Can I remind everyone of the Blight Watch service aimed at commercial growers but free so good for us home growers.
This web site monitors weather conditions to calculate the likelihood of Blight affecting crops. By putting in your postcode to can see the temperature/humidity pattern by day and night for your locality and whether it constitutes a “Smith†period. This is when the weather is suited to the spread of the fungus that spreads blight.
I have had 2 near misses in recent days so will continue spraying with Dithane as soon as the threat of rain is gone tomorrow:
http://www.blightwatch.co.uk
Jerry
I thought they were Beaumont periods, not Smith! Shall have to read up now.. :)
How does one use Blightwatch? I can't get in without registering, and I'm not a commercial grower...
moonbells
Well you learn something every day!
Found on http://www.teagasc.ie/research/reports/crops/4312/eopr-4312.htm
"One of the first forecasting schemes for potato blight, based on cloudiness, dew, rainfall and temperature was developed in the Netherlands (van Everdingen, 1926). Others were developed in the UK (Beaumont & Staniland, 1933) and the USA (Crosier & Reddick, 1935). Subsequently, Beaumont formulated the Beaumont Period (Beaumont, 1947) which was later superseded by the Smith Period (Smith, 1956). An attempt to refine the system by Sparks (1980) was not successful and the Smith Period continues in use in the UK to the present day. "
second edit:
http://www.bspp.org.uk/bsppnews/bsppnews42/bsppnews42f.htm
"His ‘Smith Period’ was the result of reworking the 1950-1955 operations charts of A Beaumont (of the ‘Beaumont Period’, the classic UK potato late blight forecasting scheme published in 1947) to test the validity of using a shorter period of higher humidity. He found that 29 out of the 43 failures of Beaumont would have been valid using a 90% humidity criterion for 11 h in each of two days instead of the 75% for 48 h. Smith records that “The differences in effectiveness of the two systems, however, would appear to be small in practice and there would be little point in altering an established system unless the benefits are likely to be considerableâ€. It was not until 1975 that the Smith period came into full operation and formed the basis of blight forecasting in the UK. "
third edit (!) Not quoting this one, but makes interesting reference reading.
http://www.foresight.gov.uk/Detection_and_Identification_of_Infectious_Diseases/Reports_and_Publications/Final_Reports/T/t5_7.pdf
oh ok, one quote (!)
" The commonly used forecasting scheme in the UK, the Smith
Period (Smith 1956), uses criteria of two consecutive days, ending at 09.00,
when the minimum air temperature does not fall below 10°C and the relative
humidity is at least 90% for 11 hours or more on each day.
"
Um, it won't let me view the forecast, but I can't see where to register.
I think you need to register from this site:
http://www.potatocrop.com/content/default.asp
However, I did that a while ago and now it won't recognise me anymore!
Hmmm..... sorry
I registered years ago and Dandilion's link should explain all, you have to give an email address to register but it is free.
Jerry
Registered again. It is working this time :)!
Good one Jerry.
Jerry, does this apply to Tomato Blight as well?? Sorry but last year I lost nearly 50lbs of tomatoes to blight and I will do anything to protect this year's crop. Thanks Dinger
Same disease, and toms are close relatives, so I assume it works the same way. For some reason I only got it on my toms last year, and not the potatoes. I'm taking a calculated risk just leaving mine out with no precautions, but if I do get an outbreak, I want to be able to compare all the varieties I'm growing, to see if some do better than others.
blimey! my full smith criteria is today!