Impact on yield

Yield levels

Fig. 1. Five year running average winter wheat yield in 6 EU countries. Source: Eurostat.

Wheat is the most important cereal crop grown in EU. The yield levels and cropping conditions vary considerably between the different EU countries (Fig. 1). In the countries most suitable for wheat production (Germany, the UK, France, Belgium, the Netherlands, Ireland, Denmark) average yields vary between 7 and 8 tonnes/ha, whereas in countries with more restricted cropping conditions (Hungary, Italy, Spain, Poland, Greece) yields vary between 3 and 5 tonnes/ha.

Yield losses

Yield losses from specific diseases in the 8 countries involved in the ENDURE activity were estimated, (Table 1). Based on these estimates septoria leaf blotch, brown rust, take-all and fusarium head blight are considered as the most important diseases in the main wheat growing countries with respect to yield loss and quality of grain. Yield losses between 5 and 15 dt/ha are common in many regions. Yellow rust, powdery mildew, tan spot and eyespot are also regarded as important diseases; however, their distribution is much more regional.

Table 1. Estimated yield losses [dt/ha] caused by specific diseases in different countries. Source: ENDURE

Country Tapesia S. tritici P. striiformis P. triticina Fusarium Take all Blumeria
FR 3 15 0 10 2 0-20 1
DE - 3.2 2.5 2.7 0.4 - 1.7
UK 2 10 1 1 0.5 8 1
NL 1 5 1 1 2 1 1
PL 5 4 1 10 1 12 -
DK 2 8 1 1 1 3 2

Stagnating winter wheat yields

Danish scientists point at two possible reasons for stagnating wheat yields in Denmark: 1) Lower grain prices during the period may have reduced cultivation management intensity due to reduced use of pesticides and less time spent in the field and 2) An increased frequency of winter wheat in the crop rotation with a tendency towards continued wheat cultivation can be an overlooked problem because a poor crop rotation increases the negative effects of plant pests (weeds, insects, fungi and viruses). Data is, however, insufficient to analyse these two factors more deeply.

The scientists also point out that the stagnating yields are not only a Danish phenomenon but have been observed in other north-western European countries. The Danish regulations regarding nitrogen fertilizer and the use of animal manure are often mentioned as causes of stagnating yields in Denmark.

Source:

In France a scientific study showed that genetic progress has not declined but this was partly counteracted, from 1990 on, by climate change which in general is unfavorable to cereal yields in temperate climates because of heat stress during grain filling and drought during stem elongation. Other negative effects on yield is a decline of legumes in the cereal rotations, replaced by oilseed rape and to a lesser extent the decrease in nitrogen fertilization.

Source:

Why are wheat yields stagnating in Europe? A comprehensive
data analysis for France / Nadine Brisson et al., 2010. Field Crops Research 119 (2010) 201–212. doi:10.1016/j.fcr.2010.07.012

Revideret 27.09.2022
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Jens Grønbech Hansen