late blight

Pests & Pathogens, Tomatoes

I just got back from spraying my tomato plants. We had a little rain yesterday and I’ve been spraying with a copper fungicide after every rain to protect against late blight. My plants look really good this year, so I’m hoping for a good harvest before the blight comes in.

The latest info on tomato blight is at this site:

Late blight was spotted early this year, July 3, in some commercial tomato fields near my garden and in other parts of the New England. But it seems that it isn’t spreading very rapidly.

A couple weeks ago, I sent out this notice to gardeners in our Community Garden.


Bad news – On July 3, Late Blight was confirmed on tomato plants near us (Middlesex County MA). This is a very aggressive pathogen that can kill an entire field of tomatoes or potatoes within a few days.

As you may remember, we had a terrible year at the Belmont Victory Gardens with Late Blight in 2009. It affected the whole garden and the entire NE region with devastating effects for commercial growers.

We would like to ask you to do the following:
–    Please read some of the links and information on the bulletin board (we will post photos and info soon) to learn about Late Blight and how to identify it.
–    Check your tomato and potato plants carefully for Late Blight and report it immediately to me if you find any (UMASS extension service like to follow locations of outbreaks and fellow gardeners will also like to know). If you find damage that looks like late blight it must be removed from the Gardens and disposed of at home in your trash. Do not compost it! Late Blight spreads very quickly and it is important to do what we can to contain spread of the pathogen.
–    To protect your plants from infection (especially important in shadier and low lying areas):
o    Remove leaves at the bottom of tomato plants to increase airflow
o    Increase airflow around potatoes and tomatoes by trimming nearby plants, removing weeds, removing vines from fences, and keeping the paths mowed
o    Spray tomatoes and potatoes before every rain with a fixed Copper fungicide spray that is organic approved.

I walked through the Belmont gardens today and checked tomatoes and potatoes in many plots. I did not see any Late Blight, but did not have time to check all gardens. Actually, I think the tomatoes and potatoes look really good this year. There is a bit of Septoria leaf spot around as usual, which is a less aggressive fungus that causes small brown spots and yellowing from the edges of the leaves on both tomatoes and potatoes, but not much.

In my garden, I removed the Septoria damaged tomato leaves and disposed of them in my trash at home. I will be spraying with a copper fungicide soon. This is available at Hillside Garden Center as a powder or spray. Geno recommends a spray combination of Rotenone (also organic) and copper that is available at Agway in Waltham.

Some helpful links: (lots of good photos here to learn how to identify Late Blight)

Our Yahoo and Facebook sites and are good places for conversations and advice. Also feel free to email me.

Coordinator, Belmont Victory Community Gardens

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trying to prevent late blight