13 August 2009

Late Tomato blight strikes again this year


Green Beefheart Tomatoes, originally uploaded by hardworkinghippy.

I've hardly commented on how the vegetable garden is doing this year but - apart from tomatoes - things are coming along nicely and we should have enough vegetables to eat fresh and to store to last us all year.

I say apart from tomatoes because although we've a had a few kilos of early tomatoes, I've noticed the dreaded late blight rear it's ugly head and I'm hanging on in there hoping that the precautions I'm taking help to delay the onset of the disease just long enough for me to harvest our main crop.

Over the past couple of years we've had a problem with tomato blight, a fungal disease spread by spores in the atmosphere. The disease is highly contagious and although I've noticed that some varieties like Brandywine resist blight slightly longer all tomatoes succumb in the end and there is no cure for blight.

It's so annoying because I plant a lot of tomatoes and really look forward to getting a good crop which we use almost every day for salads throughout the summer and have loads left over to purée into tomato sauce and add to ratatouille which I bottle and keep in the cellar for the winter.

Late blight is caused by Phytophthora infestans an oomycete or water mould. (Early blight, caused by Alternaria solani, is usually called "potato blight".) Late blight was the major culprit in the devastating 1845 Irish and 1846 Highland potato famines.

The spread of the infection is most rapid during conditions of high moisture and moderate temperatures. It's spread by the wind or by rain splashing the spores on to the plants. Once the blight really takes hold the leaves, stems and even the tomatoes themselves go brown and the whole plant withers and dies. It spreads rapidly, devastating a crop in a few days.

The first year I saw blight I took the brown leaves off and burned then - composting them spread the disease. That stopped it for a while and my early season tomatoes ripened well. Later into summer - with a rainy and cool August the bottom leaves of all the the plants curled and started to have brown mottled patches.

I don't like putting anything on my plants so I decided to cut my losses and ripped them all up and burned them plus their wooden stakes in the fire and sterilised the metal electric fence posts to use again next year.

To try to prevent blight, I give my vegetables a very thick mulch to stop the earth splashing on them when it rains. I always water my tomatoes at ground level and never on the leaves. I plant tomatoes in full sun. This year we made a new raised bed using a hugelkultur bed and I decided to use it for growing tomatoes because almost all my existing garden has at some time or another had tomatoes on it and the new bed is tucked away behind trees and protected from the wind.

Last year for the first time I used Bordeaux mixture and it did help to delay the spread of the disease.

This year, I've sprayed the beautifully formed tomatoes once again hoping that they won't take long to get to to the stage when they start to go even slightly red and I can pick them and ripen them indoors. The blue haze on the plant isn't pretty and I have to forgo one of the garden's treats of being able to take a perfect ripe warm tomato from a plant and pop it straight into my moth - but needs must.

Although Bordeaux mixture is deemed suitable for organic growers, if it's used excessively (Hopefully once a year isn't "excessive"!) the Copper, it's principal ingredient, can lead to the destruction of beneficial organisms and cause an imbalance in the soil nutrients that probably reduce the ability of the organisms and the plants themselves to fight off disease naturally.

In that case, the truth of the saying "You are what you eat" leads me to believe that for the good of my own immune system, I should try to allow my vegetables to grow as naturally as possible and if they can't grow without my interference then I should replace them with something else.

That's very easy to say, but trying to replace tomatoes isn't going to be easy and for the time being I'll take my chances that nature will help me to restore the balance in the soil for the years to come.

10 comments:

Anonymous said...

So sorry to hear about that & I hope you can save them. For me, tomatoes are the treat of the season & a joy to have in the winter & almost irreplaceable in cooking.

Demi/Sally.

Anonymous said...

Yes, it really feels like high-summer when one is eating fresh ripe tomatoes strait out of the garden. For the past two years I have been using resistant F1 hybrid tomato seed. Last year I got a very good harvest before the Phytophera really damage the plants. This year looks like I will have the same result. I don't like having a plastic roof over my plants like many around here because I don't think it looks good. It also costs money to build on the other hand the F1 seed is rather expensive.

I really enjoy your blogs and pictures.

cheers

Jerry Leverenz, Stadthagen, Germany

Ian and Luis said...

Similar situation here.....warm, humid and tomatoes just about to 'give in'. We have cropped several kilos but considering ripening off-vine for a good few more in the hope we have some to process for the rest of the year. We have also used Bordeaux (once) and feel very much the same about it. Good luck.

Diane said...

Thanks for taking the time to share a bit of your life with all of us. Luck with your tomatoes...here in California mine are in the blooming stages along with small/med green tomatoes. We have had a cooler than normal summer but the last few days lots of sun & very warm temps. Fortunaltely for us we can have warm/sunny days thru Sept so still hope in ripening all of them.

detroit dog said...

So sorry that your entire crop is in danger.

Here is a link to an article in the NY Times, which explains the late blight currently spreading throughout the northeast U.S., and how its affecting "the industry." It also looks at personal responsibility by those of us who purchase our plants and are "backyard" gardeners. Very interesting now that times are changing.

http://www.nytimes.com/2009/08/09/opinion/09barber.html?scp=2&sq=tomato&st=cse

detroit dog said...

In case you can't open the link, the story was titled "You Say Tomato, I Say Agricultural Disaster."

MrsL said...

Sorry about the blight, it's dreadful when it strikes. I've never had it on tomatoes, and only once on potatoes last year, so am doing well in 22 years! Must be heartbreaking to lose such a lovely crop - one of my favourites, especially the Brandywine. Glad the res is doing fine, though.

MrsL

xx

Riana Lagarde said...

we have blight too, i was just talking to some other friends around here that say it happens to them each year. we got some decent tomatoes for about a month, but now i have to uproot them all tomorrow morning. it's so sad and frustrating when we are trying to grow our own food. the neighbors have a blue haze on their plants, guess i should go and borrow some...

La Ferme de Sourrou said...

It's nerve racking isn't it ?

So far the blight hasn't spread too much and I'm picking red tomatoes off every day but I that spring in my step is missing as I turn the corner into the garden bed where the tomatoes are...

Good article detroit dog, it really brings home the importance of this crop to us all.

randomplantings.com said...

If it's any comfort, I've just read that they are having the same problem this year over at 'One Straw' in the US.
http://onestraw.wordpress.com/2009/08/18/n-late-blight/

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