Project Summary:

Purpose: To attend the Beltwide Cotton Conference to gain the latest knowledge on two key biosecurity risks to Australian cotton, guava root-knot nematode (GRKN) and areolate mildew (AM). To meet with Dr Bissonnette, Director of Agricultural Research at Cotton Incorporated and other pathologists to develop professional relationships and learn from international experts the management challenges of these new threats to Australian cotton.

What was achieved: Knowledge gained on the latest research conducted in the US on pathogens of concern to Australia and discussed opportunities with pathologists to learn from each other through collaboration.

The fungicide 'Revytek' showed promise for managing AM. Although results were variable across seasons, reduced incidence, increased yields, and economic benefit reported.

Given the limited fungicides available to manage this disease in Australian cotton and potential for the development of resistance to fungicides, a predictive model to determine when spraying is most likely needed to minimise loss is recommended. Potential to collaborate with Dr Allen.

Research undertaken in US to determine what races of GRKN are present, as all are not infective on cotton. GRKN is being monitored, but other plant parasitic nematodes such as reniform are of greater concern. To manage reniform nematodes, rotation sequences that include resistant cotton varieties and non-host crops, as well as a nematicide treatment are needed. Resistant cultivars are not yet available in Australia, and without these, it is extremely difficult to manage this pest. Farm hygiene and efforts to reduce spread to new fields and regions are crucial.

In the US, the fungus Xylaria necrophora is a pathogen of soybean and cotton is a new host. Cotton becomes diseased at the seedling stage and yields 1 – 14% less in seed cotton depending on seed treatment. Interestingly, this pathogen belongs in the same order of fungi as Eutypella, causing reoccurring wilt.