J2 In Soil Research Articles

Performance of biological and chemical nematicides in different soils to control Meloidogyne incognita in tomato plants

AbstractThree fluorinated, one carbamate nematicide, as well as two biological control agents were tested in greenhouse trials to determine their efficacy against Meloidogyne incognita on tomato plants in three different soils. Each soil was treated with one of the following chemical nematicides at the labelled rate: fluensulfone, fluopyram, fluazaindolizine, and oxamyl. The biocontrol agents used were Metacordyceps chlamydosporia and Pasteuria penetrans. In one additional treatment, a combination of the biocontrol agents was applied. After 60 days, root‐knot nematode population data, tomato plant growth, and root galling were assessed. Of the chemical nematicide treatments, fluazaindolizine had the strongest effect on M. incognita J2 in soil, with a 99% reduction relative to the untreated control. More than 99% reduction in the number of eggs per root system was achieved by all three fluorinated nematicides. The strongest effect on M. incognita J2 in soil by a biological control agent was in a combined M. chlamydosporia + P. penetrans treatment that resulted in an 87% reduction. This combined treatment was also the most effective on the eggs per root system, reducing the number of eggs by 69% relative to the untreated control. The different soils affected the efficacy of the biocontrol agents more than the efficacy of the fluorinated nematicides. For example, the percentage reduction in M. incognita J2 by the biocontrol treatments ranged from 40% to 65% for the three soils. For the fluorinated nematicides this range was 96% to 97%. These trials demonstrate the influence of the growth substrate on the efficacy of the biocontrol treatments. Overall, the tested biological control agents did not match the novel nematicides' early protection of tomato transplants.

Anaerobic soil disinfestation with ethanol or sucrose reduces the viability of Meloidogyne javanica and Stromatinia cepivora

Anaerobic soil disinfestation (ASD) is an ecological alternative to chemical soil fumigation. However, little is known about the potential of this technique for the management of Meloidogyne javanica and Stromatinia cepivora. To test the hypothesis that ASD reduces the viability of these two pathogens, we assessed ethanol (5%, v:v) and sucrose (5%, m:v) as carbon sources for ASD, for an incubation period of three weeks. Twenty kilograms of soil naturally infested with M. javanica (82 ± 43 J2 100 cm-3 soil) were placed into a plastic container. Polyester traps, each with 15 S. cepivora sclerotia, were buried at 10 and 20 cm depth per container. ASD with diluted ethanol or sucrose (5% v:v or m:v) was compared to the untreated control (UTC), chemical fumigant metam sodium (MS), and soil saturation with water. In comparison to the UTC, ASD using ethanol reduced the numbers of J2 in soil and the galls in tomato roots by more than 93%, a degree of suppression similar to that achieved when using MS. The viability of sclerotia of S. cepivora was reduced by ASD using ethanol or sucrose from 38.12 to 58.1% compared to the UTC. ASD for three weeks using ethanol or sucrose (5%) reduces the viability of M. javanica and S. cepivora in the microcosm.

Efficacy of moringa (Moringa oleifera) formulations on suppression of root-knot nematodes (Meloidogyne javanica) and growth of eggplant (Solanum melongena)

Eggplant (Solanum melongena L.) is one of the premier vegetables and is widely cultivated. One of the most important reasons for reduced yield of eggplant is root-knot (Meloidogyne species) nematode. So, it is important to control this pest; therefore, an investigation was conducted in 2022 at the Aquaculture Research Unit lab to evaluate the effectiveness of moringa (Moringa oleifera Lam.) application in controlling root-knot nematode in eggplant. During this study, Meloidogyne javanica (Treub) was identified from the rhizosphere soil samples. Fresh leaf extracts of moringa, including positive control (fenamiphos), were investigated in vivo for efficacy against M. javanica in root and soil. Seedlings of eggplant were inoculated with 3000 eggs and second-stage juveniles (J2) of M. javanica in pot trials, with treatments comprising fresh leaf extracts of moringa (M. oleifera) in a series of concentrations. Fifty-six days after inoculation, the Phyto nematicide had reduced eggs and J2 in soil by 62-89%, gall number by 58-87%, and gall index by 35-87%. The best treatment was moringa (80 ppm) which was significantly superior to moringa (40 ppm) and moringa (60 ppm) (P less than 0.05). However, fenamiphos had no significant difference (P greater than 0.05). The results showed that moringa (80 ppm) was the best treatment for controlling root-knot nematode in eggplant.

Nematicidal effect of chitosan on Meloidogyne incognita in vitro and on tomato in a pot experiment

The present study investigated to evaluate the potential of liquid chitosan of three concentrations (0.5, 1 and 2%) on Meloidogyne incognita (Kofoid and White, 1919) Chitwood, 1949 in vitro and on tomato under controlled conditions ((24 ± 1 °C, 60 ± 5% humidity). In vitro assay, the effect of the liquid chitosan concentrations on suppressing of hatching from eggs and second juvenile larvae (J2) mortality was determined. The reducing effect of the concentrations on the number of gall and egg mass on tomato roots and the J2 density in the soil was evaluated under controlled conditions. All concentrations suppressed hatch and increased J2 mortality more than control in vitro. The most effective concentration was found at 2% in vitro and its nematicidal effect on egg and J2 was over 70%. The results demonstrated that 0.5, 1 and 2% concentrations were significantly decreased gall/root, egg mass/root and J2 in soil compared to negative control under controlled conditions. No statistically significant difference was found between the nematicidal effects of the concentrations on the gall and egg mass (P≤0.05). It has been determined that 1 and 2% concentrations better suppress the J2 in soil than 0.5%. Although the nematicidal effect of 2% concentration was high in vitro and under controlled conditions, it was determined that it negatively affected plant biomass. Also, only 1% concentration of chitosan application controlled M. incognita on tomato by 58%. The present results show that the use of 1% liquid chitosan concentration against M. incognita will be more effective.

Interactive Effects of Filamentous Fungi and Cucurbitacin Phytonematicide on Growth of Cowpea and Suppression of Meloidogyne enterolobii.

Cowpea [(Vigna unguiculata (L.) Walp)] is highly susceptible to the emerging guava root-knot nematode, Meloidogyne enterolobii, with available management options being limited due to the withdrawal of effective fumigant nematicides from the agrochemical markets. Filamentous fungi, available as Biocult (a.i. Glomus species + Trichoderma asperellum Lieckf and Nirenberg) and Nemafric-BL phytonematicide (a.i. cucurbitacin B) each improves plant growth and suppresses nematode population densities. However, when filamentous fungi like Biocult are combined with other biocontrol agents, the combined effects either have synergestic or antagonistic effects on the test variables. The combined effects of Biocult and cucurbitacin phytonematicides on plant growth and nematode suppression remain undocumented. The objective of this study was therefore to determine the combined effects of Biocult and Nemafric-BL phytonematicide on growth of cowpea var. Eureka and suppression of M. enterolobii population densities. Eureka was subjected to the effects of the two products in a 2 × 2 factorial experiment on a field infested with M. enterolobii. At harvest, the interaction of Biocult and Nemafric-BL phytonematicide was highly significant (P ≤ 0.01) on plant and nematode variables, with a two-way table used to assess the findings. Relative to untreated control, Biocult alone increased plant growth variables from 15 to 74%. Similarly, NemafricBL phytonematicide increased plant variables from 14 to 61%, whereas the combined effects significantly increased dry shoot mass (19%) and dry harvestable leaf mass (21%), but did not have significant effects on plant height and stem diameter. Relative to untreated control, Biocult alone reduced nematode eggs in root (80%), J2 in root (84%) and J2 in soil (53%), whereas the combined relative effects of the two products did not have significant effects on nematode population densities. In conclusion, Biocult and Nemafric-BL phytonematicide had antagonistic effects on growth of cowpea and suppression of M. enterolobii population densities and therefore, should be used separately in cowpea production.

Nematicidal Activity of some Nanoemulsions of Monoterpenes on Tomato Root-Knot Nematodes (Meloidogyne javanica)

The present study was initiated to explore at the nematicidal activity of some nanoemulsions of monoterpenes, i.e. (R)-carvone, cinnamaldehyde, citral, geraniol and pulegone against tomato knot-root nematode M. javanica, in both laboratory and under greenhouse conditions The results show that the pure and NE-monoterpenes tested considerably and severely decreased egg hatching at doses ranging from 25 to 1000 μg/ml. NE-Cinnamaldehyde, significantly, showed higher J2 mortality (90.67 %) and egg-hatching inhibition (8.67) than pure cinnamaldehyde. The most successful therapy for reducing root galls and the number of egg masses was NE- Cinnamaldehyde, which showed 90.3% and 92.8% reduction, followed by NE- Pulegone 84.2% reduction, respectively. The population of J2 in soil was considerably decreased after using the tested nanoemulsion monoterpenes. NE- Cinnamaldehyde was the most effective treatment, suppressing the final population of M. javanica by 81.8%. Beyond oxamyl, NE-Cinnamaldehyde was the most efficient treatment for increasing the weights and lengths of both fresh shoots and roots in infected tomato plants, consecutively. Meanwhile, pulegone measured the intermediate values of fresh root and shoot weights as well as for lengths. Normal and nanoemulsion cinnamaldehyde ranked the first as it increased polyphenoloxidase (PPO) activity, compared to the other treatments followed by nanoemulsion and normal pulegone. The highest enzyme activity was noticed 7 and 15 days after treatment. Peroxidase activity (POD) also increased by nanoterpene treatments in a trend similar to that of the PPO. Consequently, these effective monoterpene nanoemulsions could be effective potentially and environmentally safe to control tomato knot-root nematode.

Field Application of Trichoderma spp. for Controlling the Root- Knot Nematode, Meloidogyne javanica in Peanut Plants

A field experiment was conducted to study the effect of three Trichoderma species, T. harzianum, T. viride and T. virens on root- knot nematode, Meloidogyne javanica infecting peanut plants, compared to commercial product Bio-Nematon® (Purpureocillium lilacinum) and chemical nematicide of Oxamyl®. The averages of total microbial soil community, i.e. aerobic bacteria, spore-forming bacteria and fungi in peanut rhizosphere as well as the frequency % of common fungi with different treatments, during growing season, were recorded. Treatments significantly (P=0.05) suppressed J2 in soil and J2, females, galls and egg masses in roots and improved peanut plant growth and yield parameters. At mid-season, Trichoderma spp. had more effective nematicidal effects in reducing nematode parameters than Bio-Nematon® in some cases. The highest percentages reduction in J2 in soil (being 81%) was recorded with T. viride followed T. harzianum (77%) and T. virens (73%), compared to untreated control. At harvest time, T. viride recorded the highest nematode reduction in J2 in soil (68%), but T. harzianum recorded the highest reduction in total developmental stages of nematode (68%), galls (84%) and egg masses (84%), compared to T. viride, T. virens and Bio-Nematon®. The treated soil rhizosphere differed in total microbial counts as well as frequency of common fungi according to the tested treatment that increased total microbial counts. The treatments highly increased the growth and yield criteria of peanut as indicated by fresh & dry weights of plants as well as number & weight of pods and weight of 100 seeds of peanut plants.

Application of dry powders of six plant species, as soil amendments, for controlling Fusarium solani and Meloidogyne incognita on pea in pots

BackgroundApplication of organic amendments could improve soil properties as well as controlling of soil-borne pathogens. Soil amendments with dry powders of six plant species materials, i.e. caraway seeds, fennel seeds, garlic gloves, onion bulbs, pomegranate peel and spearmint leaves were separately applied for controlling Fusarium solani and Meloidogyne incognita on pea plants in pots. The control is untreated check pots for Fusarium solani and Meloidogyne incognita.ResultsThe dry powder of pomegranate peel (as the rate of 10 g/1 kg soil)highly reduced the Fusarium- disease assessments (pre-emergence and post-emergence damping-off and root-rot diseases incidence), followed by spearmint leaves, caraway seeds, fennel seeds, garlic gloves and onion bulbs, respectively. The tested dry powder of plant species showed the nematicidal activity on M. incognita criteria, i.e. second juvenile (J2) in soil and roots as well as galls and egg-masses in roots of pea. The spearmint leaves, onion bulbs and fennel seeds highly reduced the J2 in soil and roots as well as galls and egg-masses. The pea plant growth parameters i.e. length of shoot, fresh & dry weights of shoot and fresh weight of roots, yield parameters, i.e. fresh and dry weight of pea pod and pod parameters as well as Rhizobium nodules number were increased in pea plants with reducing infestation with F. solani and M. incognita.ConclusionsSoil amendments with dry powders of six plant species materials were used in this study reduced F. solani and M. incognita and improved pea plants

Cost-effective bacteria-based bionematicide formula to control the root-knot nematode Meloidogyne spp. on tomato plants

Abstract. Asyiah IN, Prihatin J, Hastuti AD, Winarso S, Widjayanthi L, Nugroho D, Firmansyah K, Pradana AP. 2021. Cost-effective bacteria-based bionematicide formula to control root-knot nematode Meloidogyne spp. in tomato plants. Biodiversitas 22: 3256-3264. The root-knot nematode, Meloidogyne spp. can infect and cause loss production in various horticultural plants, including tomatoes. In the previous study, we found 3 endophytic bacteria isolates and 1 rhizobacterium isolate that could control several plant-parasitic nematodes. In this study, we formulated these bionematicide isolates with cheap and environmentally friendly organic materials. The formula was fortified using several organic matters, vitamin sources, protein sources, and sugar sources. The research was conducted in an experimental land with a history of severe root-knot nematode infection. The analysis showed that there were 63.7 J2 Meloidogyne spp. per 100 ml of soil on the experimental land. The application was given at a time interval of 2 weeks at the concentration of 0.5%, 1%, 1.5%, and 2%, with a dose of 100 ml per plant. As a negative control, the plant did not give any treatments, and as a positive control, the plant was given 5 g carbofuran per plant. The results revealed that treatment with 2% bionematicide formula concentration showed the best consistent result. This treatment increased canopy wet weight by 38.63% and root dry weight by 106.97% compared to negative control. The P4 treatment was also found effective to increase fruit weight by 33.61% and fruit diameter by 26.16% as compared to negative control. Increased plant growth in P4 treatment was closely related to the total of root-knot suppression and root damage intensity. In the P4 treatment, the total of root-knots and root damage intensities was 44.83% and 32.66%, respectively, compared to the negative control. This suppression also occurred in the nematode population and nematode eggs. In the P4 treatment, the total of Meloidogyne spp. J2 in soil and root was lower by 60.74% and 66.24%, respectively, compared to the negative control. A similar phenomenon also occurred in the total of eggs, which was 79.40% lower than the total of eggs in the negative control. This study provides the latest information about a cost-effective bacteria-based bionematicide formula, which is effective in suppressing Meloidogyne spp. infection in tomato, and promotes the growth and development tomato plant.

Induction of Systemic Resistance in Tomato by some Abiotic Com-pounds Against Meloidogyne javanica

The comparative of some abiotic compounds (Ascorbic acid, Citric acid, DL-Aspartic acid, Indole-3Acetic acid, Indole-3Butyric acid, DL-leucine, Gibberllic acid, L-Arginine and Sulfosalicylic acid), as resistance inducing for managing Meloidogyne javanica infecting tomato (Super strain B Australian cv.) was studied under greenhouse conditions. The results showed that all tested compounds reduced all nematode parameters compared with untreated control. Application of Citric acid caused a superior effect in the reduction percentage of J2 in soil (95.2%) followed by L-arginine (92.9%) and then Gibberllic acid (92.2%). Also, DL-Aspartic acid gave the highest effect in the reduction percentage of root galls (95.6%) followed by Citric acid and then L-Arginine acid as following (94.3% and 93.02%) respectively compared with untreated control. The treatments of L-arginine followed by Gibberllic acid were recorded the best in plant growth response of tomato plants compared with the untreated control. Tested abiotic agent inducers activators had the potential to suppress M. javanica infection through the stimulation of tomato tolerance. Most of the treatments showed a significant reduction in the percentage values of total and non-reducing sugars comparing with infected and healthy control, while Sulfosalicylic acid and L-arginine recorded high amounts in total and non-reducing sugars. On the other hand, Dl-Aspartic acid, Indol-3Acetic acid and Citric acid showed a high percentage of total phenols comparing with untreated control. Among all treatments, only Dl-leucine showed a significant increment in proline comparing with untreated control and healthy control. The level of Polyphenol oxidase and peroxidase activity increased in the treated plants compared with untreated plants.

Management of root-knot nematode Meloidogyne incognita of eggplant using some growth-promoting rhizobacteria and chitosan under greenhouse conditions

BackgroundEggplant (Solanum melongena) is one of the most popular vegetable crops in Egypt. It is affected by a wide range of pests; prominent among them is root-knot nematode (RKN) Meloidogyne spp. which constitutes a major group of plant-parasitic nematodes causing great economic losses worldwide especially in Egypt.Main bodyThe present investigation was performed under greenhouse conditions to evaluate the potentials of 3 growth-promoting bacteria, Azospirilum brasilense, Azotobacter chroococcum, and Bacillus subtilis, as well as chitosan for the control of the nematode Meloidogyne incognita causes root-knot disease of eggplant cv. Baladi. All treatments reduced (p ≤ 0.05) the nematode population in soil and roots as well as enhanced the plant growth parameters of eggplant remarkably than the control. The applied treatments varied in their efficacy against the plant nematode infection in correspondence to the time of application. The recorded results demonstrated that maximum reduction in J2 in soil, egg mass/root, and eggs/egg masses were obtained by treating the soil with Bacillus subtilis followed by Azospirilum brasilense and Azotobacter chroococcum. Also, chitosan resulted in high reduction in root galls compared to control treatment.ConclusionThe use of plant growth-promoting rhizobacteria, Azospirilum brasilense, Azotobacter chroococcum, Bacillus subtilis, and chitosan achieved efficient control to Meloidogyne incognita and consequently increase eggplant growth parameters under greenhouse conditions. The present results suggested introducing such rhizobacteria in integrated nematode management program.

Using Pseudomonas fluorescens and Bromoxynil herbicide for controlling pests and improving growth and productivity of two faba bean cultivars

Pseudomonas fluorescens and Bromoxynil herbicide, alone or in combination, were applied in the field naturally infected with Rhizoctonia solani (root rot disease), Meloidogyne arenaria (root-knot nematode) and different weed species for improved growth and productivity in two faba bean cultivars. All treatments reduced the root rot incidence in the range of 33 to 82%, compared to the untreated control and application of P. fluorescens alone had the best inhibitory effect. Combined P. fluorescens with the herbicide reduced the nematode parameters (i.e. J2 in soil and J2, females, eggs, galls & egg-masses in roots) as well as the weed growth parameters, compared to individual treatments or untreated controls. P. fluorescens alone or in combination with Bromoxynil increased faba bean growth and yield parameters. Most enhancement effects on growth and yield of faba bean achieved by P. fluorescens alone treatment. Total microbial and Rhizobium nodules counts were increased as affected by microbial treatments.

Application of Bacillus species for controlling root-knot nematode Meloidogyne incognita in eggplant

BackgroundEggplant (Solanum melongena L.) is one of the important vegetable crops infected by Meloidogyne incognita all over the world, including Egypt. Chemical nematicides frequently cause environmental pollution and toxic hazards to human, plants, and animals; certain biocontrol agents that are environmentally friendly and safe to humans and animals were tested against the root-knot nematode Meloidogyne incognita in eggplant.ObjectiveThis work is aimed to determine the nematicidal activity of Bacillus spp., viz., B. subtilis and B. pumilus, against M. incognita in three separated experiments to study their ability in controlling M. incognita and in improving the growth parameters of eggplants. Bacillus spp. were applied as single or in combination (experiment I), single treatment at different doses (experiment II), and different times (three times) of application (experiment III).ResultsThe results of experiment I revealed that Bacillus sp. + B. subtilis significantly reduced the second-stage juvenile (J2) in soil and galls and egg masses in roots, while Bacillus sp. + B. pumilus significantly reduced J2 in roots. Bacillus spp. in pairs were more effective against M. incognita. In experiment II, Bacillus sp. (40 ml) significantly reduced the J2 in soil and galls and egg masses in roots, while B. pumilus (40 ml) significantly reduced the J2 in roots. The nematicidal activity of Bacillus spp. was increased by increasing the applied dose. In experiment III, B. subtilis, when applied three times, significantly reduced the J2 in soil and the J2 and galls in roots, while B. pumilus (applied three times) significantly reduced the egg masses in roots. All Bacillus spp. treatments highly increased the tested growth parameters compared to the controls.ConclusionsThe tested biocontrol agents used more than once or in combination are more effective than those used only once in controlling nematode parameters in eggplant under greenhouse conditions with a consequent increase in eggplant growth. These bacterial isolates need to be studied under different field conditions for confirmation.

Influence of three rates of salinity on okra plants (Abelmoschus esculentus L.) infected with root-knot nematode in vivo

A greenhouse experiment was carried-out to evaluate the effect of three rates of salinity as abiotic stress on okra plants (Abelmoschus esculentus) infected with the root-knot nematode (Meloidogyne incognita) as biotic stress. Plant lengths and weights were significantly (p ≤ 0.05) reduced except root weight and there was a positive correlation between increasing the salinity concentration from 0.1 to 0.3% and increasing the rate of reduction in plant criteria. The number of J2 in soil, galls, and eggmasses were decreased linked to increased salinity rate as compared to nematode control treatment. However, peroxidase and catalase activities were significantly reduced linked to increasing the salinity concentration from 0.1 to 0.3%. There was no significant difference between total phenols at all treatments. Meanwhile, there was no significant improvement in N, P, and K contents whereas photosynthetic pigments (a, b) and carotene were significantly (p ≤ 0.05) reduced by nematode infection and increasing the salinity rate from 0.1 to 0.3%.

Efficacy of Nemafric-BL phytonematicide from fresh Cucumis africanus fruit on suppression of root-knot nematodes and growth of tomato plants

Cucurbitacin-containing phytonematicides are prepared from fruits dried at 52oC in air-forced ovens, which could not be available for use by resource-poor farmers to prepare the products. The objective of this study was to determine the influence of Nemafric-BL phytonematicide prepared using fermented crude extracts of fresh fruit from wild watermelon (Cucumis africanus) on growth of tomato (Solanum lycopersicum) plants and root-knot (Meloidogyne species) nematodes. Seedlings of tomato cultivar ‘Floradade’ were inoculated with 3000 eggs and second-stage juveniles (J2) M. incognita race 2 in pot trials, with treatments comprising a series of Nemafric-BL phytonematicide concentrations. Fiftysix days after inoculation, the phytonematicide had reduced eggs and J2 in roots by 8497%, J2 in soil by 49–96% and total nematodes by 70–97%. Plant variables and log22transformed concentrations of Nemafric-BL phytonematicide exhibited quadratic relations, with the model being explained by 74–98% associations. In conclusion, fresh fruit of C. africanus could be used for the preparation of Nemafric-BL phytonematicide.

Grafting and Paladin Pic-21 for Nematode and Weed Management in Vegetable Production.

Two years of field trials conducted in a Meloidogyne incognita-infested field evaluated grafting and Paladin Pic-21 (dimethyl disulfide:chloropicrin [DMDS:Pic] 79:21) for root-knot nematode and weed control in tomato and melon. Tomato rootstocks evaluated were; 'TX301', 'Multifort', and 'Aloha'. 'Florida 47' was the scion and the nongrafted control. A double crop of melon was planted into existing beds following tomato harvest. Melon rootstocks, C. metulifer and 'Tetsukabuto', were evaluated with nongrafted 'Athena' in year 1. In year 2, watermelon followed tomato with scion variety 'Tri-X Palomar' as the control and also grafted onto 'Emphasis' and 'Strongtosa' rootstocks. Four soil treatments were applied in fall both years under Canslit metalized film; Paladin Pic-21, methyl bromide:chloropicrin (MeBr:C33, 67:33), Midas (iodomethane:chloropicrin 50:50), and a herbicide-treated control. M. incognita J2 in soil were highest in herbicide control plots and nongrafted tomato. All soil treatments produced similar tomato growth, which was greater than the herbicide control. All treatments reduced M. incognita J2 in roots compared to the herbicide control. 'Multifort' rootstock produced the largest and healthiest roots; however, the number of M. incognita isolated from roots did not differ among the tomato rootstocks tested. Galling on tomato was highest in herbicide control plots and nongrafted plants. In melon, M. incognita J2 in soil did not differ among melon rootstocks, but numbers isolated from melon rootstocks increased in 'Tetsukabuto' compared with C. metuliferus. 'Tetsukabuto' were larger root systems than nongrafted 'Athena'. All fumigants provided protection for all melon rootstocks against galling by M. incognita compared to the herbicide control. Galling on C. metuliferus rootstock was less in all fumigant treatments compared with nongrafted 'Athena' and 'Tetsukabuto'. In watermelon, M. incognita in soil and roots did not differ among soil treatments or watermelon rootstocks, and yield was lower in both grafted rootstocks compared with the nongrafted control. All soil treatments increased average fruit weight of watermelon compared with the herbicide control, and provided effective weed control, keeping the most predominant weed, purple nutsedge (Cyperus rotundus L.), density at or below 1/m row. Grafting commercial scions onto M. incognita-resistant rootstocks has potential for nematode management combined with soil treatments or as a stand-alone component in crop production systems.

Controle alternativo sobre Meloidogyne incognita em soja

The alternative control is an environmentally safe and ecologically viable option for controlling plant pathogens. Considering the great importance of nematodes in soybean, this study aimed to evaluate the efficacy of nematophagous fungi against the root-knot nematode Meloidogyne incognita in soybean. The experimental design was in randomized blocks, with five treatments and four replicates. The treatments were Pochonia chlamydosporia , Paecilomyces lilacinus , Coprinus comatus , a mixture of P. chlamydosporia and P. lilacinus , and control plants inoculated with M. incognita and without treatment. We evaluated number of eggs and second stage juveniles (J2) in soil and roots, number of galls and reproduction factor (RF). There were no differences among the treatments and the control plants for number of eggs and J2 in soil and roots, number of galls and RF. The P. chlamydosporia treatments caused the reduction of the number of J2 in roots. Thus, was possible to conclude that P. chlamydosporia has potential to control M. incognita in soybean plants. Normal 0 21 false false false PT-BR X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Tabela normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri,sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-fareast-language:EN-US;}

Biological control of Meloidogyne incognita and Fusarium solani in dry common bean in the field

Meloidoyne incognita (root-knot nematode) and Fusarium solani (root-rot pathogen) were the common soil-borne pathogens and cause severe damage to bean plants in newly reclaimed sandy soil in Nubaryia district, Behera Governorate, Egypt. The antagonistic effects of Trichoderma album and Trichoderma viride as well as three commercial products namely Rhizo-N® (Bacillus subtilis), Bio-Arc® 6% (Bacillus megaterium) and Bio-Zeid® 2.5% (T. album) were tested against M. incognita and F. solani under naturally infected field conditions. T. album and T. viride highly reduced the frequency (%) population of pathogenic fungi such as Fusarium spp., F. solani and Rhizoctonia spp., than the commercial products. Results indicated that all the tested bio-control agents reduced, significantly, the nematode criteria as evidenced by the number of juvenile (J2) in soil and number of galls and egg masses on roots of common bean and Fusarium root-rot incidence (%). Rhizo-N® highly reduced the number of J2 in soil, while T. album was the best in reducing the number of galls and egg masses in roots. The bio-control agents also increased the plant growth parameters of common bean plants i.e. plant height, plant weight, branch no./plant, pods no./plant, pod weight/plant, pod weight, seeds no./plant, fresh seeds weight/pod, dry seeds weight/pod and dry weight of 100 seeds.

Indications of variation in host suitability to root-knot nematode populations in commercial tomato varieties

The host suitability of 21 local, commercial tomato varieties were evaluated in concurrent greenhouse trials for resistance to Meloidogyne incognita race 2 and Meloidogyne javanica, respectively. M. incognita race-2-resistance identified in variety ‘Rhapsody’ during the latter study was subsequently verified in a follow-up microplot trial using differential initial population (Pi) densities and as well as in a field trial with four soil amendments. Substantial variation existed among the tomato varieties in the greenhouse screening with regard to resistance to the respective root-knot nematode species. Comparison of the different indicators of resistance used for the two species showed that labelling of specific varieties as resistant should not only be based on one criterium, since it could be insufficient. Strong non-linear relationships were shown in the microplot trial between Pi and Pf in the roots of both tomato varieties but nematode reproduction was poor on the resistant ‘Rhapsody’. Significantly lower Pf in roots and J2 in soil was obtained for ‘Rhapsody’ compared to the susceptible Moneymaker. In the soil-amendment field trial, ‘Rhapsody’ also maintained significantly lower M. incognita numbers compared to ‘Moneymaker’ in all treatments. These results confirm the superior resistance of ‘Rhapsody’ to local M. incognita race-2 populations used in this study. More frequent and extensive screenings of commercial tomato material are recommended in order to provide resource-poor producers with better options for improved and sustainable yields.

Effects on Meloidogyne incognita of chitinase, glucanase and a secondary metabolite from Streptomyces cacaoi GY525

Streptomyces cacaoi GY525, isolated from liquid compost containing crab shell powder, produced a secondary metabolite 3-benzyl-1,4-diaza-2,5-dioxobicyclo[4.3.0]nonane (BDDB) and lytic enzymes including chitinase and β-1,3-glucanase. To examine the effect of the bacterial culture filtrate (CF) and BDDB on mortality of second-stage juvenile (J2) and hatch inhibition of Meloidogyne incognita, different concentrations of them were added in 24-well plates containing ca 250 eggs and 250 J2, respectively. With increasing concentrations of CF and BDDB mortality of J2 increased while hatch decreased. In pot trials, tomato plants were treated with the GY525 culture (SC), culture medium (CM), commercial nematicide (5% ethoprophos) (CN) and combination of CN and SC (CN+SC). Tap water (TW) was used as a control. During the experimental periods, growth of tomato plants treated with SC markedly increased compared with TW and CN treatments. After 7 weeks the number of egg masses in TW was over 220, while that in SC was around 40 per plant. Population of J2 in soil and the number of egg masses in plant roots in SC, CN+SC and CN were significantly lower than those in TW and CM. Our results suggest that S. cacaoi GY525 has potential as a biological control agent against root-knot nematodes.