Eyespot development in crops is difficult to predict. The risk can be assessed based on visible presence of eyespot at stem extension or by using risk assessment including local experiences and weather data. Risk of disease development is relatively higher if the preceding crop is wheat and sowing was early. Minimal tillage has sometimes been found to reduce the risk compared to ploughing, but the trend might differ. There is a strong weather influence on disease development. Wet spring weather increases risk. In order to make a visible assessment, take out a sample of approximately 100 plants between GS 30 and 32. Rinse the plants under tap water and look at the plant basis to see if eyespot symptoms are present or not (see pictures). Only plants whose tillers have penetrating lesions (beyond the outer leaf sheath) should be included. Thresholds vary depending on the countries between 20 and 35% attacked plants.

Crops must be inspected carefully for small patches of infection (foci) before, and during, stem extension. Look out for the disease on all green parts between GS 29 and 60 and once the disease is seen in the crop, it is recommended to spray. The most recently emerged leaves always appear disease free between GS 32 and GS 39. However, the crucial final three leaves are at risk of infection as soon as they emerge. Keep a check on national ranking of the cultivars' susceptibility in order to be aware if you have a high or low risk situation. In very susceptible cultivars the treatments should be repeated after 2-3 weeks, before new symptoms appear. Autumn attacks may be found but are not generally found to have economic importance.

Brown rust is usually more evenly distributed through a crop than yellow rust. However, pustules are tiny and easy to miss during early stages of disease development. It is important to spot the disease early as even low levels of visible infection on susceptible varieties may lead to a sudden epidemic in warm weather. Look out for the disease on all green parts between GS 30 and 71. The control threshold is approximately 30% measured as frequency of plants attacked assessing all green leaves. Autumn attacks may be found but are not generally found to have economic importance. In northern countries the disease appears normally quite late and is first considered as a problem from GS 37 onwards. Keep a check on national ranking of the cultivars' susceptibility in order to be aware if you have a high or low risk situation.

Powdery mildew is generally most important at early growth stages in spring. Risk is often linked to specific regions and soils where the farmers from experience need to be very alert. The risk is often considered to be high on late sown crops, near hedges and on sandy soil. Look out for the disease on all green parts between GS 29 and 55. The control threshold early in the season is low in susceptible cultivars. Effective control using specific mildewicides requires treatments at low disease levels. Autumn attack may be found but is not considered to have economic importance. Control is not regarded to be economical after heading. Keep a check on national ranking of the cultivars susceptibility in order to be aware if you have a high or low risk situation. Mildew is so visible that the likely amount of damage may be overestimated. Low levels of attack as often seen around heading on the lower part of the crop are regarded not to have economic importance.

Septoria is often easy to find during winter and early spring. The severity depends on precipitation, and due to a long latent period (3 weeks) the control threshold is linked more to rain events than to symptoms in the crop. If several rain events occur during elongation (from GS 32), the risk is considered high. In more resistant cultivars the threshold is higher and the count of rainy days can be delayed to GS 37. Occasionally the disease appears despite few rain events and therefore the 3rd leaf can also be used to decide whether to spray or not during heading and flowering. Attacks of economical importance are very common in major regions with regular precipitation events during elongation of the crop. This gives to a large extent rise to more or less routine treatments.

Tan spot appears particularly in intensive wheat production where minimal tillage is practised. The disease appears typically in early spring when temperatures above 10ºC appear. If more than 10% of plants show attack from GS 35 onwards, control is recommended. In fields with a high level of debris the risk is high.