| Highlights from the 2006/2007 Winter Wheat survey |
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- Head blight affected 83% of samples, the highest figure recorded since records began in 1987.
Symptoms were assessed on almost 20% of ears; the previous highest figure was 12% in 1998.
- The incidence of brown rust, 49.8% of samples affected, was the highest since 1974. Disease
severity, per cent area of leaf two affected, was more than eight times the ten year mean.
- The severity of Septoria tritici on leaf two was lower than for any year since 2001.
However, it was still the most common foliar disease accounting for 92% of samples.
- Although tan spot was evident in 3% of samples, this was not as prevalent as in the previous
two surveys with 11% and 19.7% of samples affected in 2005 and 2006 respectively.
- Eyespot severity was lower than for any survey since 1982. Moderate + severe symptoms were
less than one third of the ten year mean.
- Three cultivars Einstein, Robigus and Alchemy accounted for 48% of the sample.
- More than 50% of crops were sown before the end of September a trend first seen last year.
- The mean number of fungicide applications per crop increased to 3.02 compared with 2.71 in 2006
and 2.82 in 2005.
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| National and regional severity of diseases |
| Brown rust severity, per cent area leaf 2 affected, exceeded levels in all surveys with the
exception of 1974 and 1975. |
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| Fig. 1 National foliar disease levels (mean % area leaf 2 affected). |
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| Brown rust was most widespread in the south east region where more
than 60% of samples were affected, followed by the eastern region with 58%. Here severity was
highest with 1.6% area of leaf 2 affected compared with 1.4% in the south east. The highest
incidence and severity of S. tritici was recorded in the north east region where it affected
every sample with a mean of 6.2% area of leaf 2 affected. Only S. tritici, brown rust and
powdery mildew were recorded in every region. Tan spot was found in samples from the west midlands,
east and south east regions and yellow rust in yorkshire and the humber, west midlands and the eastern
regions. |
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| Fig. 2 Regional incidence and severity of brown rust. |
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| Fig. 3 Regional incidence and severity of Septoria tritici. |
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| Eyespot was less damaging than in any year since 1982. Ordinal severity resumed, last year more
stems were affected with moderate lesions than slight. |
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| Fig. 4 National levels of eyespot (mean % stems affected). |
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| No damaging eyespot (moderate + severe symptoms) was recorded in the
north west region. The highest levels were recorded in samples from the yorkshire and humber region.
For the second consecutive year the highest incidence of eyespot occured in the west midlands region
with 85% of samples affected compared with 96% last year. |
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| Fig. 5 Regional levels of eyespot (mean % stems affected). |
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| This season has seen the highest incidence and severity of head blight
since records began in 1987. Disease severity, 1.2% mean area of the ear affected, was almost twice
the previous high of 0.7% in 1998. Disease incidence was highest in the north west region where all
samples were affected by head blight symptoms and lowest in the west midlands region where 60% of the
samples were affected. |
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| Fig. 6 National incidence and severity of Fusarium head blight symptoms. |
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| Fig. 7 Regional incidence of Fusarium head blight symptoms. |
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More information on Fusarium Head Blight incidence in 2007.
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| Cultivar use |
| Three cultivars, Einstein, Robigus and Alchemy accounted for 18%, 16%
and 14% of the sample respectively. They were the only cultivars encountered in all eight regions.
The sample comprised twenty nine cultivars of which four (Sahara, Oakley, Humber and Timber) were
sampled for the first time. Of the eight most popular cultivars the highest average level of
S. tritici was recorded on Gladiator with 5.3% of leaf 2 affected and the lowest on Alchemy
with 0.9%, in line with their resistance ratings of 5 and 7 respectively. Brown rust levels were highest
on Consort, 4.1% of leaf 2 affected, and the lowest on Gladiator at trace levels, again reflecting
their resistance ratings of 3 and 8 respectively. |
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| Fig. 8 Severity of S.tritici
and brown rust on the main cultivars (mean % area leaf 2 affected). |
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| Levels of moderate + severe eyespot were highest on Solstice (resistance
rating 4). Only slight eyespot lesions were recorded on Gladiator, although having the same or lower
resistance rating as other cultivars in the top eight, only one crop was a second wheat. Overall,
crops which were a second (plus) wheat had a higher eyespot severity score than those after a break
crop and those after grass only had lesions in the slight category recorded. |
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| Fig. 9 Total foliar disease levels (average per cent leaf 2 affected) and eyespot severity (moderate + severe categories) for the most popular cultivars. |
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| Sowing dates |
| Almost 25% of crops were sown before 20th September, the highest figure
ever recorded in the commercial surveys. For the second consecutive year moderate + severe eyespot
was more severe on crops sown at this time. Over the last ten years eyespot severity has been
greater in crops sown in September in seven out of ten surveys. |
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| Fig. 10 Sowing dates of survey crops (%). |
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| Fungicide use |
| Overall, crops received an average of 3.02 fungicide applications,
more than in any previous survey. Five crops were not treated and were organically grown (1.8%).
A three-spray programme was the most popular spray regime accounting for 38% of crops. However,
31% had a four spray regime, the highest percentage since records began. Eighty-two per cent of
these crops received sprays aimed at all the key timings. Overall, 48% of crops received an application
at T0, 95% at T1, 71% at T2 and 72% at T3. This year more crops were treated at T3 than at T2 which
last occured in 1993; probably reflecting the poor travelling conditions at the time of T2 applications
and the disease pressure from rusts and head blight. |
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| Fig. 11 Fungicide applications during the growing season. |
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| There was a slight increase in the use of strobilurin fungicides.
This year 85% of treated crops received at least one application compared with 81% in 2006.
Pyraclostrobin was the preferred strobilurin at T2; it was used on 44% of crops sprayed at this time.
At T3 azoxystrobin was the most widely used strobilurin; being part of the spray regime for 37% of crops
treated at this time. Forty one per cent of strobilurin applications were applied at T2 and 43% at T3. |
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| The active ingredient chlorothalonil, from the phthalonitrile chemical
group, is a key component in S.tritici control programmes. This year, 83% of treated crops
received at least one application with an average of 1.53 applications per treated crop compared
0.18, 0.44, 1.12, 1.20, 1.27 applications from 2002 to 2006 respectively. Twenty five per cent of
chlorothalonil applications were applied at T0, 40% at T1 and 24% at T2. Overall more than 64% of
chlorothalonil treated crops received 2 or more applications. |
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| This year morpholine use increased, 44% of crops received at least one
application compared with 33% in 2006. |
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| DMI-fungicides, comprising the azole, imidazole and triazole chemical
groups, were the most often used fungicide group. DMI treated crops received an average of 2.75
DMI sprays each, with the majority (42%) receiving three applications and 35% receiving two.
Thirty-four per cent of DMI applications were applied at T1, 27% at T2 and 26% at T3. The most
commonly encountered active ingredients were epoxiconazole (triazole) used on 77% of crops treated
at T2, 46% at T1 and 43% at T3, prothioconazole (azole) used on 39% of crops treated at T1, 25%
at T2 and 20% at T3 and tebuconazole (triazole) used on 37% at T3 and 14% at T2. |
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| Fig. 12 Fungicide use: per cent of treated crops receiving applications from the major fungicide groups and the ai. chlorothalonil post emergence. |
| * includes the chemical groups morpholines, piperidines and
spiroketalamines (as reductase/isomerase inhibitors). |
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| Fig. 13 Fungicide use: per cent of crops treated at the key timings with the major fungicide groups and the ai. chlorothalonil. |
