Danger of infection with downy mildew in grapevines and vegetable crops

During the past period, the agrometeorological conditions were determined by unstable – warm, even hot weather with local showers.

During the period 15-21 June the weather will continue to be unstable, with frequent showers expected and a decrease in temperatures. The likelihood of hail and damage to agricultural crops remains.

According to the forecast meteorological conditions, the water demand of spring crops will increase significantly in the second half of the period due to their transition to the reproductive stage of development. The highest values will be in the fields of Southwestern and the entire central part of Southern Bulgaria and will reach maximum values of up to 36-40 mm for the period.

Regardless of the frequent showers, various degrees of deficit in soil moisture reserves are observed throughout the country. The values of the water deficit are gradually increasing from northeast to southwest and reach maximum values of up to 20-26 mm.

In winter cereal crops, the milk, dough and full ripeness stages will be observed. In sunflower, leaf formation and budding will take place, and in maize, leaf formation. In areas where water reserves are below optimum in the root-inhabited soil layer, irrigation should be initiated.

The meteorological conditions during this period will also maintain the risk of infection with downy mildew in vineyards and vegetable crops. The oriental fruit moth will continue to cause damage to fruit species. There is also a risk of development of powdery mildew and scab on the fruits. The warm and dry weather at the end of May and the beginning of June favoured the multiplication and increase of aphid populations. In tomatoes, necrosis (blackening), transmitted by aphids, causes damage, which necessitates control of the vector. Affected plants are uprooted and removed.

Conditions suitable for spraying against diseases and pests will occur towards the end of the period, when the probability of precipitation is expected to decrease.

Source: NIMH