A very important part of autumn care of winter rapeseed plants is a system of foliar feedings, with which mineral nutrition in the critical phases of plant development can be improved. The laying down of the generative organs of winter rapeseed, which determine yield potential, takes place in the initial phases of its organogenesis. The differentiation of generative organs occurs when plants are in the rosette stage (6–8 leaves). Balanced mineral nutrition and a longer period of bud formation at the top of the root collar ensure a higher yield. For this winter rapeseed plants need a sufficient level of NITROGEN, necessary for the growth of vegetative mass, PHOSPHORUS, which ensures root system growth and is part of nucleic acids, and MAGNESIUM, which takes part in the synthesis and function of chlorophyll and in the synthesis of ATP, the energy carrier in plants. In autumn magnesium promotes better outflow of sugars from the leaves to the root system.
Nitrogen shortage shows as pale strips in the field where a large amount of crop residues has been incorporated, delayed growth and small leaves. Phosphorus shortage causes a violet colour of leaf blades and petioles. Magnesium shortage in winter rapeseed shows on older leaves as yellowing and sometimes reddening.
The most important microelements for the crop in this period are boron and manganese. MANGANESE regulates nitrogen uptake, BORON regulates sugar accumulation and the health of the root's vascular bundles. Signs of boron shortage in autumn show clearly as chlorosis of young leaves, red-violet spots and microcracks on the main root. Deficiency of this element is most often seen on soils of light texture, waterlogged, acidic and limed soils, and in periods of severe drought. Acute boron shortage in the autumn period can slow the growth and development of the root system and growing point, reduce sugar accumulation and its transport to the root collar, and worsen the frost and winter hardiness of the plant and overwintering in general.
Autumn weather conditions, cold and rainy weather and sharp temperature swings, adversely affect the vascular system of rapeseed plants, especially with boron deficiency (which can occur at low temperatures even with a sufficient content of this element in the soil). This often causes the development of pathogenic microflora in the root zone, both fungal and bacterial. Applying foliar feeding with phosphite-based fertilizers to a considerable extent prevents such problems and keeps rapeseed plants healthy and able to form a high yield potential for the next year.
For plants under stress caused by adverse weather, products with amino acids have a positive effect.
According to the results of many years of ECOORGANIC trials, the optimal autumn foliar feeding scheme for winter rapeseed includes ECOLINE Boron (Organic) (or ECOLINE Boron (Premium)) 1.0–1.5 l/ha + ECOLINE Phosphite (K) 1.0 l/ha. For better boron uptake by plants we recommend applying the boron fertilizer in two passes. Under stress conditions it is advisable to use ECOLINE Phosphite (K-Amino) 1.0–1.5 l/ha. On fields with a pH below 5.0 molybdenum shortage may appear; for such areas it is better to use the boron fertilizer ECOLINE Boron (Opti) 1.0–1.5 l/ha.
If a need for other nutrients is established, the corresponding fertilizers should be applied, for example ECOLINE Magnesium (Chelates) 1.0 l/ha or ECOLINE Manganese (Chelate) 1.0 l/ha.
