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Collecting Weather Information in Orchards
Collecting weather data is becoming more important to successful implementation of integrated pest management (IPM) and making orchard cultural management decisions. Weather information is useful for monitoring disease infection periods, operating insect degree-day models, monitoring irrigation systems, applying fruit thinning chemicals, and operating computer-based orchard management software.
This section describes ways to record weather data to obtain information for making fruit-production decisions. The emphasis is on setting up a weather station, choosing instruments, taking observations, and modifying TV and radio forecasts for local conditions. However, customized weather prediction services that are specific for your farms can also be purchased from private companies. While many weather variables can be observed routinely to describe local weather, only a few of the most critical are discussed here. For more information, consult the reference list at the end of this guide.
Weather can vary over small distances, owing to variations in terrain, vegetative cover, proximity to water bodies, and other factors. Therefore, weather observations taken at one location may not be representative of another location, even within the same county, farm, or orchard. Similarly, weather forecasts for a nearby city or area may not be adjusted for local weather influences (i.e., terrain) within a county or on a farm. It is therefore necessary for growers to take weather observations on their own farms to make informed decisions. If there are significant differences in the locations of your orchards, you may need to take weather observations at several sites on the farm. You can use these as a basis for adjusting more general TV and radio weather forecasts to your local conditions.
Both manual and automated weather instruments are available for recording weather data. Automated instruments provide continuous observations of weather and their data can be automatically downloaded into a personal computer. Automated instruments will cost between $500 and $6,000 depending on the number and type of sensors and the accompanying software. Manual instruments are less expensive and need less maintenance, but observations must be taken at least on a daily basis. Data collection, summary, and input into the computer is performed manually by the observer.
Comparisons of Weather Monitoring Equipment
Many environmental monitoring systems exist for collecting weather data in orchards. These systems must be compared for information reliability and ease of use. Most of the systems that are commercially available will collect accurate weather information in orchards. The factor that often determines whether a grower utilizes farm-based weather information to make decisions is the ease-of-use of the system they are operating.
Weather collection systems
Weather collection systems have been tested for use in orchards by Penn State personnel since the early 1990s. Many weather collection systems have been tested for ease of use and accuracy. This summary will review a manual system, consisting of thermometers and a hygrothermograph; several automated systems, including the Sensor Field Monitor™ and Metos; and a weather data delivery service, SkyBit E-Weather, which delivers daily summaries and forecasts. Each system presents different features, but all provide temperature, relative humidity, precipitation, and leaf wetness information. There are several other weather collection systems that are commercially available but are not included in this summary.
Quality of the weather data
As a generalization, all of the systems measured temperature and relative humidity well. There were some discrepancies in precipitation and a general disagreement on leaf wetness. However, the accuracy of the weather information provided by all of the systems was adequate for day-to-day orchard IPM decision making.
Rating ease of use: how each system compared
Setup often requires a pole or shelter for mounting the equipment, and some smaller poles or stakes to mount the gauges and sensors. Most of the automated systems could benefit from better manuals. Additionally, all of the systems are susceptible to failure. Each system we used experienced some data loss from a variety of causes, such as low batteries, insects in the equipment, problems with software, and difficulty operating the unit. To get the most out of the electronic units, a computer is necessary. If you don't have a phone line to connect to the electronic units, you will need a portable computer to take into the field to collect the data.
Manual systems: hand-operated sensors and hygrothermagraph
A hand-operated (thermometer, rain gauge) weather collection system is the least expensive system. An on-farm hand-operated collection system can be purchased for as little as $100. The shortcoming of a hand-operated system is the lack of hourly information that is necessary for most disease and insect predictive models. Hand-operated systems require daily readings of thermometers and rain gauges at the same time each day. The hand-operated instrument observer routinely visits the weather station each morning at the same time to record the weather records form the previous 24-hour period. Commitment and time is required to operate manual weather systems. Hygrothermographs eliminate the need for daily readings. They are reliable and accurate when regularly calibrated. The charts must be changed once a week, and information must be retrieved manually from the charts. Weather information must be manually summarized and entered into the computer. These instruments are becoming more expensive, costing in the range of $1,800 to $2,000. The hygrothermagraph is also prone to human error, since people perform all readings and manually summarize the information.
SkyBit E-Weather
SkyBit E-Weather is quite different from the other systems. There is no equipment in the field. Site-specific weather information is provided daily by e-mail or fax. The grower must provide the latitude, longitude, and elevation of the orchard site to the company. If you are comfortable with e-mail or have a fax machine, EWeather is easy to get and use. Additionally, E-Weather provides a forecast, which can provide the grower with the information to plan for pesticide applications or labor management. E-Weather also provides weather trends, degree-day accumulations, and disease and insect predictive model outputs. Daily leaf wetness and precipitation information provided by E-Weather is less accurate than the orchard units described earlier. The quality of forecast data is very good for temperature and relative humidity, but not as reliable for precipitation and leaf wetness.
Which system is the right choice?
No single system is the right choice for everyone. The prices range from as little as $100 to several thousand dollars for a field monitoring unit. Weather monitoring units placed in the orchard have the advantage of very accurately recording the weather at the orchard site, but they must be maintained and routinely accessed for weather information retrieval. SkyBit E-Weather calculates the weather information for the site without the need to place and maintain an orchard unit. In addition, SkyBit E-Weather provides forecast information for a specific orchard. The system a grower chooses depends on the needs of the individual grower.
All of these systems are being tested by Penn State personnel. Please contact your local extension agent if you have questions about the selection of a weather monitoring system.
Distributors
E-Weather
Skybit, Inc.
369 Rolling Ridge Drive
Bellefonte, PA 16823
1-800-454-2266
Hygrothermagraph
Belfort Instrument Company
727 S. Wolfe Street
Baltimore, MD 21231
1-800-937-2353
Thermometers, rain gauges, etc.
Ben Meadows Company
P.O. Box 5277
Janesville, WI 53547-5277
1-800-241-6401
Forestry Suppliers, Inc.
205 West Rankin Street
P.O. Box 8397
Jackson, MS 39284-8397
1-800-647-5368