Controlling rapeseed stem weevil: monitor its arrival for optimum insecticide positioning
Rapeseed stem weevils are the main pests of spring rapeseed, and can cause stem bursts that penalize yield components, particularly in dry years. Control methods are still effective. But the positioning of the intervention is crucial to ensure effective protection.
Rapeseed stem weevils are the main pests of spring rapeseed, and can cause stem bursts that penalize yield components, particularly in dry years. Control methods are still effective. But the positioning of the intervention is crucial to ensure effective protection.
Vigilance when flights are early and massive
Stem weevils are the first insects to colonize rapeseed plots at the end of winter. A thaw above 9°C triggers the first flights, which can intensify when temperatures rise above 12°C. Depending on the year's climatic conditions, flight can be early (mid-February) or late (during March). The installation of a yellow spoon on the vegetation is a good way of spotting the arrival of the insect. We consider that there is a risk of damage to the crop as soon as the insects are present and the rapeseed is in the bolting stage (C2 to E). Past experience shows that years with early and massive flights are the years in which we see the most damage (frequency and intensity) in plots across a territory.
Intervening at peak flight
Farmers wishing to secure their production should intervene 8 - 10 days after the first "significant" captures, or ideally at the regional flight peak (consult the BSV for the date of the flight peak at regional level). The aim is to intervene when as many insects as possible are in the plot, and before egg-laying begins. Intervening as soon as the first insects are caught usually means spraying too early. It's better to wait a few days, even if it's true that the organization of work sites (sowing, nitrogen, etc.) and weather conditions can complicate implementation at this time of year. On the other hand, late infestations or re-infestations should not be overlooked, as they can occur right up to the end of bolting (E stage). Generally speaking, a single well-timed intervention is enough to control most of the risk. However, if a second flight peak occurs 2-3 weeks after application, re-intervention may be necessary.
Do not confuse rapeseed stem weevil with cabbage stem weevil, which is considered to have little or no harmful effect on rapeseed.
The rapeseed stem weevil (left) has black leg tips. The smaller cabbage stem weevil (right) has red leg tips and a whitish dorsal spot between the thorax and abdomen.
Les solutions insecticides sont toujours efficaces
L’efficacité de la lutte chimique dépend avant tout du positionnement de la protection et de sa persistance d’action. A ce jour, Terres Inovia n’a pas constaté de perte d’efficacité au champ. Et le monitoring réalisé par l’Institut ne montre pas de phénomène de résistance émergent inquiétant.
Les références DECIS PROTECH 0.33 l/ha et KARATE ZEON 0.075 l/ha sont efficaces pour réduire les dégâts du charançon de la tige du colza (réduction du nombre de tiges déformées et/ou éclatées). TREBON 30 EC est comparable aux références. En cas d’infestation tardive, il présente l’intérêt d’être également efficace sur méligèthes. SHERPA 100 EW et CYTHRINE MAX sont un peu en retrait. MAVRIK SMART est inférieur aux références (synthèse des essais Terres Inovia).
OAD Prédiction du vol de charançon de la tige du colza
Pour prédire la dynamique des vols de ce ravageur, Terres Inovia met à disposition l’Outil d’Aide à la Décision « Prédiction des vols de ravageurs ». L’outil informe sur la probabilité de capture en cuvette jusqu’à J+7, sous forme graphique et sous forme de carte. Il s’agit d’un outil de mise en alerte complémentaire aux réseaux d’observation sur le terrain.
En savoir plus
Watch out for rapeseed stem weevil
Les charançons de la tige du colza pénalisent les composantes de rendement. Les pontes en perturbant le flux de sève sensibilisent les plantes aux stress ultérieurs et limitent leurs capacités de compensation. Un stress hydrique ou une attaque d’un autre ravageur au printemps sur un colza affaibli préalablement par le charançon de la tige sont ainsi plus dommageables. Le positionnement de l’intervention insecticide est déterminant pour garantir l’efficacité de la protection.
Le raisonnement tactique repose sur les relevés rapportés par les réseaux de cuvettes jaunes (BSV ou autres) et un bon examen du stade du colza.
Lire article sur la cuvette jaune
Pensez à nettoyer et à remettre votre cuvette sur la végétation pour détecter le début du vol. Le réchauffement actuel pourrait déclencher l’arrivée des premiers charançons dans les colzas, même si les pluies associées ou non à des vents sont plutôt défavorables aux déplacements d’insectes.
En ce début février, les colzas les plus avancés du Centre-Val de Loire se situent au stade C2 (apparition de la tige) voire même D1 ponctuellement. En Poitou-Charentes ils sont au stade C1 (formation de nouvelles feuilles). En Normandie et Ouest Ile-de-France, les plantes atteignent fréquemment le stade C2, selon les variétés, les réserves en azote, les types de sol... Attention, les infestations en larves d’altises peuvent être élevées cette année.
Dans ces cas, les éventuelles pertes de biomasse en janvier associées aux conditions hivernales renforcent la nécessité d’une vigilance accrue pour la suite de la campagne.
Quelques charançons de la tige du colza ont été capturés en région Centre-Val de Loire (BSV du 3 février 2026).
OAD pour prédire les vols de Charançon de la tige
Pour accompagner la surveillance de vos colzas, Terres Inovia met à disposition un OAD de prédiction de vol du charançon de la tige. Sur la base des captures relevées sur le territoire depuis 2011 par les observateurs BSV et en se basant sur un réseau de stations météorologiques couvrant les différents bassins de production, le modèle fournit une courbe de probabilité de piégeage sur la commune renseignée, jusqu’à J+7.
Lorsque la courbe se rapproche du seuil d’alerte (ligne en pointillés), vous devez vérifier régulièrement les captures dans votre cuvette.
Une vue d’ensemble sur une carte de France est également consultable pour indiquer le risque journalier de la date sélectionnée et jusqu’à J+7.
| Attention : Les informations prédites par les outils ne tiennent pas compte des spécificités de chaque parcelle et ne dispensent pas de la surveillance au champ (cuvettes jaunes placées à hauteur de végétation et observation de l'état du colza). |
Pour les 7 prochains jours, le risque de capture de charançons de la tige du colza est nul à faible et reste globalement sous le seuil d’alerte
Découvrez l'outil :
Intervenir au pic de vol
La sécurisation du potentiel conduit à intervenir idéalement lorsque le pic de vol régional est atteint et que les femelles sont aptes à pondre.
Il est recommandé d’intervenir lorsque les captures traduisent une présence significative d’insectes dans le réseau de parcelles, et avant l’entrée en phase de ponte. Un traitement réalisé dès les toutes premières captures peut conduire à une application prématurée.
Les solutions insecticides sont toujours efficaces
Le succès de la lutte chimique dépend du positionnement de l’intervention et de la persistance d’action. À ce jour, Terres Inovia n’observe pas de baisse d’efficacité au champ. Les résultats du monitoring ne montrent pas l’émergence de résistances inquiétantes.
DECIS PROTECH 0.33 l/ha et KARATE ZEON 0.075 l/ha sont efficaces pour réduire les dégâts du charançon de la tige du colza (réduction du nombre de tiges déformées et/ou éclatées). TREBON 30 EC est comparable à ces références et en cas d’infestation tardive et de présence de méligèthes, il présente l’intérêt d’être également efficace sur méligèthes...
SHERPA 100 EW et CYTHRINE MAX sont un peu en retrait. MAVRIK SMART est quant à lui inférieur aux références sur charançon de la tige et est à réserver pour la lutte éventuelle contre méligèthes entre les stades D1 et E-F1.
Attention : veiller à réserver les produits TREBON 30 EC ou MAVRIK SMART pour la lutte éventuelle contre méligèthes entre les stades D1 et E-F1.
Julien Charbonnaud - j.charbonnaud@terresinovia.fr - Centre-Val de Loire
Jean Lieven - j.lieven@terresinovia.fr - Normandie, Ile-de-France Ouest
Thomas Mear – t.mear@terresinovia.fr - Bretagne, Pays de la Loire
Elodie Tourton - e.tourton@terresinovia.fr - Poitou-Charentes, Vendée, Limousin
Camelina nutrition
Camelina requires very little fertilizer. Its powerful taproot system enables it to extract the nutrients it needs for growth from deep within the soil. Fertilization management differs according to how camelina is grown.
Camelina requires very little fertilizer. Its powerful taproot system enables it to extract the nutrients it needs for growth from deep within the soil. Fertilization management differs according to how camelina is grown
Fertilization management for camelina as a main crop
Nitrogen nutrition
Nitrogen dose trials have been carried out. Camelina yield increases with nitrogen fertilization, until it reaches a plateau (see graph below - source: Malhi et al., 2013, Canada). This yield increase is explained by improvements in several components: the number of plants per square meter, the number of branches, the number of siliques per plant, as well as the number of seeds per silique. On the other hand, thousand kernel weight (MGW) does not seem to be affected (source: Agegnehu et al.1996, USA).
The optimum dose of nitrogen to be applied is between 80 and 100 units per hectare, depending on residues, corresponding to the economic optimum. For spring camelina, nitrogen can be applied in a single application just after sowing. However, it is possible to split the application according to the following recommendations: 30% of the dose at sowing, then the remainder at the rosette stage. For winter camelina, the application should be made when vegetation resumes before bolting.
In addition, the use of a sulfur fertilizer is recommended to ensure an application of 12 to 24 units of sulfur per hectare (source: Camelina Company).
Beware of excess nitrogen, which makes the crop more susceptible to disease, particularly albugo, and can accentuate the risk of lodging.
As nitrogen fertilization increases, so does the nitrogen content of the plant and the protein concentration of the seed. On the other hand, oil content and nitrogen use efficiency decrease (source: Malhi et al., 2013, Canada).
Concerning fatty acid composition, oleic and linoleic acid percentages increase with nitrogen dose, while linolenic acid percentage decreases. The concentration of iron (Fe) and zinc (Zn) in the seeds also decreases (source: Magdalena Czarnik et al., 2027, University of Rzeszów, Poland).
Phosphorus and potash
Camelina has moderate phosphorus and potassium requirements. Inputs should be rationed throughout the rotation, based on soil analysis results. In a well-supplied soil, we recommend applying 40 units per hectare of phosphorus and 40 units per hectare of potash. These fertilizations can be carried out at any time during the intercropping period preceding camelina planting, or directly at sowing time.
Fertilization management for camelina in summer intercropping
Camelina is a cruciferous plant. It needs nitrogen from the start of its cycle to express its full potential right up to harvest.
Managing nitrogen fertilization depends on the previous crop. In the case of cereals, 40 units of nitrogen per hectare must be applied at sowing. It is strongly recommended to apply this fertilizer locally. No additional nitrogen should be applied during vegetation. Excessive nitrogen applications could lengthen the vegetative phase of camelina, delaying maturity.
Where peas are grown before camelina, the nitrogen residue is generally sufficient to ensure good camelina development. Therefore, nitrogen is not essential. However, an optional fertilization of 10 units of nitrogen per hectare at sowing can be considered.
No background fertilization is required.
Camelina editions
Cameline - Cultivation Guide 2024
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Keys to success with camelina in catch crops
Louis-Marie Allard, Terres Inovia development engineer for the North and East zone, explains the basics of successful summer cover crops with camelina.
Louis-Marie Allard, Terres Inovia development engineer for the North and East zone, explains the basics of successful summer cover crops with camelina.
Camelina editions
Cameline - Cultivation Guide 2024
Our other articles
[COMING SOON] Predicting pest flights
Provide information on the statistical probability of catching a fish in a cuvette
The tool displays :
- In graphic form: the evolution of the daily probability of capture up to D+7, for a given commune
- In map form: probability levels over the whole territory, for a given date (up to D+7).
The alert threshold is defined by the model's algorithms. Above this threshold, the probability of capturing the pest increases significantly.
The rapeseed stem weevil flight prediction tool was developed thanks to the Produire project of the Cap Protéines program, and received support from the French Ministry of Agriculture and Food Sovereignty as part of the recovery plan.
The terminal bud weevil flight prediction tool was developed thanks to the Adaptacol² project and received support from the Casdar.
The agronomic benefits of camelina
Camelina (Camelina sativa) is a cruciferous plant (Brassicaceae) native to Europe and Southwest Asia. It has historically been cultivated in Europe, notably in France, where the first traces date back to the Bronze Age, for the production of vegetable oil and fodder.
Camelina (Camelina sativa) is a cruciferous plant (Brassicaceae) native to Europe and Southwest Asia. It has historically been cultivated in Europe, notably in France, where the first traces date back to the Bronze Age, for the production of vegetable oil and fodder.
It was widely cultivated until the early 20th century, producing an oil used in soaps and paints, before gradually disappearing in the face of competition from more productive oilseed crops such as rapeseed. At the time, the solid residues obtained after oil extraction were used as a feed supplement for livestock or as fertilizer; the stalks were used to make brooms.
Today, it is making a comeback on the European agricultural scene, and is attracting interest from a wide range of players, both farmers and manufacturers, thanks to its agronomic advantages and the new outlets it opens up.
Good adaptation to soil and climate conditions
Camelina has one major advantage: it adapts to a wide range of soil and climate conditions, and is particularly well suited to low-potential soils. It is often presented as a hardy crop, thanks to its low input requirements and resistance to drought and high temperatures. It is also fairly tolerant of pests and resistant to lodging. Camelina requires little fertilizer or pesticide, so its introduction into cropping systems has both economic and environmental benefits.
No special equipment required, but some adjustments are necessary
What's more, it doesn't require any special equipment, making it easy to introduce to farms. Nevertheless, due to its small seed size (PMG ≈ 1-1.5g), the planting and harvesting phases require adjustments and special attention.
A short-cycle crop
An interesting feature of camelina is the length of its cycle, which varies according to variety and sowing period, from 90 to 250 days (1700 to 1900 degrees day at base 0°C, depending on variety). Camelina can therefore be grown as a main crop, in association with lentils, for example, or as a catch crop for short-cycle varieties (link to page on how to insert camelina into the SoC).
An asset for organic farming
Its low input requirements, combined with its strong competitive power - provided it emerges regularly and evenly - mean that it has a place in organic farming rotations (link to organic farming page). Some farmers even report that it has an "allelopathic" effect, i.e. that it can naturally inhibit the growth of other undesirable plants around it. To our knowledge, this has not yet been demonstrated in the field.
Conclusion
All these advantages make it a crop that can be easily integrated into a variety of cropping systems in France and around the world, in both organic and conventional farming, as a main crop or as a catch crop.
Camelina editions