- Rapeseed has great adaptability, but this year it had to deal with many stress factors.
- This unusual year turned out to be unfavorable for winter rapeseed. The weather conditions were not bad, but the rapeseed production capacity was not fully utilized.
- There were agrotechnical mistakes. An unusual year, an unusual approach to agrotechnics. Those who stuck to routine and did not react to the current situation usually lost out.
The yield of winter rapeseed is assessed when it is already on the trailer. Otherwise, it is easy to make an error in estimation. More and more farmers inform us about their production results, and they are amazing. The problem with very low yields is mainly reported by farmers from Lower Silesia and the Opole region. Yields in the range of 2.5-3.5 t/ha from good farmers indicate that the harvest from these regions will not be good.
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Rape is growing poorly in Lower Silesia. There are no revelations
Average yields are reported by farmers from the province. Kuyavian-Pomeranian Voivodeship (from 2.5-3.9t/ha), but it is difficult to find a farmer with a yield of 4t/ha, which was the norm last year, good for rapeseed. Farmers from the center of the country (Łódź and Masovian Voivodeships) also report poor harvests. Yield of 3-3.5t/ha are the most common signals from these regions. However, we managed to obtain information from a farmer from the province. Łódź province with a yield of 4.1t/ha. As summarized by most of the farmers we talked to, yields are lower compared to last year by about 1-1.2 tons per ha, depending on the farm and location.
So what happened that we are not collecting records in 2024?
To sum up, it can be said in one word that it was not an easy season, but full of unexpected twists. There was a lot going on, because rapeseed has been growing in the field for about 11 months. During this time, many factors affect the plants, from weather to agrotechnical factors, which are often related to the decisions made by farmers. Theoretically, it seemed at first that everything would go smoothly. The rapeseed plant sprouted well, was well stocked, overwintered well and started spring with vigor, pleasing the eye for many weeks of the growing season. So what happened that there are no records? It is a combination of many factors whose impact on yield may vary depending on the region or farm. But what did we pay attention to at different stages of vegetation? We have briefly listed several factors that we consider important.
1. Starvation of rapeseed in autumn
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Common nitrogen deficiencies in winter rapeseed and the nitrate program. How to reconcile this?
Fall 2023 was long and exceptionally warm. Rapeseed collected the sum of effective temperatures very quickly and jumped dynamically through development phases. In some places the plants were exuberant, those previously sown required a lot of control in terms of regulation and, importantly, nutrient resources in the soil after good harvests from the 2023 harvest were depleted in many places. Where farmers did not pay attention to balanced fertilization, visual symptoms of deficiency often occurred already in autumn. Malnourished rapeseed picked up these signals, and the deficiency of nutrients could translate into disturbances in physiological processes. It has long been said that the yield is largely determined by autumn agrotechnics. Therefore, if the farmer did not respond appropriately to the needs of the canopy, it could translate into building the structures of the generative organs (the number of side branches and the number of siliques).
2. Wet spring
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Ponds of water in fields. Are they dangerous?
In early spring, we struggled with strange weather. Theoretically, it was warm and the rapeseed started growing quickly. On the one hand, it required fertilization with nitrogen and other deficient macronutrients, but on the other hand, in many regions of the country it was not possible to drive heavy equipment into the fields for a long time. Flooded sites (especially those with defective soil structure) suffered the most from this. Wetlands appeared and the soil lacked oxygen. Wet, draining soils also took a long time to warm up, which also did not go well with the rapid vegetation.
3. Numerous pests, including stem weevils – problem no. 1
Spring pests came as a surprise as they arrived at the plantations exceptionally early and in large numbers. First of all, many farmers failed to effectively protect their plantations against stem borers. Initially, their feeding symptoms did not irritate the eye, but the effects of their numerous appearance had an impact mainly at the end of the vegetation. Other pests also left their mark on the crop. In places, numerous appearances of the rapeseed leaf mite were recorded, followed by the saffron beetle, which, together with the midge, damaged the pods. The thing about pests is that their feeding usually steals the crop directly. However, some of them are responsible for indirect damage, such as virus infection. IOR-PIB already in autumn pointed out that aphids infected rapeseed with the TuYV turnip yellows virus.
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Weevil larvae in the stems. The problem is common
Unfavorable weather conditions during the growing season are most often responsible for the decline in yield. However, more numerous pests – including pests – may also have a significant impact on its reduction. This season (like last year), strong pressure of stem beetles (swede beetle and four-toothed beetle) was recorded on winter rapeseed plantations. For example, in Greater Poland, the first individual individuals were caught in yellow vessels in the first week of March. A week later, their numbers (especially the four-toothed butterfly) exceeded the economic harmfulness threshold. Anyone who did not systematically monitor the plantation and did not apply the eradication treatment in time will probably reap a smaller harvest today. The presence of these pests is evidenced by the fragments of stems damaged by their larvae remaining in the stubble fields. The damage caused by them during the growing season is not as visible as that caused by the sweet beetle and pod pests, but it significantly hinders the transport of assimilates feeding the upper parts of the blades and is often a source of additional infestations by the disease perpetrators. Such an extreme combination may result in a yield reduction of up to half – says Dr. Hab. Przemysław Gwiazdyński from IOR-PIB in Poznań.
4. Spring frosts and pollination problems
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Has frost damaged rapeseed? The symptoms are already clearly visible
The formation of frost layers, i.e. fragments of shoots without pods, is a characteristic symptom of very strong frosts that occurred mainly in the south of the country (but not only) around the third decade of April this year. Rapeseed was already blooming at that time, so it had little opportunity to compensate for the damage. Where no frosts were recorded, it does not mean that they had no impact on rapeseed. During cold weather, pollinators did not visit this crop. Moreover, after this period there was a deficit in rainfall, and in some regions this was another stress factor.
5. Local water shortage
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The spring water shortage mainly affected the eastern wall of our country. Spot and irregular rainfall only saved the situation where they occurred, although strong plant transpiration quickly changed this situation. In other regions, water shortage combined with other stresses (light, imperfect locations, etc.) resulted in the accumulation of factors adversely affecting the yield (stabilization of the number of pods and MTN). Drought was confirmed by IUNG-PIB also in the case of winter rapeseed.
6. Hailstorms for unlucky people
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Hail decimated crops in Greater Poland
And finally, we cannot ignore the unstable weather in June. There was hail in many regions, which often spotted the rapeseed. The damage at this stage is not so severe until harvesting, when sometimes due to the alternating wetting and drying of the pods, they open prematurely. Hail-damaged pods were often infected with diseases such as cruciferous blackworm. Fortunately, during the actual rapeseed harvest (currently), hailstorms did not occur on a large scale, although this may change in the coming days due to the announced numerous storms, which after a period of heat can cause damage of very serious economic importance.
