Tuesday, July 27, 2010


Late Blight Alert!
Late Blight, caused by Phytophthora infestans was found on tomato plants earlier this week on Tuesday July 20th and today July 23rd in Hadley Massachusetts. These are the first two positive diagnosis that has come into the UMass Plant Diagnostic lab this season and the first confirmed cases in Massachusetts. The source of the inoculum is unknown at this point but it is suspected that the spores came from long distance transport or a volunteer potato plant in the area. Although the disease is not known to overwinter in the Northeast as of yet, overwintering can not be ruled out. A sample has been sent to the North Carolina State University to detrmine the clonal lineage. This information may provide us with some clue as to where the initial source of the pathogen came from. Suspected plant samples should be sent the UMass Plant Diagnostic lab immediately (413-545-3209) for confirmation. We would expect to see late blight show up along rivers or where fog tends to collect. These foggy areas should be inspected closely and frequently. Conventional potato growers should now be using systemic fungicides on their fields. Tomato crops should be protected with fungicides specific to downy mildew and inspected regularly for symptoms of blight. For a list of recomended fungicides see this weeks full late blight report.

The murmur of blight is vibrating through the farms and gardens across the pioneer valley. It can obviously do some real damage to crops and farmers are advised to literally rip up and dig under any plant that looks infected.

This is what our alarming tomato looks like:

I am not really worried as of yet but only time will tell.

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