A SCLEROTE can survive up to seven years in the soil after it has infected a canola plant, making rotation management a key factor in the prevention of sclerotinia.
Curtin University’s Centre for Crop and Disease Management researcher Sarita Bennett presented her trial at the WANTFA Canola Spring Field Day in Cunderdin last week on the management of interactions affecting the incidence of sclerotinia stem rot in canola across the Wheatbelt.
“The aim of this trial was to determine whether differences in sclerotinia stem rot infection in canola occur in relation to site climatic conditions, variety or management,” Ms Bennett said.
The trial included four different varieties, two open pollinated – Bonito and Mako – and two hybrids – Hyola 559TT and InVigor T 4510.
Half the plots were sprayed last week.
“We sprayed fungicides to see if we could control sclerotinia at the 30 per cent flowering stage,” she said.
Sclerotinia is a canola disease that is prevalent in wetter years.
“It starts as sclerotes that you find in the stems of the plant or in the soil which then germinate when the conditions are right with humidity build up in the canopy and moisture,” Ms Bennett said.
“The sclerotes then germinate and look like little mushrooms which are a maximum of five millimetres.
“The germinated sclerotes release spores which blow in the wind and land on the petals of the canola and infiltrate the petals.
“Once the petals of the canola are infected they will drop and land on the leaf.
“If the conditions are right, the spores will grow into the plant and then you see the white lesion which stops the movement of water and nutrients up the stem, eventually killing the plant.
“The new sclerotes then form in the stem for the next year.”
Ms Bennett said because the sclerotes could live between five and seven years, a bad canola infection one year, before switching to wheat and then returning to canola meant there was a really high risk of infection in following years.
Sclerotinia has recently emerged as a serious production constraint in almost all WA canola growing regions, except some low rainfall areas.
Over the past few years the basal sclerotinia infection pre-flowering is becoming a more serious issue in some canola crops.
Due to the susceptibility of current canola varieties to sclerotinia, disease management relies on adopting some cultural practices and the use of fungicides.
Since the introduction of Triazine Tolerant (TT) canola, canola has become the primary break crop for farmers that grow it in rotation with cereals.
Ms Bennett hopes to discover the potential yield losses from sclerotinia and the possible window for spraying fungicides to help control the spread of disease.