What was it all about?

Fusarium wilt is one of the most severe diseases of watermelon and is caused by the soil-borne fungus Fusarium oxysporum f. sp. niveum (Fon). Although found in other Australian states, Fon was first detected in the Northern Territory in 2011.

This project, which ran from 2012 to 2015, comprised the following work:

• Identification of the Fon race(s) found in the NT and comparison with other Australian and international (USA) Fon isolates
• Screening of rootstocks and grafted watermelon seedlings for resistance to Fon 
• Raising awareness of Fusarium wilt and propose management options to industry through extension strategies.

The two Fon isolates found in NT were identified as race 3, the most aggressive and virulent race, previously only recorded in Maryland, USA. Race typing using isolates from Queensland, Western Australia, Victoria and New South Wales showed that race 3 was present across these states as well.

A glasshouse trial using three Cucurbita rootstocks grafted with Royal Armada were found to be 100 per cent resistant to the two NT Fon isolates in contrast to the highly susceptible non-grafted Royal Armada.

Two seedless cultivars tested, Kalahari and Bullseye, showed low tolerance to both NT isolates, but testing is needed to find out if grafted Cucurbita rootstocks could provide resistance in Fon-infested field.

Researchers recommended further research to identify other rootstock types that are suitable for NT growing conditions and compatible with commercially desired scions. Since the study showed that race 3 has spread throughout Australia, seed companies need to focus on breeding for resistance to this aggressive strain of Fon. 

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Read more about the study and its findings on the NT Department of Primary Industries and Resources website