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Adjustment of soil-surface pH and comparison with conventional fungicide treatments for control of lettuce drop Sclerotinia minor


Wilson, CR and De Little, J and Wong, JAL and Schupp, P and Gibson, LE, Adjustment of soil-surface pH and comparison with conventional fungicide treatments for control of lettuce drop Sclerotinia minor, Plant Pathology, 54, (3) pp. 393-400. ISSN 0032-0862 (2005) [Refereed Article]

DOI: doi:10.1111/j.1365-3059.2005.01188.x


The use of soil-surface applications of finely powdered calcium hydroxide (Ca(OH)2) to inhibit Sclerotinia minor sclerotial germination and infection at the collar region of lettuce plants is described. In the laboratory, a pH > 8.0 reduced sclerotial germination of the three S. minor isolates tested. In the glasshouse, surface applications of 2-10 t Ca(OH) 2 ha-1 raised the pH of the top 1-2 cm of a duplex sandy loam soil above 8.5 for at least 8 weeks without affecting soil pH within the transplant root zone. There was a linear relationship between the rate of Ca(OH)2 applied and disease control, with complete disease suppression at 10 t Ca(OH)2 ha-1. In field trials on two soil types (duplex sandy loam, pH 6.0; and red ferrosol, pH 6.9), a rate of 2.5 t Ca(OH)2 ha-1, maintained soil-surface pH above 8.5 for 1-3 weeks and provided up to 58% reduction in lettuce drop. Application of polyvinyl alcohol (a soil-conditioning polymer) over the Ca(OH)2 layer appeared to reduce Ca(OH)2 loss by wind, but did not improve retention of raised soil-surface pH or disease suppression. Ca(OH)2 treatment gave similar disease control to the industry standard treatment of a procymidone-based fungicide seedling drench. A combined treatment of Ca(OH) 2 and fungicide drench gave greater control than either individual treatment, and equivalent control to fungicide drench and three procymidone foliar sprays, offering integrated management options. The use of soil-surface-applied Ca(OH)2 with fungicides, rotation and drip irrigation offers an opportunity for enhanced and sustainable control of lettuce drop. © 2005 BSPP.

Item Details

Item Type:Refereed Article
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Horticultural production
Research Field:Horticultural crop protection (incl. pests, diseases and weeds)
Objective Division:Plant Production and Plant Primary Products
Objective Group:Horticultural crops
Objective Field:Field grown vegetable crops
UTAS Author:Wilson, CR (Professor Calum Wilson)
UTAS Author:De Little, J (Miss Jennifer De Little)
UTAS Author:Schupp, P (Mr Paul Schupp)
UTAS Author:Gibson, LE (Mrs Lisa Gibson)
ID Code:26265
Year Published:2005
Web of Science® Times Cited:3
Deposited By:Agricultural Science
Deposited On:2005-08-01
Last Modified:2006-06-21

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