Greencover crops are widely recommended to provide predators and parasitoids with floral resources for improved pest control. We studied parasitism and predation of European grapevine moth (Lobesia botrana) eggs and pupae as well as predatory mite abundances in an experimental vineyard with either one or two sowings of greencover crops compared to spontaneous vegetation. The co-occurrence between greencover flowering time and parasitoid activity differed greatly between the two study years. Parasitism was much higher when flowering and parasitoid activity coincided. While egg predation was enhanced by greencover crops, there were no significant benefits of greencover crops on parasitism of L. botrana eggs or pupae. Predatory mites did not show an as strong increase on grapevines in greencover crop plots as egg predation. Overall, our study demonstrates only limited pest control benefits of greencover crops. Given the strong within- and between year variation in natural enemy activity, studies across multiple years will be necessary to adequately describe the role of greencover crops for pest management and to identify the main predators of L. botrana eggs.

Flavescence dorée (FD) and Bois noir (BN) are the principal grapevine yellows in Europe caused by distinct phytoplasmas: BN by Candidatus Phytoplasma solani, FD by 16SrV-C and -D phytoplasmas (FDp) transmitted by the introduced Nearctic Deltocephalinae Scaphoideus titanus. FDp is listed as a quarantine pest in the European Union (Regulation (EU) 2019/2072). Black Alder (Alnus glutinosa) is a common asymptomatic host of 16SrV phytoplasmas in Europe and considered the original host of FDp (Malembic-Maher et al. 2020). Palatinate grapevine yellows (PGY) transmitted from alder to grapevine by the Macropsinae Oncopsis alni is not transmissible by S. titanus (Malembic-Maher et al. 2020). Germany is considered free from FD in grapevine and from its vector. A single case in a nursery in 2014 was eradicated (EPPO 2017), and FD was never before detected in a vineyard. Since S. titanus appeared in 2016 in the neighboring French Region of Alsace, monitoring of FD was carried out in Germany following a risk based strategy. It was focused on vineyard plots within a distance of 100 m from stands of alder. A geodata-based risk map (Jalke 2020) was used to localize those plots. All symptomatic vines sampled until September 2020 proved to be infected by BN or, occasionally, by PGY. Eight vines with typical symptoms were sampled in vineyards adjacent to alder stands in the winegrowing region of Rheinhessen in September 2020. Symptoms comprised leaf rolling and discoloration, incomplete lignification, and black pustules arranged in lines along the shoots. Diseased shoots were black and necrotic in December. Leaf midribs were sampled for total nucleic acids extraction. The phytoplasma 16S rRNA gene was amplified by generic primers R16F2/R2-mod followed by a nested PCR using 16Sr(V) group-specific primers R16(V)F1/R1, and primers R16(I)F1/R1 (Lee et al. 1995) to detect ‘Candidatus Phytoplasma solani’, associated with BN. While BN was detected in seven vines, one sample tested positive for 16SrV phytoplasma. This result was confirmed by triplex real-time Taq-Man assay based on rpl14 gene sequences (IPADLAB), by multiplex real-time PCR of map locus as well as by Loop-mediated isothermal amplification (LAMP) according to the EPPO diagnostic standard PM 7/079(2) (EPPO 2016). PCR-products of the map and the vmpA genes (Malembic-Maher et al. 2020) were sequenced and compared to reference sequences to distinguish between FD- and non-FD genotypes. The isolate from the diseased vine (GenBank MW 727272) exhibited 100% identity with map-M38 (GenBank LT221933), a genotype of the map-FD2 cluster. The same genotype was detected in A. glutinosa and Allygus spp. sampled at the infested site. A 234 bp sequence of the first repeat of the vmpA gene (GenBank MW727273) showed 100% identity with the homologous part of isolate FD-92 (GenBank LN680870) of the vmpA-II cluster. It can be concluded, that the symptomatic grapevine was infected by FD and not PGY This is the first report of FD in a productive vineyard in Germany. The infected vine of cv. Silvaner was 25 years old. While infected planting material is an unlikely source of the infection, a transmission of FDp from alder is highly probable. Finding a single FD-infection after several years of testing implies a low risk originating from the wild compartment, but the approach and possible establishment of S. titanus expected to be able to colonize the area (Jeger et al. 2016) justifies further monitoring activities. The infected vine was eradicated.

Uncovering the entire process of oviposition could enable the development of innovative pest control strategies. The European grapevine moth Lobesia botrana as well as the European grape berry moth Eupoecilia ambiguella are serious insect pests, which still threaten viticulture in many parts of the world. By creating an artificial semiochemical emitting surface, in form of a card, we tried to develop an egg-monitoring tool for the oviposition of these two species in vineyards. The idea was to create a decision support system that facilitates timing and necessity of insecticide treatments.This article deals exclusively with the initial step towards the development of this tool: the influence of physical factors (colour, shape or texture) of a surface on the oviposition behaviour of L. botrana and E. ambiguella under laboratory conditions. The acceptance of different artificial substrates as oviposition site was analysed exclusive of volatile organic compounds emitted by a host plant. We investigated particular colours of the surface, which could be a visual stimulus to trigger the oviposition of both species. Apparently, the colour green, the texture of the material and the light conditions turned out to be highly important stimuli for oviposition. K E Y W O R D Sattraction, colour, shape, tactile responses, texture

Grapevine yellows (GY) are serious phytoplasma-caused diseases affecting viticultural areas worldwide. At present, two principal agents of GY are known to infest grapevines in Germany: Bois noir (BN) and Palatinate grapevine yellows (PGY). Disease management is mostly based on prophylactic measures as there are no curative in-field treatments available. In this context, sensor-based disease detection could be a useful tool for winegrowers. Therefore, hyperspectral imaging (400–2500 nm) was applied to identify phytoplasma-infected greenhouse plants and shoots collected in the field. Disease detection models (Radial-Basis Function Network) have successfully been developed for greenhouse plants of two white grapevine varieties infected with BN and PGY. Differentiation of symptomatic and healthy plants was possible reaching satisfying classification accuracies of up to 96%. However, identification of BN-infected but symptomless vines was difficult and needs further investigation. Regarding shoots collected in the field from different red and white varieties, correct classifications of up to 100% could be reached using a Multi-Layer Perceptron Network for analysis. Thus, hyperspectral imaging seems to be a promising approach for the detection of different GY. Moreover, the 10 most important wavelengths were identified for each disease detection approach, many of which could be found between 400 and 700 nm and in the short-wave infrared region (1585, 2135, and 2300 nm). These wavelengths could be used further to develop multispectral systems.

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