Agrometeorological forecast for the month of May

This year, the cool weather during the first half of spring delayed the development of agricultural crops. During most days in May, agrometeorological conditions will be determined by unstable weather.

The forecast above-normal temperatures at the beginning of May will accelerate vegetative processes in the autumn-sown stands and the sown spring crops. During the first ten-day period, various stages will occur in wheat: stem elongation, transition to heading, and heading. In barley in the southern regions (Agrometeorological Station Sandanski), the flowering stage will be observed. In rapeseed, flowering, fertilization and pod formation will take place.

After the warm weather at the beginning of the month, normalization of thermal conditions is forecast for the second half of the first ten-day period. The expected precipitation during this period will delay the implementation of some seasonal agrotechnical activities – completion of grain maize sowing, pre-sowing tillage and sowing of late thermophilic spring crops (beans, cotton, peanuts, etc.).

During the second and third ten-day periods, the development of agricultural crops will proceed at a moderate pace, at mean daily temperatures close to the climatic norms. The expected precipitation in the second half of May will maintain a very good level of moisture reserves in the 50 cm and 100 cm soil layers, above 85% of field capacity (FC). It will have a beneficial effect on winter cereal crops, in which grain formation and grain filling will be underway. At the end of May, in part of the wheat and barley stands in the southern regions, 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, the formation of the inflorescence will be observed.

In fruit crops, the formation and enlargement of fruit set will occur. In grapevine, inflorescence emergence will be observed, and at the end of the month – the beginning of flowering – these stages are critical for downy mildew infection.

Frequent precipitation in May will create conditions for the development of a number of fungal diseases: rusts (brown, yellow) and septorioses in wheat; downy mildews in vegetable crops and grapevine; blossom blight, shot-hole and scab in fruit trees, etc. During the month, more suitable conditions for carrying out plant protection spraying will occur at the beginning of the first, in the middle of the second and at the beginning of the third ten-day period.

In May, critical minimum temperatures for agricultural crops are not forecast, but the probability of hail remains increased. In case of hail damage, it is recommended 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