VG06046 Parsley Root Rot

This report details the outcomes of a 12-month project continuing the research from a previous scoping study investigating root rot in parsley (VG04025).

This project carried out trials to identify parsley cultivars tolerant to root rot in both Queensland and Victoria and evaluated fungicide alternatives and a biocontrol agent for disease control.

Scientists continue to unravel the problem of root rot in parsley and investigate control options. The
disease can cause up to 100% crop losses in Victoria and Queensland.

In Victoria, parsley root rot
during summer was associated with the fungus Fusarium, but in winter, it was caused by the water
moulds Pythium and Phytophthora.

Symptoms of summer parsley root rot, associated with Fusarium, were dry, cracked, red-brown
lesions on the roots with no above ground symptoms and minimal crop losses. Chemical controls may
not be required under such conditions. However, this may not be the case if Fusarium has a major
impact on crop yields.

Winter parsley root rot, associated with the water moulds Pythium and Phytophthora, attacks both
seedlings and mature plants, causing a spongy dull brown rot resulting in a complete and often rapid
collapse of the root system and major crop losses.

The screening of flat-leaf cultivars in Victoria identified that the cultivar Shamrock had up to 70%
less root rot than other cultivars. It could be a useful cultivar to grow in areas where both summer and
winter root rot is an issue.

A fungal biocontrol preparation of the naturally-occurring mycoparasite water mould, Pythium
oligandrum, was effective against water moulds in pot trials, but the commercial preparation of the
same fungus, Polyversum™, was ineffective in the field under both low and high disease pressure.
The mycoparasite may be of use in the hydroponics industry.

Information resulting from this research can be accessed from the HAL final report VG06046 ‘Identification and management of parsley root rot’ and nationally through the Vegetable Industry
Development Officer network.

This research was led by scientists at the Department of Primary Industries Victoria Knoxfield Centre,
in collaboration with Queensland Department of Primary Industries and Fisheries.

The project was
facilitated by Horticulture Australia Limited (HAL) in partnership with Federation of Potato and
Vegetable Growers Australia Limited (AUSVEG) and was funded by the National Vegetable Levy.

The Australian Government provides matching funding for all of Horticultural Australia’s Research
and Development activities.

The researchers gratefully acknowledge the financial support of the
Department of Primary Industries through Primary Industries Research Victoria.