[Ian_P]

For the last two years blight has runined my tomato and potato crops. Sometime back I read in a magazine that you could tell when it was time to get out and spray by monitoring the number of succesive days when the weather was over a specific temperature and humidity, but I can't find the article.

Now here's the clever bit. I got a weather station for Christmas and as I sit here typing I can tell you that the temperature in the garden is 35.2F and the humidity 89%. I can even ask it to warn me when the specific parameters are reached. That's not the plot but it is only  amile away so it won't be so different.

Does anyone know what they should be. I seem to remember they were call XXX Days but I'm blowed if I can remember the name.

Thanks

I

[nicchick]

Yep, it's to do with the humidity reaching a certain level and staying there for (ithink) three days. Pippa Greenwood mentioned it on GQT last week. I can't remember what it's called either!

[nicchick]

It was Anne Swithinbank and it's the Beaufort Scale, see it was bugging me too!

[mumofstig]

Blight forecasting has often been based on the occurrence of "Smith periods". A "Smith period" is a 48 hour period in which the minimum temperature is 10°C or more and the relative humidity exceeds 90% for at least 11 hours during the first 24 hours and for at least 11 hours again during the final 24 hours. However, any period of warm, humid weather increases blight risk

Any help? quote is from aunt sally's useful topics

[DD.]

It's simply called a "Smith Period".

[DD.]

Have a read of this page, then register with "Blightwatch" - link on that page.

http://www.blightwatch.co.uk/content/bw-Home.asp

You'll get notification of full Smith Periods, near misses and outbreaks in your area.

[BestBreast]

I have registered, hope this helps. Or I can see a lot of green tomato chutney cumming my way. I did save potatoes and green toms can be ripened. Toms will hopefully be in the greenhouse this year which I hope will protect them and get them to crop earlier.

Thanks for the link.

[Salmo]

Blight forecasting has often been based on the occurrence of "Smith periods". A "Smith period" is a 48 hour period in which the minimum temperature is 10°C or more and the relative humidity exceeds 90% for at least 11 hours during the first 24 hours and for at least 11 hours again during the final 24 hours. However, any period of warm, humid weather increases blight risk.

The above from the very good information on this site under potatoes. There was a similar Beamont Period but the boffins redefined it and changed the name.

In other words any damp thundery weather in June / July.

Even if you do not get a Smith's Period it may well be locally humid down amongst your potato furrows, especially if they have been watered.

[Ian_P]

Thanks everyone. Smith Periods was what I couldn't remember. I had looked at Blightwatch before posting but thought it was for commercial growers only.

I'm all signed up now.

I

[Salmo]

Ian P - As far as I can see Blightwatch is for commercial growers only unless you registered with a fictional Company name and job title. How very dishonest that would be!!

[RichardA]

does tomato blight and potato blight follow exactly the same rules ?? Are they the same??
Last year I suffered slightly on greenhouse toms but nothing on outsied toms or potatoes. Was this luck -- I removed all affected leaves very quickly.
R

[DD.]

Ian P - As far as I can see Blightwatch is for commercial growers only unless you registered with a fictional Company name and job title. How very dishonest that would be!!

I had no problem last year - Business I put down as "Other" - Company name as "Home". Nothing dishonest there!

[DD.]

You don't have to be registered to use the maps though.

http://www.potato.org.uk/department/knowledge_transfer/fight_against_blight/index.html

[andreadon]

does tomato blight and potato blight follow exactly the same rules ?? Are they the same??
Last year I suffered slightly on greenhouse toms but nothing on outsied toms or potatoes. Was this luck -- I removed all affected leaves very quickly.
R

It looks like I'm going to have to hi-jack this thread too - I'm totally ignorant when it comes to blight!!
Please help us!
 

[DD.]

Best thing to do is not worry about it in early February.

Stayed tuned to this forum as I can guarantee there will be plenty of postings & questions about it as the season approaches. Too much too soon will only be information overload, a lot of it quickly forgotten!

Praying for a long hot, dry summer with occasional showers might help!