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Florian Leiber - One of the best experts on this subject based on the ideXlab platform.

  • milk fatty acid composition of dairy cows fed green whole plant buckwheat Phacelia or chicory in their vegetative and reproductive stage
    Animal Feed Science and Technology, 2014
    Co-Authors: Tasja Kalber, Michael Kreuzer, Florian Leiber
    Abstract:

    tThe hypothesis was tested that the phenological stage of dicotyledonous forages influencesmilk fatty acid (FA) composition of dairy cows. For this purpose buckwheat (Fagopyrum escu-lentum) and Phacelia (Phacelia tanacetifolia; both in their first year of cultivation) as well aschicory (Cychorium intybus; second year) were cultivated in mixture with ryegrass (Loliummultiflorum). After 35 days of growth, feeding the green forages to 3 × 6 late lactating dairycows at ad libitum access started. The realized dietary dry matter proportions of the testplants were (vegetative and reproductive stage): buckwheat, 0.60 and 0.55; chicory, 0.70and 0.69; Phacelia, 0.51 and 0.48. Experimental feeding lasted for 23, 17 and 26 days withbuckwheat, chicory and Phacelia, respectively. The complete diets additionally contained2 kg of concentrate and 1 kg of barley straw per day per animal. Milk and feed sampleswere analyzed from every second day. Feedstuffs were analyzed for proximate contents,FA and fractions of phenolic compounds. In milk samples solids and FA were measured.Contents of FA and of phenol fractions decreased during advancing development stage inall test plants except total extractable phenols and total tannins in Phacelia. This decreasewas particularly pronounced for a-linolenic acid (ALA) and linoleic acid (LA) in buckwheat.Phenological stage had no influence on milk yield and gross composition, but ALA and LAproportions of milk fat declined with time in all groups. Proportions of ALA (14.2 g/kg FA)and total poly-unsaturated FA in milk fat were highest with Phacelia. Levels of conjugatedlinoleic acid (CLA) in milk fat were not affected by treatment or phenological stage. Vaccenicacid in milk fat was slightly elevated when feeding buckwheat and Phacelia in the repro-ductive stage whereas it decreased with ongoing development in the chicory group. Nosystematic influence of phenological stage on the relative recovery of feed FA in milk fatoccurred. The study did not confirm the hypothesis that the recovery rate of ALA wouldincrease with maturing of the forages. In terms of generating a desired milk FA profile,Phacelia and chicory seem however to be generally promising.

  • flowering catch crops used as forage plants for dairy cows influence on fatty acids and tocopherols in milk
    Journal of Dairy Science, 2011
    Co-Authors: Tasja Kalber, Michael Kreuzer, Janina S Meier, Florian Leiber
    Abstract:

    Abstract The effect of several flowering dicotyledonous catch crop plants (dicots) on milk fat quality in cows was investigated to test the hypothesis that their phenolic compounds may inhibit ruminal biohydrogenation and thus enhance the transfer to milk of intact, plant-derived polyunsaturated fatty acids. Berseem clover ( Trifolium alexandrinum ), buckwheat ( Fagopyrum esculentum ), and Phacelia ( Phacelia tanacetifolia ) were sown in mixture with ryegrass ( Lolium multiflorum ; intended biomass proportion of 0.2) on 1ha. For comparison, nonflowering chicory ( Cichorium intybus , also sown in mixture with ryegrass) and pure ryegrass were cultivated. Realized biomass proportions (wet weight) were 91% for berseem clover, 69% for buckwheat, 54% for Phacelia, and 51% for chicory. At the start of flowering (or from d 47 after sowing onward), cultures were harvested daily and fed for 20 d ad libitum to groups of 6 midlactation cows each. Additionally, 1kg each of energy and protein concentrate and pure ryegrass hay were fed. Individual intake and milk yield of the cows were measured daily. Milk samples were obtained twice daily 5 d before and from 11 to 20 d after the start of treatment feeding. Feed samples were drawn twice a week from the fresh feeds. Apart from standard traits, feeds and milk were analyzed for fatty acids, tocopherols, and phenolic fractions. Only a few substantial treatment effects on intake and performance were observed. All diets based on dicots increased α-linolenic acid (ALA) concentrations in milk fat compared with the ryegrass diet even though the corresponding swards were not generally richer in ALA. The highest ALA concentration in milk fat (1.3 g/100g of fatty acids) occurred with the berseem clover diet. Transfer rate of ALA from feed to milk was highest with the buckwheat diet (0.09) and lowest with ryegrass (0.05). This was congruent with the differences in total extractable phenols, being high in the buckwheat sward (2.6% of dry matter) and low in the ryegrass sward (1.2% of dry matter). Intermediates of ALA biohydrogenation were lowest in the milk fat of the buckwheat group, indicating an inhibitory effect of this treatment, which provided the highest dietary levels of phenols. The α-tocopherol concentration in milk was higher with the buckwheat diet than with berseem clover and Phacelia diets. The study provides evidence that the ALA concentration in milk fat could be enhanced by feeding flowering dicots; however, this was due to different modes of action.

Stephen D. Wratten - One of the best experts on this subject based on the ideXlab platform.

  • host plant selection by the wheat bug nysius huttoni hemiptera lygaeidae on a range of potential trap plant species
    Journal of Economic Entomology, 2018
    Co-Authors: Sundar Tiwari, Nicholas M Dickinson, David J Saville, Stephen D. Wratten
    Abstract:

    The wheat bug, Nysius huttoni L. is an endemic New Zealand pest. The seedlings of forage brassicas are highly susceptible to direct feeding damage by this insect, and this can reduce plant establishment. Prophylactic use of pesticides is the usual practice for N. huttoni management. These practices have been linked to environmental pollution, biodiversity loss, and pollinator population declines in brassicas and other crops. Habitat management of the bug utilizing potential trap crops can be a better option for its management. A series of choice, no-choice, and paired-choice tests were conducted in a controlled-temperature room to evaluate the pest’s preferences on seedlings of eight plant species. Kale plants (Brassica oleracea) were used as a potentially susceptible control, and seven non-kale plants were compared with kale as potential trap-plant species. These were: Lobularia maritima (L.) Desvaux (alyssum), Triticum aestivum L. (wheat), Phacelia tanacetifolia Bentham (Phacelia), Fagopyrum esculentum Moench (buckwheat), Coriandrum sativum L. (coriander), Trifolium repens L. (white clover), and Medicago sativa L. (lucerne). In choice tests, wheat was the most suitable followed by alyssum, buckwheat, and Phacelia, all significantly more favored than kale. In no-choice tests, alyssum was significantly more favored than kale and the other plant species except wheat and Phacelia. First feeding damage was recorded on alyssum in both the above test conditions. For paired-choice tests including kale, wheat, and alyssum were significantly more suitable than brassica. These findings are important for developing agro-ecological management strategies. Alyssum followed by wheat were the most suitable trap plants for N. huttoni. These two plant species can be deployed in and around brassica fields either independently or as in a multiple trap-cropping system to reduce bug damage, minimizing or avoiding pesticides, and delivering a range of ecosystem services.

  • host plant selection by the wheat bug nysius huttoni hemiptera lygaeidae on a range of potential trap plant species
    New Zealand Plant Protection, 2017
    Co-Authors: Sundar Tiwari, Nicholas M Dickinson, David J Saville, Stephen D. Wratten
    Abstract:

    Nysius huttoni is an endemic New Zealand insect pest. Its feeding can seriously reduce crop establishment in forage brassicas. A series of choice, no-choice and paired-choice tests were conducted in a controlled- temperature room to evaluate the pest’s host preferences on seedlings of eight plant species: Lobularia maritima (alyssum), Triticum aestivum (wheat), Phacelia tanacetifolia (Phacelia), Fagopyrum esculentum (buckwheat), Coriandrum sativum (coriander), Trifolium repens (white clover) and Medicago sativa (alfalfa), and Brassica oleracea (kale) as a potentially susceptible control. In choice tests, wheat was the most preferred followed by alyssum, buckwheat and Phacelia, all being signi cantly more favoured than kale. Survival rate of wheat bugs over 120 h was: on Phacelia (71.0%), clover (69.0%), alyssum (48.0%) and wheat (47%), which were all signi cantly higher than on kale seedlings. Alyssum and wheat were more susceptible to N. huttoni feeding damage than were other tested plants. High survival rates were recorded in paired choice tests on kale and alyssum (78.3%) compared with the other paired choice tests. The implications of these ndings are important for developing ecological management strategies in, or around, forage brassica elds.

  • floral nectar affects longevity of the aphid parasitoid aphidius ervi and its hyperparasitoid dendrocerus aphidum
    New Zealand Plant Protection, 2006
    Co-Authors: Salaheddin Araj, Stephen D. Wratten, Hannah L Buckley
    Abstract:

    In this study, the potential consequences of making a three- or four-trophic level system more complex by adding floral resources was studied in the laboratory for a range of plant nectar sources, the aphid parasitoid Aphidius ervi and its hyperparasitoid Dendrocerus aphidum. Parasitoids exposed to flowering buckwheat survived 4-5 times longer than those in the control (water only) and 3-4 times longer than those provided with Phacelia, alyssum or coriander. Hyperarasitoids provided with buckwheat survived 5–6 times longer than those in the control and 3-5 times longer than those on the other flowering plants. Buckwheat, Phacelia, alyssum and coriander can therefore enhance the ‘fitness’ of A. ervi without benefiting its aphid host, which does not feed on nectar. However, the ‘fitness’ of the hyperparasitoid may increase relatively more than that of the parasitoid, depending on the nectar source.

  • the effects of floral understoreys on parasitism of leafrollers lepidoptera tortricidae on apples in new zealand
    Agricultural and Forest Entomology, 2006
    Co-Authors: N A Irvin, S L Scarratt, R B Chapman, Stephen D. Wratten, Christopher M. Frampton, Jason M. Tylianakis
    Abstract:

    Field and laboratory experiments on the conservation biocontrol of lepidop- teran leafroller pests were carried out in apples at Lincoln, New Zealand. 2 Apple understoreys were planted with replicated treatments of alyssum (Lobularia maritima), Phacelia (Phacelia tanacetifolia) and buckwheat (Fagopyrum esculentum). 3 Rates of parasitism of experimentally released larvae of the light-brown apple moth, Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae), by Dolichogenidea tasmanica (Cameron) (Hymenoptera: Braconidae) were signifi- cantly lower in Phacelia and control treatments, and leafroller pupae were significantly more abundant in controls than in buckwheat and alyssum treatments. 4 Naturally occurring leafroller damage was up to 29% lower above all the floral understorey treatments compared with controls and there were more than twice as many D. tasmanica cocoons in the alyssum and buckwheat treatments than in controls. 5 Suction sampling of the understoreys gave D. tasmanica adult densities that were significantly more abundant in alyssum compared with other treatments. Numbers of Anacharis zealandica (Hymenoptera: Figitidae) (a parasitoid of larvae of the predatory brown lacewing) did not differ between treatments. 6 In the laboratory, flowering buckwheat and alyssum enhanced D. tasmanica longevity by up to 78% compared with the control, and buckwheat also enhanced potential fecundity by 62%. 7 In choice experiments, leafroller larvae in the laboratory consumed more than three-fold more apple leaf material than they did of the three understorey species, although alyssum increased leafroller fecundity and longevity. 8 The use of floral understoreys for conservation biocontrol of apple pests is discussed, along with the potential negative effects of some flowering species on pest populations and orchard agronomic practices.

Tasja Kalber - One of the best experts on this subject based on the ideXlab platform.

  • milk fatty acid composition of dairy cows fed green whole plant buckwheat Phacelia or chicory in their vegetative and reproductive stage
    Animal Feed Science and Technology, 2014
    Co-Authors: Tasja Kalber, Michael Kreuzer, Florian Leiber
    Abstract:

    tThe hypothesis was tested that the phenological stage of dicotyledonous forages influencesmilk fatty acid (FA) composition of dairy cows. For this purpose buckwheat (Fagopyrum escu-lentum) and Phacelia (Phacelia tanacetifolia; both in their first year of cultivation) as well aschicory (Cychorium intybus; second year) were cultivated in mixture with ryegrass (Loliummultiflorum). After 35 days of growth, feeding the green forages to 3 × 6 late lactating dairycows at ad libitum access started. The realized dietary dry matter proportions of the testplants were (vegetative and reproductive stage): buckwheat, 0.60 and 0.55; chicory, 0.70and 0.69; Phacelia, 0.51 and 0.48. Experimental feeding lasted for 23, 17 and 26 days withbuckwheat, chicory and Phacelia, respectively. The complete diets additionally contained2 kg of concentrate and 1 kg of barley straw per day per animal. Milk and feed sampleswere analyzed from every second day. Feedstuffs were analyzed for proximate contents,FA and fractions of phenolic compounds. In milk samples solids and FA were measured.Contents of FA and of phenol fractions decreased during advancing development stage inall test plants except total extractable phenols and total tannins in Phacelia. This decreasewas particularly pronounced for a-linolenic acid (ALA) and linoleic acid (LA) in buckwheat.Phenological stage had no influence on milk yield and gross composition, but ALA and LAproportions of milk fat declined with time in all groups. Proportions of ALA (14.2 g/kg FA)and total poly-unsaturated FA in milk fat were highest with Phacelia. Levels of conjugatedlinoleic acid (CLA) in milk fat were not affected by treatment or phenological stage. Vaccenicacid in milk fat was slightly elevated when feeding buckwheat and Phacelia in the repro-ductive stage whereas it decreased with ongoing development in the chicory group. Nosystematic influence of phenological stage on the relative recovery of feed FA in milk fatoccurred. The study did not confirm the hypothesis that the recovery rate of ALA wouldincrease with maturing of the forages. In terms of generating a desired milk FA profile,Phacelia and chicory seem however to be generally promising.

  • flowering catch crops used as forage plants for dairy cows influence on fatty acids and tocopherols in milk
    Journal of Dairy Science, 2011
    Co-Authors: Tasja Kalber, Michael Kreuzer, Janina S Meier, Florian Leiber
    Abstract:

    Abstract The effect of several flowering dicotyledonous catch crop plants (dicots) on milk fat quality in cows was investigated to test the hypothesis that their phenolic compounds may inhibit ruminal biohydrogenation and thus enhance the transfer to milk of intact, plant-derived polyunsaturated fatty acids. Berseem clover ( Trifolium alexandrinum ), buckwheat ( Fagopyrum esculentum ), and Phacelia ( Phacelia tanacetifolia ) were sown in mixture with ryegrass ( Lolium multiflorum ; intended biomass proportion of 0.2) on 1ha. For comparison, nonflowering chicory ( Cichorium intybus , also sown in mixture with ryegrass) and pure ryegrass were cultivated. Realized biomass proportions (wet weight) were 91% for berseem clover, 69% for buckwheat, 54% for Phacelia, and 51% for chicory. At the start of flowering (or from d 47 after sowing onward), cultures were harvested daily and fed for 20 d ad libitum to groups of 6 midlactation cows each. Additionally, 1kg each of energy and protein concentrate and pure ryegrass hay were fed. Individual intake and milk yield of the cows were measured daily. Milk samples were obtained twice daily 5 d before and from 11 to 20 d after the start of treatment feeding. Feed samples were drawn twice a week from the fresh feeds. Apart from standard traits, feeds and milk were analyzed for fatty acids, tocopherols, and phenolic fractions. Only a few substantial treatment effects on intake and performance were observed. All diets based on dicots increased α-linolenic acid (ALA) concentrations in milk fat compared with the ryegrass diet even though the corresponding swards were not generally richer in ALA. The highest ALA concentration in milk fat (1.3 g/100g of fatty acids) occurred with the berseem clover diet. Transfer rate of ALA from feed to milk was highest with the buckwheat diet (0.09) and lowest with ryegrass (0.05). This was congruent with the differences in total extractable phenols, being high in the buckwheat sward (2.6% of dry matter) and low in the ryegrass sward (1.2% of dry matter). Intermediates of ALA biohydrogenation were lowest in the milk fat of the buckwheat group, indicating an inhibitory effect of this treatment, which provided the highest dietary levels of phenols. The α-tocopherol concentration in milk was higher with the buckwheat diet than with berseem clover and Phacelia diets. The study provides evidence that the ALA concentration in milk fat could be enhanced by feeding flowering dicots; however, this was due to different modes of action.

Robert Patterson - One of the best experts on this subject based on the ideXlab platform.

  • nomenclatural adjustments in Phacelia sect glandulosae hydrophyllaceae boraginales
    Western North American Naturalist, 2016
    Co-Authors: Genevieve K. Walden, Laura M Garrison, Robert Patterson
    Abstract:

    Abstract. Three taxa are recognized at the rank of species based on molecular phylogenetic studies in Phacelia sect. Glandulosae (Hydrophyllaceae, Boraginales). Results of those studies did not support a monophyletic Phacelia crenulata Torr. ex S. Watson, because 3 varieties of that species were supported as distinct lineages based on molecular (nuclear and chloroplast) and morphological characters. Typification and status is clarified for P. corrugata A. Nelson and P. orbicularis Rydb. A new nomenclatural combination for P. crenulata var. angustifolia N.D. Atwood is established to elevate that variety to species rank, as Phacelia angustifolia (N.D. Atwood) Walden, comb. et stat. nov.

  • phylogenies and chromosome evolution of Phacelia boraginaceae hydrophylloideae inferred from nuclear ribosomal and chloroplast sequence data
    Madroño, 2014
    Co-Authors: Genevieve K. Walden, Laura M Garrison, Greg S Spicer, Frank W Cipriano, Robert Patterson
    Abstract:

    Abstract This project sampled throughout Phacelia using the internal transcribed spacer region (ITS-1, ITS-2, and 5.8S gene) of nuclear ribosomal DNA (nrITS) and the chloroplast DNA gene (ndhF) to infer phylogenies for nuclear and plastid partitions. Nuclear and plastid partitions were incongruent in our analyses. Phylogenetic analyses (maximum parsimony, maximum likelihood, and Bayesian inference) recovered gene tree topologies similar to previous molecular studies. We corroborate incongruence between nuclear and plastid topologies for placement of some problematic groups (e.g., Draperia, Romanzoffia and “core” Phacelia subg. Pulchellae, Phacelia sect. Baretiana). Combined analyses resulted in better resolution than separate analyses, and in a topology that favored the separate plastid topologies. Romanzoffia was sister to a monophyletic Phacelia in the combined analyses. Our results support combining incongruent partitions in a combined analysis to seek support for internal nodes. Maximum likelihood ana...

  • nomenclature of subdivisions within Phacelia boraginaceae hydrophylloideae
    Madroño, 2012
    Co-Authors: Genevieve K. Walden, Robert Patterson
    Abstract:

    Abstract Nomenclature of subdivisions within Phacelia Juss. (Boraginaceae: Hydrophylloideae) reflects an update to the classification of the genus, based largely upon the structure offered in summary by Ferguson. We consider this proposed classification a continuation of efforts to better understand interrelationships within the genus and tribe Romanzoffieae Dumort., and anticipate future research offering insights into systematics of Phacelia. New names, changes in status, and combinations include the following: Phacelia sect. Baretiana Walden & R. Patt., sect. nov.; P. subsect. Bipinnatifidae (Small) Walden & R. Patt., stat. nov.; P. subsect. Cosmantha (Nolte ex A. de Candolle) Walden & R. Patt., stat. nov.; P. subsect. Cosmanthoides (A. Gray) Walden & R. Patt., stat. nov.; P. subsect. Dubiae (Small) Walden & R. Patt., stat. nov.; P. subsect. Eutoca (R. Br.) Walden & R. Patt., stat. nov.; P. sect. Glandulosae (Rydb.) Walden & R. Patt., stat. nov.; P. subsect. Humiles Walden & R. Patt., subsect. nov.; P....

  • NOMENCLATURAL KANKEDORTS IN Phacelia (BORAGINACEAE: HYDROPHYLLOIDEAE)
    Madroño, 2011
    Co-Authors: Genevieve K. Walden, Robert Patterson
    Abstract:

    Abstract The following nomenclatural combinations in Phacelia (Boraginaceae) are established: P. campanularia A. Gray var. vasiformis (G. W. Gillett) Walden & R. Patterson, stat. nov.; P. imbricata Greene var. bernardina (Greene) Walden & R. Patterson, stat. nov.; P. imbricata Greene var. patula (Greene) Walden & R. Patterson, stat. nov.; and P. nemoralis Greene var. oregonensis (Heckard) Walden & R. Patterson, stat. nov. Typification and clarification of nomenclature is provided for Phacelia floribunda Greene and Phacelia phyllomanica A. Gray. Synonymies are provided for all names.

  • phylogenetic relationships between and within Phacelia sections whitlavia and gymnobythus boraginaceae
    Systematic Botany, 2009
    Co-Authors: Debra R Hansen, Greg S Spicer, Robert Patterson
    Abstract:

    Abstract Phylogenetic relationships between and within Phacelia sections Whitlavia and Gymnobythus are inferred based on nuclear ribosomal DNA [5.8S, and flanking internal transcribed spacers (ITS) 1 and 2] and chloroplast DNA (rpl16 intron) sequences. These two sections share morphological characters and have been thought to be closely related. The purpose of this study is to test whether each of the two sections is monophyletic as well as whether they form sister clades. Our results indicate that section Gymnobythus is monophyletic, and members of section Whitlavia form two clades that correspond to subsections previously suggested by Gillett. In the ITS dataset, the two Whitlavia groups are not sister clades, but there is little support for their placement. The rpl16 and rpl16 + ITS combined datasets provide resolution and strong support for monophyly of both sections. Both datasets indicate hybridization or a recent divergence between Phacelia parryi and Phacelia minor, as well as a close alliance bet...

Müller J. - One of the best experts on this subject based on the ideXlab platform.

  • Der Einfluß der Kulturdauer verschiedener Zwischenfrüchte auf die Abundanzdynamik von Heterodera schachtii Schmidt
    Nachrichtenblatt des Deutschen Pflanzenschutzdienstes, 2018
    Co-Authors: Müller J., Steudel W.
    Abstract:

    Bei vier verschiedenen Zwischenfrüchten wurde die Abundanzdynamik von Heterodera schachtii nach vier Saatterminen und nach vier Umbruchterminen untersucht. Unter Phacelia lag der natürliche Rückgang bei 30 %. Resistenter Ölrettich war mit Populationsabnahmen zwischen 50 und 60 % deutlich überlegen.Ein erstmals im Feldversuch geprüfter resistenter Senf lag im Bereich der Neutralpflanze Phacelia. Die unterschiedlichen Vegetationszeiten beeinflußten die Nematodenvermehrung nur unter anfälligem Ölrettich. Bei den resistenten Zwischenfrüchten und bei Phacelia war die Populationsentwicklung von H. schachtii unabhängig von den Saat- bzw. Umbruchterminen. The influence of the growing time of different green manure crops on the population dynamics of Heterodera schachtii Schmidt The population dynamics of Heterodera schachtii was investigated in four different green manure crops after four different sowing times and after four dates of destroying the crop by rotary hoe. In Phacelia the natural population decline was 30 %. Resistent oil radish (Raphanus sativus L.) reduced nematode populations to 40-50 %, and therefore was superior to the non-host crop. The effect of resistant mustard (Sinapis alba L.), which was tested for the first time in a field trial, was comparable to that of Phacelia. The different growing times had only in susceptible oil radish an influence on nematode multiplication. In the resistant green manure crops and in Phacelia the population decline was independent of sowing time or time of destroying the crop

  • Untersuchungen zum Einfluß einiger Zwischenfrüchte auf die Abundanzdynamik des Rübennematoden (Heterodera schachtii Schmidt) in einer Zuckerrüben-Getreide-Fruchtfolge
    Nachrichtenblatt des Deutschen Pflanzenschutzdienstes, 2017
    Co-Authors: Steudel W., Schlang J., Müller J.
    Abstract:

    In einer dreijährigen Fruchtfolge von Zuckerrüben, Winterweizen und Wintergerste wurden Phacelia tanacetifolia, Ölrettich 'Siletina' und 'Pegletta' sowie Weißer Senf 'Maxi' als Zwischenfrüchte angebaut. Das Feld war mit Rübennematoden verseucht; die Abundanzdynamik von Heterodera schachtii wurde von 1983 bis 1988 regelmäßig getrennt für drei Bodentiefen untersucht. Aus den gefundenen Daten lassen sich die folgenden Erkenntnisse ableiten: Zwischen den Bodentiefen 0-15 cm und 15-30 cm bestehen nur geringe Unterschiede in der Abundanzdynamik, während der Verlauf in 30-45 cm Tiefe davon deutlich abweicht. Die unterste Bodenzone enthält ein vergleichsweise hohes Infektionspotential.Die direkte Wirkung der resistenten Zwischenfrüchte auf H. schachttii entspricht den bisherigen positiven Erfahrungen hinsichtlich des Populationsabbaus. Der Bekämpfungserfolg ist in der untersten Bodenzone besonders deutlich.Neben der direkten Wirkung im Anbaujahr muß auch die Folgewirkung der Zwischenfrüchte beachtet werden. Anfälliger Ölrettich 'Siletina' vermehrte zwar zunächst die Nematoden, unter den folgenden Zuckerrüben ging in einem Jahr die Populationsdichte aber wieder zurück. Dagegen hatte Phacelia als Vorkultur unter Zuckerrüben die höchste Vermehrungsrate zur Folge, so daß der Besatz in diesem Versuchsglied langfristig das höchste Niveau erreichte.   Studies on the influence of catch crops on population dynamics of the sugar beet nematode (Heterodera schachtii Schmidt) in a sugar beet/cereal rotation Phacelia tanacetifolia, oil radish 'Siletina' and 'Pegletta' and white mustard 'Maxi' were grown as catch crops in a three year rotation of sugar beet, winter whcat and winter barley. The field was infested with beet cyst nematodes; the population dynamics of Heterodera schachtii was investigated separately for three soil depths from 1983-1988. The following conclusions are drawn: Population dynamics are similar in 0-15 cm compared to 15-30 cm soil depth, but they differ considerably from the situation in 30-45 cm. The deepest soil layer contains a remarkable nematode potential.Resistant catch crops have a direct effect on H. schachtii, which is in accordance with previous positive results. A high control level is reached especially in the deepest soil layer.Not only the direct, but also the long-term effect of catch crops must be taken into account. Obviously the susceptible oil radish 'Siletina' multiplied the nematode, but in the following sugar beet crop the population density decreased. On the other band, Phacelia as precrop caused high multiplication rates under sugar beet, and on the long-term highest population levels were observed in this treatment