In 1851, the Census of Ireland Commissioners recorded 24 harvest failure of the potato crop going back to 1728, of varying severity. General crop failures, through disease or frost, were recorded in 1739, 1740, 1770, 1800, and 1807. In 1821 and 1822, the potato crop failed in Munster and Connacht. In 1830 and 1831, County Mayo, County Donegal, and County Galway suffered likewise. In 1832, 1833, 1834, and 1836, dry rot and curl caused serious losses, and in 1835 the potato failed in Ulster. Widespread failures throughout Ireland occurred in 1836, 1837, 1839, 1841, and 1844. According to Woodham-Smith, "the unreliability of the potato was an accepted fact in Ireland".. How many years of crop failures were recorded through disease or frost?