Introduction:

Let’s embark on our informative practical and scientific journey of Plant Parasitic Nematodes Species in Egypt! This article offers a simple overview of Egypt’s most common Nematode species. Review their sneaky infection symptoms and learn practical control measures to contaminate their hazardous infection in our Egyptian Lands.

Plant-parasitic nematodes (PPNs) rank among the top five pests wreaking havoc on our valuable crops. These organisms parasitize plants, ideal significant damage that can lead to complete crop loss during severe infestations. The destructive impact of PPNs is not limited to their parasitic nature alone. They often form a collaboration with other organisms, particularly fungi and bacteria, which maximizes the harm caused to the host. 

To combat this threat, it is crucial to direct our attention towards the primary enemy: nematodes. Utilizing an Integrated Pest Management approach, we can use various control methods to contain nematode populations and effectively avoid the risk of associated fungal or bacterial infections. By focusing on nematode control, we can safeguard our crops and promote sustainable agricultural practices as we will focus on that in the Nematode Management section.

PPNs Definition:

In order to gain a wide understanding of Nematodes, it is essential to define them based on their behavioural and morphological characteristics. The most accurate definition of nematodes is as follows: they belong to one of the largest groups of multicellular animals. These invertebrates have a cylindrical or worm-shaped body structure that is not visible to the naked eye, requiring microscopic observation. Nematodes are aquatic organisms, functioning as parasites that target agricultural crops. They negatively impact various plant parts. They could live in the soil, roots, tubers, or even freshwater. The presence of water is crucial for nematodes, as it is essential for their survival and the completion of their life cycle.

Common PPN Species in Egypt:

In this article, our focus will be on four plant-parasitic nematode species that account for over 90% of the nematode population in Egypt. These species have significant economic damage to the majority of the Egyptian agricultural landscape. To provide you with an extensive understanding of these nematodes, we have prepared a table that highlights characteristics and key differences among them. Table References “Technical Recommendations for Agricultural Pest Control -EG Agricultural Pesticides Committee”

Root Knot Nematodes (Galls):

Root lesion Nematodes:

Cyst Nematode photos:

Slow Degradation Nematode (Citrus Rot):

Management Strategies Controlling PPNs Outbreaks:

To manage PPNs outbreaks we need to take initial procedures to prevent Nematodes invasion as we all know this common expression “Prevention is better than cure”, so, let us embark on the prevention methods:

·        Plant Resistance Variety: ensure the safety of seedlings, seeds, tubers, and rhizomes prepared for cultivation and that they are free from infection. Experts recommend using varieties which have resistance features against nematodes and avoiding cultivating sensitive ones.

·        Ensure that trees that act as windbreakers are free from Nematodes and make sure they are free from infection before planting them.

·        Tiling the soil continuously, which leads to ventilation and exposure of soil to the sun. It is very effective in controlling many nematodes and other soil pathogens.

·        Always get rid of weeds, as it is an attractive and alternative host for harmful nematodes, pests and organisms.

·        Removing crop residues and infected roots and cleaning the soil and burning the plant parts that bear symptoms of infection with the entire root system in order to eliminate all stages of nematodes carried on them. It is forbidden to transfer it to another field.

·        Ensure that organic fertilizers such as manure organic compost are free of nematode infection or that they do not contain plant parts infected with nematodes.

·        Providing enough organic matter could help to control many different PPNs in the soil, as that increases the free-living nematodes, and other beneficial organisms as they excrete substances that have destructive features managing PPN outbreaks.

·        Assure that the soil, agricultural machinery, and equipment are free of nematodes. We could use sterilizers to prevent any potential infection that may transfer with them.

·        Prevent any irrigation canals passing from farms contaminated with nematodes and avoid cultivating sensitive plants to nematodes on the edges of irrigation canals, as water could transmit the infection to other non-infected farms.

·       Crop rotation is highly important avoiding the buildup of the various nematodes. The Crop cycle is a sequence cultivating of sensitive crops to other resistant crops, which leads to reduced nematode numbers in the soil. It is an effective and low-cost control method.

·       The Egyptian Agricultural Quarantine We cannot ignore the role of this organization in maintaining and preventing the entry of a harmful pest from one country to another or from one place to another within the same country as they are inspecting plants imported abroad, executing the contaminated or infected parts and treating infected seedlings or seeds with one of the controlling methods before releasing them.

Having explored several PPN prevention methods, we shall now proceed to discuss the management of infections and nematode outbreaks through the implementation of Biological and Chemical treatments.

Biological Control Methods:

The biological control of PPNs means reducing the number of PPNs or their ability to feed on the plant through other living organisms such as fungi or bacteria, that happens naturally as a result of the presence of these organisms in the nematode environment, or by treating nematode environment by these organisms.

1-     Bacteria:

·        Rhizobacteria such as Bacillus spp., Pseudomonas spp. These bacteria have the ability to colonize the rhizosphere and produce some substances such as toxins, enzymes, and Anti-nematode secondary metabolites, that affect nematodes directly and kill them. Moreover, these bacteria stimulate plant resistance and encourage plant growth.

·        Obligate endo-parasitic (endospore-forming) bacteria such as Pasteuria penetrans → This bacterium has the ability to parasites on the nematodes larva (Juvenile) and kill them, also it could last in the soil for a long time and resists heat and drought.

2-     Fungi:

·        Fungi parasitize nematode eggs such as Paecilomyces lilacinus, Pochonia chlamydosporia → They parasitize eggs and other stages of nematodes through the mycelium, where it penetrates the egg wall or the body wall of the nematode through the excreting enzymes that dissolve these cell wall and feeds on the egg content.

·        Predacious Fungi: this type of fungi can prey, After the nematode is caught, the fungus mycelium penetrates the nematode's body and feeds on all its contents.

There are multiple types of fungus prey on nematodes:

1-     Adhesive Hyphal Networks Fungus such as Monacrosporium cionopagum.

2-     Compression ring trap fungi such as Arthrobotrys oligospora, A. superba, Dactylella pseudoclavata.

3-     Spores Fungus such as Meristacrum spp.

4-     Sticky nodes fungus such as A. haptotyla, Nematoctonus spp.

·        Rhizospheres colonize fungus:

1-     Selective fungal parasite such as Trichoderma spp., this type of Fungus has a significant influence on Root-Knot Nematodes as they excrete enzymes and secondary metabolites that dissolve Nematode larvae, protect roots as a mechanical barrier against nematodes and stimulates plant growth.   

2-     Mycorrhiza → promotes the nutrients needed for plant growth, and also reduces plant infection with nematodes.

Chemical Control Methods

In this section, together we will explore how to control Nematodes with Chemical based Nematicides and organic-based Nematicides.

Let’s undertake Chemical based Nematicides first as it is common, and the majority of farmers and growers use them the most.

Let’s brainstorm some questions. What do Nematicides mean? How to reach the maximum effectiveness of Nematicides? And What are the registered Nematicides in Egypt?

What do Nematicide mean?

Nematicide is any chemical substance used to kill or inhibit the movement of nematodes in a short period of time. They are usually used as a soil treatment.

How to reach the maximum effectiveness of Nematicides?

 Factors to be considered when using nematicides in soil:

reference “Technical Recommendations for Agricultural Pest Control - Agricultural Pesticides Committee”

1-     The appropriate chemical pesticide should be selected due to variations in the susceptibility of the nematode species to the chemical pesticides. In general, it is preferable to use systemic insecticides to control intestinal nematodes within root tissues and to use high-volatile pesticides to control externally parasitic nematodes in the soil.

2-     Economic value of the crop: Avoid the use of fumigant nematicide on crops of low economic value due to their high prices. In such cases, non-fumigant nematicide can be used for cheap prices. Fumigants can be used on crops of high economic value, in greenhouses and nurseries.

3-     The method of treatment depends on the nature of the chemical pesticide where highly volatile pesticides are placed in the soil at a depth of 15-20m to be effective with the need to be covered with plastic plugs. Non-volatile pesticides used in liquid or granular form are placed on the soil surface.

4-     The application rate varies depending on the soil type. Dense soil needs a larger amount of pesticide than light soil. Higher doses are used when the growing crop has deeper roots than the surface-rooted crop.

5-     Choosing the appropriate pesticide, as it is preferable to use systemic pesticides for nematodes that parasitize inside the roots of the host and in contact with those that intrude externally.

6-     Take into account when using nematode pesticide adherence to the pre-harvest period of the pesticide PHI and make an analysis of the soil and roots of the plant to ensure the presence of types of harmful nematodes and in numbers that cause economic damage greater than the costs of control.

7-     The economic value of the crop.

What are the registered Nematicides in Egypt?

Nematicides Active Ingredients groups:

-        Phosphoramidate Nematicides

·        Phosphoramidate Nematicides

1- Imicyafos (30% SL)

2- Fosthiazate (10% GR, 75% EC)

3- Fenamiphos (10% GR, 40% EC)

·        Organothiophosphate Nematicides

4- Cadusafos (10% GR, 20% CS)

5- Ethoprophos (10% GR, 20% EC, 40% EC)

-            Avermectin Nematicides

6- Abamectin (2% SC)

-            Carbamate Nematicides

·        Oxime carbamate nematicides

7- Oxamyl (10% GR, 24% SL)

Organic Nematicides:

Organic Nematicide is any Organic substance used to kill or inhibit the movement of nematodes in a short period of time. They are usually used as a soil treatment.

Examples:  Azdirachtin Extraction from Neem Oil, Chitosan, Geranium Oil, Cinnamon Oil, Quillaja Saponaria, Nano Zinc … etc

In conclusion, it is imperative to prioritize the protection of crops and soil against PPNs by gaining a comprehensive understanding of the types of PPNs and implementing Integrated Pest Management (IPM) programs. By employing various IPM strategies, one can ensure more effective nematode control, achieve higher yields, and enhance the resilience of field crops. Furthermore, embracing IPM and adopting precise control measures aligns with the global movement towards sustainability, thereby promoting the application of environmentally-friendly solutions in agricultural practices.

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Written by: 

Bilal Mohamed

Agricultural Copywriter at Numumarket

Masters Degree Researcher at Al-Azhar University