SAO PAULO, Jan 18 (Reuters) - Brazilian farmer group Aprosoja Brasil is requesting permission from the Agriculture Ministry to directly import Diquat, a herbicide mainly used as a desiccant to aid harvesting, citing a shortage of the product when farmers need it the most, according to a statement on Tuesday.

Brazil's soybean farmers have reaped less than 2% of their 2022 soy crop, and January is a key month for harvesting work in top growers like Mato Grosso state.

Aprosoja said Diquat orders are not being fulfilled by Syngenta, which is the holder of the product's registration in Brazil.

The ministry did not have an immediate comment.

"The huge demand for Diquat has not been met by the industry," Aprosoja, which represents about 400,000 soy and corn farmers, said in the statement. Aprosoja said Syngenta issued a note on Dec. 23 saying there was not enough of the product available on the market to meet Brazilian farmers' demand.

In a statement to Reuters, Syngenta recognized short-term challenges to supply products with Diquat as an ingredient. It cited issues affecting production of certain active ingredients for pesticides in China, global logistics disruptions and heated demand for Diquat in 2021.

Syngenta, owned by ChemChina, said it is fully committed to increasing Diquat supplies in Brazil.

"We are looking for additional supply alternatives from all possible sources around the world, including viable alternatives in China itself," the statement said.

Aprosoja said the company has been unable to deliver product that has already been ordered, worrying farmers.

The problem arose after Anvisa, the Brazilian health watchdog, banned the use and marketing of the herbicide Paraquat, Aprosoja said. Lack of the substitute Diquat made the desiccant's price more than triple compared to the last harvest, it added.

Syngenta said there was a lack of Diquat products available for immediate delivery anywhere, adding direct imports into Brazil would not solve the matter.

(Reporting by Ana Mano; editing by Jonathan Oatis, Lisa Shumaker and Sandra Maler)