Agrometeorological forecast for November

The prolonged autumn drought has delayed the development of winter cereal crops and rapeseed and has cast doubt on the survival of part of the emerged stands. The moisture content of wheat in the 50 cm and 100 cm soil layers is unusually low for mid-autumn in most of the country. In some areas of Northwestern Bulgaria, the Sofia Field and the Upper Thracian Lowland (agrometeorological stations: Knezha, Bǎzovec, Lozen, Plovdiv, Pazardzhik, Sliven) the level of soil moisture reserves in the one-metre soil layer is below 50% of field capacity.

During the first half of November, the agrometeorological conditions will be determined by above-normal temperatures. The forecast precipitation at the beginning and at the end of the first ten-day period, in most of the arable areas, will be insufficient to overcome the moisture deficit in the upper soil layers for winter cereals and rapeseed.

Precipitation of agronomic significance and a substantial increase in soil moisture reserves in the 50 cm layer are forecast for the second half of November. On most days of this period, the development of winter cereal crops and rapeseed in the arable areas will proceed at mean daily temperatures close to the climatic norms.

At the end of the second ten-day period, a substantial decrease in temperatures is expected and, in the higher fields, where snowfall is not excluded, the vegetative processes in the autumn crops will subside.

During the third ten-day period of November, the development of autumn crops in most of the arable areas will proceed at a slow pace at temperatures approaching the biological minimum required for the vegetation of wheat, barley and winter rapeseed. Conditions for more active vegetative processes in the autumn crops will be created mainly in the southern and southeastern regions of the country. At the end of November, the third leaf growth stage will predominate in wheat and barley. The emergence stage will be observed in the later sown November stands. In part of the winter cereal crops in the far southern and eastern regions, which formed 2–3 leaves in October, the tillering stage will be observed. In rapeseed, as a result of the autumn drought, only a small part of the stands will manage by the end of November to enter the beginning of the rosette formation stage (5–6 leaves).

The forecast minimum temperatures during the month, in the range of minus 5–8ºC, are above the critical levels for the delayed winter cereal crops at the emergence stage.

More suitable conditions for planting fruit trees and for carrying out autumn plant protection spraying in November will occur during the first half of the month.

During the first two weeks of November, autumn crops, especially those grown in monoculture, should continue to be monitored to determine the population density of certain pests: cereal flies, common vole, rapeseed sawfly (false caterpillars), and, where their numbers exceed the economic injury level (EIL), timely treatment should be carried out. The EIL for the common vole is 2 active colonies per decare, and for the larvae (false caterpillars) of the rapeseed sawfly – 2–3 per m².

Source: NIMH