Аgrometeorological forecast for the month of April

During the first ten-day period of April, agrometeorological conditions will be determined by temperatures above the climatic norms. The forecast above-normal thermal conditions will accelerate the vegetation processes of the winter cereal crops, and a large part of the stands in the field areas will massively enter the stem elongation stage. In rapeseed, branching and the beginning of the budding stage will be observed.

During most days of the ten-day period, significant precipitation is not expected and conditions in many parts of the country will allow the performance of pre-sowing tillage and the sowing of sunflower. The first ten-day period of April is the agrotechnical deadline for sunflower sowing in Northern Bulgaria.

At the end of the first and the beginning of the second ten-day period, a decrease in temperatures, stabilization of the weather and a substantial change in agrometeorological conditions are forecast. During this period, significant precipitation is expected and an increase in soil moisture reserves, including in the two-meter layer. At the beginning of spring, in most of the field areas, soil moisture reserves for wheat in the one-meter layer reached levels above 90% of field capacity. Exceptions occur in some eastern regions – agro-stations Razgrad, Dolni Chiflik, Sliven – where the level of moisture reserves is lower, below 80% of field capacity.

At the end of the first and the beginning of the second ten-day period of April, a short-term stabilization of the weather and suitable conditions are forecast for carrying out certain urgent plant protection sprayings in orchards: at the flower bud stage in pome fruit species (apple, pear) against scab; post-bloom treatments in some early-flowering stone fruit species against blossom blight (early brown rot) and shot-hole disease; in cherry and sour cherry against the most dangerous fungal disease – cylindrosporiosis (so-called white rust), and others.

During the second ten-day period of April, the development of agricultural crops will proceed at a slower pace, under below-normal thermal conditions. At the end of the ten-day period, an increased probability of frost formation is forecast, which should be taken into account when hardening vegetable and tobacco seedlings. The forecast minimum temperatures, in some places down to minus 2–3°C, will be critical for the blossoms and young fruit sets of fruit trees if they persist for a longer time.

At the beginning of the third ten-day period, warming is expected and in the field areas soil temperatures in the ten-centimetre layer will reach suitable values for sowing grain maize. 

During the third ten-day period, the vegetation of agricultural crops will proceed at a moderate pace at temperatures close to the climatic norms. During this period, in winter cereal crops there will be a transition from stem elongation to heading and the heading stage. In rapeseed, the flowering stage will predominate.

In April, frequent precipitation will create conditions for an increase in the infectious background of a number of fungal diseases in orchards – blossom blight (early brown rot), scab, shot-hole disease, peach leaf curl, and others. More suitable conditions for carrying out plant protection sprayings in fruit crops will occur during most days of the first and during the first half of the third ten-day period.

Source: NIMH