Biofungicides provide Post-harvest Disease Protection in Potatoes

Sustainable Crop Protection - Results from the Pesticide Risk Reduction Program

Dry rot and silver scurf are important post-harvest diseases of potatoes. Developing in storage, these diseases can infect up to 60% of stored tubers, leading to significant economic losses. Currently, the fungicide Mertect (thiabendazole) is used for post-harvest disease control, but concern that the diseases are developing resistance to the fungicide is mounting and sustainable control options are needed. Research funded by the Pest Management Centre of Agriculture and Agri-Food Canada showed biopesticides have efficacy against both pathogens. The research is supporting registration in Canada ultimately making new tools available to our growers for use in a competitive market. Biopesticides have the potential to contribute to safe and sustainable management for these diseases, putting integrated pest management to work well after the crop has been harvested.

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Healthy potatoes
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Potatoes infected with Fusarium sambucinum
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Potatoes infected with Helminthosporium solani

(all photos courtesy K. Al-Mughrabi)

  • Dry Rot, caused by the soil borne fungus Fusarium sambucinum, enters the tuber at wounded or bruised sites caused by planting, harvesting, grading or transport. In storage, the disease can cause extensive rotting, tissue shrinkage and eventual collapse.
  • Silver Scurf, caused by Helminthosporium solani, often comes from previously infected seed pieces. Signs of the infection can be missed during harvest, allowing the disease to continue developing in storage. The pathogen causes silver colored discolorations on the surface of the tuber, making the product unmarketable.

To address these concerns, the biocontrol product Bio-Save® (10LP and 11LP) was evaluated for control of dry rot and silver scurf of potatoes. This biopesticide contains Pseudomonas syringae, a naturally occurring bacterium that is normally present on fresh produce surfaces prior to processing. The bacterium suppresses the development of pathogenic fungi by out-competing disease pathogens for nutrients, a process known as competitive inhibition.

Efficacy of Bio-Save, Mertect, and a combination of both against Helminthosporium solani strains

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  Prince Edward Island - Strain 1 Prince Edward Island - Strain 2 Alberta - Strain 1 Alberta - Strain 2 New Brunswick strain
Control Growth Growth Growth Growth Growth
Biosave 11LP Little growth Little growth Little growth Some growth Little growth
Mertect SC Little growth Little growth Little growth Little growth Little growth
Mertect SC and Biosave 11LP Little growth Little growth Little growth Little growth Little growth

The efficacy of Bio-Save® against F. sambucinum and H. solani isolates, representing New Brunswick, Prince Edward Island and Alberta strains, was tested in the lab and in storage trials. In the lab, Bio-Save®, applied on its own or in combination with Mertect, effectively suppressed the growth of both pathogens. In storage trials, when applied on its own or in combination with Mertect, the incidence and severity of both pathogens in NB and PEI were significantly reduced.

These results provide support for the registrations of Bio-Save® 10LP for silver scurf: and Bio-Save® 11LP for silver scurf and dry rot on potatoes in Canada. Using Bio-Save® and Mertect in alternation as part of an integrated pest management program reduces crop losses from disease. Resistance development in the pathogens is also decreased, therefore introducing a new reduced risk product for long term sustainable management.

Biopesticides are new tools which, when used with beneficial management practices in all phases of the production and storage of potatoes, can help protect the growers' investment planting disease free seed, ensuring clean farm equipment, minimizing damage to the potato at harvest, promoting wound healing and appropriate storage temperature and humidity which are all integral parts of a sound strategy. This project adds another tool to the IPM toolbox, which will reduce the incidence and severity of storage diseases of potato.

For more information contact:

Dr. Khalil I. Al-Mughrabi

Pathologist, Potato Development Centre
Department of Agriculture and Aquaculture
39 Barker Lane, Wicklow, NB E7L 3S4, CANADA
Tel: 506-392-5199; Toll-free: 1-866-778-3762
Fax: 506-392-5102

Lucie Grant

President, JET Harvest Solution
P.O. Box 915139, Longwood FL 32791, U.S.A.
Tel: 407-523-7842; Toll-free: 1-877-866-5773
Fax: 407-298-2377

About the Pesticide Risk Reduction at Agriculture and Agri-Food Canada

The Pesticide Risk Reduction team delivers viable solutions for Canadian growers to reduce pesticide risks in the agricultural and agri-food industry. The team achieves this goal by funding integrated pest management projects and coordinating pesticide risk reduction strategies developed through consultation with stakeholders and pest management experts. Other sustainable crop protection factsheets are available. For more information please visit the Pest Management Centre.