South African farmers are considering a switch out of corn into sunflowers, despite record yields in their latest harvest, in response to the threat of drought posed by El Nino.

Commercial farmers, who harvested record corn yields of 4.78 tonnes per hectare in their latest harvest, are to cut plantings by an estimated 7.3% when the sowing season starts later this year, a US report has said.

Farmers' concerns over corn have been stoked by low prices and expectations of a "full-scale" El Nino weather pattern setting in which, for South Africa, typically means low rainfall in summer months.

"The El Nino conditions are expected to cause above-normal rainfall during spring, but below normal rainfall during midsummer... which may result in drought conditions," US attach - Dirk Esterhuizen said in a report from Pretoria.

Farmers may switch to sunflowers "which are well adapted to hot and dry climates and can be produced economically even when there is not enough moisture to produce most of the other summer crops", the briefing added.

Key indicator

The report follows data from Australian meteorologists showing that the so-called Southern Oscillation Index, a measure of the differences in air pressures between Tahiti and northern Australia, had turned negative.

A sustained negative reading is viewed as a key indicator of an El Nino setting in, and the frequency of positive figures has prompted questions whether the risk of the weather pattern is unlikely as some forecasters have been making out.

However, other observers are already blaming El Nino conditions for the weak monsoon in India where, after the driest June in 83 years, the crop sowings are down 20% year on year, Pranab Mukherjee, the country's finance minister, said on Tuesday.

He added that more than a quarter of India's districts faced the threat of drought.