Rapeseed (Brassica napus) is an annual herbaceous plant that occupies a special place in the world economy. Its seeds are a rich source of vegetable oils, used in food or industry (biofuel). Rapeseed cultivation has the following advantages: it has a favorable reaction to fertilization, it can be cultivated mechanically, it is sown and harvested outside the busy cultivating periods, it is a good preceding plant and it is also a melliferous plant.

The main diseases of rapeseed

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White mold (Sclerotinia sclerotiorum)

Diseased plants turn yellow and wither. At the base, there are light-colored spots, white or light yellow. Over time, the spots become bigger, turn brown, and are covered with a white felt that represents the fructification of the fungus. The fungus overwinters in the soil in the form of sclerotia.

Prevention and control measures:

• avoiding the cultivation of rapeseed on low and damp soils;
• treating the seeds before sowing;
• crop rotation;
• plowing at optimal depth (20-25 cm)
• carrying out treatments with specific fungicides.

Downy mildew of Brassica species (Peronospora brassicae)

It occurs frequently in young plants. It is characterized by the appearance of yellow spots on the leaves, which later turn brown. On the underside, the spots are covered with a white-gray fuzz, which represents the fructification of the fungus. The conidiophores are dichotomously branched, and the conidia are ellipsoidal and colorless.

Prevention and control measures:

• destroying the attacked plants;
• proper agrotechnics;
• sowing early;
• crop rotation;
• weed control;
• treating the seeds before sowing;
• carrying out treatments with specific fungicides.

Powdery mildew (Erysiphe cruciferarum)

The disease manifests through the appearance of a fine, whitish, pasty coating on the surface of the leaves. Later, in the felt-like layer, brown-black spots develop, which represent the fructification of the fungus. The conidia are cylindrical, colorless, unicellular. The cleistothecia are globular, blackish-brown, provided with numerous filamentous appendages.

Prevention and control measures:

• avoiding the cultivation of rapeseed on low and damp soils;
• crop rotation;
• plowing to the optimum depth (20-25 cm);
• treating the seeds before sowing;
• carrying out treatments with specific fungicides.

Clubroot disease (Plasmodiophora brassicae)

On the roots, there are thickenings and swellings along their entire length. Over time, the attacked roots turn brown, soften and rot. The disease occurs in all stages of vegetative growth. The early attacked plants remain small and the leaves turn red. In mature plants, the disease causes the leaves to turn blue-green.

Prevention and control measures:

• using resistant hybrids;
• crop rotation;
• avoiding the cultivation of rapeseed on low and damp soils;
• maintaining a neutral soil pH.

Alternaria (Alternaria brassicae)

Small, punctiform, or linear blackish spots develop on the silique. The spots become bigger and cover large portions. The strongly attacked siliques no longer grow and open easily, allowing the seeds to fall. A brownish-black powder develops on the surface of the spots, consisting of conidiophores and fungal conidia.

Prevention and control measures:

• avoiding the cultivation of rapeseed on low and damp soils;
• crop rotation;
• plowing to the optimum depth (20-25 cm);
• carrying out treatments with specific fungicides.

The main pests of rapeseed

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The rape beetle (Meligethes aeneus)

It gnaws the buds on the outside, and on the inside, it consumes the stamens and the pistil. The buds dry up and fall, and the ones that are the least attacked develop small, thin siliques with twisted tips. The female gnaws the flower bud and lays 1-2 eggs on the stamens. Sometimes, in a flower bud, there are up to 15 eggs, laid by different females.

Prevention and control measures:

• crop rotation;
• proper agrotechnics;
• gathering and destroying the plant remains;
• carrying out treatments with specific insecticides.

The red turnip beetle (Entomoscelis adonidis)

It gnaws the edges of the leaves irregularly, sometimes leaving only the ribs. It can attack the siliques and flower buds. The beetle develops on spontaneous crucifers. The female lays 800-900 eggs in chambers, at a depth of 3-4 cm in the ground.

Prevention and control measures:

• treating the seeds before sowing;
• crop rotation;
• proper agrotechnics;
• gathering and destroying the plant remains;
• carrying out treatments with specific insecticides.

The turnip sawfly (Athalia rosae)

The leaves are gnawed or perforated on the underside. At first, the perforations are small, then become bigger, round or oval, and with irregular edges. The larvae are approx. 17-18 mm long. They have blackheads and legs, and the rest of their bodies are gray.

Prevention and control measures:

• crop rotation;
• proper agrotechnics;
• carrying out treatments with specific insecticides.

Cabbage shoot weevil (Ceutorhynchus assimilis)

Adults gnaw small cavities in the stems, peduncles, and flower buds, and the larvae consume the seeds. During its development, a larva consumes 6-9 seeds. The egg-laying takes place in the developing siliques. The female gnaws a hole in the silique’s wall and lays an egg in each hole. One female lays 35-50 eggs. This pest is present in all areas cultivated with rapeseed.

Prevention and control measures:

• crop rotation;
• proper agrotechnics;
• gathering and destroying the plant remains;
• carrying out treatments with specific insecticides.

The cabbage-stem flea beetle (Psylliodes chrysocephala)

The larvae gnaw the petiole of the lower leaves and as a result, they can reach the top of the shoots. The galleries dug by the larvae can become filled with water, which might freeze in winter. These galleries also represent gateways for phytopathogens.

Prevention and control measures:

• crop rotation;
• carrying out treatments with specific insecticides.

Apple blossom beetle (Epicometis hirta)

In the case of rapeseed, it consumes the floral organs and sometimes also the young leaves. The adult is 9-12 mm long, matte black, covered with a gray fuzz. It produces only one generation per year and it overwinters in the adult stage, in the soil. Females lay eggs 4-8 days after mating. The larvae do not cause any harm.

Prevention and control measures:

• carrying out treatments with specific insecticides.

The large white (Pieris brassicae)

The larvae have a 40-50 mm long body. In the first stage of development, they have a yellow color, and at full development the larvae are gray. It has yellow longitudinal stripes. The larvae belonging to the last generation attack the rapeseed leaves, in autumn. The attacked plants do not grow properly until winter.

Prevention and control measures:

• carrying out treatments with specific insecticides.

Bee protection

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In order to prevent bee poisoning, the owners of agricultural and forestry areas who carry out chemical treatments on the agricultural and forestry crops they own are obligated to notify, in writing, the local councils at least 48 hours

The local councils, as well as the administrators of the agricultural or forest lands, must announce, in writing or by phone, the beekeepers who have a stationary/permanent or temporary/pastoral apiary, at least 24 hours before the owners of agricultural or forestry lands carry out the treatments with chemical substances, in order to prevent the intoxications to the bees.