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Dissertation
EXPLORING THERMOTHERAPY SPRAY APPLICATIONS FOR PEAR PSYLLA (CACOPSYLLA PYRI) SUPPRESSION
Washington State University
Doctor of Philosophy (PhD), Washington State University
05/2024
DOI:
https://doi.org/10.7273/000006499
Abstract
Addition of thermotherapy to spray applications of a plant-based horticultural oils has been reported to increase their pesticidal efficacy. This dissertation aimed to critically evaluate the feasibility of horticultural oil thermotherapy (HOT) for suppression of winterform pear psylla. The first objective was focused on development and evaluation of a field-scale thermotherapy spray delivery system. The system was evaluated for spray patterns using a vertical patternator and then for coverage on matured pear trees. Spray coverage was acceptable (50–88%), but heat in the spray mix dissipated within 0.6 m from the nozzle. This motivated the second objective which focused on evaluating role of heat in HOT. A bioassay study was conducted with four different oil products, two heat conditions, and at two spray distances. Study results were in general agreement with previous research, i.e., heating oils increased biological efficacy, for two of the four tested oils at 0.3 m spray distance. At 0.6 m, the effect of heating the spray mixture, regardless of product, failed to significantly increase the psylla mortality. Thus, objective 3 efforts were undertaken to characterize the thermal and evaporative losses for thermotherapy sprays with six different disc-core hollow cone nozzles commonly used in tree fruit crop protection. The spray experienced significant thermal energy loss immediately after release from nozzle(s) which was likely a function of latent heat of vaporization. An empirical equation was developed to generalize the decay of the bulk spray temperature for the six tested nozzles. Future work needs to explore alternative methods of thermotherapy applications in orchard environments and an economic evaluation of such technologies.
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Details
- Title
- EXPLORING THERMOTHERAPY SPRAY APPLICATIONS FOR PEAR PSYLLA (CACOPSYLLA PYRI) SUPPRESSION
- Creators
- Mark Jacob Schrader
- Contributors
- Lav R Khot (Co-Chair)Elizabeth H Beers (Co-Chair)Michelle M Moyer (Committee Member)Sindhuja Sankaran (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Biological Systems Engineering, Department of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 124
- Identifiers
- 99901120941101842
- Language
- English
- Resource Type
- Dissertation