Do You Need a Weather Station in Your Vineyard?

by Bill Pregler

Grape growers are beginning to use information technology to make informed weather-related decisions, as well as choices about vineyard development.

All sectors of the wine industry have embraced new technologies, from better laboratory equipment to marketing software, but one area that is often overlooked is the vineyard itself. Now driven by increased competition, grape growers are using information technology as a way to more quickly adapt to the uncertainties of nature. The newest weather stations provide real-time, site-specific data, allowing growers to instantly and precisely monitor weather conditions at specific vineyard locations, including multiple locations simultaneously. They even assist vineyard developers in evaluating sites for potential development.

Identifying and tracking weather conditions in the vineyard allows growers to make informed weather-related decisions, saving time and money, and ultimately improving the quality of the fruit. More accurately detecting weather parameters and soil moisture, and acting on this information, also results in more reliable frost protection, the ability to irrigate based on demand, and, over time, the capacity to employ pest and disease models that will indicate if and when spraying is necessary.

Wine Business Monthly found that there is a wide range of units available for any size operation, from low cost-of-entry stations for monitoring a nearby vineyard to highly sophisticated, satellite-based data-retrieval services that can track conditions in the most remote locations. Functions and features also vary, allowing the grower to purchase a basic, off-the-shelf system, or custom-design units to detect a wide range of the most subtle vineyard conditions.

How the Systems Work

There are only a few key components that make up the majority of today's best weather stations. The first and most obvious are (1) the sensors, which collect various raw data into a data logger. Traditional systems require all sensors to be hardwired directly to the data logger, which involves burying cable to the location to be monitored. Newer systems that utilize wireless technology (cellular and WiFi) employ sensors that are hardwired to remote transmitters (called nodes or motes) that wirelessly transmit data from specific vineyard sites back to the data logger. After the data is collected by the sensors and transmitted to the weather station, there must be (2) some form of telemetry, a means by which the data can be transmitted from the weather station to a computer for analysis. This can be a simple wire, a radio antenna, a cell phone or a satellite link. Finally, there is (3) the computer software to process the collected information.

Most systems are easily assembled by the customer and have simple electrical connections. The hardware itself is usually mounted on some type of mast, most as simple as a tripod base and pole assembly. The mast and related hardware are simply bolted together. For more complex systems utilizing satellite telemetry, there is usually an installation agreement with the dealer, which is part of the purchase price.

Basic Sensors

There are six basic parameters that should be monitored by any vineyard weather station you consider. The majority of weather stations on the market today come with sensors designed to monitor these parameters:

• air temperature
• relative humidity
• wind speed
• wind direction
• solar radiation
• precipitation

Some inexpensive systems offer most of these monitoring features, but not all, while high-end systems might provide more data than you will actually ever need. The grower must determine what makes sense for a particular vineyard, keeping in mind that individual bits of information, which might not be helpful on their own, supply the grower with a better understanding of a wide range of conditions when combined with other individual parameters.

For example, frost control measures are largely based on air temperature and relative humidity (moisture in the air). By monitoring these conditions in real time, you can predict alert situations, which can be communicated in various ways, including in-field alarms, signals to pagers, cell phones, flashing lights and even automatic irrigation. Stations should report conditions at least every 15 minutes to be sufficient for frost protection.

Evapotranspiration (ET), another important calculation that can be made with basic raw data, is based on air temperature, relative humidity, solar radiation and wind speed. ET is a sum total of evaporation (the movement of water into air from sources such as the soil or bodies of water) and plant transpiration (water that transpires from nearby leaves) and an indicator of how much water a vineyard will require over a given period of time. Growers analyze ET when considering how and when to irrigate their vineyards.

Weather stations can also prove to be an effective tool when determining the safety and effectiveness of spraying. Relative humidity, along with wind speed and direction, help growers conform to local regulations pertaining to when they may spray and how drift can be minimized. Temperature is also important as hot, dry conditions can result in evaporation, reducing the effectiveness of chemicals.

Optional Sensors

As an adjunct to the basic sensors, additional detection can be applied to monitor conditions in the soil and the leaf canopy, focusing on moisture content and temperature.

Soil Sensors:

Soil temperature and moisture sensors are used to monitor the conditions of the soil. Irrigation calculations can usually be based on weather, but soil conditions do not necessarily follow logically. Soil sensors provide insight into the fate of the water applied. Usually two to four sensors are used per station, buried at different depths within the root zones (up to about four feet) and in different locations. Aside from monitoring the soil conditions within the immediate root zones, soil sensors are helpful in erosion control and aeration decisions.

Leaf Sensors:

Leaf sensors monitor surface wetness on leaves or other surface areas of the plant. This is important because of the influence moisture has on diseases and pest infestation. This reading, in conjunction with air temperature and humidity, can help monitor conditions for powdery mildew, botrytis, orange tortrix, spider mites, leafhopper and others. The sensors are generally placed in leaf and fruit zones.

Placement of Sensors

Proper placement of sensors is critical. The rule of thumb is to try to locate your equipment in an area that best duplicates the microclimates you are interested in monitoring. Canopy and soil sensors must be placed in proximity to the vine, but wind sensors must not be obstructed, and air temperatures must be made away from large paved surfaces (because they retain heat).

If your vineyard is relatively uniform, flat, and equally exposed to wind and sun conditions, a single weather station with sensors on or near the station might meet your needs. For instance, Fasano says he can easily monitor a relatively flat, homogenous 60-acre vineyard with one station.

If, however, your vineyard has wide variations in terrain and contains several microclimates, you might need to take measurements in multiple locations. In this case you have two basic options: (1) use multiple weather stations with hardwired sensors; or (2) use one weather station and place remote wireless sensors throughout the vineyard.

The way in which remote sensors transmit information to the weather station is one of the primary distinctions among the kinds of weather stations available today. Most times these sensors are hardwired to the station. Sensors hardwired to the weather station must be within 300 feet of the weather station. Generally, though, the sensors are placed in close proximity to the station because the cable (shielded and high-quality) is expensive. Newer systems that utilize wireless technology offer a greater range than hardwired sensors. Remote sensors using wireless transmitters can be placed up to a half-mile from the weather station.

Telemetry

The possibilities available for transmitting data from a weather station to a remote computer or to the Internet are predicated on the location and accessibility of your vineyard. If you are lucky enough to have a vineyard that is close to your location and/or your computer, chances are you will be able to comfortably work within the parameters of a low-cost system.

The simplest stations are hardwired to the computer, and their range is limited. For other low-cost systems, data transmission is accomplished via a radio and is often limited to 1,000 feet. This is generally referred to as "line-of-sight." With the addition of "repeaters," wireless transmission from these stations can be improved to a few miles. Obstructions are also important to evaluate when considering telemetry. A general rule is that the stations must be separated from obstructions such as trees and buildings by a distance of ten times the height of that object.

Data transmission can be achieved by telephone modem, radio telemetry (VHF, UHF, spread spectrum), manually downloading directly from a weather station to a laptop or Ethernet or satellite network. Vineyards in remote areas, or in hilly locations, valleys or surrounded by forested areas barely able to support cell phone communication, require different technology. In these circumstances, satellite may be the only option for transmitting data from the weather station to the computer.

The cost of telemetry is relatively inexpensive. Hardwire transmission is free as is line-of sight-radio transmission. Cellular and modem transmission is priced on a monthly usage basis, just as cell phones and high-speed Internet access. Even satellite transmission is not prohibitive. For example, Automata in Nevada City, California, a company that processes the data and makes it available on their Web server, charges 50 cents per sensor per month.

Where you locate your station will also determine the power supply required to operate the sensors and telemetry. Virtually all systems will have a primary power source utilizing batteries. How long those batteries will last, before they need replacement, is important, but they will also need the power to handle the data transmission requirements. In most situations, however, the best solution will be solar-charging systems. Several stations have evolved to the point they are totally self-contained and rarely need visitation other than for maintenance and cleaning.

Software

All weather station manufacturers offer software packages for their systems, and this is the least expensive component of any system. They all provide basic graphics and charts, all with easy downloads. The software keeps track of each of the parameters discussed earlier, and performs the algorithms required to combine pieces of information and create profiles. Again, of interest to the grower are the combined conditions, which would signal an alert for diseases and pests. Generally, these programs will produce reports with graphs showing the modeled pest pressure.

Probably the most important calculation is the frost alert, the one threat that has the capacity to destroy an entire crop. Once detected, the program should have a dial-out feature to contact the grower in the event of an emergency. The detection of a single event that saves an entire crop can easily offset the cost of a single station

Finally, the software should have the ability to download to other programs, such as Excel. One important part of data collection is the compilation of a history. This accumulated data will allow you to create a profile against which you can compare year-to-year findings. Probably the most important of all profiles is the degree-day calculation, which is an accumulated heat index. Because grapes need to reach a certain temperature in order to move from dormant to crop, the ability to track temperature to time is a valuable tool.

Buying into the Technology

Once you've assessed your vineyard's specific needs, how sophisticated does the equipment need to be to accomplish the task? Again, wide variations in terrain may result in a single vineyard containing several microclimates.

Probably the easiest and least expensive system available is a handheld unit that is simply carried into the vineyard and held near the zone to be monitored. These are most commonly used for monitoring wind speed and temperature for spray conditions. For John Derr at Pina Vineyards in Napa, covering eight hundred acres requires the ability to move. "We can build data on degree-days from vineyard to vineyard, from valley floor to hilltop," said Derr. The unit from Nielsen-Kellerman, known as the Kestrel, provides real-time data and has storage capability. It also comes with its own software so that information can be downloaded at the end of the day. Because it is inexpensive, several vineyard people can each have a unit that is portable among properties. One drawback is that it will not signal an alarm for frost conditions.

Intermediate-priced stations have the distinct advantage of being on location to sense conditions but are usually relegated to a single location. Again, if your vineyard is small, relatively flat and consistent with regard to soil and exposure, one "site-specific" monitor is probably sufficient.

If you are growing in Napa, Sonoma, Lake County or Paso Robles, the hills and valleys create a wide array of microclimates and pose potential transmission problems. In the hillside vineyards of the Russian River area of Sonoma, for example, the bottom of your vineyard may be in coastal fog while the vines at the top are in brilliant sunshine. In this case you might need to take measurements in multiple locations and therefore require more than one station, or a single station with multiple remote sensors.

Paul Sloan, of Small Vines Viticulture, is a vineyard developer and manager who specializes in high-density planting in the Russian River and Sonoma Coastal appellations of Sonoma County, California. Because of the wide range of site-specific weather in these zones, from thick fog to bright sunshine, weather data is critical, not only for frost alerts but also when evaluating a property for development.

"Because of our unique locations on these hillsides," said Sloan, "it is important that we know the diurnal temperature swings and locate those areas, for example, that may trap cold air. And with accurate weather data, coupled with existing soil information, we can attract more winemakers to a vineyard project."

When you know the precise real-time conditions of the vineyard, you can also optimize equipment usage and accurately schedule labor. Since so many of Sloan's vineyards are remote, it makes sense to know a site's exact conditions immediately before sending a crew and equipment to respond to a possible mildew alert. "If they arrive with the spray equipment and the wind speed and direction is wrong, they have wasted a considerable amount of time," said Sloan. He added, "knowing the conditions in advance, we can predict if we will have time to finish the job as opposed to stopping, cleaning up and having to revisit the vineyard."

Larger vineyards, and those with complex communication needs, will likely require custom specification, and the answer is usually satellite links. Companies offering this level of equipment have evolved so as to provide complete packages and service arrangements. Picovale Services, Inc., based in Grass Valley, California, is a full-service company that will configure a station (or stations), drawing components from several custom manufacturers to accomplish the task. Thereafter, the grower can either purchase the hardware or lease it.

The multiple units are portable, can be placed anywhere and require only a clear view of the sky. In addition to the equipment costs, there is a service fee for the satellite service and Web access to the data. The information is processed, stored and delivered via the Internet. The grower can access vineyard conditions via a Web browser or any web-enabled device such as a PDA or mobile phone. "We had too many holes in monitoring our vineyards and are now very site-specific," said Toby Halkovich, head of viticulture for Cakebread Cellars in Rutherford, California. "We are pleased with how user-friendly and convenient the system is." He also said that they like the service agreement "because it means they monitor the equipment constantly and take care of all the maintenance. We just get the information."

As the technology continues to improve, the business of data collection services will grow. A recent entry to the field is Grape Networks, Inc. of San Ramon, California and their Climate Genie. Battery-powered sensors called "motes," developed for the U.S. military, are scattered throughout a vineyard and create a "mesh network" whereby each mote, via radio, communicates with the others and sends data to a data logger that directly transmits information to the Internet, where users can access their information on a password-protected site. Instead of using a single weather station, the radios become information transporters. They are placed 30 to 40 feet apart.

"This is definitely the next level of technology to be applied to the vineyard," said Nick Dokoozlian, vice president of viticulture for E&J Gallo. "In the past we could not get a true representation of a vineyard, but now we will be able to monitor an entire field and get an accurate profile of all the different microclimates." He added, "due to the density of sensors, we can have a powerful tool when making better front-end decisions in the vineyard." While E&J Gallo is still evaluating this new technology, field studies are already in process at Beringer Vineyards in St. Helena, California (10,300 acres). The product is being designed to accommodate vineyards of 100 acres or more and will be available in early 2007.

Another weather station supplier new to the market is Ranch Systems of San Francisco, California. Up to 50 wireless sensor nodes can be positioned a half mile from a base station. Each node can handle two sensors, and multiple nodes can be stacked to accommodate custom, site-specific readings. The base station transmits block level information via a directional cell antenna that allows for easy online data access and customized software.

In Sum

From the simplest of systems to the most expensive, weather station technology affords the grower control in the vineyard, reducing guesswork with regard to weather-related decisions. Accurate vineyard information allows the grower to deal with obvious concerns, such as frost, pests, and irrigation, and, if interpreted correctly, can have an impact on other decisions, such as when to spray and how to develop a vineyard site.

The best system for your specific needs will be determined by assessing : (1) the parameters you want to measure and how you want to use the information; (2) microclimates within the vineyard, to determine how many data collection points are necessary; and (3) the proximity of the vineyard to the computer that will be used to analyze the data.

Foreign competition will continue to exert pressure on our industry, forcing growers to do everything possible to control expenses and improve quality, which translates into dollars at the crush pad. Weather station technology is rapidly evolving and should prove to be one means to this end.