- Sowing rapeseed in September can be risky, but recent years have shown that slight delays in sowing do not result in significant yield reductions, and there are even situations where such plantations yield at the level of those from the optimal dates.
- It all depends on the weather conditions that occur after sowing rape. Access to water and the quality of the site and even the selection of varieties are also important.
This year's sowing began around mid-August, at that time the soil was sufficiently moist, which guaranteed quick emergence. Unfortunately, in many regions of Poland after August 15 there were violent storms with heavy rainfall. This stopped sowing, and many plantations were destroyed or "clogged".
– Unfortunately, this is another season in which we are dealing with uneven emergence and low planting. On such plantations, it will be difficult to make decisions on when to perform the shortening procedure. An additional limitation in the development of rapeseed is the heat and lack of rainfall, which we have been dealing with since the beginning of September. Due to the weather, in some regions, sowing is still underway or plantations are being sifted – Artur Kozera, Rapool Polska, tells farmer.pl.
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Rapeseed is emerging and the first pests are present
Can you sow rapeseed in September?
In recent seasons, farmers have indicated that, due to higher reasons, they usually sowed at the beginning of September and successfully managed to achieve similar production results as from plantations with optimal sowing. However, it should be noted that recent autumns have been long, warm and rapeseed can collect the appropriate amount of effective temperatures that determine the passage of plants through subsequent development stages. What is more, even less developed plantations overwintered very well, because the winters were not severe.
At this stage, however, no one can predict what this year's autumn and winter will be like and whether they will be kind to plantations sown late.
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Locally difficult rape emergence. How to break the soil crust?
Can September sowing be successful?
It depends on many factors, but recent years have shown that taking such a risk made sense, because such plantations developed properly.
However, it should be remembered that rapeseed is a plant that strongly responds to the length of the day. But this factor is not the only factor that determines the proper development of plants. It is believed that in autumn, plants need about 75-80 days of autumn vegetation and the accumulation of average daily temperatures at the level of 850 °C.
Access to soil moisture is also a condition for proper plant development. And it is the temperature and moisture that determine the pace at which rapeseed goes through its development phases during its autumn vegetation.
Scientific research shows that rapeseed needs to be harvested at around 90°C for full emergence. To develop the first pair of leaves, it takes 150°C. Around 300°C to enter the 4-leaf stage (BBCH 14). 450°C to reach the 6-leaf stage. 10-12 leaves is already around 850°C to harvest.
It is hard to predict how this year's autumn conditions will turn out. Climate change is heading towards long, warm autumns and mild, but snowless winters.
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High temperatures deepen drought. Rapeseed with difficult emergence
In the current season, similarly to previous years, we are dealing with variable weather conditions, and consequently with delays in rapeseed sowing. The shift is most often due to the fact that the soil is too dry, and in such conditions, unfortunately, we have to reckon with problems during emergence. The second reason for sowing after the sealing and crusting of the top layer of soil – comments Kozera.
So is it possible to delay sowing until early September?
– The answer is simple: yes. And this results from several facts related to climate change. The autumn vegetation period has been prolonged, it is relatively warm, which favors late-sown rapeseed to collect the optimal sum of effective temperatures – adds Kozera.
According to Kozera, later sowing also means lower pressure from pests, such as aphids, which are the vector of the turnip yellows virus. As he points out, genetics also meets the needs of rapeseed growers; new genetically advanced varieties with a package of pro-health features, in favorable conditions in the autumn period, even with delayed sowing, provide a chance to obtain yields at the level of varieties sown at the optimal time.