2011 Annual Report
1a.Objectives (from AD-416)
The objective of this project is to enhance food and ornamental production through improved means for delivering agrochemicals such that utilization of the materials is maximized while losses from leaching, drift, or off-target loss are minimized. These methods will provide abundant, safe food and ornamental crops. These discoveries will minimize environmental impact, reduce production costs, and reduce worker exposure. The specific objectives for the next five years include:
Objective 1: Develop new or enhanced delivery technologies that provide the most efficacious application of production materials, including nutrients and pest management materials. Sub-objectives: Identify application factors affecting distribution and quality of deposits of pest management materials applied to nursery, floricultural, vegetable, fruit, and field crops, and to integrate findings with Drift Reduction Technology (DRT) research into crop production programs. Develop automated or mechanized chemical delivery technologies for greenhouse production systems based on pest population information and/or plant development and plant stress information.
Objective 2: Improve understanding of substrate chemical, physical, and biological properties to improve container crop production while minimizing agrichemical leaching. Sub-objectives: Evaluate the use of regional agricultural/forest byproducts and synthetic materials for use as a substrate in nursery containers. Determine the effects of irrigation parameters and hydraulic properties of soilless substrates on nutrient and pesticide leaching from pot-in-pot production systems.
1b.Approach (from AD-416)
Application systems will be evaluated by examining deposition patterns on artificial targets and plant tissue, atomization characteristics, and off-target spray movement on passive ground and airborne collectors. The effect of air and travel speed and their interaction with droplet size on deposition patterns on artificial targets placed within different field crop canopies will be examined in field trials. Full assessment of the potential benefits of any DRT will be measured in the field under varying canopy conditions. The effect of air speed and its interaction with droplet size on deposition patterns on artificial targets placed within different field crop with horizontal and vertical target surfaces will be examined in field trials. Droplet size distributions and droplet velocities from atomizers will be determined using a particle/droplet laser image analysis system. Granular delivery systems will be evaluated for their ability to apply herbicides to potted surfaces. Pneumatic and mechanical means for aiding in movement through canopies will be incorporated into the delivery systems. The effectiveness of the delivery systems will be evaluated by examining the deposition granule patterns on the target surface as well as measurement of the amount of active ingredient. To improve safety, reduce production costs, and to put spray only where needed, a carrier system will be evaluated to automate spray delivery in greenhouse and sheltered environments. First studies will utilize a wheeled, hand-cart to evaluate technology to target spray delivery. Air-assist and electrostatic technology appropriate to a greenhouse production system will be evaluated. One or more synthetic materials and one or more agricultural materials will be compared with conventional pine bark for production of nursery plants. Polyethylene terephthalate (PET) is a synthetic material currently used for many applications that has potential as a substrate component. Another strategy will be to grow the substrate. Agricultural crops which produce large amounts of biomass will be grown, harvested, and processed into a substrate. PET, switchgrass chips and willow chips will be the first candidates tested for suitability as substrates.
To determine the effects of irrigation parameters and hydraulic properties of soilless substrates on nutrient and pesticide leaching from pot-in-pot production systems a commercial pot-in-pot (PIP) system will be used. Pine bark will be amended with peat at three rates and irrigation will be applied either with a timer or automatically activated according to soil moisture readings from a neutron probe irrigation sensor. A complete fertilizer package and an insecticide will be incorporated into the substrate during the mixing process. A preemergence herbicide will be applied to the substrate surface of all containers after they are filled and planted. All production inputs and all climactic inputs will be recorded by data loggers. Leachates will be collected weekly and analyzed for all macro- and micro-nutrients using ICP analysis; insecticide and herbicide concentration in the leachates and plant tissue will be quantified with GC-MS analysis.
Significant progress was made on this research project in FY2011 in the areas of identifying application parameters to best manage wheat diseases of the wheat head, stems and leaves as well as understanding the delivery of granular herbicides to potted nursery shrubs. Greenhouse experiments were initiated to characterize movement of insecticides through a zinnia plant following treatment of either the root zone by a drench application or foliar treatment made to a single leaf in the middle of the canopy.
Additional progress has been made in identifying and evaluating biomass materials for use as alternative substrates in greenhouse and nursery container substrates. Research has been completed in documenting the change in physical properties of straw-based substrates over time. Other research has documented the impact of several amendment types on chemical properties of straw-based substrates. New research has been initiated and is in progress to evaluate the utility of locally-available pine and forest biomasses for use as potting substrates.
Mechanized delivery of herbicide to potted nursery plants to improve weed control. ARS researchers at the Application Technology Research Unit in Wooster, OH, identified means for assessing herbicide deposition on potted plant leaf surfaces, evaluated the effectiveness of irrigation water for moving granular herbicides down through a leaf canopy on to the substrate surface, and evaluated the uniformity of granular herbicide distribution from an air-assisted, granular spreader. Irrigation is commonly recommended to move herbicide granules off a canopy following an application. A unique collection system was devised for collecting granular and liquid herbicides as well as for measuring the amount of irrigation water collected under the canopy of a potted plant. Preliminary ARS research found that this practice provides minimal measureable change in the amount of herbicide on the potted plant surface substrate. A granular applicator developed originally for golf course lawn treatments was successfully adapted to deliver granular herbicides through canopies at different stages of development at higher rates of speed than traditional hand-held applications. ARS scientists are working with Ohio State staff to demonstrate the application of air-assist, broadcast, granule spreaders and these research findings to the nursery industry for increasing the efficiency of their weed control programs.
Use of wheat straw as an alternative to pine bark in container substrates. An ARS researcher at the Application Technology Research Unit in Wooster, OH, engineered an effective substrate composed primarily of locally produced wheat straw to replace imported pine bark in nursery container substrates. Pine bark is currently used as the primary potting substrate for the nursery industry, but its cost is increasing, its availability is decreasing, and it currently must be imported from the southern U.S. and transported over long distances. ARS scientists developed a new potting substrate comprised primarily of wheat straw and low levels of pine bark. On-farm trials have shown that these substrates are effective in a variety of production systems. Adoption of these substrates would reduce dependency on pine bark imported from distant southern states, and instead use locally sourced wheat straw biomasses for nursery crop substrates.
Development of a new technique for measuring water availability in greenhouse and nursery potting mixes. An ARS researcher at the Application Technology Research Unit in Wooster, OH, developed a new method to correlate moisture level and plant-available water in nursery and greenhouse potting mixes. Traditional methods for this process were developed for mineral soils. These methods were not precise for porous soils near saturation, and thus not useful for greenhouse and nursery potting mixes composed of pine bark, peat moss, and other potting mix components. This new method allows for cost-effective measurement of soil moisture and plant-available water, and will be applied to irrigation models, allowing for more accurate crop irrigation. This will result in more efficient irrigation with less water, nutrient, and pesticide runoff in greenhouse and nursery production.
Insecticide movement through plants and implications for insect control. ARS Researchers at Wooster, OH initiated greenhouse studies to understand pathways of systemic pesticide movement in plants and how insecticide delivery could influence biological efficacy. Application Technology Research Unit scientists have previously documented how difficult it is to apply insecticides uniformly around plant canopies from traditional spray devices. Trials included delivery of a systemic insecticide to two different parts of the plant: application of high volume drench to the potted root zone of plants or application to a single leaf in the middle of the plant canopy. Evaluation of chemical residue in leaf tissue and mortality of green peach aphids caged on select leaves at five different elevations on the target plants demonstrated that the drench treatment to the plant roots produced more uniform chemical movement and aphid mortality along the plant profile than a foliar application. Technology transfer opportunities are being used to demonstrate to floral producers how to implement these findings into their pest management programs to improve the success of systemic insecticide application programs which will in turn reduce chemical expenses and produce higher quality floral products.
Altland, J.E., Locke, J.C. 2011. Use of ground miscanthus straw in container nursery substrates. Journal of Environmental Horticulture. 29:114-118.
Altland, J.E., Owen Jr., J.S., Fonteno, W. 2010. Developing moisture characteristic curves and their descriptive functions at low tensions for soilless substrates. Journal of the American Society for Horticultural Science. 136(6):563-567.
Altland, J.E., Krause, C.R. 2010. Modification of switchgrass substrate pH using compost, peatmoss, and elemental sulfur. HortTechnology. 20:950-956.
Derksen, R.C., Ranger, C.M., Canas, L.A., Zhu, H., Krause, C.R. 2010. Greenhouse evaluation of air-assist delivery parameters for mature poinsettias. Applied Engineering in Agriculture. 26(6):947-953.
Altland, J.E., Wehtje, G., Sibley, J., Miller, M., Gilliam, C., Krause, C.R. 2011. Differential response of liverwort (Marchantia polymorpha) tissue to POST-applied quinoclamine. Weed Technology. DOI: 10.1614/WT-D-10-00135.1.