Sclerotinia apothecia found in lupins
Plant pathologist Ciara Beard (DPIRD) has found apothecia under a narrow-leaf lupin crop at Yandanooka (south east of Mingenew). The crop came up in early May and is at 1-2cm pods on main spike. The crop is dense and has great yield potential. As significant rain is forecast for the weekend the grower is going to apply fungicide to some parts of the paddock to assist Mingenew Irwin Group and DPIRD in gathering some trial data (sprayed vs unsprayed) on Sclerotinia disease management in lupin.
Sclerotinia management in lupin crops
Sclerotinia in lupin is a sporadic disease. It is usually only a problem in paddocks that have a history of sclerotinia in canola or lupin and depends a lot on seasonal weather conditions. Often the disease affects only a percentage of the crop where the crop is densest and stays moist longer.
DPIRD research has found that fungicides applied at or after 100% flowering stage to early podding can significantly reduce disease levels in lupin but a yield response is not guaranteed.
Of the 11 trials conducted in the Geraldton port zone from 2016-2019, sclerotinia was at moderate to high levels in only four and there was a yield response in only one (in 2016 when there was a soft finish). Of the four trials with significant disease, two were conducted in 2016 and two in 2018, both years when rainfall was average to above average, crops were bulky and had good yield potential. In all four trials, sclerotinia infection was predominantly on the main spike and pods rather than the stems and this explains why a later fungicide timing to protect pods is appropriate. All fungicide timings applied from 100% flower to early podding on the main stem reduced incidence and severity of main spike sclerotinia infection as well as pod lesions.
More research is required but the benefits from managing the disease in lupin may lie in reducing sclerote production rather than increasing crop yield - that is reduced need to grade seed for sclerote contamination and reduced future risk of sclerotinia in future canola/lupin roations.
There was a grain quality response in one trial in 2016 so there could also be grain quality benefits from fungicide application even if no yield response.
A list of registered fungicides and rates for lupin sclerotinia can be found at DPIRD’s Registered foliar fungicides for lupin in Western Australia page. It is important to follow label recommendations and observe withholding periods.
For more information on sclerotinia stem rot in lupins refer to DPIRD’s Lupin foliar diseases: diagnosis and management.
To read about previous sclerotinia apothecia activity this season refer to DPIRD’s 2020 PestFax Issue 8 article Sclerotinia apothecia are being found.
For more information on sclerotinia in lupins contact DPIRD Plant pathologists Ciara Beard, Geraldton on +61 (0)8 9956 8504 or Geoff Thomas, South Perth on +61 (0)8 9368 3262
Article author: Ciara Beard (DPIRD Geraldton).
Article input: Geoff Thomas (DPIRD South Perth).