Wheat Rust Advisory No. 8 22 November 2018 Wheat Rust Advisory – risk assessment of wheat rust outbreaks and spread in Ethiopia Summary Period: 22 October – 21 November 2018 Summary:
• Most wheat growing areas are now at or getting close to harvest, with the exception of late planted areas (Belg growing areas e.g., Bale etc).
• Recent surveys in Oromia (Holeta, Ambo, Bako, Kulumsa, Sinana) indicate that both stem and stripe rust are prevalent in most of the areas surveyed. In Holeta surveys stem rust was present in 39% of survey fields and stripe rust in 75%. In Ambo surveys stem rust was present in 94% of survey fields and stripe rust in 30%. In Sinana surveys stem rust was present in 68% of survey fields and stripe rust in 95%. In Bako surveys stem rust was present in 92% of survey fields and stripe rust in 84%. In Kulumsa surveys stem rust was present in 25% of survey fields and stripe rust in 34%.
• Northern areas based on available survey data appear to have relatively lower rust pressure, especially stem rust but stripe rust was present in pocket areas in Amhara
• Environmental/climate suitability forecasts for stripe rust infection (Cambridge Uni/UK Met Office) are now showing much lower risk of infection, due to the cessation of rains.
• Dispersal models indicate a west to south-westerly dispersal direction with Bale/Arsi/West Arsi, SNNPR and east Wellega likely to have the highest spore deposition. into SNNPR highlands from known infected sites in Bale/Arsi. Based on previous years it is likely that these dispersal patterns will continue.
Recommendation:
• In any late planted areas in Oromia/SNNPR there is a continuing risk, especially stem rust outbreaks. Highest risk areas are in Bale, West Arsi, Arsi (e.g., Arsi Robe, Sude) and SNNPR (late planted areas). Control should be undertaken in areas with emerging rust infections. Other at risk areas should be monitored closely and control undertaken if needed on susceptible varieties.
• Awareness should be raised amongst stakeholders at all levels, including farmers, to be vigilant for appearance of rusts (both stripe and increasingly stem rust)
• Control should be considered if susceptible varieties are grown and disease is present (>10-20% of leaf / stem area infected). Early control to stop increased spread and further build-up of disease is very important.
• Sampling of both stem and stripe rust should be undertaken to determine races present.
Overall Risk Level: Caution: local HIGH
Field Surveys:
Maps 1 & 2 summarize all the Meher season survey data reported to date. These surveys cover the period 10th August to 21st November 2018. These are updates of surveys since the last advisory.
Tigray:
No new updates
Amhara:
No new updates
Oromia:
Holeta:
A total of 61 fields were surveyed during the period 23-30 Oct 2018. Stem rust was observed in 24 of the fields (39%), with moderate / high incidence in 16 of these fields. High severity was observed in 6 fields – up to 90S on Kubsa; with Alidoro, Kakaba and Danda’a also susceptible. Stripe rust was observed in 46 fields (75%), with moderate/high incidence in 31 fields. Highest severity was 80S on both Digalu and Danda’a.
Ambo: A total of 33 fields surveyed during the period 31st Oct – 2 nd Nov. Stem rust was observed in 31 of the fields (94%), with moderate/high incidence in 7 of the fields. Highest severity was 40S on Danda’a. Stripe rust was observed in 10 of the fields (30%), with moderate/high incidence in 3 fields. Highest severity was 70S on Digalu. Crops were mainly at dough to maturity stage.
Sinana: A total of 22 fields were surveyed during the period 20th Oct to 8th Nov 2018. Stem rust was observed in 15 fields (68%), with moderate/high incidence in 2 fields. Highest severity was 40S on Hidasie. Stripe rust was observed in 21 fields (95%), with high incidence in 13 fields. Highest severity was 60S on Ogolcho. Crops were mainly at flowering to milk stage.
Bako: A total of 25 fields were surveyed during the period 21-22 Nov 2018. Stem rust was observed in 23 fields (92%), with moderate/high incidence in 13 fields. Highest severity was 60S on unknown variety. Stripe rust was observed in 21 fields (84%), with high/moderate incidence in 18 fields. Highest severity was 80S on Digalu. Crops were mainly at dough stage.
Kulumsa: A total of 107 fields were surveyed during the period 9-29th Oct 2018. Stem rust was observed in 27 fields (25%), with moderate/ high incidence in 4 fields. Highest severity was 40S on Hidasie. Stripe rust was observed in 36 fields (34%), with moderate/high incidence in 19 fields. Highest severity was 50S on Kubsa and an unknown variety. Crops were mainly at flowering to dough stage.
SNNPR: No updated reports Wheat Rust Advisory No. 8 22 November 2018 Map 1. Stripe Rust Incidence Meher season surveys (to 21 st Nov 2018) Wheat Rust Advisory No. 8 22 November 2018 Map 2. Stem Rust Incidence Meher season surveys (to 21st Nov 2018) Rust Races Present: Stem Rust: Initial analysis by the Ambo group on 73 samples have detected 5 races – TKTTF (n=23), TTTTF (22 samples), TKKTF (22 samples), TTRTF (4 samples), and TTKTF (2 samples). Further race analysis is on-going. Race TKKTF is emerging as a dominant race. This race is being detected on Hidasie. Dispersal Forecast: Most recent dispersal forecasts (22-29th Nov) run by the UK Met Office and Cambridge University are displayed. The most recent source locations are included for both stem and stripe rust. Stem rust: for the period 22-29 November (Map 3A) the dispersal pattern is towards south-west with the majority of spore deposition occurring in Bale / Arsi / West Arsi, SNNPR, West Shewa/SW Shewa/Eats Wellega. Based on previous years, it is highly likely that this south-westerly dispersal from Bale will continue. Wheat Rust Advisory No. 8 22 November 2018 Map 3A: Stem rust weekly dispersal pattern 22-29th Novenber 2018 NB. Map shows estimated total of number of spores deposited. Darker colours represent higher deposition. Wheat Rust Advisory No. 7 23 October 2018 Stripe Rust: for the period 22-29th November (Map 3B) most source locations showed a westerly / southwesterly trend in dispersal. Highest spore deposition was in Bale/Arsi/West Arsi and SNNPR. Map 3B: Stripe rust weekly dispersal pattern 21-28 th October 2018 NB. Map shows estimated total of number of spores deposited. Darker colours represent higher deposition NB: It cannot be discounted that additional rust sources are present in other parts of Ethiopia, but have not been reported Wheat Rust Advisory No. 7 23 October 2018 Environmental / Climatic Suitability – Risk of Infection Forecast Risk of Infection Forecast Stripe Rust (20-27th November 2018) These forecasts give the probability of stripe rust infection occurring based on meteorological factors. The maximum infection efficiency that can occur is 45%. This means that 45% of the spores deposited on susceptible wheat plants could complete the infection process. Therefore, a forecast Infection Efficiency of 45% indicates a very high risk of stripe rust infection occurring in susceptible wheat varieties. Over the entire wheat area of Ethiopia risk of infection is much lower than previously due to cessation of rains. Areas with highest relative risk of infection include: Bale, Arsi and West Arsi