|Zondag, R - OSU EXTENSION|
Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 22, 2003
Publication Date: May 6, 2004
Citation: Krause, C.R., Zhu, H., Derksen, R.C., Brazee, R.D., Fox, R.D., Horst, L., Zondag, R.H. 2004. Detection and Quantification of Nursery Spray Penetration and Off-Target Loss with Electron Beam and Conductivity Analysis. Transactions of the ASAE. 47(2):375-384. Interpretive Summary: Nursery crops produce about ten percent of all income from agricultural products. Many of the products are attacked by pests and require sprayed chemical or natural pest control agents. To obtain the optimum pesticide spray management, delivery systems must be operated economically and effectively with minimum canopy damage and minimum spray drift. Techniques to assess spray penetration and drift from nursery sprayers are needed to obtain optimum spray performances with minimum drift potential. Spray distribution within two different types of nursery tree canopies, spray deposition on the ground and airborne sprays from two types of sprayers were assessed with different methods by detecting residues of either calcium nitrate foliar fertilizer or copper hydroxide fungicide. Electron beam analysis (EBA) was used to analyze residues on electron microscope stubs, upper and lower sides of leaves and needles placed and collected at several locations and heights in the canopy. Profile-tape samples were evaluated with a laboratory spray deposit analyzer using a conductivity detector. Spray deposit analyzer quantified spray deposition profile across trees. EBA detected and quantified the percent residue coverage on both leaf and stub surface areas within tree canopies, and provided a useful assessment method to determine spray penetration performances for nursery spray applications. The methods to assess spray penetration and drift would be greatly beneficial to nursery growers to enhance spray performances and reduce off-target loss.
Technical Abstract: Spray penetration and off-target spray drift from a conventional, air-assist, axial fan sprayer and a high-clearance, boom-type sprayer were investigated in Honey Locust (Gleditsia triacanthos) and Canadian Hemlock (Tsuga canadensis) trees located in two different production nurseries. Aqueous tracer solutions of either Ca(NO3)2 foliar fertilizer or Cu(OH)2 fungicide were used in the experiments. Spray distribution and drift were assessed via residues collected on foliage, electron microscope stubs, vertical and ground-level profile tapes, and high-volume air samplers. Electron beam analysis (EBA) was used to assay residues on stubs, leaves and needles placed and collected at several locations and heights in the canopy. Profile-tape samples were evaluated with a laboratory spray deposit analyzer using a conductivity detector. Both assessment methods used in the present study were useful for detection and quantification of Ca or Cu spray penetration within tree canopies. The average spray deposit on upper surfaces of leaves was three times that deposited on lower surfaces within the Honey Locust trees. Spray deposit at the top of Canadian Hemlock tree canopies was 14 times higher than that at the middle and the bottom of canopies. Spray deposit on ground targets greatly decreased as the distance from the spray path increased. However, airborne spray deposits did not decrease as much with increasing downwind distance as ground deposits in both nurseries.