NSW Farmers Orange branch chair Bruce Reynolds said the shortages would affect broad-acre crop farmers including those producing canola, wheat, oats and barley.

Mr Reynolds said farmers in Blayney, Cumnock, Yeoval, Manildra, Canowindra and other Cabonne Shire council areas would be most affected by the shortage.

He said it would not affect orchardists.

Chinese factories producing spray chemicals including glyphosate (such as Roundup) shut down when the country's isolation laws came into effect to try to stop the spread of coronavirus.

While some have resumed production there are virus-related transport issues limiting supplies to Australia.

Mr Reynolds said there would be enough supplies for all, including from Australian manufacturers, as long as farmers did not overstock.

"Don't panic-buy," he said.

"Only buy what what you think you will need. We don't want a toilet paper situation.

"Don't go overboard because potentially others will miss out," he said.

Canobolas Eggs director Robert Peffer said he had enough chemical supplies for a few months but would need more for his property at Molong.

"I'm sure it will have an impact," he said.

"For the sowing component we are well prepared. We will need more chemicals before September."

Mr Peffer said there had been reports of people buying more eggs due to the coronavirus but he said it was not like the panic-buying of toilet paper.

He said his business had been hit by a cut in supplies of egg cartons from China but he had fixed that through Australian suppliers.

Mr Peffer said he was concerned spread of the virus could cause staff shortages over the next six months.

"Labor shortages will really hurt us. The chickens will not stop laying, they need to be fed. We work 365 days a year," he said.

"We just can't shut our farm and leave 200,000 chickens to die," he said.