Aim:The aims of the study were to isolate and characterize the nematode trapping fungus, Arthrobotrys oligospora, to investigate the suppressive and predacious activities of the fungus against Meloidogyne incognita and to study the potentiality of A. oligospora in controlling root-knot caused by M. incognita on tomato plants. Methods and Results: Arthrobotrys oligospora (MRDS 300) was isolated from sandy soil samples collected from Al-Beheira, Egypt. In vitro experiments revealed a high efficiency of the fungus in capturing and suppressing M. incognita second juveniles (J 2 ). Microscopic observations showed that the fungus develops adhesive traps consisting of loops of hyphae. Moreover, an in vitro experiment showed that the culture filtrate of A. oligospora had a high toxic effect on the nematode. Pot experiments carried out in two seasons (2018-2019) showed that A. oligospora significantly suppressed root knot on tomato plants caused by M. incognita. The number of females, galls and nematodes in different developing stages were reduced significantly. The treatment with A. oligospora had a prominent effect on enhancing plant growth. Conclusion: Arthrobotrys oligospora had significant suppressive and predacious effects against root-knot nematode, M. incognita. The fungus developed different forms of trapping devices in addition to secreting toxic metabolites to M. incognita. The fungus had a plant-growth promoting effect. Significance and Impact of the Study: Arthrobotrys oligospora (MRDS 300) is a potential biological control agent that can be utilized in controlling the rootknot diseases caused by M. incognita.

No abstract

Two greenhouse experiments were conducted to evaluate the nematicidal activity of certain alkaloid plants namely, periwinkle (Catharanthus roseus), datura (Datura stramonium), lupin (Lupinus albus), pomegranate (Punica granatum) and fenugreek (Trigonella foenum-graecum) against root-knot nematode Meloidogyne incognita infecting cucumber (Cucumis sativus) and reniform nematode (Rotylenchulus reniformis) infecting cantaloupe (Cucumis melo var.cantaloupensis). Dried powdered parts of such plants were screened at three rates (1, 3 and 5g / plant). In most treatments data indicated a positive correlation between tested rates and plant biomass. Dried leaf powder of C. roseus (62.5%) as well as dried seed powder of L. albus ( 52.8%), and T. foenum-graecum ( 43.2 %) induced remarkable improvement in total plant fresh weight of cucumber at the rate of 5g/plant. However, dried leaf powder of D. stramonium (41.4%) recorded a significant increase in total plant fresh weight at the rate of 3g/plant. By all treatments of alkaloid plants root-knot nematode population whether in soil and roots, root galling and number of egg masses were significantly suppressed. Dried leaf powder of C. roseus at three tested rates (71.8, 71.6 and 72.6%) performed the best and suppressed total nematode population of M. incognita followed by T. foenumgraceum at 5g/plant (70.1%). On the other hand, a slight to moderate improvement in plant growth parameters of cantaloupe infected with R. reniformis was indicated in pots receiving alkaloids plants. The highest percentage of increase in total plant fresh weight was noticed with dried leaf powder of C. roseus at three tested rates (28.5, 31.4 and 32.6%) respectively. The best protection of cantaloupe against R. reniformis was recorded with dried seed powder of T. foenum-graecum (57.9, 65.2 and 75.0%) and P. granatum (55.4, 55.9 and 61.7%) at three tested rates, respectively which ultimately suppressed R. reniformis population.

Root-knot nematode Meloidogyne incognita is among the biotic factors which has greatly affected both the yield and the quality of the tomato crop. The egg parasitic nematode, Purpureocillium lilacinum (Pl) is considered as one of the most promising agents in controlling and overcoming this plant pathogen. The nematicidal effect of the native isolate Pl AUMC 10149 on second stage juvenile’s survival and egg hatching of M. incognita at different times of exposure was tested in vitro. The obtained data showed that Pl gave a maximum percentage of J2 mortality (97.6%) and egg hatching inhibition (79.8%) after 72 hours of exposure. The potentiality of Pl as well as Bio-Nematon to control M. incognita infecting tomato was conducted using different times of application in vivo. Nine treatments with five replicates were used for such bioagents compared with the nematicide Oxamyl. Each seedling was inoculated with 1000 J2s of nematode/pot and 10 mL of Pl (1x1010 CFU/mL) or Bio-Nematon spore suspension (1x108 CFU/mL) 10mL/pot. The results indicated that the most effective treatments in reducing nematode population, number of galls and egg masses of M. incognita in plant roots was performed with treatment by Pl pre-planting and post-infection with Pl (Rf 1.9) giving a significant enhancement in plant length (64.9%), fresh weight (72.52%) and shoot dry weight (163.41%) without negatively impacting environment. Therefore, the present study confirmed that using P. lilacinum AUMC 10149 can be used as a practical supplement to environmentally friendly disease management of root-knot nematodes in Egypt.

No abstract

In comparison to a chemical nematicide (Oxamyl), humic acid and three commercial bioagents namely Abamectin (Streptomyces avermitilis), Clean Root (Bacillus subtilis) and Nemastrol (chitinase, glycosynolates, Glucanase, cytokinins and flavonoids) were tested in a greenhouse and field to see how they affect the population density of root-knot and citrus nematodes and, as a result, the effects on plant growth parameters. In greenhouse test, humic acid gave the highest results in terms of increasing total plant fresh weight (403.8 %) and shoot dry weight (400%) compared to untreated plants. Regardless chemical nematicide used, Abamectin showed the best results in suppressing Meloidogyne incognita reproduction with a reduction percentage of (85.4%), while Nemastrol resulted the best reduction percentage of Tylenchulus semipenetrans population (84.4%). Six months after treatment, Nemastrol showed the highest decrease percentage of root-knot nematode (82.4%) and citrus nematode (75.6%) in a field experiment. On the other hand, Oxamyl and humic acid outperformed other treatments in terms of improving the percentage of fruit weight (166.84 and 145.87 %), respectively. Furthermore, all treatments had an impact on the fatty acid composition of olive oil. At the same time, compared to untreated trees, such treatments resulted in lower peroxidase and polyphenoloxidase activities. In terms of phenol content, it was clear that Nemastrol, followed by humic acid improved total phenol content. However, Clean Root gained the highest overall protein concentration. Furthermore, humic acid increased the total carbohydrate level.

Biological control is considered an important approach in the recent years for controlling many plant diseases. Trichoderma spp. is a unique genus with a wide range of activity against most important plant pathogens. In this investigation, we have evaluated antagonism of four species of Trichoderma (T. album, T. asperellum, T. hamatum and T. koningii) against rootknot nematode (Meloidogyne javanica) and Fusarium wilt disease (Fusarium oxysporum f. sp. cucumerinum) on cucumber plant at two locations (Giza and Sakha) under greenhouse conditions. Effect of Trichoderma on disease severity of F. oxysporum f. sp. cucumerinum and mortality of M. javanica (J2) were examined under laboratory conditions. Results indicate that all tested Trichderma spp. inhibited the mycelial growth of F. oxysporum f. sp. cucumerinum and gave high mortality % of M. javanica juveniles in vitro. The best antifungal activity was shown by T. album and T. hamatum against cucumber wilt pathogen. After 24 hours, T. hamatum and T. album had almost 100% nematode mortality. Under greenhouse conditions, a significant enhancement was found in growth parameters of cucumber treated with T. album and T. hamatum at two locations. The application of T. hamatum to soil infected with F. oxysporum and M. javanica resulted in the highest antagonistic effect at Giza location. All treatments caused a reduction in final population density of M. javanica whether in the presence of Fusarium or not. At Giza location, the treatment utilizing T. album were shown to be the most effective in lowering the total number of galls and egg masses on cucumber roots infected with nematodes. However, in the presence of Fusarium fungus + nematodes, T. hamatum was the best treatment. At Sakha location, no significant differences were observed among Trichoderma spp. when nematodes and fungus were used together. T. koningii with nematode only resulted in a lower number of egg masses. Most treatments were more effective in reducing M. javanica reproduction factor (RF) when the nematode was present alone. In both sites, the highest increase in chitinase activity was recorded with treatment by T. hamatum and Fusarium.

One of the most significant pests of vegetable crops is known as root-knot nematode (Meloidogyne spp.). Although, using synthetic nematicides to manage nematodes are a triedand-true successful method, this tactic raises concerns due to its high costs and negative environmental impacts. In order to control root-knot nematode infection and infestation on eggplant cv. Black Beauty seedlings in an environmentally friendly manner, experiments were carried out using a chemical fertilizer (NPK), an organic fertilizer (humic acid), and some antioxidant substances (selenium, vitamin C, and E) individually and in combination under greenhouse and field conditions. The obtained results of these investigations, revealed that all tested treatments have the ability to reduce nematode populations, which would raise yield. Vitamins C and E combined with NPK fertilizer significantly increased shoot and root fresh and shoot dry weight over control in greenhouse conditions. They also significantly decreased total final nematode population with reproduction factor (Rf =0.44) less than control. Additionally, simultaneous application of humic acid, selenium, and NPK boosting plant conditions and greatly reduced J2s, gall formation, and number of egg masses. Plant height, fresh and dry weight, yield per plant, N, P, and K contents, as well as fruit quality (total carbohydrates, vitamin A, and C) were all estimated during field trials. As for, parameters of eggplant as affected by application of humic acid and/or antioxidants concomitantly with NPK fertilization were significantly increased. Furthermore, reducing activity in total nematode population in soil and root was achieved by all tested treatments. It could be observed that humic acid and different antioxidant when combined with NPK induced systemic which consequently caused suppression in eggplant against root knot nematode.