Spelling suggestions: "subject:"plant nematode.""
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Effect of soil factors on parasitic nematodes of sugarcane in KwaZulu- Natal, South Africa.Dana, Pelisa. January 2004 (has links)
Nematicides are not only expensive and unaffordable to small-scale farmers but are also harmful to the environment as they kill both the target organisms and non-target micro and macro-organisms, thereby destabilising the ecosystem. Most developed countries have or are in the process of banning use of chemicals for pest management, implying that agricultural products from developing countries using pesticides will not be marketed in the developed countries. In former studies, it was shown that plant parasitic nematodes posed serious problems in sugarcane fields as their attacks on sett roots during germination period decreased sett root weights, delayed bud germination or led to fewer buds germinating as most buds abort. Those that germinate later are then faced with competition for food, space and light from the "older" shoots and often die. The attacks on shoot roots may lead to inefficient uptake of water and nutrients by the plant thereby leading to stunted plants. Fewer and shorter sugarcane stalks due to nematode attacks result in poor yield. In this study, it has been shown that a large number of endoparasites would be needed to reduce sett root weights. Agricultural systems based on monoculture are rarely successful in the long term and because sugarcane fields have been monocultured for a very long time, they are losing their productive capacity and this is termed "Yield Decline". Instead of using nematicides, alternative methods can be used for the management of nematode communities. Research has shown on other plants that nematode communities dominated by Helicotylenchus dihystera are less pathogenic to the plants than other ectoparasitic nematodes, e.g., Xiphinema elongatum and Paratrichodorus spp. A study conducted as a pot experiment showed that sugarcane grown in soil with high H. dihystera grew taller and produced greater root and aerial biomass than one grown in X elongatum infested soil. To induce a nematode community dominated by H. dihystera in the field, two strategies were followed: (i ) abiotic factors that influence the nematode's environment were identified. Certain elements found in soil and sugarcane leaves were found to be correlated to certain species, e.g., H. dihystera was negatively correlated to soil sulphur, medium and coarse sand while X elongatum was positively correlated to these soil types and soil elements. Sugarcane leaves with high levels of Ca, Zn, Cu and Fe were found in areas with high percentages of H. dihystera while the reverse was true for X elongatum. (ii) organic amendments were used to improve the sugarcane growth, modify the environment and decrease competition among species within a community. Application of organic matter to the soil improves soil properties such as water infiltration, water holding capacity, erodibility and nutrient cycling, increases suppressiveness of soils to plant parasitic nematodes and stimulates other anti-nematode micro-organisms, e.g., nematode-trapping fungi. Organic amendments were therefore used in this study not only as screens to protect sugarcane roots from nematode attacks but also to manipulate nematode communities for the less pathogenic species, H. dihystera. In a field study where organic amendments were used, plots treated with filter cake, thume + filter cake, trash + filter cake, filter cake + furfural and Temik (aldicarb) had high percentages of H. dihystera while control plots had high percentages of X elongatum. However, the change in relative proportion of H. dihystera by certain treatments was not followed by an average increase in yield, probability because of the overall variability. The yield results, however, showed that for all treatments, including control, the highest yields corresponded to plots with higher H. dihystera proportions, conflicting the initial hypothesis. As a result, if an organic amendment that can substantially increase the relative proportions of H. dihystera can be found, a substantial increase in yield can be expected. Although the organic amendments did not successfully manipulate the nematode communities for the less pathogenic species, H. dihystera, plots with higher yield were those that had high H. dihystera percentages in their nematode communities. / Thesis (Ph.D.)-University of Natal, Durban, 2004.
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Lettuce stunt : effect of Pythium populations and interactions between Pythium tracheiphilum and nematodesGracia, Javier January 1989 (has links)
This research has focused on the determination of natural populations in the fields, the effect of different inoculum densities on lettuce growth and a study of the association of this fungus with two nematodes (Pratylenchus penetrans Cobb and Meliodogyne hapla Chitwood). Under conditions of artificial infestation of soil the results were satisfactory, but in trials with naturally infested soil the fungus could not be detected. The effect of different inoculum densities was measured at different stages of growth, and only in those plants inoculated 2 weeks after seeding were differences significant and consistent. Some evidence of the detrimental effect of wounding the root system prior to attack by the fungus led to studies of the relationship between this fungus with either P. penetrans or M. hapla. In the first case a negative interaction seemed to exist; no significant increase of the damage caused to the lettuce was observed. In contrast, when the root-knot nematodes and P. tracheiphilum were combined there was a marked reduction of lettuce growth. The interaction was found to be additive.
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Some potato cyst nematode, Globodera rostochiensis and G. pallida, issues related to Swedish potato production /Manduric, Sanja. January 2004 (has links)
Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniversitet, 2004. / Härtill 4 uppsatser.
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Pathological and ecological relationships between Xiphinema americanum Cobb and commercial spruceGriffin, Gerald Dougal, January 1962 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1962. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 66-68).
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Host-parasite relationship of Xiphinema americanum Cobb, 1913, on apple, corn, and strawberryWhite, Lyle Vernon, January 1960 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1960. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
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Evaluasie van twee nematosiede teen plantparasitiese nematode op piesangsVan Niekerk, Johannes Lodewicus 16 April 2014 (has links)
M.Sc. (Nematology) / Please refer to full text to view abstract
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Non-phytotoxic concentration and application interval of nemarioc-al phytonematicide in management of meloidogyne javanica on potato cultivar 'mondial G3'Kobe, Selaelo Patrisia January 2019 (has links)
Thesis (M. A. Agriculture (Plant Protection)) -- University of Limpopo, 2019 / Potato (Solanum tuberosum L.) is highly susceptible to root-knot (Meloidogyne species)
nematodes, with no known nematode resistant genotypes. In Limpopo Province, two
cucurbitacin-containing phytonematicides had been researched and developed. The
active ingredients of the cucurbitacin-containing phytonematicides are cucurbitacins,
which are allelochemicals that could induce phytotoxicity on crops being protected against
nematode damage. The objectives of this study were to determine: (1) mean
concentration stimulation point (MCSP) of Nemarioc-AL phytonematicide on potato
cultivar ꞌMondial G3ꞌ for managing M. javanica and (2) application interval of Nemarioc
AL phytonematicide on potato cultivar ꞌMondial G3ꞌ. Sprouted tubers were planted in 10
cm deep/pot with each pot filled with steam-pasteurised soil and Hygromix at 3:1 (v/v)
ratio in the field under microplot conditions. After 100% emergence (2 weeks), each plant
was inoculated with 5 000 M. javanica eggs and second-stage juveniles (J2). Seven
treatments, namely, 0, 2, 4, 8, 16, 32 and 64% Nemarioc-AL phytonematicide were
arranged in a randomised complete block design, with 11 replications. In Objective 2, four
treatments, namely, 1, 2, 3 and 4 weeks were arranged in randomised complete block
design, with 15 replications. Plant variables and nutrient elements were subjected to the
Curve-fitting Allelochemical Response Data (CARD) model to generate biological indices
used to compute MCSP using the relation MCSP = Dm + Rh/2 and the overall sensitivity
value (∑k). The MCSP for plant variables and nutrient elements, were empirically derived
as 4.31% and 1.33%, with the ∑k of 18 and 4 units, respectively. Nematode variables and
increasing concentrations of Nemarioc-AL phytonematicide exhibited negative quadratic
relations where eggs, J2 in soil and roots and total population (Pf) were optimised at
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14.43, 28.23, 23.30 and 13.55%. To conduct Objective 2 which is application interval,
empirically derived MCSP value of 4.31% from Objective 1 was used. Application interval
was optimised using the concept of 1, 2, 3, and 4 weeks in weeks-per-month-of-30-days.
The application interval of 4.31% was established at 2.43 weeks which translated to 18
days [(2.43 weeks/4 weeks) × 30 days]. All nematode variables in Objective 2 were not
significantly different at all intervals. In, conclusion Nemarioc-AL phytonematicide can be
used at 4.31% concentration to control nematodes population densities without being
phytotoxic to crops at 18 days application interval. / National Research Foundation (NRF) ,
Agricultural Research Council (ARC) and the Flemish
Interuniversity Council of Belgium
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Potential cucurbitacin chemical residues and non-phytotoxic concentration of two phytonematicide formulations in nightshadeMalebe, Agreement Leago January 2019 (has links)
Thesis (M. A. Agriculture (Plant Protection)) -- University of Limpopo, 2019 / The successful cultivation of nightshade (Solanum retroflexum) as a leafy vegetable with
the nutritional potential of contributing to food security in marginalised communities of
Limpopo Province could be limited by high population densities of root-knot (Meloidogyne
species) nematodes. However, the use of Nemarioc-AL/AG and Nemafric-BL/BG
phytonematicides in suppressing nematodes and not being phytotoxic requires the
empirically-developed non-phytotoxic concentration, technically referred to as Mean
Concentration Stimulation Point (MCSP). The MCSP, developed using the Curve-fitting
Allelochemical Response Data (CARD) computer-based model, is crop-specific, hence it
should be developed for every crop. The objective of this study was to investigate the
influence of Nemarioc-AL/AG and Nemafric-BL/BG phytonematicides on growth of
nightshade, accumulation of essential nutrient elements and cucurbitacin residues in
nightshade leaves. Microplots were established by inserting 20-cm-diameter plastic pots
into 10-cm-deep holes at 0.6 m intra-row and 0.6 m inter-row spacing. Each pot was filled
with 10 000 cm3 steam-pasteurised river sand and Hygromix at 3:1. After establishment,
Nemarioc-AL and Nemafric-BL phytonematicides were applied at 7-day interval, whereas,
Nemarioc-AG and Nemafric-BG phytonematicides were only applied at planting. Two
separate experiments for Nemarioc-AL and Nemafric-BL phytonematicides were
conducted in summer (November-January) 2017/2018 under microplot conditions with
each comprising treatments namely; 0, 2, 4, 8, 16, 32 and 64%, similarly, two separate
experiments for the following phytonematicides, Nemarioc-AG and Nemafric-BG
comprised treatments namely; 0, 2, 4, 6, 8, 10 and 12 g arranged in a randomised
complete block design (RCBD), with 12 replications. The nutrient elements in leaf tissues
of nightshade were analysed using the inductively coupled plasma optical emission
spectrometry (ICPE-9000) while, cucurbitacin A and B were
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each quantified using the isocratic elution Shimadzu HPLC Prominence with Shimadzu
CTO-20A diode array detector. Plant growth and nutrient elements variables were
subjected to the CARD computer-based model to generate biological indices to generate
the curves, quadratic equations and the related biological indices (Dm, Rh, k) (Liu et al.,
2003). The MCSP values were calculated using the biological indices of plant or nutrient
element variables which, along with increasing concentration of Nemarioc-AL, Nemafric
BL, Nemarioc-AG and Nemafric-BG phytonematicides, exhibited positive quadratic
relations, with R2 ≥ 25. Using cucurbitacin A and B standards, residues of Nemarioc
AL/AG and Nemafric-BL/BG phytonematicides, were not detected in nightshade leaves,
respectively. Dry root mass and dry shoot mass of nightshade over increasing
concentration of Nemarioc-AL phytonematicide each exhibited a quadratic relationship,
with the models explained by 93 and 61%, respectively. Dry root mass, dry shoot mass,
plant height, chlorophyll content and stem diameter against increasing concentration of
Nemafric-BL phytonematicide each exhibited positive quadratic relationships with the
models explained by 95, 72, 65, 78 and 62%, respectively. Plant height, stem diameter
and dry root mass against increasing concentration of Nemarioc-AG phytonematicide
each exhibited positive quadratic relationships with their models explained by 93, 88 and
91%, respectively. Dry shoot mass and stem diameter against increasing concentration of
Nemafric-BG phytonematicide each exhibited positive quadratic relationships with their
models explained by 94 and 84%, respectively. Na, Fe and K over increasing
concentration of Nemarioc-AL phytonematicide each exhibited positive quadratic
relationships with their associations explained by 96, 91 and 95%, respectively. Zn over
increasing concentration of Nemafric-BL phytonematicide exhibited positive quadratic
relationship with the model explained by 98%. Fe over increasing concentration of
Nemarioc-AG phytonematicide exhibited positive quadratic
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relationship with the association explained by 91%. Fe, Na, K and Zn over increasing
concentration of Nemafric-BG phytonematicide each exhibited positive quadratic
relationships with their associations explained by 81, 90, 80 and 89%, respectively,
whereas, on the contrary, Zn over increasing concentration of Nemarioc-AG
phytonematicide exhibited negative quadratic relationship with the association
explained by 96%. Significant (P ≤ 0.05) plant variables were subjected to CARD, to
generate biological indices which were used to compute the MCSP using the relation:
MCSP = Dm + Rh/2 and the overall sensitivity value (∑k). In Nemarioc-AL
phytonematicide trial, MCSP = 3.02% and ∑k = 1 for plant variables, whereas, MCSP
and ∑k for nutrient elements were 12.09% and 1, respectively. In Nemafric-BL
phytonematicide trial, MCSP = 3.08% and ∑k = 0 for plant variables, while MCSP =
2484.14% and ∑k = 0 for nutrient elements. In Nemarioc-AG phytonematicide trial,
MCSP = 3.47 g and ∑k = 0 for plant variables, whereas, for nutrient elements MCSP =
8.49 g and ∑k = 1. In Nemafric-BG phytonematicide trial, MCSP = 4.70 g and ∑k = 0
for plant variables, whereas, MCSP =723.75 g and ∑k = 1 for nutrient elements. In
conclusion, the application of Nemarioc-AL/AG and Nemafric-BL/BG phytonematicides
had the ability to stimulate the growth of nightshade and enhance the accumulation of
the selected nutrient elements without leaving cucurbitacin chemical residues in leaf
tissues of nightshade. / National Research
Foundation (NRF)
and the Land Bank Chair of Agriculture
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Plant-Parasitic Nematodes in Field Pea and Potato and their Effect on Plant Growth and YieldUpadhaya, Arjun January 2018 (has links)
In this study, surveys were conducted in pea and potato fields in North Dakota and Central Minnesota to investigate the incidence and abundance of plant-parasitic nematodes in these fields. Moreover, the effect of the pin nematode, Paratylenchus nanus, on plant growth and yield of six field pea cultivars was determined under greenhouse conditions. Similarly, the influence of lesion nematode, Pratylenchus penetrans, and wilt fungi, Fusarium oxysporum alone and together on growth and yield of potato cultivar ‘Red Norland’, was evaluated in microplots under field conditions. The results indicate Paratylenchus spp. and Pratylenchus spp. are the most frequent nematodes, respectively, in pea and potato fields. Pin nematodes reproduced on field pea cultivars and caused up to 37% reduction in plant height and 40% reduction in yield. Additionally, both P. penetrans and F. oxysporum alone, and together had significant negative effect on growth and yield of potato.
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In vitro mass rearing of the knapweed nematode, Subanguina dicridis and its use as a bioherbicideOu, Xiu January 1991 (has links)
No description available.
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