Johan Dekker, professor of plant pathology at the Wageningen Agricultural University, 1969–1989     

J. C. Zadoks 《European journal of plant pathology / European Foundation for Plant Pathology》1989,95(Z1):6-17

Johan Dekker, born 26 november 1925, in's Heerenhoek (on the island Zuid Beveland in the southwest of the Netherlands), grew up in a rural environment and was initiated in all farming practices. He went to grammar school (gymnasium ) during the turbulent years of the Second World War and graduated in 1945. He continued his education at the Wageningen Agricultural University, where he chose Tropical Agronomy as a major and Phytopathology as a minor. The academic studies were interrupted to do military service (1947–1950; reserve officer), which in the unstable post-war period required many years. The then mature student apparently became fascinated with phytopathology, as testifies his undergraduate thesis onRhabdospora ramealis (purple blotch, nowR. ruborum) as the causal agent of a blueberry disease, but he did not forget about his major, vide the literature review on rubber mildew (Oidium heveae) which would have fit in the Annual Review of Phytopathology as to thoroughness and number of references. Did his student work already indicate Dekker's abilities as an editor and review writer?Johan Dekker werd geboren op 26 november 1925 en groeide op in een agrarisch milieu. Na zijn gymnasium-opleiding studeerde hij Tropische Landbouw aan de Landbouwhogeschool, met Fytopathologie als bijvak. In 1953 behaalde hij zijn ingenieursdiploma, in 1957 zijn doctorsbul. Zijn gehele carrière speelde zich af binnen wat nu de Vakgroep Fytopathologie heet en was steeds gericht op Interne Therapie door middel van chemotherapeutica (w.o. antibiotica) en resistentiebevordering. In 1969 aanvaarde Johan Dekker het ambt van gewoon hoogleraar in de Fytopathologie. Onderwijs en onderzoek kwamen tot grote bloei onder zijn leiding. Hij had de hand in enkele patenten, meer dan 90 publikaties, en meer dan 20 proefschriften. Dekker had grote bestuurlijke belangstelling en vervulde vele bestuursfuncties, universitair, nationaal en internationaal. Zijn bijdragen tot de gewasbescherming zijn internationaal zeer gewaardeerd, zoals blijkt uit drie zeldzame internationaal-wetenschappelijke onderscheidingen. In 1989 werd Johan Dekker benoemd tot ridder in de Orde van de Nederlandse Leeuw.  相似文献   

On farm evaluation of the coproantigen ELISA and coproantigen reduction test in Scottish sheep naturally infected with Fasciola hepatica     

Gordon DK  Zadoks RN  Stevenson H  Sargison ND  Skuce PJ 《Veterinary parasitology》2012,187(3-4):436-444

The liver fluke, Fasciola hepatica, is a cause of significant economic losses in sheep farming. Lack of convenient and sensitive diagnostic tests in the live animal hampers the ability to monitor infection status and treatment efficacy. Use of a coproantigen ELISA and coproantigen reduction test, based on this ELISA, may address these issues but has, to date, only been evaluated in experimental challenge studies. We evaluated the coproantigen ELISA under working farm conditions in Scotland to assess its usefulness as a diagnostic test for liver fluke infection and as a diagnostic test to help determine the efficacy of flukicide treatment in sheep. First, liver fluke infection status was monitored longitudinally in a group of lambs, using monthly blood samples for biochemical assays and serum antibody ELISA and using monthly faecal samples for faecal egg count (FEC) and coproantigen ELISA. The average serum antibody ELISA titre became positive in September, two months ahead of faecal indicators of fluke infection. In contrast to results from experimental challenge studies, FEC and coproantigen ELISA became positive at the same time point. Secondly, treatment efficacy was measured in 100 ewes, from two farms, after treatment with triclabendazole (TCBZ) or closantel. Group level estimates of treatment efficacy were similar between faecal egg count reduction testing and coproantigen reduction testing at 7, 14 and 21 days post treatment. For individual animals, some inconsistencies between tests were observed. TCBZ treatment failure was noted on both farms, despite accurate weighing of animals and dosing of treatment products. We conclude that (1) coproantigen ELISA is a more convenient test than faecal egg counts and holds promise as a diagnostic tool for natural fluke infections in sheep but further evaluation of interpretation criteria may be needed; (2) the coproantigen ELISA has performed differently in the field compared with experimental challenge studies in sheep and (3) TCBZ-resistant fluke were present on both farms.  相似文献   

Acute cortisol responses of calves to four methods of dehorning by amputation     

SP SYLVESTER  KJ STAFFORD  DJ MELLOR  RA BRUCE  RN WARD 《Australian veterinary journal》1998,76(2):123-126

Objective To measure the plasma cortisol response in calves dehorned by four different methods (scoop, guillotine shears, saw, embryotomy wire) for 9 h after dehorning.
Design A physiological study with controls.
Procedure Horn amputation was carried out on calves restrained manually in a race.
Results The four methods of dehorning provoked similarly increased cortisol responses which lasted for 6 h. During the first hour after dehorning the plasma cortisol concentrations were similar to those following ACTH injection. The overall cortisol response to control handling was about 30% of the responses to dehorning.
Conclusions The similarity of the cortisol responses produced by the four methods of dehorning suggests that the distress experienced by calves following dehorning by amputation is similar regardless of method used.  相似文献   

Survival and Extinction of Xanthomonas campestris pv. campestris in Soil     

C.G. Kocks  M.A. Ruissen  J.C. Zadoks  M.G. Duijkers 《European journal of plant pathology / European Foundation for Plant Pathology》1998,104(9):911-923

Carry-over of inoculum of X.c. pv. campestris in the soil from one cropping season to the next was studied in field experiments over three years. These studies were supported by laboratory and greenhouse experiments on quantitative assessment of bacteria by bioassay using the Most Probable Number technique, and on recovery rates of bacteria from the soil. The mean recovery rate from artificially infested soil was 58%. Extinction of X.c. pv. campestris in soil infested with infected plant debris proceeded exponentially and extinction rates depended on temperature, as did the decomposition of plant debris. In replicated field plots, over three years, infection foci of black rot disease were established. At harvest time, all plants were chopped and resulting plant debris was rotovated into the soil. The resulting soil infestation was sampled and showed clear infestation foci reflecting the original infection foci of the crop. These infestation foci decreased with time and disappeared after the winter. Follow-up crops remained virtually uninfected. The results show that in The Netherlands good crop and soil management impedes survival of inoculum from one year to the next, so that cabbage can be grown continuously. Polyetic carry-over of inoculum by debris in the soil can be avoided in The Netherlands.  相似文献   

Development of potato late blight epidemics: disease foci, disease gradients, and infection sources     

Zwankhuizen MJ  Govers F  Zadoks JC 《Phytopathology》1998,88(8):754-763

ABSTRACT Natural potato late blight epidemics were studied to assess the relative impact of various inoculum sources of Phytophthora infestans in Southern Flevoland (the Netherlands) from 1994 through 1996. Disease surveys were combined with characterization of isolates for mating type and DNA fingerprint pattern using probe RG57. Seventy-four percent of the commercial potato fields with early foci were clearly associated with nearby infested refuse piles. Characterization of isolates from refuse piles and fields confirmed the association. Infected seed tubers, volunteer plants, and infested allotment gardens appeared to be of minor importance for late blight development in potato fields. Several foci in refuse piles, potato fields, and allotment gardens contained more than one genotype. Due to favorable weather in August 1994, infested organic potato fields became major inoculum sources, resulting in the spread of P. infestans to adjacent conventional potato fields. Analyses of disease gradients, both at the field and regional levels, confirmed the role of the organic fields as mid-season infection sources. The mean slope of field gradients downwind of refuse piles (point sources) was significantly steeper (100-fold difference) than the mean slope of field gradients downwind of organic fields (area sources). The genotypic composition of the P. infestans populations along the gradient and of the source populations in the organic potato crops did not differ significantly. Analysis of the region gradient revealed genotype-specific disease gradients. Control measures are recommended.  相似文献   

International testing of incomplete resistance against brown rust (Puccinia recondita) in IPHR wheat lines     

W. A. J. de Milliano  M. A. Beek  J. C. Zadoks 《European journal of plant pathology / European Foundation for Plant Pathology》1986,92(2):49-56

Promising wheat lines from FAO's International Program for Horizontal Resistance (IPHR) in Brazil and Zambia were tested in the Netherlands against brown rust (Puccinia recondita. f.sp.tritici). Race nursery tests were performed on isolated field plots using five monopustular isolates from the Netherlands representing at least four races. Mature plants of several lines showed high incomplete resistance. For most lines, the reactions to the different races showed a high uniformity. Apparently, lines selected according to the IPHR principles can perform well when exposed to brown rust isolates to which they have not been exposed during selection.Samenvatting Veelbelovende tarwelijnen uit het Internationale Programma voor Horizontale Resistentie (IPHR) van de FAO in Brazilië en Zambia werden in Nederland getoetst tegen bruine roest (Puccinia recondita f.sp.tritici). Hierbij werd gebruik gemaakt van de fysiovelden-techniek. Geïsoleerde fysiovelden werden geïnoculeerd met vijf Nederlandse isolaten, ieder afkomstig van een sporenhoopje. Deze vijf isolaten vertegenwoordigden ten minste vier fysio's. Bij verscheidene lijnen vertoonden de volwassen planten een hoge mate van onvolledige resistentie. De meeste lijnen vertoonden in hun reactie op de verschillende fysio's een hoge mate van uniformiteit. Kennelijk kunnen lijnen, geselecteerd volgens de beginselen van het IPHR goede resultaten geven wanneer zij getoetst worden met roest-isolaten, waaraan zij tijdens het selectieproces nooit zijn blootgesteld.  相似文献   

Phytophthora infestans's 10-year truce with Holland: a long-term analysis of potato late-blight epidemics in the Netherlands   总被引：1，自引：0，他引：1  

M. J. Zwankhuizen  J. C. Zadoks ‡ 《Plant pathology》2002,51(4):413-423

A sequence of 47 potato late-blight ( Phytophthora infestans ) epidemics in the Netherlands, from 1950 to 1996, was analysed using agronomic and meteorological variables. The intensity of annual epidemics was characterized by an index of disease intensity (DI, 0 = absence of late blight; 4 = severe epidemic). Three periods were identified, with average DIs of 2·9, 0 and 2, respectively. Period I (1950–68) had relatively regular epidemics; period II (1969–78) was virtually blight free; and period III (1979–96) showed large variations in disease intensity. Disease-enhancing factors were number of days with precipitation, and number of hours with temperatures between 10 and 27°C and relative humidity >90% during the growing season. Limiting factors were number of hours with temperatures >27°C, and amount of global radiation. Linear discriminant analysis of DI using the blight status of the previous year and meteorological variables correctly classified up to 40 years out of 47 (87·0%), with five out of the six incorrectly classified years falling in period III. Blight status of the previous year and number of days with precipitation were important discriminating variables.  相似文献   

Long‐Term Outcome in Dogs After Circumcostal Gastropexy or Gastrocolopexy for Gastric Dilatation With or Without Volvulus     

ANNA V. EGGERTSDÓTTIR DVM  PhD  MARIANNE LANGELAND DVM  PhD  BJØRN FUGLEM DVM  ANE MOHN DVM  ØYVIND STIGEN DVM  PhD 《Veterinary surgery : VS》2008,37(8):809-810

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Effect of Insemination–Ovulation Interval and Addition of Seminal Plasma on Sow Fertility to Insemination of Cryopreserved Sperm     

M Abad  JC Garcia  DJ Sprecher  G Cassar  RM Friendship  MM Buhr  RN Kirkwood 《Reproduction in domestic animals》2007,42(4):418-422

In swine, the use of frozen-thawed (FT) sperm for artificial insemination (AI) is limited because of poor sow fertility, possibly associated with a post-thaw capacitation-like status resulting in fewer fully viable sperm. Sow fertility to AI with FT sperm may improve with deeper deposition of sperm within the female tract, insemination very close to ovulation, or reversal of cryocapacitation by seminal plasma (SP). We performed two experiments to examine these suggestions. In experiment 1, 122 multiparous Yorkshire sows received 600 IU equine chorionic gonadotrophin at weaning and 5 mg pLH 80 h later to control time of ovulation. The predicted time of ovulation (PTO) was 38 h after pLH injection. Thereafter, sows were assigned on the basis of parity to a single AI of FT sperm at 2 h before PTO, or at 12 h before PTO, or FT sperm supplemented with 10% SP at 12 h before PTO. Control sows received fresh semen at 12 h before PTO. All semen doses were adjusted to 3 x 10(9) live cells and deposited into the cervix. Experiment 2 employed 99 multiparous crossbred sows and repeated the treatments of experiment 1 except that all FT inseminations were intrauterine. In both experiments, farrowing rates were lower (p < 0.01) following FT inseminations with no effect of time of insemination or of supplemental SP. In experiment 1, litter size was smaller following FT insemination (p < 0.05), but no effect on litter size was evident in experiment 2. Supplemental SP had no effect on litter size in either experiment. The lack of effect of either SP or timing of FT insemination on sow fertility suggests that the non-lethal sperm cryoinjury affecting fertility involves more than just cryocapacitation.  相似文献   

Verenigingsnieuws     

Dr. J. C. Zadoks 《European journal of plant pathology / European Foundation for Plant Pathology》1963,69(3):218-220

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