Agrometeorological forecast for the month of May

At the beginning of May, the development of agricultural crops will proceed under below-normal temperatures and with good soil moisture reserves as a result of the above-normal precipitation in April. The April precipitation (Pleven - 116l/m², Veliko Tarnovo - 63l/m², Lovech – 125l/m², Razgrad - 64l/m²,  Dobrich - 60l/m², Sofia - 78l/m², Sandanski - 58l/m²,  Pazardzhik - 60l/m², Plovdiv - 58l/m², Haskovo - 89l/m², Kardzhali - 75l/m², Elhovo - 79l/m², Stara Zagora - 55l/m², Karnobat - 52l/m²), following the early spring drought, were decisive for overcoming the soil moisture deficit in the autumn-sown crops. The forecast precipitation during the first ten-day period of May will maintain a very good level of moisture reserves in the 50cm and 100cm soil layers, above 85% of field capacity (FC). This precipitation will have a beneficial effect on the winter cereal crops and rapeseed, which are in the reproductive stage of their development, with increased requirements for soil moisture. During this period, in wheat and barley in the field regions of the country, the stem elongation stage, the transition from stem elongation to heading, and the heading stage will occur. In rapeseed, flowering, fertilization and pod formation will take place.

At the end of the first ten-day period, ground frosts are forecast in the higher fields, which should be taken into account when transplanting vegetable and tobacco seedlings. A substantial improvement in thermal conditions and an acceleration of the vegetation processes in agricultural crops are expected during the first half of the second ten-day period.

During the second half of May, agrometeorological conditions will remain unstable, with frequent precipitation. The development of agricultural crops will proceed at temperatures around and above the climatic norms. During this period, grain formation and filling in winter cereal crops will take place under very good and optimal soil moisture reserves. At the end of the third ten-day period, in wheat and barley in the southern regions and in places in the Danubian Plain, the beginning of the milk ripeness stage will be observed. During the month, leaf formation will occur in maize and sunflower. At the end of May, in sunflower sown within the agrotechnical time frame, inflorescence formation will be observed. The frequent precipitation in May will create conditions for an increase in the infection background of a number of fungal diseases: in wheat   rusts (brown, yellow) and fusarium head blight; downy mildews in vegetable crops and grapevine; early brown rot and shot-hole disease in stone fruits, scab in pome fruit species, etc. During the month, more suitable conditions for conducting plant protection spraying will occur in the middle of the first, in the first half of the second, and in the third ten-day periods.

In May, an increased probability of hail is forecast. In case of partial 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 reduction of the risk of secondary infections.

Source: NIMH