August 13, 2014
Growers are reminded to investigate uneven crops to check if plant parasitic nematodes are present, after root lesion and burrowing nematodes were found in the Moora area.
Department of Agriculture and Food nematologist Sarah Collins recently visited the area where a number of wheat and barley crops have been damaged by burrowing (Radopholus) nematodes and by root lesion nematodes (Pratylenchus, RLN).
Samples were diagnosed by AGWEST Plant Laboratories as the RLN species Pratylenchus penetrans.
“This was unexpected as this species is more often associated with cropping in the cooler growing areas but we have had a number of P. penetrans diagnoses this season from locations across areas of the Wheatbelt including Moora, Northam and Wagin,” Dr Collins said. “It is one of the species that we know less about.
“The ‘burrowing nematode’ detected in a nearby barley crop is also interesting as crop damage has not been reported for this plant parasitic nematode for a number of years.”
Correct identification of nematodes is important because the choice of suitable break crops to mitigate future damage is dependent on knowing which plant parasitic nematode species are present.
“It is possible that consecutive seasons favourable to RLN and burrowing nematode and the increasing inclusion of canola to crop rotations may be contributing to the build-up of nematode numbers,” Dr Collins said.
The reports follow survey work by the Focus Paddocks project, supported by Grains Research and Development Corporation, which has detected increasing levels of RLN across 184 paddocks surveyed since 2010.
“We are seeing the highest prevalence of RLN populations in at least a decade,” Dr Collins said.
Above ground symptoms of plants infected with root lesion and burrowing nematodes include stunting, poor growth, early wilting, premature yellowing of lower leaves and dying back from the tips.
Below ground symptoms often include reduced root systems with fewer lateral roots and root hairs compared to nearby healthy plants. Brown/dark coloured lesions along the roots may also be seen.
Suspected root disease or nematode problems in-crop can be confirmed by a chargeable laboratory analysis of soil and/or roots by AGWEST Plant Labs, which are contactable on 9368 3721 or email@example.com.
Nematodes will be on the agenda at a plant disease ID course for agronomists and development officers run by the department in South Perth next week (19 and 20 Aug). The department can deliver courses on root disease identification for grower groups at their local centre. To enquire about these courses contact Dominie Wright at the department on 9368 3875.