Manage Blackleg of Canola

Transcription

1 Evaluation of Fungicides to Manage Blackleg of Canola Kurt Lindbeck/Audrey d Leo NSW Department t of Primary Industries, Wagga Wagga Steve Marcroft/Vicki Elliot Marcroft Grains Pathology, Horsham Angela van de Wouw University of Melbourne, Parkville National Canola Pathology Project (UM0051)

2 Introduction Southern NSW traditionally a profitable canola producing region Since early 1990 s (Oscar, Rainbow, Dunkeld, Karoo and Pinnacle). Mid/late 1990 s s, area increased dramatically wheat/canola/wheat/canola disease concerns rotation was profitable

3 Area sown to Canola in NSW , ,000 ha) Area sow wn to Canola ( 600, , , , , ,000 - Year

4 Introduction Late 1990 s Canola yield decline observed Level of disease observed in crops suggested increasing disease could be responsible Kirkegaard et al. ( ) High rainfall districts (Galong/Wallendbeen) Blackleg (1% lodging = 5% yield loss) Sclerotinia (1% stem rot = 1.3% yield loss) Blackleg was having an impact

5 Why is blackleg such a severe disease? 5

6 Leptosphaeria maculans in Australia stubble SUMMER sexual fruiting bodies AUTUMN windborne sexual spores lodged plants root rot stem canker cotyledon infection SPRING WINTER

7 Regional effect on blackleg High canola intensity = blackleg every year 7

8 Regional effect on blackleg Low canola intensity it = low blackleg regardless of season

9 Summary Sexually reproducing diverse populations that can evolve and overcome resistance Survives on stubble lots of inoculum in southern NSW Blackleg severity is determined by canola intensity g y y y and environment

10 Blackleg Management 10

11 Blackleg Management Current Recommended Strategies Cultivar resistance Select varieties with adequate resistance Separation from stubble Separate crops from old stubble by 500m Seed and fertiliser dressings and foliar fungicides Select appropriate level of fungicide protection Rotation groups Rotate resistance groups every 2 3 years

12 Evaluation of fungicides to manage blackleg Trials conducted at Wagga Wagga (Graham Centre) and Cowra Evaluate current registered fungicide options Jockey seed dressing Impact fungicide treated fertiliser Prosaro foliar fungicide (4 6 leaf) Applied to a range of canola cultivars Jardee (MS), Crusher (MR/MS), Thumper (R) Crusher (MR/MS) Stingray (MR)

13 Effect of fungicide treatment on blackleg internal infection e de 80.0 d % stem Infection bc c ab a a d d d c bc bc Nil Jockey Impact Prosaro Jockey + Impact Jockey + Prosaro Impact + Prosaro Jockey + Impact + Prosaro ab a a a a a a a a Jardee Crusher Thumper 5% LSD = % LSD = % LSD = 0.90

14 Effect of fungicide treatment on canola yield Yield (t/ha) e de a d d cd bc bc b ab 1.4 Nil cde cd bc b b b b ab a Jockey Impact b Prosaro ab b ab Jockey + Impact a Jockey + Prosaro Impact + Prosaro Jockey + Impact + Prosaro 0.4 5% LSD = 0.16 (t/ha) Jardee Crusher Thumper

15 Effect of fungicide treatment on Crusher (% internal infection) f 70.0 e d bcd cd ab abc a 0.0 o Nil +Jockey only +Impact only +Prosaro only +Jockey+Impact +Jockey+Prosaro +Impact+Prosaro o +Impact+J +Jockey+Prosaro 5% LSD = 10.1

16 Effect of fungicide treatment on Stingray (% internal infection) d 60.0 d bc c bc a ab a 0.0 Nil +Jockey only +Impact only +Prosaro only +Jockey+Impact +Jockey+Prosaro o +Impact+Prosaro o +Impact+J +Jockey+Prosaro o 5% LSD = 9.8

17 Fungicide tolerance. All available fungicides from the one active group Ti Triazoles (DMIs, Group 3) Strong selection pressure for fungicide resistance to evolve Isolates of Letosphaeria maculans identified with tolerance to fluquinconazole Develop lesions on Jockey treated seedlings

18 Identified five isolates with increased tolerance to fluqinconazole Avera age pathogen nicity score Westar - Nil Westar - Full rate D13 D9

19 Fungicide tolerance. Isolates identified appear to have increased tolerance rather than resistance Lesions that develop are not completely virulent Lesions develop slower on jockey treated plants compared to nil control Large scale stubble survey Australia wide early 2015 Collection and screening of isolates 200 paddocks sampled 20% currently being retested

20 Conclusions Fungicides are a valuable tool in providing protection from infection Seed and fertiliser treatment most effective Foliar fungicides effective under high disease pressure Over reliance on fungicides?? Always remember IDM Consider the level of cultivar resistance and group Consider the background disease pressure Select the appropriate combination Cultivar and fungicide

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