Australia's largest produce company Costa Group says some of its citrus farms were impacted by the hailstorm that hit Riverland on Tuesday.

The severe weather event affected numerous horticultural crops in the key South Australia growing region.

In a statement on Thursday, Costa sad three of its seven citrus farms had been affected.

The farms - Yandilla, Kangara and Amaroo - have a total of around 1,700 hectares. But of this total, the company said two-thirds sustained little or no impact.

"The trees on those parts of the farms affected have not sustained any structural damage, with the only damage being on the early stage fruitlets that are naturally forming on the trees at this time of year," it said.

Costa doesn't expect any yield impact on next year's volumes, but potential quality issues could impact on pricing. This would in turn affect the company's financial performance in 2020.

"A natural part of the citrus growing process involves the falling of some fruitlets, which occurs over the early summer period," Costa said.

"We anticipate that more of the fruitlets that fall this season will be the damaged fruitlets, with a higher proportion of the undamaged fruitlets remaining on the trees.

"However, this will not be known until the normal conclusion of this cycle in late CY19. Therefore, it is anticipated that by early in the new year we will be able to conduct a more thorough assessment of any impact on CY20 earnings."

Based on the current information, Costa expects that EBITDA next year could take an A$4-6m hit. 

ABC News reported that other crops affected in the region include grapes, stone fruit, nuts, and grain.