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Sully-sur-Loire, France

Constantin J.,French National Institute for Agricultural Research | Mary B.,French National Institute for Agricultural Research | Laurent F.,ARVALIS Institute du vegetal | Aubrion G.,ARVALIS Institute du vegetal | And 3 more authors.
Agriculture, Ecosystems and Environment

Improved agricultural practices are encouraged to reduce nitrate leaching and greenhouse gas emissions. However, the effects of these practices are often studied at annual or rotation scale without considering their long-term impacts. We have evaluated the effects of catch crops (CC), no-till (NT) and reduced nitrogen fertilization (N-) on nitrogen fate in soil-plant system during 13-17 years in three experiments in Northern France. CC were present in all sites whereas tillage treatment and N fertilization rate were tested separately at one site. Crop biomass, N uptake and N leaching were monitored during the whole period. The N balance, i.e. the difference between N inputs and crop exportations, was only affected by fertilization rate whereas leached N varied with all techniques. CC was the most efficient technique to decrease N leaching (from 36 to 62%) and remained efficient on the long term. NT and N- had a positive but smaller impact. N storage in soil organic matter was markedly increased by CC (by 10-24 kg ha-1 yr-1), decreased by N- (-7.3 kg ha-1 yr-1) and not significantly affected by NT. The differences in gaseous N losses (denitrification + volatilization) between treatments were assessed by nitrogen mass balance. CC establishment had no significant effect on N gaseous emissions while NT increased them by 3.6 ± 0.9 kg N ha-1 yr-1 and N- reduced them by 13.6 ± 4.6 kg N ha-1 yr-1. Catch crops appear as a win/win technique with respect to nitrate leaching and C and N sequestration in soil. © 2009 Elsevier B.V. All rights reserved. Source

Perennec S.,Chambre dAgriculture du Finistere | Collet J.M.,CTIFL CATE
Acta Horticulturae

In Brittany, several pests can install on artichoke crop with different frequencies and harmfulness. The artichoke green aphid (Capitophorus horni) is observed every year, either on offshoots or on older plants (two years or more), sometimes in very important numbers, which can weaken the plants. The broad bean black aphid (Aphis fabae) is also seen every year in colonies, which can make problems for the sales because they develop preferably on the buds. Owlet moths, and mainly Autographa gamma, feed on young leaves, but also buds when they are very young; this leads to perforations and deformations, especially on the cultivar Violet de Provence. Other Lepidoptera cause more occasional damages, often limited to the leaves. Less frequent or less harmful pests are safflower fly, leaf miner fly, plant bugs like Lygus sp., or leafhoppers of Eupteryx genus. It's necessary to notice also damages linked to slugs, snails, birds (scratches on buds) and voles (on stumps). Source

Monot C.,Vegenov BBV | Barbeyron G.,Vegenov BBV | Carrara M.C.,Vegenov BBV | Hallier S.,Vegenov BBV | And 3 more authors.
Acta Horticulturae

Downy mildew (Bremia lactucae) is the main disease of artichoke cultures in Brittany. Because this disease is rare in the rest of the world, only few teams work on this subject. For this reason a research program was carried out at BBV, in collaboration with the Chamber of Agriculture of Finistere and the CATE experimental station. The aim of this project was to improve our knowledge on the Bremia lactucae, pathogen of artichoke. Forty isolates of Bremia lactucae were collected in all areas of Brittany, on different cultivars of artichokes and cardoon. Isolates of Bremia lactucae of artichoke and lettuce were characterised and compared with molecular techniques. Based on the publications on B. lactucae on lettuce, we identified suitable conditions for downy mildew infection in our growth chambers. The method of inoculation of whole young plants of artichoke is now set up. A second test on foliar disk is already on trial. These tests will help, on one side, to evaluate the life cycle of Bremia lactucae of artichoke, and, on the other side, to evaluate the efficiency of phytosanitary products, conventional chemicals or alternative products. Résumé Le mildiou est l'une des principales maladies qui affectent l'artichaut en Bretagne mais il est très peu présent dans le reste du monde. C'est pourquoi, un projet d'étude a été initié depuis quelques années à BBV, en partenariat avec la Chambre d'Agriculture du Finistère et le Caté, dans le but de mieux connaitre ce pathogène. En se basant sur les connaissances publiées sur le mildiou de la laitue, les conditions d'infestation ont pu etre recréées dans nos salles de culture. Des souches ont alors été collectées en Bretagne, sur différentes variétés d'artichaut et de cardon. Cette collection est forte d'une quarantaine de souches à l'heure actuelle. Le protocole d'infestation est maitrisé sur jeune plante entière, et une mise au point sur disques foliaires est également en cours. Ces tests permettront en particulier de déterminer la durée du cycle du mildiou en fonction des conditions climatiques. Des essais de protection par l'évaluation de l'efficacité de produits sur plants d'artichaut peuvent également etre entrepris. Par ailleurs, des travaux ont été menés pour caractériser les souches de mildiou de l'artichaut par les techniques de biologie moléculaire et ainsi vérifier qu'il s'agit bien d'un Bremia lactucae, inféodé à l'artichaut. © ISHS. Source

Collet J.M.,CTIFL CATE | Perennec S.,Chambre dAgriculture du Finistere
Acta Horticulturae

Caterpillars can make damages on artichoke leaves, but also on the heads. Damages on heads consist on injured, twisted or perforated bracts; whatever the damages are, the concerned heads become non-commercial. On artichoke, caterpillar damages became economically important only around 2000. All varieties are concerned, but most of the damages concern the cultivar Violet de Provence, particularly when it is harvested in bunches. Aphids control is more and more practised with specific aphicids, which don't kill the auxiliary fauna; but these treatments don't harm the caterpillars, which then can cause heavy losses. In spite of the presence of several species, the main one met in Brittany is Autographa gamma. This species is a migrant one, which usually spends the winter in southern Europe; it can be trapped from May to September, and remains the main species from May to September, when it is joined by other species, like Helicoverpa armigera. The fact that A. gamma was the main involved species was established with the help of the trappings made by the Agriculture Chamber; they show that there are well synchronised flights at a regional scale, and that there is a good correlation between these flights and the reported damages. Alternatively, the trials made in CATE show that it's possible to significantly diminish the amounts of the damages by taking into account the trapped A. gamma flights to control the caterpillars. Treatments are recommended within a few days following a flight, to target the newly hatched caterpillars. Pyrethroids and Bacillus thuringiensis both are satisfying solutions, but pyrethroids tend to eliminate the natural auxiliary fauna, and can favour aphids increase. Source

Monot C.,Vegenov BBV | Collet J.M.,CTIFL CATE | Mezencev N.,Chambre dAgriculture du Finistere
Acta Horticulturae

The development of a model for the prediction of the risk appearance of downy mildew on Artichoke (Bremia lactucae) was based on a biological model close to the Güntz and Divoux's one established on potatoes. The model uses simple meteorological data (relative humidity of air, hourly temperatures and rainfalls) and includes user's data (treatments, irrigation, stage of the crop and variety). The first year of the model fittings showed a good visualization of the real epidemic. Laboratory tests refine our knowledge about the life cycle and, associated to field observations, will allow to quantify more precisely the models parameters. © ISHS. Source

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