Agrometeorological forecast for the month of May

During the first ten-day period of May, the development of agricultural crops will proceed at a moderate pace, with average daily temperatures close to the climatic norms. At the beginning of May, the expected precipitation will be decisive for the survival of part of the winter cereal crops in Northeastern Bulgaria. At the end of April, in many places in the northeastern regions, the level of soil moisture reserves for wheat in the 50 cm and 100 cm soil layers was unusually low for the season, below 55-60% of field capacity, as a result of below-normal precipitation during the first half of spring. For this reason, part of the wheat stands are in a critical condition. Damage and yellowing of the leaf mass (up to 50-60%), as a consequence of soil moisture deficit, have been recorded in wheat at the agrometeorological stations Silistra and Tsarev Brod.

During the first ten-day period of May, the heading stage will be observed in wheat and barley in the field regions.

At the end of the first and during the second ten-day period, an increase in temperatures and acceleration of vegetation in winter cereal crops and sown spring crops is forecast. During this period, flowering, fertilization and grain formation will take place in wheat.

During the third ten-day period, the agrometeorological conditions will be determined by unstable and cool weather for the period. The expected significant precipitation will be of exceptionally great importance for the winter cereal crops, in which grain filling will be in progress. At the end of May, part of the barley and wheat stands in places in the southern regions will enter the milk ripeness stage.

During the month, leaf formation will take place in maize and sunflower. At the end of the third ten-day period, in sunflower sown within the agrotechnical time frame, the formation of the inflorescence will be observed.

In fruit crops, the formation and enlargement of fruit set will occur. In the vine, inflorescence separation will be observed and, at the end of the month, the flowering stage as well.

Frequent precipitation in May will create favourable conditions for the development of a number of fungal diseases: downy mildews on vines and vegetable crops; scab on pome fruit species, early brown rot and shot-hole disease on stone fruit trees; rusts (yellow, brown) and fusarium head blight in winter cereal crops.

More suitable conditions for carrying out plant protection spraying will occur during the second half of the first and on most days of the second ten-day period.

In May, critical minimum temperatures for agricultural crops are not forecast, but the probability of hail remains elevated. In case of hail damage, it is advisable that the affected crops be treated at the first opportunity with copper-containing fungicides for faster healing of wounds and for reducing the risk of secondary infections.

Source: NIMH