Effect of permanent ground cover on agronomic properties and soil fertility in an organic peach orchard

In conventional orchards, weeds on the raw are mainly controlled with chemical herbicides because of their efficiency, their low cost and ease of use. The most common method in organic orchard to eliminate weeds on the raw consists of tillage operations. However, some drawbacks of these mechanical methods have been demonstrated: (1) the energetic cost (non-renewable energy) is high, (2) this method is time-consuming, (3) tillage interferes with the development of superficial roots and can hurt the trunk, (4) the physical, chemical and biological properties of the soil can be disturb and (5) erosion and runoff potentially increase. Cover crops are interesting alternatives to manage ground cover but the effect on the agronomic properties and the soil fertility of these methods should be assessed. This study is included in the national program “Casdar SolAB” supported by the French Ministry of Agriculture. The effect of a White Clover crop versus tillage practice on the tree raw was assessed in an irrigated organic Peach orchard. White Clover was sowed in 2004. Soil parameters (water and nutrients availability, soil porosity, root density, earthworms density, soil profile) and agronomic parameters (yield, fruit quality, pests and diseases damages) were recorded since 2004. A 50% decrease of the organic fertilizer supply in the White Clover treatment has not affected yield and fruit quality from 2005 to 2009. It suggests this cover crop is well adapted to our pedoclimatic conditions without exerting a significant competitive effect. Root density is higher in the superficial layers of the soil in the White Clover treatment. Simplified Beerkan test used to assess soil porosity has also shown that soil porosity is higher in this treatment. No vole damage was observed in the plot

Effect of White clover (Trifolium repens cv. Huia) cover crop on agronomic properties and soil biology in an organic peach orchard

In orchards, cover crops are interesting alternative strategies to tillage or chemical herbicides for managing weeds in the tree row. However, little is known about the effect of cover crops on agronomic properties and soil biology in organic orchards. To fill this gap, the effects of two weed managements, a White clover cover crop (CC) versus classical tillage practice (T) on the tree row, were assessed in an irrigated organic Peach orchard. White clover was sown in 2004, 2006 and 2009 in the tree row and ploughed in 2006 and 2008. Root density, earthworm density, water infiltration rate, nitrogen content and water availability were measured in the soil, in the tree row. In 2009, peach root density observed in the superficial layers was higher in CC treatment. Sampling dates and treatment have a significant effect on total earthworm density with higher abundance observed in CC. However, no difference was observed between CC and T anecic earthworm groups known to make large and vertical burrows. Infiltration rate measured with the simplified Beerkan method was higher in CC treatment. This could be explained by the thick superficial root mat which was associated to a significant higher epigeic earthworm density in CC. Whereas nitrogen supplies were twice lower in CC treatment since 2005, soil nitrogen availability was equivalent in both treatments. These results demonstrate the agronomic interest of nitrogen-fixing plants used as a cover crop in organic peach orchards

Alternatives to copper-based treatments for the control of grapevine downy mildew (Plasmopara viticola): 5-year synthesis of trials in France and Italy

The objective of the UE-funded program REPCO (FP6) was to identify new alternatives to copper fungicides in organic farming. Two pathogens have been considered: grapevine downy mildew (Plasmopara viticola) and apple scab (Venturia inaequalis). Research on grapevine was carried out by GRAB (Avignon, France) and FEM-IASMA (San Michele all’Adige, Italy). Trials were carried out under natural conditions in order to test reduced doses of copper and copper-free alternatives. Five-year trials proved that copper is the best fungicide. However, the use of new low copper rate formulations and the association of copper-free alternatives with reduced doses of copper or with reduced number of copper applications (limited to the most susceptible grapevine growth stages) were able to control of downy mildew with a concomitant reduced impact to the environment. Among the tested products, Trichodex (Trichoderma harzianum T39), Mycosin (clay), Chitoplant (chitosan), Saponin (Yucca extract), and an experimental sage extract (Salvia officinalis) gave the best results. The level of plant protection was similar to copper (standard), but not significantly different from the untreated control. Efficacy was good under low or medium disease pressure, but decreased when the pressure increased. The trials carried out after REPCO project confirmed that blossom stage is the most risky period for downy mildew infection and that a reduction of the number of treatments, with consequent reduction of the yearly total amount of copper, is possible by applying treatments during this period. These results show that more research efforts are needed to substitute copper in organic grape growing, and at present the practical approach must focus on combining strategies (alternative products and reduced copper, understanding the most susceptible stages of the plant, applying disease forecasting models, etc.)

Differentes Strategies de Maitrise de la Tavelure du Pommier

Apple scab remains one of the main disease, responsible for significant economic losses. Selection of tolerant varieties is a promising way to follow, but is not yet giving satisfying results. Thus, different strategies have to be developed and enhanced: the screening of alternative control inputs, with lower copper dosage or without any copper is essential for short term answers to growers. This research give interesting results and potential new ingredients, however not as efficient as copper sulphate. Simultaneously, biology of the fungus permits a more preventive strategy, by destroying leaves at fall season, and thus highly decreasing the scab infection potential. Results of four trials led by CTIFL (copper alternatives) and GRAB (leaves reduction) are resented and discussed

Assessment of the susceptibility to pests and diseases of 36 apple cultivars in four low-input organic orchards in France

One of the keystones of the organic orchard is the cultivar choice as one element of pest and disease control. However, few exhaustive data sets concerning the cultivar susceptibility to pests and diseases are available for growers. In order to identify cultivars adapted to organic production methods, the susceptibility to scab, aphids and powdery mildew and the agronomic properties of 36 cultivars were assessed in four French sites under different pedo-climatic conditions. Different levels of susceptibility to scab were observed for 23 scab Vf-resistant and 13 other cultivars. In the North of France where Vf resistance is overcome, the Vf cultivars displayed different levels of scab severity. A high variability in the susceptibility to aphids was observed whereas susceptibility to powdery mildew varied less. The analysis of susceptibility properties, yield and fruit quality, fruit storability and tree behaviour permitted to identify a set of interesting cultivars according to the site

IS LEAF LITTER REMOVAL MORE EFFICIENT THAN LEAF LITTER SHREDDING TO CONTROL APPLE SCAB? A FIRST ANSWER IN A COMMERCIAL ORGANIC ORCHARD

In organic apple orchards, sanitation practices are a keystone of a sustainable scab management. Because the suppression of the inoculum by leaf litter removal could be a promising practice, we carried out an experiment to assess the interest of leaf removal versus leaf shredding on disease development and fruit damages. For one of the two cultivars studied, we showed that leaf litter removal can significantly decrease scab damages on fruit and leaf in comparison to leaf shredding

Quelle sélection fruitière pour une production durable, à faible niveau d’intrants ? Méthodologie pour un réseau de sélection variétale décentralisée

In France Fruit production is cultivated on 140 thousand hectares, mainly conducted on intensive training system. Very few elements are available on low input training systems while they have to integrate the Global rule under the frame of Ecophyto 2018. In order to evaluate if another system of cultivation will be possible, a project has been developed to highlight the main factors to be integrated in low input training system. A low input multilocal experimental design has thus been investigated on apricot in two main regions of production: Rhone valley and Roussillon. A set of 9 common cultivars with 20 replications each, planted in a complete single-tree randomization design has been established. As already observed in apple orchard, a larger set of disease has been observed in our experimental plots by comparison with conventional training orchards. A large genetic variability has been set-up among the observed cultivars, but if some of them expressed components of resistance against the observed diseases no one appeared widely resistant to all the diseases. Taking in consideration the longevity of the orchard, a huge concern exists with the tested germplasm because the observed dieback was in between 10 and 80% of the trees according to the cultivars after only 6 years of observation. On the methodological point of view, a clear optimization of the experimental design is expected on the base of the observed results

Assessment of diseases susceptibility of peach cultivars in experimental plots and on-farm for organic and low-input systems. Baseline of French case studies

Despite a high turn-over of new peach cultivars, their suitability for organic and low-input systems remains unknown for most of them. Diseases susceptibility is an important criteria to consider since diseases control is a bottleneck to peach production in theses systems. Since 2001, 81 peach cultivars were assessed in 2 experimental sites and 7 on-farm plots

ÉVALUATION DE LA SENSIBILITÉ AUX BIOAGRESSEURS DE 36 VARIÉTÉS DE POMMIERS DANS UN RÉSEAU DE PARCELLES BIOLOGIQUES À FAIBLES INTRANTS

Les bioagresseurs sont une des principales limites à la production de pomme dans les systèmes conduits en AB et à faibles niveaux d’intrants. Une des clefs du contrôle des bioagresseurs dans ces vergers est le choix des variétés (Trapman et Jansonius, 2008). La variabilité de l’expression de la sensibilité variétale peut être appréhendée grâce à un réseau multi-site pluri-annuel. Quatre parcelles de pommier biologique conduites de manière semi-extensive ont été plantées en 2002 afin d’identifier des variétés d’intérêts pour les systèmes à faible intrants. 36 variétés ont été suivies afin d’évaluer conjointement leur sensibilité à la tavelure, aux pucerons et à l’oïdium.La thématique de cette étude initiée en 2002 se trouve être au coeur des questionnements récents sur la réduction des intrants en arboriculture (programme ECOPHYTO 2018). Cette étude souligne (1) la spécificité des variétés intéressantes pour un site donné, (2) l’apparation dans certains cas de maladies considérées comme anecdoctiques, (3) l’intérêt de dispositifs multi-sites et d’observations pluriannuelles pour évaluer avec fiabilité la sensibilité aux bioagresseurs, (4) la méthodologie adaptée à cette problématique (méthode de notation, type de dispositif, etc)