- The phytosanitary status of rapeseed in Poland has remained at a good level since early spring.
- Pests and rodents were more of a problem than fungal diseases.
- Rapeseed has also been infected with viruses this season.
- A non-standard approach to protection dictated by thorough inspection of plantations is the key to success in rapeseed cultivation.
The harvest of winter rapeseed is already a thing of the past. It is therefore possible not only to sum up the season in terms of yields, but it is also a good time to draw attention to the problems noted in this group of crops.
In the case of winter rape, there were quite a few, although experts say that it was mainly a combination of unfavourable weather factors that largely determined that the crops disappointed producers of black gold more often than they surprised positively. However, it was a very strange year, with accelerated spring vegetation and an unconventional approach to protection procedures. Therefore, many producers did not avoid agrotechnical errors, which also affected the yields of this species.
What does IOR-PIB indicate as the main problems in rapeseed cultivation? Following the Institute, we provide the key factors of this season.
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Rapeseed yield by region. In which region did rapeseed yield the lowest?
1. Flooding and plant rot
Spring floods and local plantations with rotting plants did not herald a bountiful harvest. Very unstable meteorological conditions in March and April caused rape to develop quickly and the development stages determined on the BBCH scale followed each other quite quickly. This contributed to limiting the occurrence of fungal diseases in certain stages, the intensity of which was very low in the spring. Later, the plants made up for the early spring weak start and rape yields assumed optimal values, although the plants were much lower and smaller in shape than in previous years.
Early spring precipitation defined the character of the new growing season. After such heavy rainfall in February 2024, the soil generally reached its maximum water capacity. This meant that all soil spaces were filled with water. When the soil dried out slightly as a result of natural drainage of excess water, it reached the so-called field capacity. The proper structure of the soil, or more precisely its porous nature, was of great importance for this process.
The ability of soil to store water depends on its granulometric composition. The content of organic matter is of great importance here, therefore, through appropriate fertilization and agrotechnics, one can influence the improvement of the soil's ability to store water.
Due to frequent and intense rainfall, the soil profile was not able to absorb such large amounts of water, resulting in the formation of ponding water.
Excess water can negatively affect the processes occurring in the soil, the development of the root system, its activity, the availability of nutrients and the biological efficiency of the soil. With excess water in the soil, the process of humus mineralization and humification of organic residues was disturbed, and in anaerobic conditions, the rotting processes intensified. In conditions of excess water, the useful soil fauna, which created the air-water balance in the soil profile, also died.
In the absence of oxygen, there was a large-scale death of aerobic bacteria, which affected nitrogen transformations in the soil, and bacteria that increased the availability of phosphorus and iron for crops. Excess water also made it difficult to enter the field to perform chemical protection treatments against pests and agrotechnical work. The pressure of the tractor wheels in such conditions caused water to be squeezed out of the soil profile, ruts to be cut and deeper layers of soil to be compacted, making it difficult for water to soak in further. The flooding phenomena, so frequently observed in the spring of 2024, can be avoided in subsequent seasons by ensuring and improving the irrigation and drainage functions of the soil. A wet period and flooding during the seed sowing period can delay the sowing date by the time needed to enter the field.
As a result of local flooding on some winter rapeseed crops, cases of plant rot were noted (February, March, April) – a characteristic smell of sauerkraut was noticeable. High air humidity also contributed to the development of powdery mildew, black rot and rapeseed dry rot.
2. Stem weevils have stormed rape crops. Yellow vessels have failed this season
In the later stages of winter rape development, similarly to spring 2023, low air temperature and high rainfall intensity contributed to reduced mobility of weevils (grenade beetles, four-toothed beetles, and rapeseed flea beetles). During plantation inspections, the only yellow vessel method used proved to be an insufficient solution and was burdened with large errors in interpreting the number of pests. When additionally scooping was carried out in the same fields, inactive individuals buried in plants were collected, and their number often exceeded the threshold of economic damage, which was not confirmed by the results of the yellow vessel method.
Based on two years of experience and observations, it is recommended to use all available inspection methods in the early spring period (the use of yellow vessels and additionally scooping).
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Where did the ton of rapeseed go? There will be no record harvest this year
3. Rodents were gnawing at winter crops
According to IOR-PIB in Poznań, in the autumn and February period, information was received about increased rodent activity in winter plantations in Lower Silesia and Wielkopolska. Among the rodents found in cereal and rapeseed plantations, the most important are the mouse-like creatures (Muridae) and the voles (Microtidae).
4. Scleroderma rot was not a threat. That doesn't mean it won't strike next season.
Sclerotia rot occurs every year in winter rapeseed plantations. This season, the scale of the infection was not high, but the infection potential is preserved in such a situation. Sclerotia, which are located in the stems, are introduced into the soil and are a source of infection in subsequent seasons. Therefore, if rapeseed comes to the field in a simplified rotation, it is worth comprehensively combating this dangerous disease. Therefore, IOR-PIB in Poznań recommends the use of non-chemical agents to reduce the occurrence of sclerotia rot before sowing rapeseed. You can use a product containing as a subtype the superparasitic fungus: Coniothyrium minitans, which is applied to the soil in the form of a spray, mixing it with the soil at a depth of 10-15 cm. The active substance has a selective effect and when applied to the soil, it acts on the spores of fungi of the Sclerotinia genus, causing their destruction, thus limiting the ability to infect plants. Products containing fungi of the Trichoderma genus have a similar effect.
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Strengthening of the Sclerotinia Protector line with increased tolerance to sclerotinia rot
5. Viral diseases
According to IOR-PIB, in the first half of 2024, agricultural crops in Poland were monitored for the presence of viruses. Mainly, plants were collected that were characterized by various disease symptoms in the form of:
– stunting and discoloration of leaves: (rapeseed, Brassica napus), (common wheat, Triticum aestivum), (triticale, Triticale), (barley, Hordeum vulgare),
The assessment of the infections of the above-mentioned winter cereals and rapeseed was performed based on the results of DAS-ELISA tests, which were performed using commercial specific sets of antibodies and conjugates from Loewe (Germany). Plant samples came from different locations in Poland. Diagnostic tests used kits for detecting the following pathogens:
-turnip yellows virus (TuVY),
– turnip mosaic virus (TuMV),
– Western yellows virus (BWYV).
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This year's winter rapeseed is also infected with viruses. IOR-PIB warns
General recommendations for the 2024/2025 growing season
Integrated protection recommendations clearly indicate the requirement to use all non-chemical methods before deciding to use a chemical plant protection product. In this context, first and foremost, proper agricultural technology is a key element of the protection strategy. The following should be mentioned here:
– appropriate fertilization – adjusted to the needs of a specific field (in the case of production in the Integrated Production system this is a requirement),
– selection of resistant varieties,
– ploughing and sowing operations performed correctly and on time,
– systematic monitoring of the occurrence of diseases and pests,
– compliance with harmfulness thresholds,
– if it is necessary to use chemical agents, it is recommended to select agents with a different mode of action as well as the selection of agents with different active substances.
