Overview
Striga orobanchoides (R.Br.) Benth. is a parasitic plant species in the family Orobanchaceae and native to Australia. It is commonly known as the lesser witchweed or lesser African witchweed. This plant is a root parasite that can cause significant yield losses in crops such as sorghum, maize, and millets in areas where it is widespread.
Appearance
The plant has slender, erect stems that can grow up to 50 cm tall. The leaves are alternate, lanceolate, and range from 1-5 cm in length. The flowers are small and tubular with a pale yellow color, arranged in dense spikes at the stem apex. The root system of Striga orobanchoides is highly specialized for parasitism, with a unique haustorium structure that allows it to penetrate host roots.
Uses
While Striga orobanchoides is considered a harmful weed, it has traditional medicinal uses in some African cultures. The plant has been used to treat various ailments such as fever, coughs, and diarrhea. However, the efficacy and safety of these practices have not been scientifically proven, and the plant should only be used under the guidance of a medical professional.
Light Requirements
The plant Striga orobanchoides requires full sunlight to grow and thrive. In shaded areas, the plant tends to have stunted growth and weakened development.
Temperature
The plant Striga orobanchoides prefers warm temperatures for optimal growth and development. Temperatures ranging from 20°C to 35°C are suitable for this plant. However, it can also tolerate temperature fluctuations to some extent, but extreme temperature changes can cause severe damage.
Soil Requirements
The plant Striga orobanchoides prefers well-drained, sandy soils with a pH of 5.5 to 6.5. It can tolerate acidic soil conditions, but prefers slightly acidic to neutral soil pH. Soil rich in organic matter helps in the growth of the plant. Poorly drained soils with high clay content are not suitable for this plant and can cause root rot.
Cultivation methods for Striga orobanchoides
Striga orobanchoides can be propagated from seeds. The seeds should be sown in well-drained soil during the rainy season. It is essential to note that the seedlings do not tolerate transplanting, so they should be planted directly in the field of cultivation.
Watering needs for Striga orobanchoides
Striga orobanchoides requires an adequate amount of moisture in the soil for successful growth. During the rainy season, the plant can get sufficient water from the rain. However, during dry seasons, irrigation may be necessary. It is important to ensure that irrigation is carried out in moderation because the plant cannot tolerate waterlogged soil.
Fertilization for Striga orobanchoides
For the best growth of Striga orobanchoides, it is essential to apply organic manure and phosphorus fertilizers to the soil. This should be done before planting. Fertilization is critical as it helps the plant develop a robust root system and increases its resistance to diseases and pests.
Pruning for Striga orobanchoides
Striga orobanchoides needs minimal pruning, and this can be done during the growing season. The plant should be pruned to remove dead or damaged stems. This promotes healthy growth and helps keep the plant in good shape.
Propagation of Striga orobanchoides (R.Br.) Benth.
Striga orobanchoides (R.Br.) Benth. is a parasitic plant that requires a host plant to grow and complete its life cycle. Therefore, it cannot be propagated through conventional methods like seeds, cuttings or division.
Host Plant
The propagation of Striga orobanchoides (R.Br.) Benth. relies on the availability of a host plant. The host plant must be suitable for Striga orobanchoides and should belong to the families Fabaceae, Poaceae or Solanaceae. The host plant provides the necessary nutrients for the growth and development of Striga orobanchoides.
Seed Germination
The seeds of Striga orobanchoides require a particular chemical signal to germinate. This signal is obtained through the root exudates of the host plant. When the seed comes into contact with the host plant's root exudates, it germinates and produces a modified root called haustorium, which attaches to the host plant's root and extracts its nutrients.
Factors Affecting Germination
The germination of Striga orobanchoides is affected by several factors, including the presence of a suitable host, temperature, water availability, and soil pH. Optimal soil pH for Striga orobanchoides germination is slightly acidic around 5.5 to 6.5. Additionally, Striga orobanchoides seeds can remain dormant for several years in the soil until a suitable host plant is available.
Control Measures
As Striga orobanchoides is parasitic and possibly infects essential food crops like maize, millet, sorghum and rice, it is essential to control its spread. Integrated pest management strategies involving crop rotation, controlling weeds, and host-trapping plants like cowpea and sunflower can help control the spread of Striga orobanchoides.
Disease and Pest Management for Striga orobanchoides Plants
Striga orobanchoides is a flowering plant that belongs to the family Orobanchaceae, commonly known as the common striga or witchweed. This plant is a parasitic weed that infects the root of several crops, leading to significant yield losses. To manage infestation, integrated disease and pest management is highly essential.
Common diseases of Striga orobanchoides plants
Striga orobanchoides usually suffers from several fungal and bacterial diseases that affect the leaves, stems, and roots of the plant.
- Leaf spot disease: This disease is caused by the fungal pathogen Cercospora strigae. The infected leaves have small dark spots, which may expand and merge to form large necrotic areas. To control it, remove and destroy the infected leaves and debris. Ensure to rotate crops and maintain field hygiene and avoid leaves' wetness by maintaining proper spacing and early morning irrigation.
- Rust: Rust is caused by the fungal pathogen Puccinia strigae, characterized by the presence of orange-brown pustules on the leaves or stem. The disease leads to the loss of vigor and defoliation of the plant. To manage the rust, plant resistant varieties of the plant, and ensure to avoid over-fertilization.
- Verticillium wilt: Verticillium dahliae is a common soil-borne fungus that causes wilting and eventual death of the plant. The best management for this disease is crop rotation and ensuring proper field hygiene.
Common pests of Striga orobanchoides plants
Several insects and mites infest the Striga orobanchoides plant, leading to significant losses.
- Termites: Termite infestation can lead to root damage, reducing the plant's growth. Ensure to reduce termite infestations through proper field hygiene and removing crop residues which could serve as a breeding ground for these insects. Chemical control should be a last resort because termites have evolved resistance to several insecticides, and it is also damaging to the soil microorganisms.
- Nematodes: Nematodes are small parasitic worms that survive by feeding on the roots of the plant. Nematodes cause stunted growth, leaf yellowing, wilting, and lower crop yields. Implement crop rotation, use of clean and certified seedlings, planting tolerant cultivars, and use of Meloidogyne-resistant rootstocks.
- Aphids: Aphids are tiny insects that suck the sap from the plant, stunting its growth. To manage an infestation, ensure to remove and destroy the infested plant parts, use of natural enemies like ladybugs and lacewings, practice early-season planting to avoid the peak population period of aphids.
