Highbush blueberry (Vaccinium corymbosum L.) is a shallow-rooted crop that is very susceptible to water stress (Bryla and Strik, 2007; Mingeau et al., 2001). The plants usually require irrigation for commercial production, even in wet climates (e.g., Byers and Moore, 1987; Haman et al., 1997). Within the United States, overhead sprinklers are typically used to irrigate blueberry in Florida, Michigan, New Jersey, North Carolina, and Oregon, whereas drip irrigation is usually preferred in Arkansas, California, Indiana, Minnesota, Mississippi, New York, and Washington (Strik and Yarborough, 2005). Each system has its advantages and disadvantages, making selection of the proper system sometimes difficult. Sprinkler systems, for example, are easier to install and maintain than drip, require little to no filtration, and enable frost and heat protection when necessary. However, overhead systems also require more water and energy, have higher installation costs, limit access to the field during and after irrigation, pose potential food safety risks when using surface water to irrigate, and occasionally lead to problems with fruit rot and other fungal diseases on leaves and canes. Drip irrigation, on the other hand, applies water directly to the roots and enables more frequent and uniform water applications, thereby increasing water use efficiency (i.e., growth and yield per unit of water applied) and potentially reducing plant water stress, but drip emitters plug readily when water infiltration is inadequate and/or the system is improperly maintained, the small wetted area produced by drip reduces root development, and by sustaining high soil moisture levels, drip may increase susceptibility to root rot disease (Bryla and Linderman, 2007). Water is usually applied one or two times per week, as needed, with sprinklers and every 1 to 3 d by drip.
Some growers are also testing low-volume microsprays (also known as microjets or microsprinklers) on blueberry. Although microsprays are not commonly used in blueberry, Holzapfel et al. (2004) found in a 7-year study in Chile that production and water use efficiency were higher with microsprays than with drip. Microspray irrigation offers advantages similar to drip irrigation but applies the water to the soil surface by a small spray. Because microsprays wet more soil volume than drip, plants tend to produce a larger root system, which may provide an advantage in a shallow, densely rooted crop such as blueberry (Patten et al., 1988, 1989). However, one major problem with microsprays is difficulties with plant interference during water applications. Once plants mature, much of the water from microspray emitters is intercepted by canes, thus reducing the uniformity of water application. This could be particularly problematic in blueberry because evidence from pot studies suggests that the plants are unable to translocate water and nutrients laterally (Abbott and Gough, 1986; Gough, 1984).
Ideally, irrigation is scheduled to replace any water lost by ETc unless compensated by rain. Weekly estimates of ETc are often accessible on the Internet from weather-based web sites such as AgriMet (Pacific Northwest Cooperative Agricultural Weather Network) and California Irrigation Management Information System. These sites obtain data from a satellite-based network of automated agricultural weather stations located throughout a region of interest. Weather data are used to estimate ET of a reference surface such as grass (ETo) or alfalfa (ETr), which is then converted to ETc using the appropriate crop coefficient for blueberry (see Allen et al., 1998 for details). Adjustments to these values are needed when plants are young or stressed (e.g., nutrient deficient). Under these circumstances, irrigators should pay close attention to soil moisture conditions to avoid under- or over-irrigating their crop.
The objective of the present study was to determine the effects of sprinklers, microsprays, and drip on vegetative growth in blueberry. Data were collected during the first 2 years after planting and focused on identifying irrigation systems that improved growth of the crop during establishment. Irrigation was also 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 (drought or flooding) in young plants may substantially increase the time for the plants to reach their full production potential.
Allen, R.G., Pereira, L.S., Raes, D. & Smith, M. 1998 Crop evapotranspiration. Guidelines for computing crop water requirements. FAO Irrigation and Drainage Paper 56 Food and Agriculture Organization of the United Nations Rome, Italy
Bryla, D.R. & Linderman, R.G. 2007 Implications of irrigation method and amount of water application on Phytophthora and Pythium infection and severity of root rot in highbush blueberry HortScience 42 1463 1467
Bryla, D.R. & Strik, B.C. 2007 Effects of cultivar and plant spacing on the seasonal water requirements of highbush blueberry J. Amer. Soc. Hort. Sci. 132 270 277
Bryla, D.R., Trout, T.J., Ayars, J.E. & Johnson, R.S. 2003 Growth and production of young peach trees irrigated by furrow, microspray, drip, or subsurface drip systems HortScience 38 1112 1116
Bryla, D.R., Yang, W.Q. & Linderman, R.G. 2008 Incidence of Phytophthora and Pythium infection and the relation to cultural conditions in commercial blueberry fields HortScience 43 260 263
Burt, C.M., Clemmens, A.J., Strelkoff, T.S., Solomon, K.H., Bliesner, R.D., Hardy, L.A., Howell, T.A. & Eisenhauer, D.E. 1997 Irrigation performance measures: Efficiency and uniformity J. Irrig. Drain. Eng. 123 423 442
Davies, F.S. & Flore, J.A. 1986 Gas exchange and flooding stress of highbush and rabbiteye blueberries J. Amer. Soc. Hort. Sci. 111 565 571
Haman, D.Z., Smajstria, A.G., Pritchard, R.T. & Lyrene, P.M. 1997 Response of young blueberry plants to irrigation in Florida HortScience 32 1194 1196
Haman, D.Z., Smajstria, A.G., Zazueta, F.S., Lyrene, P.M. & Pritchard, R.T. 2005 Microirrigation of young blueberries in Florida Univ. Fla. IFAS Bul. 301
Howell, T.A. 2000 Irrigation's role in enhancing water use efficiency 66 80 National irrigation symposium. Proc. of the 4th decennial symposium Phoenix, AZ 14–16 Nov. 2000
Mingeau, M., Perrier, C. & Améglio, T. 2001 Evidence of drought-sensitive periods from flowering to maturity on highbush blueberry Sci. Hort. 89 23 40
Nielsen, G.H., Parchomchuk, P., Nielsen, D., Berard, R. & Hague, E.J. 1995 Leaf nutrition and soil nutrients are affected by irrigation frequency and method for NP-fertigated ‘Gala’ apples J. Amer. Soc. Hort. Sci. 120 971 976
Patten, K.D., Neuendorff, E.W., Nimr, G.H., Peters, S.C. & Cawthon, D.L. 1989 Growth and yield of rabbiteye blueberry as affected by orchard floor management practices and irrigation geometry J. Amer. Soc. Hort. Sci. 114 728 732
Patten, K.D., Neuendorff, E.W. & Peters, S.C. 1988 Root distribution of ‘Climax’ rabbiteye blueberry as affected by mulch and irrigation geometry J. Amer. Soc. Hort. Sci. 113 657 661
Strik, B.C. & Buller, G. 2005 The impact of early cropping on subsequent growth and yield of highbush blueberry in the establishment years at two planting densities is cultivar dependent HortScience 40 1998 2001
Strik, B.C. & Yarborough, D. 2005 Blueberry production trends in North America, 1992 to 2003 and predictions for growth HortTechnology 15 391 398
White, L.D. 2006 The effect of pre-plant incorporation with sawdust, sawdust mulch, and nitrogen fertilizer rate on soil properties and nitrogen uptake and growth of ‘Elliott’ highbush blueberry MS thesis, Ore. St. Univ Corvallis, OR