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United States Department of Agriculture

Agricultural Research Service

Research Project: Crop Protection and Production Strategies for Horticultural Crops

Location: Application Technology Research Unit

2013 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.


3.Progress Report:
Significant progress was made in the areas of pesticide application efficiency, drift management, substrate analysis, and nursery weed management. Field studies have identified improved methods to apply pesticides in crops of different architecture such as those with the primary structure components being broad leaves or vertical stems. Greenhouse experiments characterized 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. Greenhouse trials also revealed changes needed in how hand-held applications are directed towards crops to improve distribution of pesticides. Fields studies demonstrated the potential benefits of using towers on tree sprayers as a potential Drift Reduction Technology for orchard or shade tree pest management. Nursery research revealed that as much as 95% of herbicide spray applied to a potted ornamental canopy remains in the ornamental canopy and thus is not available to provide weed control. An air-assist granular spreader is being used to demonstrate the effectiveness of applications of granular preemergent herbicides to potted ornamental nursery plants. Studies to improve the field management of bacterial diseases in Ohio specialty crops are continuing to evaluate how application technology can influence disease management and will correlate efficacy results with canopy measurements of spray deposit and spray coverage. Studies were initiated in commercial nurseries to develop application recommendations for controlling Rhizoctonia web blight in containerized azaleas.

Numerous new materials were evaluated to replace pine bark as the primary component in nursery crops substrates. Materials evaluated included: corn stover, miscanthus straw, switchgrass straw, willow chips, poplar chips, wheat straw, and whole pine trees. Strengths and limitations for each material were documented. The most promising materials, including wheat straw, switchgrass straw, and whole pine trees were evaluated in comprehensive, on-farm, field trials at multiple cooperator locations. It was determined that wheat straw and whole pine trees can be successfully used to replace pine bark in substrates for most crops. However, an economic analysis done in the final stages of the experiments revealed that current economic conditions are not favorable for using these materials. Nitrogen (N), phosphorus (P), and potassium (K) release was measured from controlled release fertilizers. By accurately modeling N, P, and K release from these fertilizers, growers will be able to more accurately time follow-up fertilizer applications and thus provide nutrients more efficiently and to limit leaching of fertilizers that could impact subsurface water sources. Research was initiated to evaluate alternatives to traditional herbicides, such as hydrogen peroxide, injected through an irrigation system, as a means for controlling liverwort. Rice hulls are also being evaluated as an alternative herbicide for managing liverwort and bittercress in sensitive nursery and greenhouse crops.


4.Accomplishments
1. Application technology for weed management in nursery ornamentals. Sustainable weed control in container grown pots is difficult because of the need to apply over and through a non-target plant. Large droplet spray applications in field crops have been demonstrated to reduce off-target spray movement. High volume and large droplet weed spray applications were shown to be effective at moving spray down to the substrate surface where preemergent herbicides are most effective. These findings demonstrate how relatively simple changes in spray equipment can be used for container plant weed management while minimizing contamination to operators and off-target areas.

2. Field management of bacterial spot in Ohio specialty crops. Bacterial disease threaten the quality and quantity of Midwestern processing tomatoes. Applications made using charged sprays or air-assisted delivery have both shown promise for improving spray deposition in row-crop canopies. Season-long use of lower volume electrostatic and air-assisted spray delivery technology as well as conventional application equipment demonstrated that the air-assist technique was best at getting spray to the most difficult areas to protect portions of tomato canopies. The lower volume treatments produced the same marketable tomato yield as the higher volume, conventional treatment. These results demonstrate that lower volume application treatments have potential to increase application efficiency and reduce worker exposure during mixing and filling operations without loss of crop yield.

3. Development of alternative components for nursery crop substrates. Fertilizer prices continue to increase due to energy costs associated with their mining, processing, and transport. Gasified rice hull biochar (GRHB) is an abundant byproduct of the rice-food industry. Gasified rice hull biochar was demonstrated to contain high levels of phosphates and potassium, two of the three primary nutrients in most plant fertilizers. Gasified rice hull biochar rates, necessary for supplying phosphorus (P) and potassium (K) to greenhouse crops, were successfully determined. Amendment of 10% of the substrate with GRHB enabled us to produce crops without any additional P or K inputs. These results demonstrate that GRHB can be used as an amendment to greenhouse crops and alleviate the need for increasingly expensive phosphorus and potassium fertilizers.


Review Publications
Altland, J.E., Krause, C.R. 2012. Substituting pine wood for pine bark affects physical properties of nursery substrates. HortScience. 47(10):1499-1503.

Altland, J.E., Locke, J.C. 2012. Biochar affects macronutrient leaching from a soilless substrate. HortScience. 47(8):1136-1140.

Altland, J.E., Krause, C.R. 2012. Change in physical properties of pine bark and switchgrass substrates over time. Journal of Environmental Horticulture. 30(3):113-117.

Last Modified: 4/16/2014
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