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Leaf parsley growth and productivity are often affected by pathogen infection. Root-knot nematodes of the genus Meloiogyne are common pathogens reported on leaf parsley. The response of leaf parsley to Meloidogyne species in tropical and subtropical regions is quite known, while in temperate regions, comparable information is still scarce. In this study, we evaluated the host status and response of three flat-leaf (Laica, Laura, Gigante d’Italia) and three curly-leaf (Grüne Perle, Orfeo, Sombre) parsley cultivars to Meloidogyne species from temperate regions, i.e., M. hapla, M. chitwoodi, and M. fallax, as well as to the southern root-knot nematode M. incognita. Evaluation was based on measuring plant biomass and nematode reproduction nine weeks after nematode inoculation. Our results showed that all four Meloidogyne species did not cause the reduction in leaf parsley growth under the given experimental conditions. Regarding the host status of leaf parsley cultivars for Meloidogyne, results were variable. All six parsley cultivars were found to be good hosts for M. hapla. Regarding M. chitwoodi, the host status could not be clarified properly; however, each cultivar allowed nematode reproduction at least in one experiment. For M. fallax, flat-leaf parsley turned out to be less susceptible than curly-leaf parsley; and for M. incognita, Orfeo, Laura, and Laica were classified as good hosts, Grüne Perle and Sombre as poor hosts, and Gigante d’Italia as a non-host. Amongst all tested cultivars, Gigante d’Italia was found to be the least susceptible cultivar due to its poor host status for M. chitwoodi and non-host status for M. fallax and M. incognita. Infection with M. hapla, M. chitwoodi, and M. incognita, but not with M. fallax, resulted in distinct gall formation on the roots of all six leaf parsley cultivars.

Das Nachrichtenblatt für den Deutschen Pflanzenschutzdienst, unser heutiges Journal für Kulturpflanzen, feiert seinen 100. Geburtstag. Seinem Ziel, „den im praktischen Pflanzenschutzdienst Tätigen Belehrung und Informationen (zu) übermitteln“, wie Otto Appel zur Einführung schrieb, ist es bis heute treu geblieben. Dies gilt auch für den Bereich der Nematologie. Die Themen haben sich dabei über die Zeit weiterentwickelt. Standen früher Biologie und Wirtspflanzenspektrum einzelner Arten pflanzenparasitärer Nematoden im Fokus des Interesses, so sind es heute Wirt-Parasit Interaktionen, Resistenz und Toleranz von Kulturpflanzen oder der Einfluss von Klimawandel und Globalisierung auf die Verbreitung und das Schadpotenzial der Nematoden. Der vorliegende Beitrag blickt zurück auf die Themen vor 100 Jahren, stellt am Beispiel laufender Arbeiten am Julius Kühn-Institut aktuelle Forschungsthemen vor und gibt einen Ausblick auf die Themen der Zukunft.

Pratylenchus penetrans is an economically important root-lesion nematode species that affects agronomic and ornamental plants. Understanding its diversity is of paramount importance to develop effective control and management strategies. This study aimed to characterize the morphological and genetic diversity among seven European isolates. An isolate from the USA was included in the molecular analyses for comparative purposes. Morphometrics of the European P. penetrans isolates generally were within the range of the original descriptions for this species. However, multiple morphometric characteristics, including body length, maximum body width, tail length and length of the post-vulval uterine sac showed discrepancies when compared to other populations. Nucleotide sequence-based analyses revealed a high level of intraspecific diversity among the isolates. We observed no correlation between D2-D3 rDNA- and COXI-based phylogenetic similarities and geographic origin. Our phylogenetic analyses including selected GenBank sequences also suggest that the controversy surrounding the distinction between P. penetrans and P. fallax remains.

Biofumigation, although a well-known method, is still controversially debated as a management strategy for plant-parasitic nematodes (PPN). Its controlling effect is attributed to the production of isothiocyanates (ITCs) following the action of myrosinase on glucosinolates (GSLs). Different ITCs are formed from different GSLs, depending on the plant species. To better understand the potential of ITCs, eight cultivars from three Brassicaceae species were investigated as biofumigation crops to control the root knot nematode Meloidogyne hapla. Since results were inconsistent, the nematicidal effect of selected ITCs were further evaluated in vitro. Based on its nematicidal potential, allyl ITC (AITC) was specifically investigated under different soil:sand compositions. A significantly lower nematicidal activity was observed in soil compared to sand. AITC was also evaluated as an additive to the biofumigation in a greenhouse trial. Its supplementation to the biofumigation process with Brassica juncea cv. Terrafit controlled M. hapla, while no control was observed using Raphanus sativus cv. Defender. Thus, the success of biofumigation seems to be strongly dependent on the soil characteristics and the ITC produced during the biofumigation process. Therefore, the supplementation of AITC in combination with the right cover crop can improve the biofumigation process to control M. hapla.

Plant-parasitic nematodes cause considerable damage to crop plants. The rhizosphere microbiome can affect invasion and reproductive success of plant-parasitic nematodes, thus affecting plant damage. In this study, we investigated how the transplanted rhizosphere microbiome from different crops affect plant-parasitic nematodes on soybean or tomato, and whether the plant’s own microbiome from the rhizosphere protects it better than the microbiome from fallow soil. Soybean plants growing in sterilized substrate were inoculated with the microbiome extracted from the rhizosphere of soybean, maize, or tomato. Controls were inoculated with extracts from bulk soil, or not inoculated. After the microbiome was established, the root lesion nematode Pratylenchus penetrans was added. Root invasion of P. penetrans was significantly reduced on soybean plants inoculated with the microbiome from maize or soybean compared to tomato or bulk soil, or the uninoculated control. In the analogous experiment with tomato plants inoculated with either P. penetrans or the root knot nematode Meloidogyne incognita, the rhizosphere microbiomes of maize and tomato reduced root invasion by P. penetrans and M. incognita compared to microbiomes from soybean or bulk soil. Reproduction of M. incognita on tomato followed the same trend, and it was best suppressed by the tomato rhizosphere microbiome. In split-root experiments with soybean and tomato plants, a systemic effect of the inoculated rhizosphere microbiomes on root invasion of P. penetrans was shown. Furthermore, some transplanted microbiomes slightly enhanced plant growth compared to uninoculated plants. The microbiomes from maize rhizosphere and bulk soil increased the fresh weights of roots and shoots of soybean plants, and microbiomes from soybean rhizosphere and bulk soil increased the fresh weights of roots and shoots of tomato plants. Nematode invasion did not affect plant growth in these short-term experiments. In conclusion, this study highlights the importance of the rhizosphere microbiome in protecting crops against plant-parasitic nematodes. An effect of pre-crops on the rhizosphere microbiome might be harnessed to enhance the resistance of crops towards plant-parasitic nematodes. However, nematode-suppressive effects of a particular microbiome may not necessarily coincide with improvement of plant growth in the absence of plant-parasitic nematodes.

Otto Appel (1867–1952) war ein leidenschaftlicher Phyto­mediziner, der sich in jungen Jahren als Wissenschaftler und später als Organisator des Pflanzenschutzdienstes in Deutschland besondere Verdienste erwarb. Anlässlich seines 150. Geburtstages soll hier an seine wissenschaftlichen Leistungen erinnert werden. Otto Appel war in vielerlei Hinsicht seiner Zeit voraus und hat mit wissenschaftlichen Methoden Lösungen für einige der drängendsten phytopathologischen Probleme der Landwirtschaft erarbeitet, die bis heute Gültigkeit haben. Nach dem Studium der Pharmazie und Botanik sowie kurz­fristigen Forschungsaufenthalten in mikrobiologischen Arbeitsgruppen in Würzburg und Königsberg kam Otto Appel am 1. Juni 1899 an die Biologische Abteilung für Land- und Forstwirtschaft des Kaiserlichen Gesundheitsamtes in Berlin. Sein Hauptaugenmerk galt der Gesundheit von Kartoffeln und Getreide, den für die Ernährung der Bevölkerung bedeutendsten Kulturen. Insgesamt war sein Arbeitsspektrum aber wesentlich breiter. Otto Appel entwickelte Verfahren zur gesunden Lagerung von Kartoffeln sowie zur Saatgutbehandlung von Getreide. Er beschrieb zahlreiche Schaderreger und überarbeitete die Gruppe der Fusarien von Grund auf neu. Intensiv untersuchte Otto Appel die Biologie der verschiedenen Schad­erreger, um Ansatzpunkte für ihre Bekämpfung zu ent­wickeln. Die von Otto Appel etablierten Pflanzenschutzverfahren haben die landwirtschaftliche Praxis nachhaltig geprägt und zu einer deutlichen Verbesserung der Nahrungsmittelsicherheit und -qualität in Deutschland und weit darüber hinaus geführt.

The potential of bacterial antagonists of fungal pathogens to control the root-knot nematode Meloidogyne incognita was investigated under greenhouse conditions. Treatment of tomato seeds with several strains significantly reduced the numbers of galls and egg masses compared with the untreated control. Best performed Bacillus subtilis isolates Sb4-23, Mc5-Re2, and Mc2-Re2, which were further studied for their mode of action with regard to direct effects by bacterial metabolites or repellents, and plant mediated effects. Drenching of soil with culture supernatants significantly reduced the number of egg masses produced by M. incognita on tomato by up to 62% compared to the control without culture supernatant. Repellence of juveniles by the antagonists was shown in a linked twin-pot set-up, where a majority of juveniles penetrated roots on the side without inoculated antagonists. All tested biocontrol strains induced systemic resistance against M. incognita in tomato, as revealed in a split-root system where the bacteria and the nematodes were inoculated at spatially separated roots of the same plant. This reduced the production of egg masses by up to 51%, while inoculation of bacteria and nematodes in the same pot had only a minor additive effect on suppression of M. incognita compared to induced systemic resistance alone. Therefore, the plant mediated effect was the major reason for antagonism rather than direct mechanisms. In conclusion, the bacteria known for their antagonistic potential against fungal pathogens also suppressed M. incognita. Such "multi-purpose" bacteria might provide new options for control strategies, especially with respect to nematode-fungus disease complexes that cause synergistic yield losses.

Endophytic bacteria have gained attention due to their interesting features related to plant growth and health stimulation. The objective of this research was to determine the populations and spectrum of indigenous root endophytic bacteria from tomato (Lycopersicon esculentum) and the biocontrol activity of the bacteria for plant protection. The isolation procedure of these endophytic bacteria was done using surface-sterilization method using alcohol and sodium hypochlorite (NaOCl). General medium trypsic soy agar (TSA) was used as the growth medium for isolation. The total population density of endophytic bacteria recovered from tomato roots ranged from 1.0 to 4.4 (in log10 scale) CFU g-1 fresh root weight. A total of 564 strains of endophytic bacteria were isolated from tomato plants grown in West Java, Indonesia. Endophytic bacterial strains were identified based on their fatty acid profile using FAME-GC-MIDI system. Fifty species and 32 genera of endophytic bacteria were found in association with tomato root. The most abundant endophytic bacterial genera were Bacillus spp. and Pseudomonas spp. One hundred and eighty one bacterial strains were tested for their in vitro antagonism towards Rhizoctonia solani, Fusarium oxysporum f.sp. radicis-lycopersici, and F. oxysporum f.sp. lycopersici. Fourteen strains showed antagonism against R. solani, nine strains against F. oxysporum f.sp. radicis-lycopersici and seven strains against F. oxysporum f. sp. lycopersici. The close relationship between endophytic bacteria and their hosts make them ideal candidates for biological control and plant growth promotion.

Am 14. April 1910 verstarb der Landwirt und Wissenschaftler Prof. Dr. Julius Kühn in Halle (Saale). Sein ungeheurer Schaffensdrang, seine immerwährende Arbeitslust aber auch unendliche Herzensgüte machten ihn zu einer herausragenden Persönlichkeit und zum Vorbild tausender Studenten, die ihn liebevoll „Vater Kühn“ nannten. Er gilt als Begründer des agrarwissenschaftlichen Studiums, hat die „Prüfungsanstalt für landwirtschaftliche Maschinen und Geräte“ aufgebaut, sich für die Gründung pflanzenpathologischer Anstalten – quasi der Vorgängerorganisation des Julius Kühn-Instituts – eingesetzt und schuf mit der „Versuchsstation für Nematodenvertilgung Halle“ den Vorläufer des amt­lichen Pflanzenschutzdienstes in Deutschland. Damit hatte Julius Kühn die erforderlichen Strukturen geschaffen, landwirtschaftliche Forschung zu betreiben, Lösungen zu erarbeiten und diese in der Praxis zu etablieren. Wie kaum ein Zweiter hat Julius Kühn die landwirtschaftliche Entwicklung in Deutschland vorangetrieben. Unter anderem etablierte er das landwirtschaftliche Versuchswesen, führte die Drillsaat in Schlesien ein, erkannte in dem Rübenzystennematoden Heterodera schachtii den wahren Verursacher der Rübenmüdigkeit und beschrieb bedeutende Schaderreger, wie Ditylenchus dipsaci und Rhizoctonia solani. Sein wegweisendes Werk Die Krankheiten der Kulturgewächse, ihre Ursachen und ihre Verhütung gilt als das weltweit erste phytomedizinische Lehrbuch. Bis heute werden die Arbeiten Julius Kühns in verschiedensten Institutionen fortgeführt, so auch im Julius Kühn-Institut, Bundesforschungsinstitut für Kulturpflanzen, dessen Namensgeber er ist. Anlässlich des 100sten Todestages von Julius Kühn soll dieser Beitrag an seine wegweisenden Arbeiten auf dem Gebiet der Kulturpflanzen erinnern.

Mitte des 19. Jahrhunderts kam der Rübenanbau im damaligen Mitteldeutschland nahezu zum Erliegen. Die Suche nach den Ursachen der sogenannten Rübenmüdigkeit führte im Jahr 1859 zur Entdeckung des Rübenzystennematoden Heterodera schachtii durch den Botaniker Hermann Schacht. Obwohl sich Schacht recht intensiv mit der Morphologie und Biologie des Tieres befasste und ihm vermutlich bewusst war, dass es sich hierbei um eine neue Art handelte, vermied er es, dem Tier einen Namen zu geben. Dies holte Adolf Schmidt aus Aschersleben nach, indem er das Tier zu Ehren seines Entdeckers Heterodera schachtii nannte. Heterodera schachtii war der erste pflanzenparasitäre Nematode, der als Schaderreger unterirdischer Pflanzenorgane beschrieben wurde. Aufgrund seiner wirtschaftlichen Bedeutung für den Rübenanbau stand von Beginn an neben der Biologie vor allem die Entwicklung von Bekämpfungsmaßnahmen im Vordergrund des Forschungsinteresses. Hier ist es vor allem dem unermüdlichen Engagement und der intensiven Versuchstätigkeit von Prof. Julius Kühn aus Halle zu verdanken, dass innerhalb weniger Jahre Verfahren zur Vermeidung und Bekämpfung des Rübenzystennematoden erfolgreich in der Praxis etabliert wurden. Kühn zeigte, dass die Rübenmüdigkeit mit recht einfachen Mitteln verhindert werden konnte, dass solchen Methoden aber arbeits- und betriebswirtschaftliche Anforderungen entgegenstanden. Somit tragen intensive Rübenfruchtfolgen bis heute dazu bei, dass H. schachtii in gemäßigten Klimaregionen weltweit einer der wirtschaftlich bedeutendsten Schadnematoden ist. Anlässlich des 150jährigen Jubiläums der Entdeckung von H. schachtii sollen in diesem historischen Überblick die frühen Arbeiten zu diesem Nematoden vorgestellt werden, die in vielen Aspekten auch heute noch von hoher Aktualität sind.

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Abstract  1,2-Dehydropyrrolizidine alkaloids (PAs), known to be nematotoxic in vitro, represent a class of secondary plant metabolites from hundreds of plant species worldwide. Pot experiments with the commercially available PA-containing plants Ageratum houstonianum, Borago officinalis, Senecio bicolor, and Symphytum officinalis demonstrate that Meloidogyne hapla is not per se repelled by these plants as all species were infested with nematodes. However, the development of M. hapla juveniles was completely suppressed on A. houstonianum and S. bicolor. Soil in which A. houstonianum and S. bicolor were cultivated and incorporated contained 200–400 times less nematodes than soil treated with Lycopersicon esculentum. Depending on their qualitative composition of PAs at least some of these plants thus appear to be valuable tools for integrated root-knot nematode management. [ABSTRACT FROM AUTHOR]