Victorian households should steel themselves for more insurance premium rises following the latest round of devastating floods, a top economist warns.

Country towns worst hit by the latest crisis were also likely to be hit with council rate increases to cover huge rebuilding costs, AMP Capital's Dr Shane Oliver said.

Farmers and local communities are bracing for further crop losses and financial devastation after a $6 billion hit to the national economy caused by previous disasters, including Victorian and Queensland floods and Cyclone Yasi.

Northern Victorian growers yesterday warned supplies of field tomatoes, nectarines and peaches could be hindered because of already stretched finances and the possibility of waterlogged trees dying.

Some Rutherglen winegrowers fear fungal diseases could taint grapes.

Clean-up costs for dairies would also be extensive.

"This is absolutely devastating for local farmers and their communities," Victorian Farmers Federation horticulture group president Sue Finger said.

Some tomato growers in the Rochester to Echuca region who suffered last year were now unable to harvest up to a quarter of rain-soaked crops.

"It's a bog heap out there," Ms Finger said.

Prime Minister Julia Gillard said it was too early to know the economic costs of the floods but ruled out extending the flood levy.

Observers said the latest heartache was not of the scale of last summer's floods, which swallowed a third of the state and cost agriculture up to $2 billion.

Dr Oliver said higher home and contents costs were inevitable.

But Deloitte partner Elaine Collins did not envision further rises, given increases already factored in. RACV said the impact on future premiums was unclear, and Suncorp said it was not yet a major claims event.

A Deloitte report released this month forecast a 20 per cent rise over two years.

The Insurance Council of Australia said several thousand claims had already been received nationwide.

Ms Gillard said emergency relief payments were being made to victims.

Premier Ted Baillieu has asked the Federal Government for extra help including clean-up and recovery grants of up to $25,000.