Weekly Late Blight Update

This page is the online version of a listserv intended to facilitate communication about late blight in New York and the contiguous states and Canadian provinces. The report is collected by Abby Seaman, NYS IPM's Area Extension Educator for Vegetables.

previous reports linked below

Our most recent report:

For 9-8-09:

I have heard about several new outbreaks in previously uninfected gardens and fields, indicating that it's still important to:

1. Destroy severely infected plants to prevent inoculum production
2. Continue to protect plants if you've chosen to spray

Online resources: see this online Food Safety Statement, posted 9/8/09, reprinted here:

Late Blight Food Safety Statement
From Meg McGrath, Assoc. Professor in Plant Pathology

Are the unaffected parts of blighted tomatoes and potatoes safe to eat?

Yes the unaffected parts probably are safe to eat. Parts with symptoms likely do not pose a health risk when consumed either, but they do not look appetizing and will have an off flavor. However, no published scientific study on this specific issue was found to confirm this conclusion, therefore consumers need to make their own decision on food safety. The conclusion that unaffected tissue is safe to consume is based on several points. This pathogen does not produce a toxin that can make people sick, as a few plant pathogens can do. Plant pathogens cannot infect people. No food safety issues have been found with other diseases that affect tomato fruit or potato tubers. Late blight appears to be like other more common diseases, e.g. anthracnose on tomato fruit and pink rot of potato (which incidentally is caused by Phytophthora erythroseptica, a pathogen related to that causing late blight), in that these do not appear to affect plant tissue beyond the area of infection. Many home gardeners likely often cut off diseased tissue rather than throw out the entire fruit or tuber having found the healthy appearing part of these to taste fine. This has not been associated with any human health issues. Diseases like late blight and anthracnose are not considered a health concern for commercial tomato processing. Fruit are sorted to remove affected ones, but this is because of the impact on fruit quality. For home canning, only disease-free, preferably vine-ripened, firm tomatoes are recommended in the USDA Complete Guide to Home Canning because fungal pathogens may raise tissue pH and thereby allow growth of potentially harmful microorganisms.

CCE's Food Preservation Expert Judy Price echoesthe caution to only can food that is of the highest quality. The possibility of a dangerous product is great when inferior and questionable food is placed in an anaerobic environment.It is also recommended that only high quality food be frozen, although the same dangers do not exist.Rather, the quality issues of an off flavor and unappetizing product should be considered in freezing tomatoes affected by blight.

Previous Issues:

8-25-09

8-18-09

8-11-09

8-4-09

7-28-09

7-21-09

7-14-09

7-7-09

6-30-09

6-23-09

6-16-09

6-9-09

Weekly Late Blight Update 2008

Weekly Late Blight Update 2007

Weekly Late Blight Update 2006

About This Site

These pages are maintained by the New York State IPM Program, part of Cornell Cooperative Extension. All material is protected by Section 107 of the 1976 copyright law. Copyright is held by Cornell University and the New York State IPM Program.