United Kingdom
March 13, 2014
High levels of yellow rust infection are present and with mild temperatures set to continue, the situation is likely to get worse particularly with the aggressive warrior strain dominant.
1. Which triazole should I base my T1 and T2 sprays on for the best yellow rust control?
Where yellow rust and Septoria are a threat, use an epoxiconazole based fungicide. Epoxiconazole is the highest rated of the triazoles for both yellow rust and Septoria control by HGCA.
Brown rust is present in some crops already, with a high pressure weather system expected to dominate over the next weeks, temperatures will reach the required 15 degrees for sporulation and spore germination.
2. Which triazole should I base my T1 and T2 sprays on for the best brown rust control?
Where brown rust and Septoria are a threat, use an epoxiconazole based fungicide. HGCA rate epoxiconazole as the strongest of the two main triazoles against brown rust, 4 stars for epoxiconazole, and prothioconazole with only 2 stars.
3. Can I further improve the activity of epoxiconazole against rusts?
Mixture products such as Tracker and Adexar will give higher activity against rusts. Furthermore, the addition of a rust active strobilurin such as Comet 200 at T1 or T2 should be considered in high rust risk situations.
Recent temperatures have been ideal for eyespot development, and with most varieties susceptible, eyespot control must be a serious consideration for 2014.
4. Where rust, Septoria and eyespot is a threat, what fungicide should I consider at T1?
Tracker is the most effective eyespot material on the market. It contains epoxiconazole so you also have the most effective triazole for rusts. Where eyespot is less of a threat at T1, but Septoria pressure is higher particularly in curative situations, Adexar is the most active fungicide against Septoria combined with rusts.
5. Where rust and Septoria is a threat, what fungicide should I consider at T2?
Adexar is the most active fungicide against both Septoria and rusts, proven over several years.
6. Should I use Chlorothalonil at T1 & T2?
Chlorothalonil must be included in the T1 and T2 spray to improve Septoria protection, increase yield and to bolster resistance management. By not using chlorothalonil, you are increasing the likelihood of the SDHIs breaking down. Tracker and Adexar are compatible with chlorothalonil, no negative effects have been observed. More often than not, the addition of chlorothalonil leads to improved Septoria control and higher yields.
7. Should I use a higher azole rate or add chlorothalonil?
Use the appropriate dose of azole at T1 and T2, at least 50% dose, but combine the azole with two other modes of action. Combining different modes of action at appropriate doses is the most effective method to keep on top of Septoria. If you have to choose between increasing the azole dose slightly or adding chlorothalonil, BASF recommend to add chlorothalonil.
| Approach to maximise rust control and yield in 2014: |
| T0 |
Opus Team 0.5 L/ha or other rust azole e.g. cyproconazole or tebuconazole |
| T1* |
Tracker 1.0-1.25 L/ha + chlorothalonil 1 L/ha (500 g/ha) |
| T2* |
Adexar 1.0-1.25 L/ha + chlorothalonil 1 L/ha (500 g/ha) |
| T3 |
Metconazole or prothioconazole based product |
* Consider using 0.4L/ha Comet 200 in high rust situations
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