Multi-annual comparisons demonstrate differences in the bunch rot susceptibility of nine Vitis vinifera L. 'Riesling' clones

Botrytis bunch rot is a major fungal disease of grapevines, and causes severe economic damage worldwide. Under humid climatic conditions, the development of bunch rot on grapes cannot be suppressed completely. Selection of planting material with lower bunch rot susceptibility represents one of the most efficient long-term tools in the complex bunch rot minimisation strategy. The present investigation conducted over four consecutive years (2013-2016) under the environmental conditions of the Moselle valley aimed at (i) detecting consistent differences in the bunch rot susceptibility within a group of nine commercially available Vitis vinifera L. 'White Riesling' clones, (ii) investigating potential underlying causes and (iii) deriving recommendations for 'Riesling' clone selection in practical viticulture. Disease severity and grape maturity (total soluble solids) progress could be well simulated by sigmoidal curves (R2 > 0.89; P < 0.038). On average of all four years, the dates when 5 % bunch rot disease severity were reached differed significantly by 9 days between the clone with the earliest epidemic (Trier 34) and the clone with the latest epidemic (Heinz 65). Multi-annual results enabled a classification of the nine clones according to (i) their relative bunch rot susceptibility as well as (ii) their relative precocity. Based on this, practical recommendations concerning a targeted clone selection as an integral long-term tool (i) in Integrated Pest Management contributing to pesticide reduction in viticulture as well as (ii) in the viticultural climate change adaptation strategy were derived

Tree islands enhance biodiversity and functioning in oil palm landscapes

In the United Nations Decade on Ecosystem Restoration1, large knowledge gaps persist on how to increase biodiversity and ecosystem functioning in cash crop-dominated tropical landscapes2. Here, we present findings from a large-scale, 5-year ecosystem restoration experiment in an oil palm landscape enriched with 52 tree islands, encompassing assessments of ten indicators of biodiversity and 19 indicators of ecosystem functioning. Overall, indicators of biodiversity and ecosystem functioning, as well as multidiversity and ecosystem multifunctionality, were higher in tree islands compared to conventionally managed oil palm. Larger tree islands led to larger gains in multidiversity through changes in vegetation structure. Furthermore, tree enrichment did not decrease landscape-scale oil palm yield. Our results demonstrate that enriching oil palm-dominated landscapes with tree islands is a promising ecological restoration strategy, yet should not replace the protection of remaining forests

Microbial community responses associated with the development of oomycete plant pathogens on tomato roots in soilless growing systems

Aims: To determine the spread of different oomycete pathogens in hydroponic, soilless tomato growing systems and their impact on established microbial communities, as baseline studies prior to future introduction of microbial inoculants for disease suppression. Methods and Results: The oomycete pathogens, Pythium group F, Pythium aphanidermatum and Phytophthora cryptogea, were introduced into small-scale recirculating tomato growing systems containing rockwool 6 weeks after set-up when roots were well-established. Two weeks later, half of the systems were switched over to run-to-waste. Pythium aphanidermatum spreads the fastest, Pythium group F the slowest and Ph. cryptogea was intermediate in its spread. The switch to run-to-waste had no effect on pathogen recovery. Microbial communities, monitored by dilution plating, were well-established at the first sampling, 6 weeks after set-up and although differences in community levels were found between experiments, changes during any one experiment were small, generally less than 1 log(10) CFU g(-1) for bacteria. Pathogen introduction increased microbial community levels in roots but the switch to run-to-waste had no effect. Analysis of bacterial communities through amplification of a fragment of the 16S rRNA gene and DGGE profiling showed that different communities were established within each pathogen experiment and that different communities were established on roots, rockwool and in nutrient solutions. However, no significant changes in microbial profiles were found over time in any experiment. Conclusions: In these systems, the microbial communities were well-established 6 weeks after set-up and were resistant to biological and physical perturbation. Significance and Impact of the Study: The implication for microbial inoculation of such systems for disease suppression is that the micro-organisms would either have to be introduced very early during the set-up of the system or be able to replace an established but variable community