the trunk of the vines where any form of mechanical cultivation seems to have issues.

In contrast, we pay $75 per acre to unhook the drip hose off of the drip wire just before irrigation begins in late May. We pay another $75 to rehang the drip hose just before mechanical harvesting. This movement of the drip hose during irrigation allows us to cultivate only once under the vines, instead of six times. It also allows us to control the drip irrigation-induced weeds with cheaper mowing passes.

Weed control is a challenge in high-wind-velocity areas in the (San Joaquin-Sacramento River) Delta. The standard for spraying to reduce drift has been to stop our spray rigs once the wind speed has reached 10 mph. This window of low wind typically occurs for about three hours in the early spring and summer mornings. Finding an employee willing to drive to work only to complete a three-hour shift is untenable. Tying up our tractors and spray rigs in wind-prone vineyards is equally uneconomical. For now, we have to rely on cultivation during the growing season, when it’s generally too windy to spray. We are in the process of building a prototype spray rig that will allow us to cover more ground in high-wind areas by creating an environment around the berms where wind speed is less than 10 mph.

We will build a stainless steel spray compartment/shield that follows the contour of the ground with tracking caster wheels. This will allow us to keep the shield as close to the ground as possible. The compartment will be lined with brushes that reach to the ground, impeding any air from whipping under the shield. The spray nozzles will be oriented to spray the brushes instead of the weeds. The brushes will be saturated with herbicide and will wet the target weeds through wicking. This design will greatly reduce drift. Many of our design ideas have been adapted from sprayers we observed in New Zealand and Australia.

This year we began another program that we hope will have some weed suppression merit. Walnut shells used to be consumed by the oil industry and by co-generation plants. Now, with the drop in energy prices, it has become too expensive to haul the shells to co-generation plants relative to the energy they provide. The consequence is that walnut shells are being stockpiled around the Central Valley.

We have taken this opportunity to use crushed walnut shells for vineyard avenue dust control as well as weed control on our berms. We are currently conducting a few 1-acre trials of 6-inch-thick mulch for berm weed suppression. Our only concern would be damage done by meadow voles. However, because the crushed shells tend to erode, much like dry sand, we believe that any tunneling by voles would be undermined. We will study the results of our experiments during the 2016 growing year.

Q: What sorts of mechanization are you looking to add in the next few months or years?

Bokisch: We are looking at pre-pruners from Pellenc and Clemens. By pre-pruning, we intend to take out the majority of the time dedicated to pulling canes out of the trellis system, allowing our pruners to walk down each row faster. When labor was cheaper and more readily accessible, the difference in cost of pre-pruning vs. not was almost insignificant. Now, with the increase in labor cost and the reduction in laborers, the difference is significant enough to justify the investment.

We are also entertaining the idea of abandoning traditional (human) suckering for either chemical or mechanical suckering, or a combination of both. We are currently studying a company out of New Zealand, Cropland, that has produced an implement that tracks the ground with wheels. The vine trunks enter a steel enclosure surrounded by stiff bristles. The inside of the enclosure has herbicide spray nozzles. The spray remains within the enclosure, surrounding the trunks. The bristles wick the herbicide to the green shoots and aid in breaking some of the most tender shoots off. Because this implement tracks along the ground, it performs very well on hillsides, where the arms can extend further downhill to the ground. Also, by adding a few more nozzles, one could direct herbicide onto the berm for further berm weed control.

Leaf pulling is a simple and repetitive task, requiring low skill level. However, it does put workers into direct contact with sulfur residues that can lead to eye and lung irritation. By purchasing an automated leaf puller, we reduce the risk of worker injury either through chemical exposure or repetitive wrist action. We also free up our labor pool to focus on more detailed tasks, such as crop adjustment. We have been looking at the Clemens leaf remover.

Weight scales on our gondola axles, coupled with GPS tracking systems, allow us to understand the cropping level in every area of our vineyard. We can then correct the underperforming areas by redesigning the fertigation system and adding more amendments with our spreaders.

Q: Why are you looking to increase mechanization?

Bokisch: Increasing mechanization is the new paradigm in California perennial agriculture. Our labor resources continue to shrink. Mechanization should not be interpreted as a means of reducing the cost of tasks in the vineyard. Rather, it is a way to slow down the creeping increase in the cost of labor. Much like solar arrays, it “fixes” your cost of operation, making them more predictable.

Mechanization has other benefits as well. Instead of having several crews of migrant workers pruning or harvesting your vineyard, you could have a few skilled and paid operators performing the same functions. Those operators would be year-round employees, vested in the successful outcome of the company that employs them and the community where they live. It has an overall stabilizing effect.

Due to the high cost of purchasing specialized vineyard tools, mechanization becomes a barrier to entry for smaller farming operations. A grower who does not have enough acreage to purchase his own pre-pruner would have to hire someone else to perform the operation. However, with the shrinking labor market, the same could be said of getting hand labor. Larger growers currently have easier access to farm labor contractors.

Take mechanical harvesting at night on a vineyard with 6 tons per acre. In a vineyard with modified vertical shoot positioning, one mechanical harvester—we use Gregoires—can pick approximately 2 acres of vineyard in one hour. This includes rest breaks, lunch, etc. We typically have four people per harvest crew: the harvester driver, two gondola drivers and the walker/quality-control person. This set-up allows me to harvest 12 tons with four individuals in one hour, or three tons per individual. Our typical hand-harvest set-up consists of two eight-picker crews, two leafers, four tractor drivers and one light-generator operator. These two crews have a total of five tractors between them. Both crews can pick 24 tons in six hours—equivalent to 4 tons per hour and 1.14 tons per person per hour.

Hand harvesting is approximately one-third the speed of mechanical harvesting, consuming far greater human and mechanical resources. Twenty-one people vs. four people, and five diesel engines vs. three diesel engines and all the wear and tear. Another consideration would be the increased opportunity for injury when coordinating so many people in a limited-light environment who are wielding harvest knives and in close proximity to tractors. If we were to account for day harvest, the difference would be exacerbated due to heat.

For a cost comparison, we typically charge $350 to mechanically harvest 1 acre. This amounts to $58.33 per ton. We charge $200 to handpick 1 ton of fruit, or nearly four times the cost of mechanical picking.

A resident of the Santa Cruz Mountains, Laurie Daniel has been a journalist for more than 35 years. She has been writing about wine for publications for more than 21 years and has been a Wines & Vines contributor since 2006.

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