Agrometeorological forecast for April 2019

At the beginning of April, uncharacteristic for the season, a limiting factor for the development of winter crops and the sown spring crops in most of the field areas will be the moisture deficit in the upper soil layers. As a result of below-normal precipitation in February and March, in many parts of the country the soil moisture reserves in the 50 cm and 100 cm layers are insufficient for the beginning of spring. The lowest level of moisture reserves in the 50 cm layer for winter cereal crops is observed in the southern and eastern regions, in places below 60% of field capacity (FC).

During the second half of the first ten-day period, precipitation is forecast and an improvement in the conditions for the vegetation of agricultural crops is expected. During this period, the wheat and barley crops that have tillered in autumn will enter the stem elongation stage. In rapeseed, which has overwintered at the rosette stage, branching and budding will take place. In the budding stage (from green to yellow bud), it is attacked by the most dangerous pest – the rape blossom beetle. If necessary (economic injury threshold >5 beetles per plant), insecticide treatment in rapeseed is carried out before the flowering stage.

During the second and third ten-day periods, agrometeorological conditions will be highly dynamic. The development of agricultural crops will proceed at a moderate pace, at temperatures close to the climatic norms. The expected precipitation, around and below the norm, will improve moisture reserves mainly in the 50 cm layer. They will be of major importance for the winter cereal crops, which will be predominantly in the stem elongation stage. In this stage, the plants’ requirements for soil moisture increase sharply. At the end of April, the earliest stem-elongated wheat crops, which reached this stage at the end of March, will enter the heading stage. The period between stem elongation and heading is critical for infection of wheat with powdery mildew and brown rust. During this period, monitoring is also required for the occurrence and harmful activity of the sunn pest, the cereal leaf beetle and the wheat thrips.

During the second half of April, rapeseed will be predominantly in the flowering stage. In sunflower and maize, depending on the sowing dates, the emergence and leaf formation stages will be observed.

By the end of the second ten-day period, the possibility of frost formation cannot be excluded, which should be taken into account when hardening vegetable and tobacco seedlings.

During the second ten-day period, soil temperatures at a depth of 10 cm in the lowland regions will reach suitable values for sowing maize for grain, and by the end of the third ten-day period – also for the thermophilic spring crops (cotton, beans, peanuts, watermelons, melons).

The expected variable weather during the month, with frequent showers, will create conditions for the development of certain fungal diseases in fruit crops (blossom blight/early brown rot, peach leaf curl, shot-hole disease, scab in apple and pear, fruitlet drop in quince, etc.). Suitable conditions for conducting plant protection spraying in orchards will occur at the beginning of April, and at the beginning and end of the second and third ten-day periods.

Source: NIMH