Sclerotinia disease in progress in WA
- Northam
- Albany
- Munglinup
Apothecia have been found in Department of Primary Industries and Regional Development (DPIRD) sclerotia depots at Northam and Albany recently. They have germinated from sclerotia. It is a warning that the cool moist weather in recent weeks has suited the start of the sclerotinia disease lifecycle.
Sclerotinia leaf lesions and early stem infection have been reported in canola crops at Munglinup. The crop stages affected range from cabbaging growth stage to first flowers.
Growers in areas with a history of sclerotinia are reminded to consider their sclerotinia risk when their crops are close to or at flowering. The disease needs to be managed before sclerotinia symptoms are observed.
Symptoms
Sclerotinia canopy infection is the most common infection pathway with aerial ascospores produced by apothecia infecting petals during crop flowering. Lesions occur in the upper half of the plant’s main stem or branches and can be observed on leaves and pods.
Basal sclerotinia infection follows a different pathway where sclerotia germinate from the mycelium and directly infect the stem at ground level in very wet conditions/seasons. White cottony-looking growth girdles the stem, causing the plant parts above the lesion to wilt and die.
Management
Currently no foliar fungicides are registered or recommended for reducing basal sclerotinia infection in canola or lupin.
DPIRD research has shown that regular rainfall and high humidity (>75%) in the three weeks before and after commencement of flowering are most conducive for damaging levels of canopy sclerotinia to occur in crops. While fungicide application reduces disease severity, it does not necessarily give a yield response, so it’s important to consider crop risk and value of disease management carefully each season. For canola crops, consider whether a response to upper canopy blackleg is also likely (refer to DPIRD’s UCI BlacklegCM - Blackleg upper canopy infection management app).
Growers need to consider the following factors to determine their risk of sclerotinia and which paddocks to prioritise:
- rotation history of the paddock
- history of sclerotinia in the current paddock and those surrounding it
- rainfall events before and after flowering
- crop growth stage
- dense crops with early canopy cover on loamy soil types are at higher risk.
The SclerotiniaCM decision support tool is available for use by canola growers during flowering to help determine the likely economic returns from applying fungicide at a specific time during flowering for the control of sclerotinia stem rot. The user can specify individual paddock data/history as well as recent and expected weather conditions so that the output relates to their own cropping circumstances. The SclerotiniaCM tool can be downloaded from the App Store or Google Play Store and can be used on both phones and tablet devices. For more information refer to DPIRD’s SclerotiniaCM decision support tool page.
Several fungicide products are registered for the control of canopy sclerotinia in canola while options in lupin are more limited. Fungicides need to be applied as recommended per product label. Strategic and responsible use of fungicides will reduce the risk of fungicide resistance developing. For more information refer to DPIRD’s Registered foliar fungicides for canola in WA and Registered foliar fungicides for lupin crops in WA pages.
Based on the extensive research conducted by DPIRD the following in-season sclerotinia management options are:
- For canola:
- Apply a single foliar application at 20% to 50% bloom, provided conditions are favourable for infection before and during flowering. See Table 1 below for recognising bloom stages in canola. Use the SclerotiniaCM tool for guidance.
- A second fungicide application at 50% bloom is generally only beneficial in seasons with an extended wet period. Fungicides cannot be applied after 50% bloom, but some products have a longer withholding period, so you do need to check the label. Use the SclerotiniaCM tool for guidance.
- For lupin:
- Aim to apply fungicide from full to late flowering on main spike in order to protect main stem pods and penetrate the lower canopy
- A range of products are now registered in lupins which can reduce sclerotinia canopy infection, such as Veritas® Opti and Miravis® Star.
| Percent bloom | Number of flowers open on the main stem |
|---|---|
| 5% | <5 |
| 10% | 10 |
| 20% (petal drop commences) | 11-14 |
| 30% | 15-20 |
| 50% (full bloom, crop is at its brightest) | >20 |
Growers and consultants are encouraged to report to the PestFacts WA service any apothecia finds or disease observations as the season progresses.
Further information
Further information can be found at:
- DPIRD’s Managing sclerotinia stem rot in canola page
- DPIRD’s Managing sclerotinia in lupins page
- GRDC’s Sclerotinia stem rot in canola factsheet.
- GRDC’s Lupin sclerotinia disease risk assessment guide factsheet.
For more information on sclerotinia in canola contact plant pathologists Andrea Hills, Esperance on +61 (0)8 9083 1144, Ciara Beard, Geraldton on +61 (0)8 9956 8504, Kylie Chambers, Northam on +61 (0)8 9690 2151 or Jean Galloway, Northam +61 (0)8 6690 2172.
For more information on sclerotinia in lupins contact plant pathologists Ciara Beard, Geraldton on +61 (0)8 9956 8504, Geoff Thomas, Perth on +61 (0)428 947 287.
Article authors: Ciara Beard (DPIRD Geraldton), Jean Galloway (DPIRD Northam) and Andrea Hills (DPIRD Esperance).
Article input: Zia Hoque (DPIRD Northam).