A Tasmanian farmer says he's lucky not to have lost his entire crop after lightning started a fire on his Central Highlands property.

Fortunately, the lightning strike did not hit the driest area of land and was spotted by a farm worker and extinguished before it spread.

As of yesterday, 64 bushfires were burning across Tasmania and authorities have called for more interstate help to battle the largest blazes, in the state's remote south-west.