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Home HortScience Irrigation Methods Compared for Highbush Blueberry Plants
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CORVALLIS, OR - Highbush blueberry is a shallow-rooted crop that is very susceptible to water stress. The plants usually require irrigation, even in wet climates. In the United States, overhead sprinklers and drip irrigation are the most common irrigation methods used by commercial blueberry growers. Some growers have also begun testing low-volume microsprays - also known as microjets or microsprinklers - on blueberries. A new study evaluated the effects of the three systems and recommended drip irrigation as the best method for establishing young blueberry plants.

According to David R. Bryla, a research horticulturist with the U.S. Department of Agriculture's Agricultural Research Service, each of the three irrigation systems used in blueberry production has unique advantages and disadvantages. While overhead sprinkler systems are easier to install and maintain than drip systems, they also require more water and energy and are more expensive to install. Drip irrigation systems enable more frequent and uniform water applications, thereby increasing water use efficiency, but have distinct shortcomings; drip emitters can plug when water infiltration is inadequate or the system is improperly maintained, and drip may increase plants' susceptibility to root rot disease.

Microspray irrigation offers advantages similar to drip irrigation but applies the water to the soil surface using a small spray. A major problem with microsprays, however, is "plant interference" during water applications. When plants mature, much of the water from microspray emitters is intercepted by the canes, thus reducing the uniformity of water application.

Bryla and his colleagues published a study in HortScience that evaluated the effects of sprinklers, microsprays, and drip on vegetative growth in blueberry crops. The scientists collected data during the first two years after planting 'Elliott' northern highbush blueberry and focused on identifying irrigation systems that improved growth of the crop during establishment.

For the study, blueberry plants were grown on mulched, raised beds and irrigated by sprinklers, microsprays, or drip at a rate of 50%, 100%, and 150% of the estimated crop evapotranspiration (ETc) requirement. Irrigation was applied at different levels to identify the optimum irrigation rate and to investigate the consequences of over- and under-irrigation with each system. "Irrigation requirements are usually much less during establishment than at maturity but are often considered very important at this stage because even small amounts of water stress (including drought or flooding) in young plants may substantially increase the time for the plants to reach their full production potential," Bryla explained.

After two years, drip irrigation at 100% Etc produced the most growth among the irrigation methods with at least 42% less water than needed for maximum growth with microsprays and 56% less water than needed with sprinklers. "The primary benefit of drip was likely the result of higher soil water content in this treatment in the vicinity of the roots," said Bryla. "In terms of plant growth and water use efficiency, drip irrigation was the best method to establish healthy blueberry plants in the present study. However, sprinklers and microsprays may be better alternatives for susceptible cultivars grown at sites prone to problems with root rot."

"This study demonstrated that drip irrigation may not only increase water use efficiency in blueberry compared with other irrigation methods, but it also may improve plant establishment. Generally, plants that establish more quickly have higher production once fruiting begins," the researchers said.

The team is planning further research to examine the effects of the irrigation methods and rates of water application on fruit production during plants’ growth to full maturity.


The complete study and abstract are available on the ASHS HortScience electronic journal web site:

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Original Article:

Evaluation of Irrigation Methods for Highbush Blueberry—I. Growth and Water Requirements of Young Plants
David R. Bryla, Jim L. Gartung, and Bernadine C. Strik
HortScience 46:95–101. [Abstract] [Full Text] [PDF]

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