Thesis
Assessment of tomato and lettuce diseases inorganically managed high tunnel cropping systems in Western Washington and isolation of soil microbes potentially capable of biodegrading agricultural mulches
Washington State University
Master of Science (MS), Washington State University
2012
Handle:
https://hdl.handle.net/2376/102444
Abstract
High tunnels (HT) offer an alternative cropping system for specialty crops grown in western Washington, where growing degree days are limited and strong demand for locallyproduced foods may offset the added expense of protected cultivation. Environmental conditions, and lettuce diseases on six cultivars representing three market classes (Boston, Leaf, and Romaine), were evaluated in HT and open field (OF) production systems from 2010 to 2012. Tomato diseases on 'Celebrity' grown with biodegradable mulches (BDM) under these two systems also were assessed. Mulch study treatments included commercial, biodegradable products: BioAgri (BA), BioTelo (BT), and WeedGuardPlus (WG); one experimental spunbondpoly(lactic) acid product; black polyethylene (BP) standard; and, a non-mulched control. For the lettuce trial, relative humidity between the production systems was similar, but average soil and air temperatures were greater in the HT compared to OF all three years. Gray mold, caused by Botrytis cinerea, was significantly higher in Romaine versus other types. Gray mold was more severe in HT compared to OF but these effects were cultivar-dependent. Lettuce drop caused by vi Sclerotinia sclerotiorum was observed in all lettuce cultivars all years. In 2012, incidence of lettuce drop was significantly higher and sclerotia more numerous in harvested heads from HT compared to OF. Verticillium wilt was noted on lettuce each year and incidence increased annually, from 0.2% to 2% to 14%. V. tricorpus was isolated from symptomatic heads each year and all isolates were pathogenic in repeated greenhouse trials. This is the first report of V. tricorpus causing Verticillium wilt on lettuce in Washington. 'Green Star' performed well in both systems, with reduced incidence of gray mold, lettuce drop, and Verticillium wilt compared to other cultivars. Fortomato, late blight was significantly lower in HT compared to OF, but severity of physiological leaf roll (PLR) was significantly higher in HT compared to OF. PLR was also significantly higher with BA, BT, and BP mulches. Root diseases were not affected by mulch treatment, and not observed on tomato plants. Methods for isolating native fungi that colonize agricultural mulches in soil were refined, and three isolates each were acquired from BA, BT, and WG.
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Details
- Title
- Assessment of tomato and lettuce diseases inorganically managed high tunnel cropping systems in Western Washington and isolation of soil microbes potentially capable of biodegrading agricultural mulches
- Creators
- Marianne Powell
- Contributors
- Debra A. Inglis (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Plant Pathology, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525096901842
- Language
- English
- Resource Type
- Thesis