CROP MONITOR

2002 SURVEY: HIGHLIGHTS

Nationally, the combined total of foliar diseases was higher than in any year since 1985 due to the high levels of Septoria tritici
Septoria tritici was the most severe foliar disease for the twelfth consecutive year, affecting on average 9.0% of the area of leaf 2 and occuring in 95% of crops sampled.
Mildew was the second most common and severe disease, being recorded in 34% of crops with an average of 0.1% of the area of the second leaf affected.
Take-all was present in 39% of crops and patches recorded in 18%, the highest severity since 1987.
Stem base Fusarium symptoms were recorded in 91% of samples. Symptoms were less widespread and severe than in 2001 with only 5.7% of stems affected by moderate plus severe symptoms compared with 6.3% in 2001 and 8% in 2000. Fusarium ear blight symptoms were recorded more often than in 2001 occuring in 24% of samples.
Claire was the most commonly sampled cultivar with 35% of the stratified sample; followed by Consort with 20%, these two varieties accounted for 55% of the samples in the stratified survey.
Nationally the highest level of S. tritici was recorded on Tanker, with an average of 13.6% of the area of leaf 2 affected, followed by Hereward and Consort with an average of 12.9% and 9.3% of the leaf area affected, respectively.
A higher percentage of crops were sown before the end of September (47%) in this survey than recorded in any previous one with 21% crops sown before 20 September compared with 11% in 2001.
Fungicides were used on 98.8% of crops, with 92% receiving two or more treatments. Ten per cent of all crops received more than three sprays, and only four crops were left untreated.
Sixty eight per cent of crops in the survey were grown from certified seed and 33% from farm-saved seed; three crops were grown from a mixture of certified and farm saved seed.
The majority of crops received a post-emergence herbicide in the autumn (80%). This was the highest percentage treated at this time since records began in 1988.
Eighty one percent of crops received an insecticide treatment compared with 62% in 2001 and 74% in 2000.

Introduction

Plant pathologists at the Central Science Laboratory (CSL) and ADAS have conducted annual disease surveys of winter wheat crops since 1970 with the exception of 1984 and 1985.

This report contains the results of the survey of foliar, stem base and ear diseases of winter wheat for the 2001-2002 growing season, and includes detail on fungicide, herbicide and insecticide use. The results, where appropriate, are compared with those from previous winter wheat surveys.

The 2002 survey of leaf, ear, and stem-base diseases of winter wheat was carried out in late June to July when crops were at the early - to medium- milk growth stage (GS 73-75). The distribution of addresses between regions was proportional to the regional area of winter wheat grown, except for Wales where additional addresses were requested in order to obtain meaningful figures for the area. The addresses were selected at random from the returns of the June 2000 DEFRA agricultural census. A map of the regions is given in Fig. 1.

Results

Selected data for the key diseases are presented in the following histograms, together with data from the previous four years to set the current results in context.

Specific details of individual diseases and their interactions with crop husbandry factors can be obtained on request from Jean Slough or fill in an enquiry form.

Diseases

National foliar disease levels

Table 1 National foliar disease levels (per cent area affected)

	Leaf 1	Leaf 2	Ear
Mildew	0.1	0.1	0.2
S. tritici	2.8	9.0	tr
S. nodorum	tr	tr	tr
Yellow rust	tr	tr	0
Brown rust	tr	tr	-
Didymella	tr	tr	-
Cephalosporium	tr	0	-
Tan spot	0	tr	-
Insect damage	0.6	0.5	-
Green leaf area	86.9	77.5	-

tr = < 0.05

Fig. 2 National foliar disease levels (mean % area leaf 2 affected)

Stem base diseases

Table 2 National stem base disease levels (per cent stems affected)

	Slight	Moderate	Severe
Eyespot	11.7	6.4	0.3
Sharp eyespot	6.3	4.0	0.9
Nodal fusarium	13.5	4.2	0.1
Internodal fusarium	5.5	1.6	0.1
All fusarium	17.2	5.5	0.2

Fig. 3 National levels of eyespot (mean % stems affected)

Fig. 4 National levels of take-all (% crops in each category)

Take-all Category description
0	no take-all seen
1	scatter of plants showing premature ripening
2	occasional small patches (less than 5m across) showing premature ripening and/or stunting - less than 1% of field affected
3	many small or few large areas affected - 1% to 10% of field affected
4	many large areas affected - more than 10% of field area affected

Fig. 5 National levels of BYDV (% crops in each category)

BYDV Category description
0	no BYDV seen
1	a scatter of plants showing BYDV symptoms (leaves, particularly the flag leaf, chlorotic with a bronze/red colour extending downwards from the tips).
2	occasional small patches (less than 5m across) showing BYDV symptoms.
3	many small or a few large areas affected (1% to 10% of field area affected).
4	many large areas affected (more than 10% of field area affected).

Regional disease levels

Fig. 6 Regional foliar disease levels (mean % area leaf 2)

Fungicide applications

Fig. 7 Per cent crops sprayed at GS 31, GS 39 and at GS 59 onwards

Herbicide applications

Fig. 8 Timing of herbicide applications (% crops sprayed)

[Post em (a) - post-emergence in the autumn, Post-em (s) - post-emergence in the spring]

Insecticide applications

Fig. 9 Percentage crops treated with an insecticide in autumn, spring or summer

	RAPID ACCESS TO THE LATEST REGIONAL CROP PEST AND DISEASE LEVELS
CropMonitor > Winter Wheat > National Surveys > 2002 overview