Control of insects and diseases with intelligent variable-rate sprayers in ornamental nurseries

Authors: Chen, Liming; WALLHEAD, MATTHEW - University Of Maine; Zhu, Heping; FULCHER, AMY - University Of Tennessee

Submitted to: Journal of Environmental Horticulture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/22/2019
Publication Date: 9/1/2020
Citation: Chen, L., Wallhead, M., Zhu, H., Fulcher, A. 2020. Control of insects and diseases with intelligent variable-rate sprayers in ornamental nurseries. Journal of Environmental Horticulture. 37(3):90-100.

Interpretive Summary: Conventional constant-rate sprayers often use excessive amounts of pesticide to achieve insect and disease control in ornamental nurseries. Recently developed intelligent variable-rate sprayers can deliver pesticides to tree canopies precisely with minimum off-target loss to the ground and air. However, there are very few reports about the efficacy of the intelligent sprayers. In this research, intelligent variable-rate spray applications were tested to control insect and disease pests in multiple-row plants in two commercial ornamental nurseries and were compared with conventional constant-rate spray applications. The intelligent spray applications reduced pesticide use by 56.1% and 51.8% on average at the two nurseries consistently in two growing seasons while maintaining equally or more effective control of insect and disease pests. Therefore, the intelligent sprayers are a highly efficient and environmental friendly pesticide application technology for the ornamental nursery industry.

Technical Abstract: Intelligent sprayer technology is anticipated to reduce pesticide use and safeguard the environment. However, the ability of this technology to effectively control insects and disease must be validated before it is adopted by growers. Comparative tests for two different laser-guided variable-rate intelligent sprayers and the same sprayers with conventional constant-rate mode were conducted to control pests at two ornamental nurseries in two consecutive growing seasons in Ohio. Crabapple (Malus 'Sutyzam' (Sugar Tyme), M. sargentii), apple (Malus pumila), maple (Acer ×freemanii ‘Jeffersred’ (Autumn Blaze), A. rubrum ‘Franksred’(Red Sunset) and A. rubrum), birch (Betula nigra and Betula populifolia ‘Whitespire’), sycamore (Platanus ×acerifolia ‘Bloodgood’) and dogwood (Cornus florida) were used as the test plants. Intelligent spray technology reduced pesticide use by 56.1% and 51.8% on average at Willoway Nurseries and Herman Losely & Son, respectively. Compared to conventional air-assisted sprayers, severity of scab on apple trees and powdery mildew in dogwood was reduced on intelligent spray-treated plants at Herman Losely & Son, and there were equal or fewer leafhoppers in maple trees and aphids in birch trees when sprayed using intelligent spray technology at both nurseries. These results suggest that intelligent, variable-rate sprayers achieve equivalent or greater insect and disease control in ornamental tree nurseries compared to conventional, constant-rate sprayers.