use of both water and fertilizers; however, the initial cost of automated subirrigation systems is high ( Ferrarezi et al., 2015a ; Thomas, 1993 ). Ebb-and-flow subirrigation is relatively cheap and easy-to-use compared with other subirrigation
Leqi Yang, Xiao Yang, Hong Zhao, Danfeng Huang, and Dongqin Tang
Martin P.N. Gent and Richard J. McAvoy
, 1977 ). The runoff of water, fertilizer, and pesticides resulting from these irrigation methods is a potential risk to the quality of the environment in proximity to a greenhouse operation. Subirrigation, and in particular ebb and flow, systems are more
Rhuanito Soranz Ferrarezi, Marc W. van Iersel, and Roberto Testezlaf
plants were sprayed with 0.4 g·L −1 of 8.5% acetamiprid (TriStar; Cleary Chemicals LLC, Dayton, NJ) to exterminate caterpillars. Plants were grown on 10 ebb-and-flow benches with 1.52 m length × 0.91 m width × 4 cm height (MidWest GroMaster, St. Charles
Marc van Iersel and Ron Oetting
Ebb-and-flow systems can be used to apply systemic pesticides to greenhouse crops without worker exposure or runoff. However, there is little information on the efficacy of pesticides applied with ebb-and-flow systems. We are using silverleaf whitefly (Bemisia argentifolii) control on poinsettia (Euphorbia pulcherrima) with imidacloprid as a model system to study pesticide efficacy in ebb-and-flow systems. The objective of this study was to determine the effect of the amount of insecticide taken up by the pot on the efficacy of whitefly control. Different amounts of imidacloprid uptake were obtained by not watering the plants for 0, 1, 2, or 4 days before the imidacloprid application. The imidacloprid (132 g·L–1) was applied once when the roots of the cuttings had reached the side of the pots. These treatments were compared to an untreated control on ebb-and-flow and a standard drench application (100 mL) to hand-watered plants. Pots in the different subirrigation treatments absorbed 12 to 175 mL of imidacloprid solution. Four days after the application, leaf tissue of the hand-watered plants contained 8 to 20 times more imidacloprid than the subirrigated plants. Efficacy was determined from the percentage of surviving mature whiteflies after 2 days on the plants and by counting the number of immatures after 2 weeks. Surprisingly, imidacloprid efficacy was better in the subirrigated imidacloprid treatments than in the hand-watered treatment. Whitefly control in all subirrigated imidacloprid treatments was excellent, irrespective of the amount of imidacloprid solution taken up by the pots.
Marsha Ann Bower, David H. Trinklein, and John M. Brown
Recent trends in greenhouse container production suggest using ebb and flow irrigation for water conservation and pollution control. A major problem in this system is management of soil borne pathogens. Some species of Trichoderma, a beneficial fungi, are known to control Pythium and Phytopthora in container production. This study investigates the potential of applying a Trichoderma conidial spore suspension in an ebb and flow irrigation system. Trichoderma conidia were collected from culture and placed in 101 l stock solution tanks at 10-2 and 10-4 colony forming units (CFU) per ml. Six inch container grown Dendranthema grandiflora `Delano', were irrigated as needed. To determine Trichoderma density in the root environment, soil samples were acquired from the container at 7 day intervals. Results showed that initial population densities of 10-4 CFU/ml were required to achieve adequate container populations to control disease after one irrigation. This study successfully demonstrated that Trichoderma could be dispersed through irrigation water into container plants in an ebb and flow system.
Erin James and Marc van Iersel
Water conservation is increasingly important for growers in the United States, but there is little information on the use of alternative irrigation systems, such as ebb and flow, for the production of bedding plants. The objective of this study was to quantify the growth of Petunia ×hybrida Hort. Vilm.-Andr. `Blue Frost' and Begonia ×semperflorens-cultorum Hort. `Ambassador Scarlet' grown in an ebb and flow system in three soilless media and fertilized with P at 0, 50, or 100 mg·L-1 in the fertigation solution. After 5 weeks, plants grown with 50 or 100 mg·L-1 P had greater dry weight, height, and width than plants grown with 0 mg·L-1 P. Begonias grown with 50 or 100 mg·L-1 P had 38% more flowers than did those grown without P. Petunias flowered 4 to 7 days earlier when no P included in the fertilizer. Growing media had little effect on the plants. Begonias grown in Metro-Mix 220 had more inflorescences than those grown in Metro-Mix 366Coir. Changes in electrical conductivity (EC) and pH of all three media were similar over the course of the experiment. The EC dropped during the third and fourth week and rose again in the fifth week. The pH of the leachate from all three media dropped by an average of 1 unit during the experiment. The results indicate that petunias and begonias may be grown successfully with ebb and flow irrigation, using a variety of fertilizers and growing media. However, P must be included in the fertigation solution for optimal plant quality.
Erin James and Marc van Iersel
The negative effects of nutrient runoff on the environment has come more to the forefront of greenhouse issues in the past few years. Alternative irrigation systems that reduce or eliminate runoff that are widely used in Europe have not yet gained much popularity in the southeastern United States, in part due to a lack of available information on their use. One such system is ebb-and-fl ow, which is a completely closed recirculating system, having no runoff whatsoever. In order to learn more about optimum growing practices using the ebb-and-fl ow system for bedding plants, marigolds and sunflowers were grown under a variety of conditions. After a 6-week period, pH of growing media of both marigolds and sunflowers decreased by 1, while EC increased by ≈1 dS/m. There were also significant differences in EC due to the different media types. The soilless medium with the highest percentage of vermiculite and lowest percentage of pine bark had the highest EC. Different types of fertilizer and fertilizer rates will be discussed, as well as interactions between fertilizer and media.
Rhuanito Soranz Ferrarezi, Geoffrey Matthew Weaver, Marc W. van Iersel, and Roberto Testezlaf
) ( Fig. 5 ). Similar designs, now known as ebb-and-flow systems, subsequently became popular ( Bauerle, 1990 ; Biernbaum, 1988 , 1990 ; Elliott, 1990 , 1992 ) and are the most common type of subirrigation used in the greenhouse industry ( Uva et al
Jaime K. Morvant, John M. Dole, and Earl Allen
Pelargonium hortorum Bailey `Pinto Red' plants were grown with 220 mg·L−1 N (20N-4.4P-16.6K) using hand (HD), microtube (MT), ebb-and-flow (EF), and capillary mat (CM) irrigation systems. At harvest, root balls were sliced into three equal regions: top, middle, and bottom. A negative correlation existed between root medium electrical conductivity (EC) and N concentration to root number such that the best root growth was obtained with low medium EC and N concentrations. EF root numbers were greatest in the middle region. The two subirrigation systems (EF and CM) had higher average root numbers than the two surface-irrigation systems (HD and MT). For all irrigation systems, root numbers were lowest in the top region. In general, less difference in medium soluble salt and N concentrations existed between regions for surface-irrigated than for subirrigated root balls. Soluble salt concentration was lowest in the bottom and middle regions of EF and the bottom region of MT and CM. For subirrigation, the highest medium soluble salt and N concentration was in the top region. For all systems, pH was lowest in the bottom region. Plant growth for all irrigation systems was similar. EF and MT systems required the least water and EF resulted in the least runoff volume.
Jaime K. Morvant, John M. Dole, and Janet C. Cole
Pelargonium ×hortorum Bailey `Pinto Red' plants were fertilized with equal amounts of N, P, and K derived from: 1) 100% constant liquid fertilization (CLF); 2) 50% CLF plus 50% controlled-release fertilizer (CRF); or 3) 100% CRF per pot and irrigated using hand (HD), microtube (MT), ebb-and-flow (EF), or capillary mat (CM) irrigation systems. The treatment receiving 100% CRF produced greater total dry weights, and released lower concentrations of NO3-N, NH4-N, and PO4-P in the run-off than the 100% CLF treatment. The percentage of N lost as run-off was greatly reduced with the use of CRF. MT irrigation produced the greatest plant growth and HD irrigation produced the least. The EF system was the most water efficient, with only 4.7% of water lost as run-off. Combining the water-efficient EF system with the nutrient-efficient CRF produced the greatest percentage of N retained by plants and medium (90.7) and the lowest percentage of N lost in the run-off (1.7).