Spread of the Musk-Rat in the Federal Republic of Germany

The spread of the musk-rat in FRG is reviewed over the period since 1962. Very few areas are now free. While it has not been possible to prevent spread to the Bodensee area (lake Constance), a clear border has been established and maintained in Schleswig-Holstein. In general, it would seem that populations are more affected by habitat and weather conditions than by trapping efforts and more work is needed on the real results of the trapping programme.     

Present status of fireblight in the Federal Republic of Germany1

The three phases of spread of fireblight in FRG are described, from its first appearance in 1971 to the present day. The disease is now well established in Schleswig-Holstein and Niedersachsen and scattered outbreaks have occurred over the whole of the rest of the country (but only one in Bayern). The control strategy now centres on destruction of diseased plants within 500 m of any outbreak found in an orchard or nursery (object protection).     

Plant Protection Forecasting Service in the Federal Republic of Germany1

In the Federal Republic of Germany, plant protection is a matter for the several Federal Lander. Each of the regional plant protection offices has built up a warning system of its own, although there are no essential differences between them. The warnings are based on field investigations which are mostly carried out by technicians. However, it is not possible to inspect all fields, orchards, etc., as the areas of crops are too vast. Warnings follow a general pattern: information on the situation, followed by conclusions on further development; recommendations for control measures; and, most importantly, indications of possible undesired or even dangerous side-effects and how to avoid them. The warnings are published and also distributed by telephone and radio. Warnings on sugar beet in the Nordrhein area are distributed by the sugar factories to each of the farmers concerned. The forecasting service can certainly be improved by scientific progress. On the other hand, practical improvement is indispensable. The main problem is how to get more information from the field. There is little hope that the personnel situation will change fundamentally, but every effort must be made, in view of the importance of the forecasting service. En République féderale d'allemagne, les Lander sont chargés de la protection des végétaux. Les bureaux régionaux ont développe leurs proprés systemes de prevision, mais ceux-ci sont neanmoins très semblables. Les avertissements sont basés sur des observations de plein champ qui sont réalisées pour la plupart par des techniciens. I1 n'est pas possible d'inspecter tous les champs, vergers, etc., en raison des enormes surfaces en jeu. Les avertissements reposent sur un système normalisé comprenant I'information sur la situation présente, suivie d'une évaluation de I'evolution ulterieure, dune recommandation sur les methodes de lutte, d'une indication sur les effets secondaires indesirables ou dangereux, ainsi que des moyens de les eviter. Les avertissements sont expedies sous forme de bulletins, ou communiques par telephone ou par radio. Dans la région de Nordrhein, les avertissements concernant la betterave sont distribues aux exploitants par les sucreries. Le système de prevision peut certainement btre ameliore, surtout sur le plan pratique en beneficiant des progres scientifiques qui sont realises. I1 est essentiel de mutiplier les observations de plein champ, mais il est improbable que les services responsables puissent disposer du personnel necessaire. Cependant, face à I'importance de la prévision, il faut tirer le meilleur parti des moyens disponibles.     

Potato Wart Disease in Newfoundland1

Techniques in use for evaluating reaction of potato selections to wart disease are described. Races of potato wart similar to European Races 1, 2 and 8 have been detected in Newfoundland. To enable the results from potato wart investigations carried out in different countries to be compared, standard test procedures and an agreed series of differential varieties must be introduced.     

Distribution of Cereal and Grass Cyst Nematodes in the Federal Republic of Germany1

A survey of cereal and grass cyst nematodes in the Federal Republic of Germany revealed that Heterodera avenae is the most widely distributed heteroderid species and common mainly in areas with light sandy soils and intensive cereal cultivation. The so-called ≪race 3 ≫ was recovered several times, and other populations differing morphologically from ≪ typical ≫ H. avenae were found. H. hordecalis, H. bifenestra, H. mani, H. iri and Punctodera punctata were also recovered in many parts of the country. In arable soils these species constituted only 7 % of all records of cereal and grass cyst nematodes, whereas they prevailed in grassland, forests and other habitats, where they amounted to almost 80 % of the records. 93 % of all H. avenae records came from agricultural soils, but only 21 % of the records of the five other species. H. hordecalis and H. bifenestra are obviously of no economic importance in FRG.     

Potato Wart Pathotypes in Europe from the Ecological Point of View

The paper gives a survey of the foci of aggressive pathotypes identified and published so far in Europe (Czechoslovakia, FRG, GDR, USSR). It reports on 17 pathotypes mainly localized in montane and submontane regions of Central Europe with a more continental climate. Most of the foci lie at altitudes above 400 m with annual precipitations above 600 mm, on weathered more acid soils of illimerized type localized in small gardens and small plots. The problem of the appearance and extinction of foci of the common and more aggressive types is discussed together with possible explanations for foci in apparently atypical localities.     

Methods to control the two forms of Arvicola terrestris in orchards in the Federal Republic of Germany1

Different methods had to be developed in the Federal Republic of Germany (FRG) for the control of the fossorial and the aquatic form of Arvicola terrestris. The fossorial form could be controlled on small areas by trapping but, on large areas where this is not feasible, satisfactory results were obtained by fumigation with carbon monoxide or carbon dioxide. The latter was judged superior as it does not endanger man and proved relatively humane. Sound-emitting devices that were tested against fossorial A. terrestris showed no effect at all. To control the aquatic form, a floating poison-bait station was developed. It was tested with baits containing bromadiolone, chlorophacinone or calciferol during 2 years on an area of 300 ha. Best results were achieved with fresh carrots soaked with chlorophacinone. Careful checks of the area under investigation did not reveal any evidence of secondary poisoning of non-target species.     

Current Research Studies on Potato Wart Disease in Newfoundland1

Research includes studies on physiology of germination of the causal agent, infectivity parameters, and systemic chemotherapeutants. Germination is studied with plant and fungal extracts, plant exudates and soil leachates. Sporangia are not found to respond readily to exogenously applied chemicals. Maturity appears to be hastened under incubation with plant products. Inoculum density, sporangial age, temperature and irrigation are studied for their influence on infection. Infection appears to be less dependent on external influences, and more dependent on internal timing mechanisms. Tomato varieties tested are found to be susceptible. European races 1, 2 and 8 are used in comparative studies. Germination and infectivity are studied to throw light on possible eradication mechanisms. Chemical control is studied with systemic fungicides. To date, no control is promised. Techniques have been developed to assay germination by secondary fluorescence, and to examine large numbers of soil samples by flotation.     

The 2019 Potato Wart Disease workshop: shared needs and future research directions

Potato wart disease is caused by the fungus Synchytrium endobioticum. A workshop on this disease was held in June 2019 at the Dutch National Plant Protection Organization (NPPO-NL) in Wageningen, the Netherlands. Over 60 participants from 20 countries and 36 organizations came together to share their knowledge via presentations and posters, to strengthen professional networks, and to identify shared needs and future directions for S. endobioticum research. The three major topics of the workshop were disease occurrence and management, understanding the pathogen, and host breeding and resistance. Many aspects of this disease were discussed and summarized in a shared statement. Future directions identified were (1) research initiatives are currently being initiated to develop standardized molecular viability tests and a molecular pathotyping test, (2) coordination is needed to come up with better standardization of the pathotyping bioassays and the set of differential cultivars described in EPPO PM 7/28 needs to be better available for testing, and (3) stacking of resistance genes is strongly recommended but resistance breeding alone is not enough and should be combined with other management strategies to contain potato wart disease. Furthermore, the attendees remarked that organizing a workshop every 2 or 3 years would be of great benefit to the potato wart disease research community.     

First record of Tapesia yallundae as the teleomorph of Pseudocercosporella herpotrichoides var. acuformis, and its occurrence in the field in the Federal Republic of Germany

Tapesia yallundae is reported for the first time in the Federal Republic of Germany. Apothecia were found on wheat and rye stubble at two sites in the north of the country and one in the centre, in April 1988. Isolates of Pseudocercosporella herpotrichoides var. acuformis were obtained from germinating single ascospores, identified on the basis of colony morphology, mode of conidial production and pathogenicity to wheat and rye.     

The Relation Between Field and Laboratory Susceptibility of Potato Cultivars to Wart Disease1)

Potato wart disease has been effectively controlled legislatively by the growing of resistant cultivars. The testing of new potato seedlings for plant breeders is undertaken so that susceptibles can be removed from the breeding program at an early stage. In the laboratory, gradation of resistance and susceptibility is noted. The range of reactions is divided into 6 arbitrary groups, 3 with necrosis and 3 without (Hills , 1965), and Hille's infection patterns have been interpreted as a set of assessment keys. Susceptible cultivars show a variation in degree of susceptibility, but infections persist even though there may be a necrotic hypersensitive reaction of the host. With some less resistant cultivars, the fungus can become established in the host and complete its life cycle, but infected tissue mostly necroses and is sloughed off. These less resistant cultivars (intermediates) grow away from infection when grown on in pots. The cultivar Red Craigs' Royal showed no infection when inoculated in soil tanks (3 soil types) with heavy watering or when grown on infested land. All evidence collected gives indication that intermediate cultivars are field resistant and not affected to any measurable extent by Synchytrium endobioticum (Schilb.) Perc.     

Development of PCR-based Detection Methods for the Quarantine Phytopathogen <Emphasis Type="Italic">Synchytrium endobioticum</Emphasis>, Causal Agent of Potato Wart Disease

PCR-based methods were developed for the detection and quantification of the potato pathogen Synchytrium endobioticum in soil extracts and in planta. PCR primers, based on the internal transcribed spacer region of the multi-copy gene rDNA were tested for specificity, sensitivity and reproducibility in conventional and real-time PCR assays. Soil extraction procedures compared included the Hendrickx centrifugation (HC) procedure, nested wet sieving (NWS) and a method used by the Plant Protection Service (PPS). The primers amplified a 472 bp product from S. endobioticum DNA, but did not amplify DNA from other potato pathogens, other plant pathogens, and related species. Standard cell disruption and DNA extraction and purification methods were optimized for amplification of S. endobioticum DNA from resting sporangia. DNA was successfully amplified from a single sporangium and equivalent DNA preparations from soil extracts. Low levels of target DNA in water did not amplify, possibly due to DNA loss during final purification steps. A real-time PCR assay, developed for soil-based extracts using primers and probe based on the rDNA gene sequences, involved co-amplification of target DNA along with an internal DNA fragment. Both conventional and real-time PCR methods performed well with HC- and NWS-extracts having a threshold sensitivity of 10 sporangia per PCR assay. Of the three soil extraction methods, only with the HC method could 100 g soil samples be efficiently processed in one single PCR assay. Such a high capacity assay could be useful for routine soil analysis in respect to disease risk assessments and to secure de-scheduling according to EPPO guidelines.     

Potato virus Y (PVY) in Seed Potato Certification

Journal of Plant Diseases and Protection - In the EU and many other countries worldwide, seed potatoes require certification to be marketed. In most of the European national and international seed...