Intelligent spray technology to control pests in nursery and orchard systems with reduced pesticide application rates

Authors: FESSLER, L - University Of Tennessee; LOCKWOOD, D - University Of Tennessee; WRIGHT, W - University Of Tennessee; PIETSCH, G - University Of Tennessee; SUN, X - University Of Tennessee; YEARY, W - University Of Tennessee; Zhu, Heping; BORDEAU, T - University Of Tennessee; RUSSO, L - University Of Tennessee; FULCHER, A - University Of Tennessee

Submitted to: International Horticultural Congress
Publication Type: Proceedings
Publication Acceptance Date: 4/20/2023
Publication Date: 12/15/2023
Citation: Fessler, L., Lockwood, D., Wright, W.C., Pietsch, G., Sun, X., Yeary, W., Zhu, H., Bordeau, T., Russo, L., Fulcher, A. 2023. Intelligent spray technology to control pests in nursery and orchard systems with reduced pesticide application rates. International Horticultural Congress. 1360:151-176. https://doi.org/10.17660/ActaHortic.2023.1360.20.
DOI: https://doi.org/10.17660/ActaHortic.2023.1360.20

Interpretive Summary:

Technical Abstract: Nursery producers and orchardists control most pests with pesticide applications made by air-blast sprayers. However, these sprayers are widely considered over-powered for the size of plants grown in current production systems. To address these known inefficiencies, an intelligent, laser-guided, variable-rate spray system was developed that adjusts spray volume based on plant characteristics in real time. Pest control and spray volume were assessed throughout the season at a 12-row block pot-in-pot nursery, 6-row block field nursery, and an apple orchard using this technology as either a prototype or retrofit to each producer’s sprayer and compared to each producer’s sprayer operated in its conventional, constant-rate mode. At the pot-in-pot nursery, there was no treatment effect on whole tree or individual branch incidence or severity of tar spot on maples. For whole tree incidence and severity of cylindrosporium leaf spot (CLS) on maples and CLS incidence on individual maple branches, all ratings were 1 regardless of treatment; however, CLS severity on individual branches was greater in the constant-rate treatment (p<0.0001). On zelkovas, there was no treatment effect on whole tree or branch incidence and severity of Japanese beetles (p>0.05). At the field nursery, treatment did not affect whole tree incidence or severity of tar spot or anthracnose on maples (p>0.05). On individual branches, treatment did not affect incidence of anthracnose and tar spot, or tar spot severity (p>0.05). Anthracnose severity was greater in the constant-rate treatment (p=0.0039). At the orchard, bitter rot and white rot were controlled by both treatments. Pollinator observations were made at all three locations and natural enemies were also observed at both nurseries. Pollinators near the ground were only observed at the orchard while at the nurseries, there were generally more beneficial insects observed per visit at the field nursery than at the pot-in-pot nursery. Compared to the constant-rate treatment, the variable-rate treatment reduced spray rate by 24, 50 and 37% at the pot-in-pot nursery, field nursery, and orchard, respectively (p<0.05). The intelligent spray system provided comparable or better pest control while reducing spray volume.