Showing papers in "Nematropica in 2000"

Penetration, Development and reproduction of MELOIDOGYNE ARENARIA on two new resistant VITIS SPP.

Abstract: Penetration, development and reproduction of a Harmony pathotype of Meloidogyne arenaria was studied on two resistant grape rootstocks, 10-23B and RS-3. Associated resistance mechanisms were examined microscopically. Cabernet Sauvignon was used as a susceptible control. The plants were inoculated with freshly hatched second-stage juveniles (J2). Significantly more J2 penetrated roots of Cabernet than 10-23B by 4 days after inoculation. Penetration was delayed by one week in roots of RS-3. Cabernet roots contained a greater number of nematodes coupled with faster development than that found in resistant rootstocks. Hypersensitive responses were expressed in the presence of penetrating J2 in resistant rootstocks only. This occurred along the root epidermis, among the cortical cells and along the differentiating vascular bundle. Cortical necrosis halted or delayed migration of J2 to vascular tissues and vascular necrosis prevented establishment of successful feeding sites which arrest

Biological Control Of Moloidogyne Incognita on Tomato and Banana with RhizOobacteria, Actinomycetes, and Pasteuria Penetrans

Abstract: Jonathan E. I., K. R. Barker, F. F. Abdel-Alim, T. C. Vrain, and D. W. Dickson. 2000. Biological control of Meloidogyne incognita on tomato and banana with rhizobacteria, actinomycetes, and Pasteuria penetrans . Nematropica 30:231-240. Glasshouse experiments were conducted to determine the efficacy of plant growth-promoting rhizobacteria, ( Bacillus cereus, B. subtilis, B. sphaericus, Agrobacterium radiobacter, Pseudomonas fluorescens, P. chlororaphis and Burkholderia cepacia ), uncharacterized actinomycetes (strains 29 and 45), and the nematode-parasitic bacterium Pasteuria penetrans (isolate 100) against Meloidogyne incognita race 1 on tomato and banana. All bacteria and actinomycetes enhanced the growth of both crops, and suppressed root-gall development on tomato as compared to control plants. Root-gall indices on tomato inoculated with M. incognita and bacteria ranged from 25 to 31% versus 94% for the nematode control. The bacteria also limited reproduction of M. incognita on bo

Effect of grafting and nematicide treatments on damage by root-lesion nematodes (Pratylenchus spp.) to Coffea arabica L. in Guatemala.

Abstract: Root-lesion nematodes, Pratylenchus spp., are among the pests with the greatest negative impact on the economy of coffee production in Guatemala. A field experiment was undertaken in southwest Guatemala to assess damage due to a root-lesion nematode and to compare two methods of manage-ment: grafting onto Coffea canephora Pierre, 1897, and nematicide treatments (terbufos). The experiment was carried out for five years, and included the first three harvests. Root population densities of nematodes, coffee berry yield losses, and plant mortality rates were highest on ungrafted C. arabica, confirming its high degree of vulnerability to this root-lesion nematode population. Grafting onto C. canephora provided efficient control of populations of root-lesion nematodes and resulted in significantly greater yields compared to ungrafted plants. Nematicide treatments suppressed populations of this root-lesion nematodes only until the second year after planting. This was sufficient to significan

Association of Phytophthora sojae with Heterodera glycines and nutrient stressed soybeans.

Abstract: Kaitany, R., H. Melakeberhan, G. W. Bird, and G. Safir. 2000. Association of Phytophthora sojae with Heterodera glycines and nutrient stressed soybeans. Nemtropica 30:193-199. Soybean cyst nematode (SCN, Heterodera glycines ), a serious pest of soybeans, has been found in 30 counties in Michigan. Phytophthora sojae , a serious and opportunistic pathogen of soybeans, has also been found in many of the fields. This study was conducted to assess the incidence of P. sojae in 12 selected soybean cultivars grown under low (fumigated) and high (non-fumigated) SCN conditions and nutrient stress. A total of 70 soil and root and stem samples (same plant) from each nematicide treatment were analyzed for SCN population densities and P. sojae. Incidence of P. sojae was highly correlated with SCN population densities in untreated plots; whereas, both organisms were low in the treated plots and poorly correlated. Leaf N and K were significantly higher in nematicide-treated plots while the reverse w

Ultrastructural response of coffee roots to root-knot nematodes, meloidogyne exigua and m. megadora

Abstract: Rodrigues, A. C. F. de O., I. M. de O. Abrantes, M. T. Melillo, and T. Bleve-Zacheo. 2000. Ultrastructural response of coffee roots to root-knot nematodes, Meloidogyne exigua and M. megadora . Nematropica 30:201-210. Histological and ultrastructural changes induced in Coffea arabica cv. Catuaiamarelo and Catimor ( Coffea arabica cv. Caturra þ Timor Hybrid) by two populations of Meloidogyne exigua and one of M. megadora are reported. All second-stage juveniles of both species penetrated through the rhizodermis of the root directly behind the root cap and reached the stele near the vascular elements. In Catuaiamarelo roots, cells acting as feeding sites increased their synthetic activity and became multinucleate cells. Nuclear activity and dense cytoplasm observed in cells of roots inoculated with M. exigua indicated a susceptible response of the coffee plants. Seedling cells fed upon by M. megadora showed retraction and roughening of the inner wall surface, great presence of param

Alteracoes anatomicas em raizes de milho (ZEA MAYS L.) Parasitadas por MELOIDOGYNE JAVANICA

Abstract: The use of corn as a rotation crop in integrated programs for controlling plant-parasitic nematodes has been widely recommended In Brazil, where most of the commercial varieties and hybrids have been rated as resistant to root-knot nematodes for many years, its inclusion in cropping sequence strategies for the control of Meloidogyne incognita and mainly M javanica became almost bligatory At present, however, it is known that many genotypes are actually tolerant hosts for M javanica, allowing the nematode to develop and reproduce in the roots, without causing root galls or plant growth reduction A greenhouse/laboratory study was carried out to increase our knowledge of the anatomical changes induced by M javanica in corn roots Corn hybrid BR 106 (a suitable host) seedlings were individually inoculated with 10 000 second-stage juveniles and maintained in a greenhouse After 60 days, slightly swollen and galled root pieces (1-3 cm long) were processed for light microscopy histol

Rotational Management of Meloidogyne Javanica in a Small Scale Greenhouse Trial in Crete, Greece

Abstract: Tzortzakakis, E. A., M. S. Phillips, and D. L. Trudgill. 2000. Rotational management of Meloidogyne javanica in a small scale greenhouse trial in Crete, Greece. Nematropica 30:167-175. The crop yields, root galling indices, and population densities of tomato avirulent and virulent root-knot nematode Meloidogyne javanica were compared in a greenhouse experiment with two croppingcycles. In the first crop, the avirulent and virulent populations were better controlled by use of resistant (Migene) tomato and pepper than by application of fenamiphos with susceptible tomato. Susceptible tomato was grown as the second crop in all plots and was treated with fenamiphos, except where it followed the resistant tomato or pepper. At the end of the second crop, fruit yields, levels of root galling and population densities of nematodes were similar for all treatments. The effect of rotational management on M. javanica for one cropping cycle seems to be equal to that of nematicide applications on a s

Population dynamics of Meloidogyne incognita and infestation levels by Pasteuria penetrans in a naturally infested field in Martinique.

Abstract: The population dynamics of Meloidogyne incognita juveniles (J2) in association with the parasite Pasteuria penetrans was studied in a field in Martinique. Data obtained at three-week intervals for one year were analyzed to study the relationship between J2 density and endospore infestation levels. Six crop sequences were evaluated in five replicates. They were: resistant tomato, okra, fallow, cabbage; susceptible tomato, okra, fallow, cabbage; bean, pepper, fallow, cabbage; eggplant, fallow; cucumber, velvetbean, fallow, cabbage; fallow, pepper, cabbage, fallow, cabbage. The J2 densities showed fluctuating trends, frequently synchronous with fluctuations of endospore infestation. The highest J2 numbers observed ranged between 1 000 and 1 500 nematodes/100 g of soil in the first four crop sequences, and between 150 and 250 J2/100 g of soil in the last two. The highest percentages of nematodes with adhering endospores ranged between 50 and 70%. The resistant tomato crop showed a sharp decrease in the nematode density at the end of the crop sequence, with a similar synchronous decrease of the endospore infestation. This trend was also observed during the fallow periods in the other treatments. Susceptible crops allowed a sharp increase of the J2 densities. During these periods of population growth, the concomitant increase of the endospore infestation levels was interrupted with fast growing J2 densities. In the last two crop sequences, the J2 densities progressively decreased because of the on-host status of velvetbean and of a longer fallow, respectively. When all the pooled data from the six treatments were considered, a significant linear correlation was observed between J2 densities and the corresponding endospore infestation values (P 0.001). This relationship appeared related to the density of females releasing J2 and/or endospores in the soil. All pooled mean densities also followed the Gutenberg-Richter power law distribution, indicating the oc-currence of chaotic effects influencing their dynamics. Although chaos implies non-predictability of J2 numbers and endospore infestation dynamics, it also suggests that large-scale fluctuations may induce local nematode suppression by P. penetrans.

Spatial distribution of nematode population densities and nematode damage in roots of three banana cultivars in Uganda.

Abstract: The spatial distribution of nematode populations and damage in roots of Nabusa (Musa AAA-group Matooke), Pisang Awak (Musa ABB) and Sukali Ndizi (Musa AB) three banana cultivars widely grown in Uganda, was investigated at three locations, each with a distinctive nematode population and composition. At Namulonge, central Uganda, where Radopholus similis was the dominant nematode species, and at Ntungamo, southwestern Uganda, where Pratylenchus goodeyi was the dominant species, suckers were removed from established mats and assessed for nematode reproduction and damage. At Namulonge, Ntungamo, and Mbarara, southwestern Uganda, where R. similis and P. goodeyi coexist, suckers removed three months after planting were assessed for nematode reproduction and damage. Nematode population density distribution along the primary roots was observed to be random for both plant types of the three cultivars at all locations. An exception was recorded for three-month-old sucker-derived plants of all

The in vitro use of olive explants in screening trials for resistance to the root-knot nematode, Meloidogyne incognita.

Abstract: In vitro explants of a rootstock and two cultivars of olive were used in a screening trial for resistance to Meloidogyne incognita. All plants were susceptible to the root-knot nematode independently of the inoculum used, egg masses or eggs. The in vitro technique allowed the completion of the screening test in only four months and avoided the seasonality problems that occur by using olive cuttings.

Notas De Investtigacion - Research Notes Cultivos De Ciclo Corto Como Plantas Trampas Para El Control Del Nematodo Agallador

Abstract: Cuadra R., X. Cruz, and J. L. Fajardo. 2000. The use of short cycle crops as trap crops for the control of root-knot nematodes. Nematropica 30:241-246. The effect of short cycle crops such as lettuce ( Lactuca sativa ) and radish ( Raphanus sativus ) to suppress the soil population densities of Meloidogyne incognita Race 2 was investigated in concrete microplots containing an organic soil mix (60% red ferralitic soil and 40% cow dung) in Havana, Cuba. Lettuce and radish crops were grown for 32 and 30 days respectively at high and low initial nematode densities. Thirty to 32 days after planting, plant root systems were completely removed from the microplots to prevent nematode reproduction in those roots and consequent nematode increase in soil. Ten percent and 6% of the lettuce and radish roots, respectively, contained mature females with egg masses. Averages of 2 160 and 21150 J2/m2 were found in the roots of lettuce plants (45/m2) at the lowest and highest infestation level of the

Pathogenicity of MELOIDOGYNE EXIGUA on coffee (COFFEA ARABICA) in pots

Abstract: The relationship between a geometric series of fourteen initial population densities (Pi) of Meloidogyne exigua between 0 and 512 eggs and juveniles/cm 3 soil and growth of coffee (Coffea arabica) was investigated in one-liter clay pots. The Seinhorst model, y = m + (1 - m)z P-T, was fitted to average plant height, internode length, and fresh top weight. Tolerance limits (T) to the nematode for height, weight and lengths of internodes of coffee plants were 5.9, 1.2 and 6.2 eggs and juveniles/cm*3 soil, respectively. The minimum relative yields (m) were 0.7 and 0.4 at Pi*3 256 eggs and juveniles/cm*3 soil for height and internode length of plants, respectively, and 0.5 at Pi*3 128 eggs and juveniles/cm*3 soil for plant top weight. Maximum nematode reproduction was 422-fold at lowest initial population densities (Pi). The histopatology of coffee roots infected by M. exigua reveals swollen root tips and axes. Nematode egg masses were visible on root surfaces only in small root-galls whe

Short-term effects of cattle grazing on nematode communities in Florida pastures.

Abstract: McSorley, R., and J. J. Frederick. 2000. Short-term effects of cattle grazing on nematode communities in Florida pastures. Nematropica 30:211-221. Effects of cattle population density on nematode community structure were evaluated in a rotational grazing study involving 16 experimental pastures (each 20-32 ha in size) at a cattle ranch in south-central Florida. Summer pastures were grazed from Apr./May to Oct./Nov. and winter pastures from Oct./Nov. to Apr./May. Experimental design was a split-plot, with two pasture locations (winter, summer) as main plots and four cattle densities (0, 15, 20, or 35 cow-calf pairs per pasture) as subplots. With a few exceptions, population densities of most nematode genera in winter and summer pastures were similar (P 0.10). Cattle density had relatively little effect on population levels of individual nematode genera or on indices of nematode community structure. Of the more than 50 nem- atode genera found at this site, Monhystera populations were

Influence of Aldicarb and 1,3-dichloropropene applications on cotton yield and ROTYLENCHULUS RENIFORMIS post-harvest populations

Abstract: A three-year nematicide study in north Florida, involving four separate cotton field trials, was conducted in loamy sand soils infested with Rotylenchulus reniformis. Cotton lint yield responses and post-harvest soil infestation levels of R. reniformis were evaluated after treatment with four single chisel application rates of 1,3-dichloropropene (1,3-D: 16, 32, 48, and 64 kg a.i./ha) and six rates of aldicarb (0.50, 0.84, 1.01, 1.18, 1.51, and 2.02 kg a.i./ha) placed in a 15-cm-wide band. All rates of 1,3-D increased (P 0.05) lint yields of cotton in three of the four trials compared to the non-treated controls. Post -harvest soil populations of R. reniformis were reduced by 1,3-D treatments in only one of the tests. Aldicarb increased cotton yield (P 0.05) at all rates in one test, and at one rate in a second test. Soil populations of R. reniformis were reduced in only one aldicarb treatment in one of the tests. Average cotton yield across treatments increased by 139 kg/ha with 1,

Correlation Between Paratrichodorus Minor Population Levels and Corky Ringspot Symptons on Potato

Abstract: Perez E. E., D. P. Weingartner y R. McSorley. 2000. Correlacion entre poblaciones de Paratrichodorus minor y sintomas de mancha de anillo corchoso en papa. Nematropica 30:247-251. Dos cultivos de papa fueron establecidos entre los aeanos 1993 y 1995. Diesiseis parcelas de papa variedad Red LaSoda fueron arregladas en un diseeano de bloques al azar. Todos los tuberculos de cada parcela fueron cosechados, enumerados, y examinados para determinar incidencia y severidad de la mancha de anillo corchoso (MAC). Muestras de suelo para extraccion de nematodos fueron colectadas durante el periodo de crecimiento de la papa. La cantidad de P . minor en cada fecha de muestreo estuvo asociada con incidencia y severidad de MAC en los tuberculos dos meses despues de plantacion en las dos cosechas (PD 0.05).

Alternatives to methyl bromide for root knot nematode management on cucumber in Lebanon

Abstract: An experiment to compare nematode management tactics was conducted in South Lebanon on cucumber in commercial greenhouses naturally infested with the root-knot nematodes Meloidogyne incognita and M. javanica. Significant increases in fruit yield and a reduction of root galling index and nematode juveniles in soil were observed in plots following soil solarization for 50 days, and in plots treated with methyl bromide. The use of bio-rational products containing naturally occurring agents with putative activity against nematodes (Bio-Act, Bio-Zymes and Sincocin) were ineffective in our tests, nor did these products enhance the efficacy of soil solarization.

Additive effect of three organic materials and nematicides on the reproduction of Meloidogyne incognita and yield of Mentha arvensis.

Abstract: Pandey, R. 2000. Additive effect of three organic materials and nematicides on the reproduction of Meloidogyne incognita and yield of Mentha arvensis. Nematropica 30:154-160. Greenhouse trials were conducted to determine the influence of three organic materials and two nematicides on reproduction of Meloidogyne incognita and yield of Mentha arvensis . Maximum reduction in M. incognita populations occurred at high doses of neem cake (Reproduction factor (Rf) = 0.64) followed by Adhatoda vasica Nees leaf powder (Rf = 0.99 to 1.40), aldicarb (Rf = 1.58), medium dose of neem cake (Rf = 1.70), carbofuran (Rf = 2.45), bavistin (Rf -- 3.38) and powdered leaf of Murraya koenigii (L.) Spreng (Rf = 3.71, 3.37), respectively. Maximum oil yield of menthol mint cv. Hy-77 was obtained in neem cake treated soil followed by powdered leaves of A. vasica, M koenigii, aldicarb, carbofuran and bavistin. Similar results were recorded with dry root and shoot weights of the plant. A phytotoxic effect of hi

Colonization of foliar tissues of an aquatic plant, ANUBIAS BARTERI SCHOTT, by RADOPHOLUS SIMILIS

Abstract: In this paper evidence is presented for the reproduction of Radopholus similis in foliar tissues of Anubias barteri Schott Burrowing nematodes colonized petioles and leaves of A barteri in addition to the rhizomes The nematode invaded the epidermis and the mesophyll of leaves causing cavities and cell disruption in the epidermis, palisade parenchyma and spongy parenchyma Cavities extended from the spongy parenchyma into the periphery of the vascular bundles disrupting the regular flow of nutrient solution in the leaf tissues Nematode feeding and migration also damaged the palisade parenchyma and cell chloroplasts inducing chlorosis and small brown lesions on the blades of the infected leaves The burrowing nematodes recovered from A barteri reproduced on sour orange and Duncan grapefruit in the greenhouse and on sour orange in the laboratory In greenhouse tests, the citrus race of R similis from citrus and the population from A barteri reproduced on four Anubias species Mo

Efficacy of "ABG-9008" against burrowing nematode (Radopholus similis) on bananas.

Abstract: DiTera is a biological nematicide of microbial origin with potential for managing several plant-parasitic nematodes in different crops. Efficacy of ABG-9008, an earlier formulation related to DiT-era, to control the burrowing nematode of bananas was evaluated using direct-contact and root-penetration assays, and in a greenhouse test. Nematodes were incubated for 48 hr at 25 C in 112 and 224 mg/ml suspensions of ABG-9008, corresponding to 112 and 224 kg/ha on a broadcast basis. Suspensions at 15 000 and 75 000 mg/ml also were included. Efficacy of ABG-9008 was assessed at the same rates on Radopholus similis-infected banana root segments in microtiter plates. Efficacy of the product was evaluated under greenhouse conditions by applications at day 0 and 5 after inoculation. Water and fenamiphos at 4.65 mg/ml (4.5 kg/ha) were included as standard controls in all experiments. Percentages of mortality in suspensions, which ranged from 16.8 to 24.6%, were not significantly different betwe

Effects of cropping system on nematode population densities in small-scale highland Guatemalan agriculture.

Abstract: Larson, B., J. L. Stimac, R. McSorley, and C. MacVean. 2000. Effects of cropping system on nematode population densities in small-scale highland Guatemalan agriculture. Nematropica 30:177-191. The effects of adding selected intercrops to small-scale corn and bean cropping systems in the western Guatemalan highland state of Sololawere evaluated to determine if the associations would increase nematode damage to the principal crops and necessitate use of additional nematode management tactics. Nematode densities were sampled four times during a year-long crop sequence in small plots of corn (Zea maysL.) in monoculture; corn in association with black beans (Phaseolus vulgaris L.), faba beans ( Vicia faba L.), and broccoli ( Brassica oleracea L.); and corn in association with black beans, cilantro Coriandrum sativum L.), and amaranth ( Amaranthus cruentus L.). Corn crops were followed sequentially by black bean in monoculture, black bean in association with tomato ( Lycopersicon escule

Comparative responses of cotton yield to preplant and at plant applications of 1,3-dichloropropene.

Abstract: Rich, J. R., and R. A. Kinloch. 2000. Comparative responses of cotton yield to preplant and at plant applications of 1,3-dichloropropene. Nematropica 30:223-229. Four field trials were conducted in northern Florida to determine the feasibility of at plant applications of 1,3-dichloropropene (1,3-D) on cotton compared to the currently recommended preplant applications for management of Rotylenchulus reniformis . The 1,3-D was injected 30-cm-deep into a sandy loam soil with a single in-row chisel at rates of 16, 32, and 48 kg a.i./ha 7 to 13 days preplant or at cotton planting. In the absence of damaging initial populations of plant-parasitic nematodes, phytotoxicity in the cotton was not observed in the at plant 1,3-D treatments, and they caused only small reductions in plant stand, plant height, or yield compared with the preplant 1,3-D treatments or untreated controls. In two tests where high initial populations of R . reniformis were present, postharvest nematode population densiti

First Finding of a Male Aphanolaimus Coomansi (Tsalolichin, 1988) in Tropical Areas

Abstract: Esquivel, A. 2000. First finding of a male Aphanolaimus coomansi (Tsalolichin, 1988) in tropical areas. Nematropica 30:161-166. The rare aquatic nematode Aphanolaimus coomansi Tsalolichin, 1988 was found in some habitats in Costa Rican Conservation Areas, permitting additional taxonomical details to be added to the original description. The first description of a male of the species is also given in this paper. The male[sub2]s relevant characteristics include: 22 pairs of epidermal glands, reproductive system with single posterior reflexed testis, six preanal tuboid supplements and long spicules, gubernaculum weakly cuticularized and tail region provided with well developed setae. A. coomansi is easy to distinguish from other South American species. Some useful diagnostic characteristics are the small body length, few number of body annuli, the origin of the lateral field near the head end and short cephalic setae.