| Highlights from the 2004/2005 Winter Wheat survey |
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- Total foliar disease levels were lower than in 2004. However, disease incidence, per cent crops affected, was much higher, the proportion of samples affected by powdery mildew was the highest since 1997 and brown rust highest since 1999.
- For the fifteenth consecutive year, Septoria tritici was the most severe foliar disease.
- Tan spot symptoms, although at low levels, was suspected in more than ten per cent of samples, however the disease was not confirmed in all cases.
- Eyespot and stem base Fusarium severity was the highest since the very high year of 2000.
- The incidence of Fusarium ear blight was lower than in 2004 and less than half of that recorded in 2003.
However, mean severity was higher.
- Robigus was the most popular cultivar in the survey accounting for 20% of the sample.
- Sowing dates remained consistent with recent surveys with 47% of the crops surveyed sown in October and 57% of these sown before 11 October. A higher proportion of crops were sown after the end of October than in any year since the wet autumn of 2000.
- Ninety nine per cent of crops were treated with a fungicide, with 95% of treated crops receiving more than a single spray.
- Crops received an average of 2.82 sprays per crop, the highest ever recorded.
- The most popular fungicides used were the DMIs, 99% of all treated crops received at least one application from this group.
- Chlorothalonil use increased for the fourth year in succession.
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| National and regional severity of diseases |
| Only Septoria tritici exceeded a mean of 0.2% area leaf 2 affected. |
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| Fig. 1 National foliar disease levels (mean % area leaf 2 affected) |
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| The highest levels of S. tritici were recorded in the south west region, however disease incidence was highest in samples from the east midlands. Only S. tritici and powdery mildew were recorded in every region, brown rust was evident in all regions apart from the north east and yellow rust was recorded in samples from the Yorkshire and the humber region only. |
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| Fig. 2 Regional incidence and severity of Septoria tritici |
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| Eyespot was more damaging than in any year since 2000. The percentage of crops receiving a fungicide application containing cyprodinil, flusilazole, or prochloraz aimed at GS31 is still declining with only 7.6% of treated crops receiving applications of these ais. However, 34% of crops treated at this growth stage were treated with products containing prothioconazole. |
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| Fig. 3 National incidence (% crops) and levels of eyespot (mean % stems affected) |
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| The lowest levels of damaging eyespot (moderate + severe symptoms) were recorded in the Yorkshire and the humber region and the highest levels in samples from the east midlands region. The highest incidence of eyespot occured in the south west region with 97% of samples affected. |
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| Fig. 4 Regional and levels of eyespot (mean % stems affected) |
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| Nationally, recorded levels of Fusarium ear blight symptoms were well below those of 2003 with 28% and 46% of samples affected respectively.
Disease severity however, was higher than in 2003 and isolation work on the pathogens involved showed that incidence
of F. graminearum was high and therefore myxotoxin risks were increased
click here for report.
Disease incidence was highest in the east midlands region where 46% of samples were affected by ear blight and lowest in the north west region where the disease was not recorded. |
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| Fig. 5 National incidence and severity of Fusarium ear blight symptoms |
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| Fig. 6 Regional incidence of Fusarium ear blight symptoms |
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| Cultivar use |
| Only two cultivars, Robigus and Claire, each accounted for more than 10% of the sample. Robigus was the most common cultivar in popularity in six out of the eight regions. Consort was the most popular in the north east and equal to Robigus in the east region. Of the eight most popular cultivars, the highest average level of S. tritici was recorded on Consort with 8% of leaf 2 affected and the lowest on Hereward with 1.3%. |
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| Fig. 7 Severity of S.tritici on main cultivars (mean % area leaf 2) |
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| Consort had the highest recorded total foliar disease levels and the lowest average number
of fungicide applications; suggesting that fungicides were either used too infrequently or were poorly timed. |
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| Fig. 8 Total foliar disease levels, average per cent leaf 2 affected, eyespot severity moderate + severe categories and average number of fungicide applications to each of the main cultivars. |
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| Fungicide use |
| The ordinal position of the key timings remained constant. Overall each crop received on average 2.82 applications, more than any other year. Forty per cent of crops received a three-spray programme with 68% of these receiving applications aimed at GS 31, 39 and 59. The use of the strobilurin group of fungicides has declined slightly over the past three years. This growing season, 86% of treated crops received at least one application compared with 96% in 2002, when use was at its peak. No crop received more than two applications, as guidelines recommend and slightly less than half of strobilurin treated crops received two applications. The use of the active ingredient chlorothalonil from the phthalonitrile fungicide group has shown almost a seven fold increase over the past five years. This year 74% of treated crops received at least one application. |
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| Fig. 9 Fungicide use: per cent of treated crops receiving applications from the major fungicide groups and the ai. chlorothalonil post emergence. |
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| Fig. 10 Fungicide applications during the growing season. |
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| Sowing dates |
| Forty seven per cent of crops were drilled during September. Seventeen per cent were drilled after 31 October, the highest figure since the wet autumn of 2000. Almost 35% of the seed sown was farm saved, a similar figure to the two previous surveys. The use of a seed treatment including an active ingredient for control of take all appeared to make little difference in the visible symptoms of second (or more) wheats when assessed in the field at GS 75, although patches of the disease appeared to be reduced. When including an aphid vector control in a seed treatment 50% of crops treated were drilled before the end of September compared with 32% where other treatments were used, or the crop was left untreated. |
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| Fig. 11 Sowing dates of survey crops (%) |
