No abstract

European stone fruit yellows (ESFY) is becoming a major economic problem for Prunus growers in Europe. The causal agent ("Candidatus Phytoplasma prunorum") and its vector (Cacopsylla pruni) have been identified, but the present knowledge of the risk factors for this disease relies, at best, on specific experiments. To assess the relative significance of several factors correlated with ESFY incidence in the field, an exhaustive survey was performed on apricot and Japanese plum orchards in the Crau plain (France). After a preliminary multivariate exploration of the data, we used a logistic regression model to analyze and predict the cumulative number of diseased trees on the basis of a set of quantitative (age, planting density, and area of the orchard) and categorical variables (species, cultivar, and rootstock). Because of the nature of the data, we used an overdispersed binomial model and we developed a parametric bootstrap procedure based on the beta-binomial distribution to obtain confidence intervals. Our results indicated that the age, species, and cultivar of the scion were the major factors explaining the observed number of diseased trees. The planting density and the rootstocks used in the zone under study were less significant, and the area of the orchard had no effect. The residuals of the model showed that some explanatory variables had not been taken into account, because part of the remaining variability could be explained by a grower effect. The spatial distribution of the residuals suggested that one of the reasons for this grower effect was the correlation between orchards closer than 100 m, possibly caused by the flight behavior of infectious vectors.

No abstract

Root-knot nematodes are causing serious economic losses of vegetable production. Actual agroecological control solutions are not effective enough to control this pest or are difficult to implement in farms. There is little knowledge on the use of crops to trap nematodes in protected cultivation systems. Therefore, we tested a resistant pepper as a trap crop for root-knot nematodes over 4 years in a commercial farm and an experimental station in Southern France. The effects of pepper trap crop on plant damages and soil infestation were compared with a sorghum cover crop. We also surveyed 28 local vegetable farmers for their interest concerning the possible use of the pepper trap crop. Our results show that nematode infestation of the soil decreased by 99 and 80%after the first and second implementation of the trap crop. The gall index measured on Swiss chard decreased from 2.5 to less than 1 after 4 years. Respectively, 21 and 36 % of farmers found the cropping system completely and partially acceptable. The most interested farmers were those having sufficient labor and available land in summer. Farmer criticisms were higher nursery costs and planting duration, versus sorghum. Overall, this is the first design of a cropping system using a resistant cultivar as a dead-end trap crop for root-knot nematodes. The process used, moving from a genetic construct to agronomic innovation through an interdisciplinary and participatory approach, holds promise for scientists seeking new integrated pest management approaches to increase the sustainability of agriculture

Although the grazing of extensive standard orchards has long been a common practice in Europe and continues to take place on a considerable portion of existing traditional orchards, it is more unusual for current specialized and intensive orchards (with bush trees) to be grazed. The way in which animals are integrated into these modern forms of orchards differs according to the animal and tree species as well as to the place relegated to livestock as well as the expected and provided ecological services of that place. However, little literature is available on these modern forms of sylvopastoralism. The objective of this paper is therefore to provide the first overview of the advantages and limitations of these systems as perceived by the actors involved. Based on several research programs, we first tracked on-farm innovations to describe a diversity of systems. We then conducted a multifactorial analysis to characterize these systems according to: (i) structural farm variables; (ii) farmer motivations to integrate livestock; (iii) technical adaptations generated by sylvopastoralism; and finally, (iv) observed services and disservices provided by livestock in orchards. A total of 34 farms and 21 variables were used to differentiate three types of systems that differed according to animal species, grazing patterns, the degree of system redesign, and compliance between initial farmer motivations and the observed services. The results showed that while the practice of livestock grazing in orchards can be agronomically effective and economically viable, its success depends on the ability of growers to integrate all of the dimensions of livestock farming into their orchard system for a win-win association. There are a large number of variables that are involved in successful orchard grazing that result in both challenges and opportunities, but success is closely linked to the grower’s ability to adapt the production system to suit the intended role of livestock and to acquire new skills. This typology paves the way for numerous combinations between orchards and livestock. The analysis of the determinants, obstacles, and benefits provided by orchard grazing provides some preliminary elements that are necessary to adapt agricultural support to a diversity of integration patterns in integrated tree and livestock systems.