The relationship of potato yield with and without nematicide to density of potato cyst nematodes, lobodera rostochiensis and G. pallida

1983 ◽  
Vol 103 (3) ◽  
pp. 471-476 ◽  
Author(s):  
E. B. BROWN
2021 ◽  
pp. 319-326
Author(s):  
Bernd Augustin

Abstract Potato is an important crop throughout Europe and especially in Germany where potatoes are grown on over 250,000 hectares. The production of potato worldwide is negatively affected by the presence of the golden and the white potato cyst nematodes (PCN) Globodera rostochiensis and G. pallida. The two species originated in South America. PCN is present with restricted distribution in all counties in Germany where potato is produced and these infestations are strictly regulated. Both species are present and often in mixed populations. Potato yield and overall production is negatively impacted by both species of PCN from planting to harvest, but there are differences in importance within the country and on crop type. This chapter discusses the economic importance, host range, distribution, symptoms of damage, biology and life cycle, integrated nematode management (including the use of nematicides, resistant cultivars and rotation), and interactions with other nematodes and pathogens, of PCN. Results are also summarized of field trials conducted between 2010 and 2017 to compare the efficacy of resistant cultivars and nematicide Nemathorin 10G with the alternative control techniques biofumigation and sowing of Solanum sisymbriifolium that has PCN suppressive activity.


Plant Disease ◽  
2017 ◽  
Vol 101 (7) ◽  
pp. 1182-1187 ◽  
Author(s):  
Wendy S. Phillips ◽  
Megan Kitner ◽  
Inga A. Zasada

Globodera ellingtonae is a recently described nematode parasite of potato, which is closely related to the economically significant potato cyst nematodes G. rostochiensis and G. pallida. Because of the close relationship of G. ellingtonae to the potato cyst nematodes, a greater understanding of its biology is critical. Two experiments were conducted in Oregon to explore the developmental biology of G. ellingtonae in field-grown potato. The first experiment was conducted in 2013 and 2014 to determine the developmental timing of G. ellingtonae life stages and reproduction by inoculating potato with soil containing cysts followed by weekly collection of soil and root samples. Life stages; second-stage juveniles (J2) in soil and roots, third-stage juveniles (J3) and fourth-stage (J4) females and males in roots, males and females or cysts in soil, and egg number and developmental state were quantified. Normalizing across years using accumulated developmental degree days above 6°C (DD6), J2 of G. ellingtonae were found in soil from 41 to 588 DD6; two peaks of J2 invasion of roots were observed. The first adult females were observed at 387 and 449 DD6 in 2013 and 2014, respectively. The next generation of eggs was first observed from 675 to 854 DD6 and 50% egg development (containing a vermiform juvenile) occurred at approximately 920 DD6. A second J2 hatch was observed in both years at 927 to 1,073 DD6. The developmental dynamics of G. ellingtonae observed here are similar to those reported for G. rostochiensis and G. pallida from several geographical locations. In the second experiment, the effect of potato and bare soil on G. ellingtonae egg hatch was evaluated; in 2014 and 2015, packages containing cysts in soil were buried under potato or in bare soil at the time of planting and eggs per cyst determined weekly. Across years, a significant reduction in eggs per cysts under potato (>50%) was observed 35 days after planting (DAP) and, at 63 DAP, eggs per cyst were reduced by 76 to 96% compared with initial egg per cyst densities. In bare soil, the maximum reduction in densities of eggs per cyst was 55 to 73%. This annual reduction in egg numbers of G. ellingtonae in bare soil is similar to that reported for G. pallida and G. rostochiensis.


1997 ◽  
Vol 40 (4) ◽  
pp. 375-381 ◽  
Author(s):  
A. Mulder ◽  
A. F. Van Der Wal ◽  
R. A. J. Velema ◽  
J. S. Roosjen

Paleobiology ◽  
1980 ◽  
Vol 6 (02) ◽  
pp. 146-160 ◽  
Author(s):  
William A. Oliver

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.


Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.


Author(s):  
Leon Dmochowski

Electron microscopy has proved to be an invaluable discipline in studies on the relationship of viruses to the origin of leukemia, sarcoma, and other types of tumors in animals and man. The successful cell-free transmission of leukemia and sarcoma in mice, rats, hamsters, and cats, interpreted as due to a virus or viruses, was proved to be due to a virus on the basis of electron microscope studies. These studies demonstrated that all the types of neoplasia in animals of the species examined are produced by a virus of certain characteristic morphological properties similar, if not identical, in the mode of development in all types of neoplasia in animals, as shown in Fig. 1.


Author(s):  
J.R. Pfeiffer ◽  
J.C. Seagrave ◽  
C. Wofsy ◽  
J.M. Oliver

In RBL-2H3 rat leukemic mast cells, crosslinking IgE-receptor complexes with anti-IgE antibody leads to degranulation. Receptor crosslinking also stimulates the redistribution of receptors on the cell surface, a process that can be observed by labeling the anti-IgE with 15 nm protein A-gold particles as described in Stump et al. (1989), followed by back-scattered electron imaging (BEI) in the scanning electron microscope. We report that anti-IgE binding stimulates the redistribution of IgE-receptor complexes at 37“C from a dispersed topography (singlets and doublets; S/D) to distributions dominated sequentially by short chains, small clusters and large aggregates of crosslinked receptors. These patterns can be observed (Figure 1), quantified (Figure 2) and analyzed statistically. Cells incubated with 1 μg/ml anti-IgE, a concentration that stimulates maximum net secretion, redistribute receptors as far as chains and small clusters during a 15 min incubation period. At 3 and 10 μg/ml anti-IgE, net secretion is reduced and the majority of receptors redistribute rapidly into clusters and large aggregates.


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