The disease , Late Blight of potatoes (caused by the fungus Phytophthora Infestans) can spread when Beaumont Periods occur. These are periods of 48 hours or more when the temperature is above a minimum of 10 deg Centigrade and the relative humdity exceeds 75 %.
The fungus spreads rapidly and kills the haulm - worse still the spores are washed down by rain into the soil where they attack what potatoes have formed , causing them to rot and become unusable.
Early potato crops tend to be harvested before conditions favourable to blight occur , so the disease largely affects maincrop tatties. Regular spraying with fungicide is required during the later growing season in humid weather. The new growth since the previous spraying is unprotected.
It has been suggested that the widespread use of imported guano that fuelled the intensivisation of agriculture in the 19th century could have contributed to the rise in potato blight. This may have been the vehicle that brought a virulent strain of blight from the Andean highlands.
Guano was being brought into Ayr - see post 'Adverts'
At the time of the emergence of the fungal blight, this appears to be the only remedy.
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| The Pilot 23 August 1848 |
