Frequent precipitation and unstable weather during the second half of May

During the forthcoming period the agrometeorological conditions will again be determined by unstable weather, with frequent precipitation, which will maintain good moisture reserves in the 50 and 100 cm soil layer.

In most parts of the country, with the exception of some locations in the eastern regions (Chirpan, D. Chiflik, Karnobat), the soil moisture reserves in the one-metre layer for the autumn-sown crops are above 80% of field capacity (FC).

During the period, the development of agricultural crops will proceed at a moderate pace, at mean daily temperatures close to the climatic norms for the second half of May. By the middle of the third ten-day period, in the field areas, the winter cereal crops will be undergoing grain formation and grain filling. At the end of the period, in barley in some locations in the southern regions (Sandanski, Karnobat) the onset of the milk ripeness stage will also be observed.

In sunflower and maize, leaf formation will be in progress.

In grapevine, the stage of inflorescence emergence will predominate. This phenophase is critical for infection of vines by downy mildew (Plasmopara viticola) and powdery mildew (Uncinula necator).

The forecast precipitation during the period will maintain favourable conditions for the development of fungal diseases: rusts, septoria leaf blotch and fusarium head blight in wheat; downy mildews in vegetable crops and grapevine; late brown rot in the fruits of early cherry cultivars.

At the end of May, damage to medium-early cherry cultivars is caused by the cherry fruit fly. To reduce the damage from this dangerous pest, it is recommended that at the beginning of the ripening stage, at the first opportunity after the cessation of precipitation, treatment be carried out with insecticides with a short pre-harvest interval.

Source: NIMH