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This survey was conducted in four locations of Ismailia governorate in the north eastern part of Egypt during the 2020-2022 seasons to investigate occurrence, population density and distribution of plant-parasitic nematodes associated with various crops. A total of 440 soil samples, were collected from infested fruit trees viz. grape (Vitis vinifera L.), guava (Psidium guajava L.), olive (Olea europaea L) and pomegranate (Punica granatum L.) and vegetable crops viz. green bean (Phaseolus vulgaris L.), pea (Pisum sativum L.), strawberry (Fragaria ananassa) and tomato (Solanum lycopersicum L.). Ten plant parasitic nematodes genera have been identified. The root-knot nematodes, Meloidogyne had the highest mean density over any nematode taxa in the tested samples. The highest density values of Meloidogyne were recorded on olive, grape and guava trees that amounted to 800, 640 and 200 juveniles/250 g soil. respectively. However, the maximum densities for Tylenchorhynchus were 160, 180, 120, and 120 juveniles /250 g soil for grape, guava, olive, and pomegranate, respectively. The maximum density values for Helicotylenchus were 180, 120 and 40 juveniles /250 g soil for guava, olive and pomegranate, respectively. Other genera were found at low density i.e. Criconemoides, Trichodorus, Xiphinema, Longidorus, and Pratylenchus. The root knot nematodes have been nearly found in all vegetable crops. The maximum densities for Meloidogyne were 600, 200, 240 and 720 juveniles /250 g soil for green bean, pea, strawberry and tomato, respectively. Generally obtained data indicated that plant-parasitic nematodes are considered as a serious threat to such plant species under variable agronomic and climatic conditions that need to further developed and implemented of control measures.

A survey of plant-parasitic nematodes (PPNs) associating wheat in Ismailia governorate, northeastern Egypt was carried-out during 2016/2017 and 2017/2018 growing seasons. Results showed that seven PPNs genera and/or species were found associating wheat roots. These genera and/or species, in descending order of frequency, were: Tylenchorhynchus spp. (14%), Helicotylenchus spp. (10%), Heterodera avenae (8%), Ditylenchus spp. (5%), Meloidogyne javanica (4%), Pratylenchus spp. and Xiphinema spp. (3%, each). Two screening pot experiments, in two consecutive growing seasons (2017/17 and 2017/18) were carried out to determine the host suitability of 15 Egyptian cereal cultivars including bread wheat (Triticum aestivum), barley (Hordeum vulgare) and oat (Avena sativa) to the cereal cyst nematode, Heterodera avenae, under greenhouse conditions. Results of both experiments were very similar and showed that oat cv. Baladi and wheat cv. Giza 171 were highly susceptible, while wheat cvs. Masr 1, Masr 2, Masr 3, Sakha 95, Seds 1, Seds 12, and Shandawel 1 were susceptible. However, barley cvs. Giza 135, Giza 123, Giza 124, and Giza 125 were found to be moderately resistant to the tested nematode. H. avenae suppressed (P ≤ 0.05) the dry weights of roots, shoots and spikes of the inoculated plants, compared to the non-inoculated checks. Another greenhouse pot experiment was carried out during the wheat-growing season 2018/2019 to determine the effect of different initial population densities (Pi) of H. avenae on the growth parameters of wheat cv. Giza 171 and on nematode reproduction. Results showed that as the nematode Pi increased, both the wheat growth parameters and the nematode reproduction factor (Rf) were decreased (P ≤ 0.05).

A field experiment was conducted over two growing seasons 2018/19 and 2019/20, at Ismailia Agric. Exper. and Res. Station, A.R.C., to determine the effect of onion plant densities (2, 3 and 4 rows of onion intercropped with sugar beet) and four nitrogen fertilizer rates (60, 80 and 100 kg N/fad) as blending fertilizer of urea formaldehyde (UF as slow-release N) and traditional urea (TU) compared to control treatment (100 kg N/fad as TU) on productivity, control of root-knot nematodes Meloidogyne spp., land and N use efficiency as well as net return. Results showed that, intercropping two rows of onion with sugar beet significantly increased root, top and sugar yields/fad of sugar beet, TSS% and bulb characters as well as NUE compared to 3 and 4 rows of onion. Meanwhile, increasing onion plant density up to four rows significantly increased plant height and onion yield/fad. Slow-release N fertilizer had a significant effect on sugar beet and onion traits. The blending fertilizer of UF at 100 kg N/fad had the highest sugar beet and onion productivity, while N rate at 80 kg/fad had the highest sugar yield/fad and NUE. Intercropping two rows of onion with application UF+TU at 100 or 80 kg N/fad had the highest values of sugar beet and onion traits, without significant differences in most cases. The applying treatments were studied against root-knot nematodes under field conditions. Generally, the nematode parameters were negatively correlated with intercropping onion with sugar beet compared to check treatment (solid sugar beet). The most effective treatment in reducing the number of galls, eggmasses per root system, root gall index (RGI), egg-masses index (EI) as well as a number of second-stage juveniles (j 2) in soil was 4 rows with 80 kg nitrogen in two successive seasons. Intercropping two rows of onion with sugar beet and application blending N fertilizer of UF at 80 kg N/fad had the highest LER value 1.31 and 1.34 and maximizing net return/fad compared to solid sugar beet. Therefore, growing two rows of onion with sugar beet that received 80 kg N/fad as a mixture of UF and TU could be controlled root-knot nematodes, Meloidogyne spp. and increased sugar beet productivity, maximizing land use and grower profitability as well as reduced N fertilizer usage.