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A Survey of Plant Parasitic and Associated Species of Nematodes in the Carrot Producing Area of Cedar Valley, Iron County, UtahFitzgerald, Paul R. 01 May 1950 (has links)
Plant parasitic nematodes have long been known to cause extensive crop losses through reduced yields, shortened productive life, or lowered value of produce. The rood knot nematode, Heterodera marioni, is cosmopolitan. It destroys crops and causes economic losses equal to those of any other plant parasitic speies. in 1948 this nematode caused an estimated loss to the carrot raising industry in Iron County, Utah of approximately $15,000. No estimates for the years prior to 1948 are available; however, reports of the county agent (14) for Iron County show that carrot production in the Cedar Valley is decreasing, and is possibly due to this nematode. The importance of the root knot nematode to the carrot industry in the Cedar Valley was Recognized by farmers at harvest time in 1948. Experimental applications of soil fumigants were tried on many farms with varying success in the spring of 1949. (See figure 1 page 2). One of these experimental plots showed spectacular results. When carrots were harvested in the fall those grown in fumigated soil were found to be of the highest quality and were growing in excellent stands; wheras, the carrots grown in unfumigated soil produced poorer stands of poor quality carrots. Before any conclusions as to the practical value of soil fumigants in carrot raising can be reached, additional tests must be conducted in the area. The fact remains that the root knot nematode is present in the area and causes damage to carrots. If carrots, or any other susceptible crops, are to be grown on economical method of controlling this nematode must be found.
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Hospedabilidade de plantas daninhas a Meloidogyne spp. e interação entre herbicidas e nematicidas para a cultura de cana-de-açúcar / Hospitability of weeds to Meloidogyne spp. and interaction between herbicides and nematicides for the cane sugar cultureGiraldeli, Ana Ligia 11 December 2015 (has links)
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Previous issue date: 2015-12-11 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / The sugarcane has great economic importance in Brazil. To keep productivity several
biotic and abiotic factors can positively or negatively influence. Among them, weeds,
nematodes and synergistic action between pesticides to control both can be cited. Thus, the
present work aimed at studying possible common weeds in the mechanized harvesting
system that can serve as hosts for the root knot nematode: Meloidogyne incognita and / or
M. javanica and study the interaction between herbicides and nematicides used in the
groove planting of sugarcane. Two experiments were carried in a greenhouse at the
Agricultural Sciences Center (CCA-UFSCar), Araras, SP. The first experiment evaluated
the host status ten weeds, as follows: Ipomoea triloba (Dammer), Merremia aegyptia (L.)
Urban, Luffa aegyptiaca Mill, Euphorbia heterophylla L., Ricinus communis L., Crotalaria
spectabilis Roth, Mucuna aterrima ( Piper & Tracy) Holland, Chloris polydactyla (L.) Sw.,
Digitaria horizontalis Willd., Urochloa decumbens (Stapf) RD Webster and the control
(tomato Santa Cruz Kada) when inoculated with M. incognita or M. javanica in a
completely randomized design in a factorial 11 x 2, with six repetitions. The plants were
inoculated with 2.000 eggs and J2, and there were three plants per plot (6.000 eggs and J2
per pot - repetition). Sixty days after inoculation (DAI) the plants were removed and
evaluated according to the reproduction factor (FR), final nematodes population (PF) and
reproduction index (IR). In the second experiment the effect of interaction between two
nematicides applied in contact with the stalks was evaluated. The nematicides tested were:
benfuracarb (5,0 L ha-1) and carbofuran (50 Kg ha-1), and the herbicides applied
preemergence of culture were: sulfentrazone (1,6 L p.c. ha-1), diuron + hexazinone (2,5 Kg
ha1), saflufenacil (0,14 Kg p.c. ha-1) and amicarbazone (1,5 Kg p.c. ha-1). The experiment
was carried in a completely randomized design in a factorial 15 x 5, with four replications
in three sugarcane varieties (RB867515, RB975952 and RB975201). The first factor was corresponded to the 15 treatments and the second, to the five evaluation periods.
Evaluations of intoxication symptoms were performed at 7, 15, 30, 45 and 60 days after
emergence (DAE) of culture. In the last assessment biometric parameters height (cm), leaf
area (cm²) and dry biomass of the aerial part (g) were evaluated. Regarding to the host
status of weeds, it was found that L. aegyptiaca behaved as host of both nematodes, with
FR > 1, higher than the control. The D. horizontalis was classified as host of M. incognita
and non-host of M. javanica. C. spectabilis had the lowest FR and PF. R. communis and I.
triloba present galls when inoculated with M. incognita, but were not considered host for
presenting FR < 1. None of the weeds tested was considered immune, that is, with RF = 0.
Regarding the interaction of herbicides and nematicides in all treatments, plants recover 60
DAE, and in treatments with the use of sulfentrazone increase in symptoms of poisoning
was observed. As for the biometric parameters evaluated at 60 DAE, there was no
statistical difference only in the variety RB867515 for height. In this case, the treatments
amicarbazone / benfuracarb and amicarbazone / carbofuran plants were higher than the
control and other interactions. / A cana-de-açúcar tem grande importância econômica no Brasil. Para manter sua
produtividade diversos fatores bióticos e abióticos podem influenciar positiva ou
negativamente. Dentre eles, podem ser citados as plantas daninhas, os nematóides e a
interação entre produtos fitossanitários para o controle de ambos. Em função disto, o
presente trabalho teve como objetivo estudar possíveis plantas daninhas comuns no sistema
colheita mecanizada que possam servir de hospedeiras para os nematóides-das-galhas:
Meloidogyne incognita (raça 3) e/ou M. javanica e estudar a interação entre herbicidas e
nematicidas usados no plantio da cana-de-açúcar. Foram desenvolvidos dois experimentos
em casa-de-vegetação do Centro de Ciências Agrárias (CCA-UFSCar), em Araras, SP. O
primeiro experimento avaliou a hospedabilidade de dez plantas daninhas a nematóides,
sendo elas: Ipomoea triloba (L.), Merremia aegyptia (L.) Urban, Luffa aegyptiaca Mill.,
Euphorbia heterophylla L., Ricinus communis L., Crotalaria spectabilis Roth, Mucuna
aterrima (Piper & Tracy) Holland, Chloris polydactyla (L.) Sw., Digitaria horizontalis
Willd., Urochloa decumbens (Stapf) R. D. Webste e a testemunha (tomateiro Santa Cruz
Kada) quando inoculadas com M. incognita (raça 3) ou M. javanica, em delineamento
inteiramente casualizado, em esquema fatorial 11 x 2, com seis repetições. As plantas
foram inoculadas com 2.000 ovos e juvenis de segundo estádio (J2), sendo que havia três
plantas por unidade experimental (6.000 ovos e J2 por vaso – repetição) e 60 dias após a
inoculação (DAI) as plantas foram retiradas e avaliadas segundo o fator de reprodução
(FR), população final de nematóides (PF) e índice de reprodutividade (IR). No segundo
experimento foi avaliado o efeito da interação entre dois nematicidas aplicados em contato
com os toletes, sendo eles: benfuracarbe (5,0 L ha-1) e carbofuran (50 Kg ha-1), com os
herbicidas aplicados em pré-emergência da cultura: sulfentrazone (1,6 L p.c. ha-1), diuron + hexazinone (2,5 Kg ha-1), saflufenacil (0,14 Kg p.c. ha-1) e amicarbazone (1,5 Kg p.c. ha-1).
O experimento foi conduzido em delineamento inteiramente casualizado, com quatro
repetições, em três variedades de cana-de-açúcar (RB867515, RB975201 e RB975952). As
avaliações de sintomas de intoxicação foram realizadas aos 7, 15, 30, 45 e 60 dias após a
emergência (DAE) da cultura. Na última avaliação foram determinados os parâmetros
biométricos altura (cm), área foliar (cm²) e biomassa seca da parte aérea (g). Com relação à
hospedabilidade das plantas daninhas, foi verificado que L. aegyptiaca comportou-se como
hospedeira de ambos os nematóides, com FR > 1, sendo superior a testemunha. A D.
horizontalis foi classificada como hospedeira de M. incognita (raça 3) e não-hospedeira de
M. javanica. A C. spectabilis apresentou os menores FR e PF. A R. communis e I. triloba
apresentaram galhas quando inoculadas com M. incognita (raça 3), mas não foram
consideradas hospedeiras por apresentarem FR < 1. Nenhuma das plantas daninhas foi
considerada imune, ou seja, com FR = 0. Com relação a interação dos herbicidas e
nematicidas, em todos os tratamentos as plantas se recuperaram aos 60 DAE, sendo que
nos tratamentos com o uso do herbicida sulfentrazone foi observado os mais elevados
sintomas de intoxicação. Quanto aos parâmetros biométricos avaliados aos 60 DAE, houve
diferença estatística apenas na variedade RB867515 quanto à altura, nesse caso os
tratamentos amicarbazone / benfuracarbe e amicarbazone / carbofuran foram superiores à
testemunha e demais interações.
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Diamondback Moth, Plutella xylostella (L.), (Lepidoptera: Plutellidae ), and Other Insects of Canola, Brassica napus L., in Gauteng Province, South AfricaMosiane, M S January 2002 (has links)
Canola, Brassics napus L. is a relatively new crop in South Africa. Insect pests have not yet been a major problem, but the notorious brassica specialist, diamondback moth (DBM), Plutella xylostella (L.) (Plutellidae) is establishing itself as a serious pest of this crop. DBM is the most important insect pest of plants from the family Brassicaceae throughout the world. It has developed resistance to all chemical pesticides used against it in the field and to toxins of the bacterium Bacillus thuringiensis. The pest status of DBM in South Africa is lower than in other countries with similar climates. However, due to indiscriminate use of pesticides, local populations of DBM are showing signs of resistance. An initial survey has indicated that in addition to DBM, canola is also attacked by aphids, Myzus persicae (Sulzer), Brevicoryne brassicae (L.), Lipaphis e1ysimi (Kaltenbach), (Aphiade), thrips, Thrips tabaci (Lindeman) and other pests mostly brassica specialists. The study was initiated to determine the composition of the community of insects found on canola, the seasonal phenology of DBM populations in canola, and the composition, relative abundance and seasonality of its parasitoids. Monitoring of the insects was carried out at weekly intervals for three years at Rietondale and Bapsfontein in Gauteng province of South Africa. Berlese funnels have been found to be useful in extracting insects from plants, and were used to indicate the presence ofDBM larvae and other insects found on canola. Adults of DBM were monitored with synthetic pheromone traps; larval and pupal populations were monitored by scouting canola plants. Samples of larvae, pupae and parasitoid cocoons were brought into the laboratory. Parasitoids that emerged were identified and their incidence recorded. Monolepta cf bifasciata (Chrysomelidae) and Listroderes costrirostris (Schoener) (Curculionidae) were the most abundant of the coleopteran pests. (DBM) and Heliothis armigera (H.) (Noctuidae) were most abundant lepidopteran pests of Canola. There was a high proportion of first and second instar larvae as indicated by the results of the Berlese funnels as compared to visual scouting in Bapsfontein. From May to August the infestation level of DBM was high, reaching the maximum of 0.25 larvae per plant in June 1996, then declined and remained low for the rest of the season in Rietondale. From September to December for all three years of the study, the population levels Of DBM were high, reaching a maximum of 9.6larvae per plant in September 1997, and remained low from January to August in Bapsfontein. The number of adult moths per trap per week ranged from 0 to 91 in Rietondale, peaking in January 1996 and September 1997. There was no correlation between infestation levels and the pheromone trap catches. In contrast to Rietondale, there was a high correlation between pheromone trap catches and subsequent larval infestations at Bapsfontein. Although DBM infestation levels were generally low, parasitism levels often reached 100% caused by a complex of parasitoids. During the period of study, the following hymenopteran parasitoids were recorded: Cotesia plutellae (Kurdjumov) and Apanteles eriophyes (Nixon), Braconidae), both larval parasitoids, Diadegma mollipla (Holmgren) (Ichneumonidae), and Oomyzus sokolowskii (Kurdjumov) (Eulophidae), larval-pupal parasitoids, Diadromus collaris (Gravenhorst) (Ichneumonidae) pupal parasitoid, and the hyperparasitoids Mesochorus sp. (Ichneumonidae) and Pteromalus sp. (Pteromalidae). Cotesia plutellae was the most abundant parasitoid occurring throughout the year..
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Biometrical analysis of pathogenicity in the Ustilago hordei--Hordeum vulgare host-parasite systemPope, David D. January 1982 (has links)
This study involves a measure of the variability of descendants from a cross between Ustilago hordei race 7 and race 11, on two varieties of barley, Trebi and Odessa. Components of variability were defined, statistically described and compared. Biometrical analyses uncovered the action of
significant additive and non-additive genetic effects. Differential interactions between treatments and varieties revealed the existence of at least one virulence gene. Specific polygenes and the virulence gene were found to produce significant interactions with different environmental conditions. Homogeneity of variance of the genetic components of the F2 from three randomly chosen F1 dikaryotic lines demonstrated the highly homozygous condition of the parental teliospores. Covariance - variance regression analysis was used to study the dominance and epistatic differences between treatment dikaryons. There is evidence for ambidirectional dominance. The number of effective factors operating against the varieties, Trebi and Odessa, were estimated to be between 4-6 and 1-2 respectively. / Science, Faculty of / Botany, Department of / Graduate
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Developing phytonematicides using indigenous cucumis africanus and cucumis myriocarpus fruits for tomatoproduction systemsPelinganga, Osvaldo Manuel January 2013 (has links)
Thesis (Ph. D. Agriculture (Plant Protection)) -- University of Limpopo, 2013 / Global withdrawal of synthetic fumigant and non-fumigant nematicides due to their ecounfriendly
impacts and high toxicity to non-target organisms, respectively, increased the
research and development of alternatives for managing population densities of plantparasitic
nematodes, particularly the root-knot (Meloidogyne species) nematodes.
Although Meloidogyne species had been managed using genotypes that are resistant to
plant-parasitic nematodes in various crops, various challenges negate the available or
introgressed nematode resistance. In tomato (Solanum lycopersicum) production,
nematode races and instability of nematode resistant genotypes under certain
conditions necessitated the continued research and development of alternatives since
most of the existing commercial tomato cultivars are highly susceptible to various
biological races of Meloidogyne species. The aim of the study was to research and
develop appropriate dosages of two phyto- nematicides which could be applied through
drip irrigation system in open field tomato production systems, while the specific
objectives were to: (1) determine whether a computer-based model could provide nonphytotoxic
concentrations to tomato plants using fresh fruits of wild watermelon
(Cucumis africanus) and wild cucumber (C. myriocarpus) under greenhouse conditions,
(2) determine whether computer-based concentrations from the two plant species when
using dried fruits would be less phytotoxic and more suppressive to nematodes, (3)
investigate application time intervals for the two products, (4) determine responses of
plant growth in tomato and nematode suppression in respect to the derived dosages,
and and (5) validate dosages of fermented crude extracts from the two plant species
with respect to plant growth of tomato and suppression of nematode numbers.
xxxiii
Greenhouse, microplot and field studies were set to test the hypotheses intended to
achieve the stated objectives, with reliability of measured variables being ensured by
using statistical levels of significance (P ≤ 0.05) and coefficients of determination (R2),
while validity was ensured by conducting experiments at the same location over two
seasons and/or by setting up factorial treatments. Firstly, fermented plant extracts of
fresh fruits from C. africanus and C. myriocarpus consistently reduced population
densities of Meloidogyne species by 80-92% and 50-90%, respectively. Tomato plants
were highly sensitive to the two products as shown by the total degree of sensitivities
(Σk) and biological index of 0 and 3, respectively. Also, the mean concentration
stimulation range (MCSR) of 11% and 7% concentrations, respectively, attested to this
phytotoxicity. Secondly, fermented crude extracts of dried fruits from C. africanus and C.
myriocarpus also reduced population densities of Meloidogyne species by 78-97% and
87-97%, respectively. Tomato plants were highly tolerant to the two products in dried
form as shown by the total degree of sensitivities (Σk) and biological index of 4 and 3,
respectively. The MCSR values for C. africanus and C. myriocarpus dried fruits on
tomato were 2.64% and 2.99%, respectively, which for the purpose of this study were
individually adjusted to 3%, which translated to 36 L undiluted material/ha of 4 000
tomato plants. In subsequent studies, 3% concentration was used as the standard,
along with double strength concentration, namely, 6% concentration. Thirdly, the MCSR
values derived in Objective 4, namely 3% and 6% concentration for both Cucumis
species using the CARD model were used in the optimisation of application time interval
using the innovative concept of weeks (0, 1, 2, 3 and 4) in a 30-day month period.
Application time interval for 3% and 6% concentrations of C. africanus fruits was
xxxiv
optimised at 2.40 and 2.61 weeks in a 30-day month period, respectively, which
translated to 18 days [(2.4 weeks/4 weeks) × 30 days] and 20 days [(2.6 weeks/4
weeks) × 30 days], respectively. In contrast, for both concentrations from fermented
crude extracts of C. myriocarpus fruits, application time interval was optimised at 16
days for 2.2 and 2.1 weeks, respectively. During optimisation of application frequencies,
fermented crude extracts from C. africanus and C. myriocarpus reduced final population
densities of M. incognita race 2 by 70-97% and 76-96%, respectively. Fourthly, optimum
application intervals (time), allowed computation of dosage, which is a product of
concentration and application frequency (dosage = concentration × application
frequency). Fifthly, validation of the dosages under open field conditions suggested that
6% × 16-day dosage under crude extracts from C. myriocarpus fruit significantly (P ≤
0.05) improved growth of tomato plants when compared with those of either 0%
(untreated control) or 3% at 16 days. In contrast, dosages of C. africanus fruit at two
application frequency had no effect on growth of tomato plants – suggesting that either
of the dosages was suitable for use in tomato production since both reduced nematode
numbers. During validation, the materials reduced nematode numbers by margins
similar to those observed previously under other environments. In conclusion, crude
extracts of the two Cucumis species have stimulatory concentrations which have
potential similar reductive effects on population densities of Meloidogyne species and
could serve as botanical nematicides. However, since plant responses to the two
products differed in terms of their respective dosages and active ingredients, it implied
that for further improvement of the two, the overriding focus should be on their
interaction with the protected plants and nematode numbers. Ideally, future research
xxxv
should include environmental impact studies, especially on the influence of the products
fruit quality of tomato, earthworms, fish and bees.
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A Functional Genomics Analysis of Glycine Max Vesicle Membrane Fusion Genes in Relation to Infection by Heterodera GlycineSharma, Keshav 14 August 2015 (has links)
Soybean cyst nematode (SCN), a major pathogen of soybean worldwide, causes huge losses in soybean production. Various approaches including cloning of genes to combat this devastating disease help to better understand the cellular function and immune responses of plants. Membrane fusion genes are the important regulatory parts of vesicular transport system, which works through packaging of intracellular compounds and delivering them to apoplast or nematode feeding sites to induce an incompatible reaction. The incompatible nature of membrane fusion proteins such as SNAP25, Munc18, Syntaxin, Synaptobrevin, NSF, Synaptotagmin and alpha-SNAP are conserved in eukaryotes and regulate the intracellular function to combat abiotic and biotic stress in plants. Overexpression of these genes in G. max [Williams 82(PI518671)] which is a susceptible cultivar of soybean to nematodes resulted in a reduction of the SCN population providing further insights of molecular and genetic approaches to solve the SCN problems in agriculture.
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Seasonal abundance and biology of hyperparasites and their hosts associated with Pieris rapae (L.) (Lepidoptera: Pieridae) in the Brassica crop systemGaines, David N. 10 June 2009 (has links)
Hyperparasitism of beneficial parasites of Pieris rapae was studied on Brassica crops in Montgomery County, Virginia. The goal of the study was to determine whether the hyperparasites attacking the larval parasites of P. rapae were capable of eliminating an introduced population of the larval parasite Cotesia rubecula (Marshall) (Hymenoptera: Braconidae).
Pieris rapae was found to be active from April to November with possibly six generations per year in this region. It was attacked throughout this period by five generations of the larval parasite Cotesia glomerata (L.) (Hymenoptera: Braconidae). Although P. rapae larvae were twice as numerous on broccoli (var. Premium Crop) than on cabbage (var. Rio Verde), a higher proportion of P. rapae larvae was parasitized by C. glomerata on cabbage, indicating that C. glomerata preferred to forage for P. rapae in cabbage.
In spring plantings, up to 36.9% of C. glomerata cocoon masses had been affected by the hyperparasite T. galaetopus (Ratzeburg) (Hymenoptera: (Eulophidae) and 23.3% by the hyperparasite Spiloehaleis torvina Cresson (Hymenoptera: Chalcididae). In the fall, 93.2% and 4.2% of the cocoon masses were affected by T. galaetopus and S. torvina, respectively.
Tetrastiehus galaetopus activity was observed from May to November, but it was most active after mid July. Tetrastiehus ga/aetopus had little impact on the gregarious C. glomerata, and even though it could affect >90% of the C. glomerata cocoon masses for extended periods, 500/0 of the cocoons in each mass were unaffected. However, it's high reproductive capacity could adversely affect a solitary host such as C. rubecula. Spilochalcis torvina was observed as early as late May but it was most active during the mid summer months. It's reproductive activity ceased by early October even though hosts were abundant in the month which followed. Four generations were seen between June and October. Spilochalcis torvina's hosts were Cotesia orobenae Forbes (Hymenoptera: Braconidae), C. glomerata, and Plutella xylostella (L.) (Lepidoptera: Plutellidae), but the principal host was C. glomerata. However, the proportion of female S. torvina progenies was <31% from the Cotesia spp. hosts and 70% from P. xylostella hosts. Spilochalcis torvina typically hyperparasitized <4 pupae per Cotesia spp. cocoon mass in the field. In laboratory experiments, S. torvina hyperparasitized an average of <7 C. rubecula pupae daily, and the maximum number hyperparasitized was 12. Due to its apparently low reproductive rate in the laboratory, and its low rate of hyperparasitization on hosts in the field, it is unlikely that S. torvina is a danger to populations of parasites like C. rubecula. / Master of Science
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Plant parasitic organisms in the rizosphere of apple trees in the Western Cape, with special reference to woolly apple aphidVan Jaarsveld, Alwyn Jacobus 12 1900 (has links)
Thesis (MScAgric)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: Various aspects of the biology and ecology of woolly apple aphid, Eriosoma
lanigerum, were investigated, including initial galling damage caused by E. lanigerum to
the roots of apple trees, the possible relationship between E. lanigerum and Xiphinema and
Pratylenchus nematodes and the effectiveness of Biostart 2000® and Furfural® as possible
control agents of E. lanigerum in the orchard.
Preliminary root damage by first instar E. lanigerum feeding was characterized by
the mechanical injury of endodermis and parenchyma tissues. Damage by second, third and
fourth instar E. lanigerum was similar, but the symptoms were more pronounced. Damage
caused by adults included a pronounced swelling at infected areas of the root. Cell walls
hardened until the root was radially strengthened with sclerenchyma tissue and nonconducting
xylem vessels while the cuticle expanded greatly through the growth of corklike
cambium tissue.
There was no direct relationship between the population dynamics of E.
lanigerum and those of Xiphinema and Pratylenchus nematodes. The occurrence of E.
lanigerum appeared to be seasonal while P. penetrans and Xiphinema numbers fluctuated
erratically. Undamaged root nitrogen levels seemed to correspond with the normal root
growth cycle. Nitrogen levels from galled roots were significantly lower than those of
undamaged roots, probably due to E. lanigerum feeding. Soils rich in fine sand and clay
sustained higher populations of E. lanigerum and Xiphinema than sandy soils. The number
of E. lanigerum found in soil samples correlated well with the damage index allocated to
the samples. The numbers of Xiphinema found in soil samples also correlated well with the
damage index allocated to the samples according to suspected Xiphinema damage
symptoms.
Both Biostart 2000® and Furfural® were effective as control agents of woolly apple
aphid. Furfural'Ï, a chemical waste product of the sugarcane industry, was however not as
effective as Biostart 2000®, a product that includes an activator and three bacterial species,
Bacillus laterosporus, B. chitinosporus and B. licheniformis. The bacteria in the Biostart
2000® treated pots could replicate themselves under suitable conditions while Furfural®
dilutes with each watering. Biostart 2000® is also easier to prepare than Furfural® since the
components of Biostart 2000® readily mix to form a paste easily thinned by water, whereas
Furfural® is an oily substance that does not easily disperse in water.
Root damage was initiated soon after E. lanigerum started feeding, however there
was no apparent relationship between E. lanigerum and the nematode species. The most
promising, environmentally friendly control measure was Biostart 2000®. / AFRIKAANSE OPSOMMING: Verskeie aspekte van biologie en die ekologie van die appel bloedluis, Eriosoma
lanigerum, was ondersoek insluitende aanvanklike galvorming veroorsaak deur E.
lanigerum op wortels van appelbome, die moontlike verwantskap tussen E. lanigerum en
Xiphinema en Pratylenchus nematodes en die effektiwiteit van Biostart 2000® en Furfural®
as moontlike beheeragente van E. lanigerum in die boord.
Aanvanklike wortelskade deur eerste ins tar E. lanigerum voeding was gekenmerk
deur die meganiese beskadiging van endodermale en parenchiem weefsel. Skade
veroorsaak deur tweede, derde en vierde instar E. lanigerum was soortgelyk alhoewel die
simptome meer beklemtoond was. Skade deur volwassenes het 'n meer duidelike swelsel
by geïnfekteerde wortelareas ingesluit. Selwande het verhard totdat die wortel
radiaalsgewys versterk was met skierenchiem weefsel en nie-geleidende xileemvate terwyl
die kutikula grootliks toegeneem het deur die groei van kurkagtige kambiumweefsel.
Daar was geen direkte verwantskap tussen die bevolkingsdinamika van E.
lanigerum en dié van Xiphinema en Pratylenchus nematodes nie. Die voorkoms van E.
lanigerum was seisoenaal terwyl P. penetrans en Xiphinema se getalle onvoorspelbaar
gefluktueer het. Onbeskadigde wortel stikstofvlakke het ooreengestem met die normale
wortel groeisiklus. Stikstof vlakke van galwortels was noemenswaardig laer as dié van
onbeskadigde wortels, heel waarskynlik as gevolg van voeding deur E. lanigerum. Grond
ryk aan fyn sand en klei het groter bevolkings van E. lanigerum en Xiphinema onderhou as
sanderige gronde. Die aantal E. lanigerum in grondmonsters het goed ooreengestem met
die skade indeks wat aan die monsters toegeken was. Die aantal Xiphinema in
grondmonsters het ook goed ooreengestem met die beskadigingsindeks wat aan die
monsters toegeken is weens vermoedelike Xiphinema skade simptome.
Beide Biostart 2000® en Furfural® was effektief as beheeragente van die
appelbloedluis. Furfural'", 'n afvalproduk van die suikerriet industrie, was egter minder
effektief as Biostart 2000®, 'n produk bestaande uit 'n aktiveerder en drie bakterie spesies,
Bacillus laterosporus, B. chitinosporus en B. licheniformis. Die bakterië in die Biostart
2000® behandelde potte kon vermeerder onder gunstige toestande terwyl Furfural® na elke
besproeiing verdun het. Biostart 2000® is ook makliker om aan te maak as Furfural®
aangesien die bestanddele van Biostart 2000® geredelik meng tot 'n wateroplosbare pasta,
terwyl Furfural® 'n olierige vloeistofis wat moeilik 'n waterige suspensie vorm.
Wortelskade het plaasgevind kort nadat E. lanigerum begin voed het, alhoewel daar
geen duidelike verwantskap tussen E. lanigerum en nematode spesies voorgekom het nie.
Die mees belowende omgewingsvriendelike beheermaatreël was Biostart 2000®.
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Integrated system for the management of meloidogyne javanica in potato productionSeshweni, Mosima Dorcus January 2016 (has links)
Thesis (M. Agricultural Management (Animal Production)) -- University of Limpopo, 2016 / Cultivated potato (Solanum tuberosum L.) cultigens do not have resistant genotypes
to root-knot (Meloidogyne species) nematodes. Currently, efforts are underway to
introgress nematode resistance in potato breeding programmes, whereas other
environment-friendly nematode management strategies are being assessed in
various cultigens. Nemafric-BL and Nemarioc-AL phytonematicides have being
researched and developed for managing the root-knot nematode whereas Biocult
Mycorrhizae are intended to enhance crop productivity through improved absorption
of P, which is inherently low in most South African soils. The objectives of the study,
therefore, were: (1) to determine the interactive effects of Nemacur (N), Biocult
Mycorrhizae (B) and Nemarioc-AL or Nemafric-BL phytonematicide (P) on population
densities of M. javanica and growth of potato plants, (2) to investigate the effects of
Nemacur (N), Velum (V), Biocult Mycorhizae (B) and Nemarioc-AL or Nemafric-BL
phytonematicide (P) on population densities of M. javanica and growth of potato
plants. For the microplot experiment, potato cv. ‘Mondial G3’ seeds were sown in 25
cm-diameter plastic pots with 5 000 ml steam-pasteurised river sand and Hygromix-T
at 3:1 (v/v) growing mixture in autumn (March-May) 2015. Pots were buried 80%
deep into the soil in with 0.5 m inter-row and 0.5 m intra-row spacing. Potato cv.
‘Mondial G3’ seeds were dipped in a mixture of Mancozeb with a wettener for
disease management prior to sowing. Appropriate treatments were applied soon
after emergence of leaves. Each plant was inoculated by dispensing a mixture of 5
000 eggs and M. javanica J2. Eight treatments, control (N0B0P0), Nemacur (N1B0P0),
Biocult (N0B1P0), phytonematicide (N0B0P1), Nemacur × Biocult (N1B1P0), Nemacur ×
phytonematicide (N1B0P1), Biocult × phytonematicide (N0B1P1) and Nemacur ×
Biocult × phytonematicide (N1B1P1), were arranged in a randomised complete block
xxvi
design (RCBD) with 8 replications (n= 64). Under field conditions the study was
conducted in summer (October 2015 - January 2016), with 30-cm furrows dug and
potato seeds placed in the soil with 30 cm inter-row and 40 cm intra-row spacing.
The four treatments, namely, (1) untreated control, (2) Nemacur or Velum (3) Biocult
Mycorrhizae and (4) Nemarioc-AL or Nemafric-BL phytonematicide, were arranged
in RCBD, replicated three times for the Velum experiment and five times for the
Nemacur experiment. At 56 days after inoculation, the second order interaction
(N1B1P1) was highly significant (P ≤ 0.01) for eggs in root and total nematodes,
contributing 13 and 12% to total treatment variation (TTV) of the two variables,
respectively, in the Nemarioc-AL phytonematicide study. Relative to untreated
control, the second order interaction (N1B1P1) reduced eggs in root and total
nematodes by 42 and 36%, respectively. In both Nemarioc-AL and Nemafric-BL
phytonematicide experiments, the combination of phytonematicide and Biocult
Mycorrhizae reduced gall rating. Nemacur, Biocult and Nemarioc-AL
phytonematicide, the treatment effects were highly significant on eggs, J2 in root and
total nematodes, contributing 53, 68 and 57% to TTV of the three variables,
respectively. Nemacur, Biocult and Nemafric-BL phytonematicide treatments each
was not significant (P ≤ 0.05) for nematodes variables. Both treatments for Nemacur,
Biocult and Nemarioc-AL or Nemafric-BL phytonematicides were significant for gall
rating, contributing 92 and 70% to TTV of the variable, respectively. In Nemarioc-AL
phytonematicide, relative to the untreated control, gall rating was reduced by 48 to
56%, whereas in Nemafric-BL phytonematicide the variable was reduced by 33 to
56%. In the Velum study, Biocult and Nemarioc-AL or Nemafric-BL phytonematicide,
the treatment effects in both experiments were highly significant (P ≤ 0.01) on eggs
in root, contributing 88% to TTV of the variable. Both treatments from Nemarioc-AL
xxvii
and Nemafric-BL phytonematicides had no significant effects on all plant variables
measured. In microplot, the second order interaction (Nemacur × Biocult ×
Nemarioc-AL phytonematicide) was highly significant for nematode eggs in root and
total nematode. In a three-way matrix, the N1B1P1 interaction had the highest effects
on eggs, followed by Biocult alone, then Nemacur alone and then the
phytonematicide. The same trend was observed in the three-way matrix for total
nematodes. However, in two-way matrix for eggs, Biocult outperformed Nemacur, as
was the phytonematicide on J2. In another microplot study, the second order
interaction (Nemacur × Biocult × Nemafric-BL phytonematicide) was significant for J2
in soil and roots, with the three-way matrix showing, that Biocult alone had higher
effects than the N1B1P1 interaction on J2 in root. A three-way matrix also showed that
Nemacur was outperformed by the phytonematicide alone, Biocult alone and the
interactions on J2 in soil. In conclusion, Nemarioc-AL and Nemafric-BL
phytonematicides could each be used with Biocult Mycorrhizae in the management
of population densities of M. javanica in potato production since the impact from
Nemacur which is a synthetic nematicide does not have that much difference from
that of phytonematicides interacted with Biocult Mycorrhizae. / Agricultural Research Council
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Caracterização de Mutantes de Xanthomonas citri Gerados por Disrupção Gênica Randômica Usando Transposon / Characterization of Xanthomonas citri mutants generated by random gene disruption using transposonGarcia, Julio Cesar Levano 06 February 2003 (has links)
Xanthomonas axonopodis pv citri (Xac), uma bactéria gram negativa, é a causadora da doença Cancro Cítrico que ocasiona enormes prejuizo na citricultura brasileira. Com o seqüenciamento do genoma deste patógeno foram encontradas inúmeras sequências codificadores com funções desconhecidas. Assim com a finalidade de estudos funcionais do genoma de Xac, foram gerados mutantes randômicos usando o transposon EZ::TN, que induziu disrupção aleatoria de seus genes com o intuito de avaliar que genes inativados afetam a patogenicidade da bactéria. Para o mapeamento do local de inserção do transposon foi desenvolvida uma metodologia baseada na técnica de PCR touchdown utizando oligonucleotídeos semidegenerados. A confiabilidade deste novo método foi comprovada através do mapeamento por Southem blot de alguns mutantes. Conseguiu-se mapear 90 mutantes randômicos com este método. Os testes de patogenicidade em citros mostraram mutantes com sua patogenicidade afetada observando-se variações nos sintomas da doença. Mutantes interessantes contendo uma ORF hipotética inativada ou tendo uma inserção num espaço intergênico foram achadas, sendo também detectados alguns mutantes com nocaute de genes nos seus plasmídeos pXac33 e pXac66. / Xanthomonas axonopodis pv citri (Xac), a gram-negative bacteria, is the causer of the Citrus Canker disease that produces enormous losses to the brazilian citrus sector. Many coding sequences with unknown functions were found in the genome sequence of this pathogen. Therefore, with the goal of functional studies of Xac\'s genome, random mutants using the EZ::TN transposon, have been generated, which carry aleatory disruptions of their genes, with the aim of evaluating inactived genes that potentially affect bacterial pathogenicity. A method based in the PCR touchdown technique using semidegenerate primers was developed for the mapping of the transposon insertion site. The reliability of this new method was tested by means of mapping some mutants using Southern blot. Ninety random mutants were mapped with this method. The pathogenicity tests in citrus showed mutants with their pathogenicity affected and variations in the disease symptoms were observed. Interesting mutants containing an inactive hypothetical ORF or with an insertion in intergenic regions have been found, and also some mutants with inactivated genes in their plasmids pXac33 and pXac66 were detected.
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