Management of silver scurf and Fusarium dry rot of potatoes in storage using Bio-Save 10LP and Bio-Save 11LP (Pseudomonas Syringae)

Project Code: BPI07-170

Project Lead

Khalil Al-Mughrabi - Province of New Brunswick

Objective

To assess the efficacy of the biopesticides Bio-Save 10LP and Bio-Save 11LP against silver scurf and dry rot diseases of stored potatoes and to provide data in support of registration of these products in Canada

Summary of Results

Silver scurf of potatoes, caused by the fungus Helminthosporium solani is an important disease in Canada and worldwide. Although primary infection occurs in the field, it is considered a problem of storage potatoes, often adversely affecting the appearance and skin color of potato tubers and ultimately resulting in reduced consumer acceptance. Fusarium dry rot caused by Fusarium sambucinum is another important post harvest disease of potato which develops as a result of injury such as bruises or cuts of the tuber. Extensive rotting, tissue shrinkage and collapse may result. Very few fungicides are effective against the silver scurf and dry rot pathogens and pathogen resistance has developed for at least one of these (thiabendazole).

Bio-Save 10LP and 11LP are microbial pest control products based upon the organism Pseudomonas syringae and are registered for control of silver scurf and dry rot in the United States. This project was initiated to assess the efficacy of these biopesticides against silver scurf and dry rot and to provide the data generated in support of registration of these biopesticides in Canada.

Potato samples infected with silver scurf and Fusarium dry rot were collected from NB, PEI and AB. These samples were used to isolate, purify, identify and store silver scurf and dry rot fungal cultures. Subcultures were identified based on morphological characteristics and also using molecular techniques, and were deposited at the National Fungal Identification Service of Agriculture and Agri-Food Canada, Ottawa. Fusarium sambucinum was the most frequently isolated strain from dry rot samples. However, other strains including F. tumidum, F. coeruleum, F. culmorum, and F. avenaceum were also isolated. The efficacy of Bio-Save 10LP and Bio-Save 11LP against F. sambucinum and H. solani isolates representing NB, PEI and AB were tested both in vitro and in stored potato trials. The products were tested separately and in combination with Mertect (thiabendazole). Bio-Save 11LP was effective in vitro against F. sambucinum and H. solani while Bio-Save 10LP was effective against H. solani only. The Fusarium dry rot isolate from NB was more sensitive to Mertect than those from AB and PEI. The silver scurf isolates from AB were more sensitive to Mertect than those from NB and PEI. Postharvest application of BioSave (10LP or 11LP) or Mertect alone or in combination with each other significantly reduced the incidence and severity of dry rot and silver scurf in storage compared to the control. The results of the present trial indicate that the use of Bio-Save (10LP or 11LP) or Mertect alone or the combination of both appears to be a potentially sound strategy that can be used in the management of both H. solani and F. sambucinum and the resistance management of both products.

Data generated during the course of this work has been used to support an application for registration of BioSave in Canada.

Factsheet on Biofungicides provide Post-harvest Disease Protection in Potatoes

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