Beauty Farming Life

Definition and terms use in Plant Pathology 1. Parasite: An organism living upon or in another living organism (the host) and obtaining the food from the invading host.  2. Pathogen: An entity, usually a micro-organism that can cause the disease. 3. Biotroph: A plant pathogenic fungus that requires living host cells i.e. an obligate parasite.  4. Hemibiotroph: A plant pathogenic fungus that initially requires living host cells but after killing the host cell grows on the dead and dying cells.  5. Necrotroph: A pathogenic fungus that kills the host and survives on the dying and dead cells.  6. Pathogenicity: The relative capability of a pathogen to cause disease. 7. Pathogenesis: It is a process caused by an infectious agent (pathogen) when it comes in contact with a susceptible host.  8. Virulence: The degree of infectivity of a given pathogen.  9. Infection: The initiation and establishment of a parasite within a host plant....

Objectives of Plant Pathology Plant Pathology (Phytopathology) deals with the cause, etiology, resulting losses and control or management of the plant diseases. The objectives of the Plant Pathology are the study on:  i. the living entities that cause diseases in plants; ii. the non-living entities and the environmental conditions that cause disorders in plants; iii. the mechanisms by which the disease causing agents produce diseases; iv. the interactions between the disease causing agents and host plant in relation to overall environment; and  v. the method of preventing or management the diseases and reducing the losses/damages caused by diseases.  Scope of Plant Pathology Plant pathology comprises with the basic knowledge and technologies of Botany, Plant Anatomy, Plant Physiology, Mycology, Bacteriology, Virology, Nematology, Genetics, Molecular Biology, Genetic Engineering, Biochemistry, Horticulture, Tissue Culture, Soil Science, Forestry, Physics, Che...

Importance of the Plant Diseases Globally, enormous losses of the crops are caused by the plant diseases. The loss can occur from the time of seed sowing in the field to harvesting and storage. Important historical evidences of plant disease epidemics are Irish Famine due to late blight of potato (Ireland, 1845), Bengal famine due to brown spot of rice (India, 1942) and Coffee rust (Sri Lanka, 1967). Such epidemics had left their effect on the economy of the affected countries.  Classification of Plant Disease To facilitate the study of plant diseases they are needed to be grouped in some orderly fashion. Plant diseases can be grouped in various ways based on the symptoms or signs (rust, smut, blight etc.), nature of infection (systemic or localized), habitat of the pathogens, mode of perpetuation and spread (soil-, seed- and air-borne etc.), affected parts of the host (aerial, root disease etc.), types of the plants (cereals, pulses, oilseed, ornamental, vegetable,...

Question Bank of Plant Pathology (206). https://cststudy.blogspot.com/ Question Bank of Plant Pathology (206) (1) Introduction to Plant Pathology: (a) Define plant pathology. (10, 12) (b) Define plant disease. (11, 12, 13, 14, 15) (c) Narrate endemic, epidemic and sporadic disease. (12) (d) Describe in brief the history of plant disease with special reference in Bangladesh. (10, 15) (e) Write down the classification of plant disease. (10, 11, 14) (f) Define following terms;     (i) Pathogenicity. (10, 13)     (ii) Saprophyte. (10, 11, 13, 14)     (iii) Pathogenesis. (10, 11, 13, 14)     (iv) Secondary inoculum. (10, 13)     (v) Primary inoculum. (11, 14)     (vi) Cause and causal organism. (11)     (vii) Penetration. (11, 13, 14)     (viii) Infection. (11, 14)     (ix) Symbiosis. (11, 14)     (x...

B.Sc.Ag. (Hons) Part-III     Blast disease of rice. https://cststudy.blogspot.com Blast disease of rice  Occurrence: The blast disease of rice occurs world wide and one of the most important disease of rice, particularly where rice is irrigated or receives high amounts of rainfall and high levels of N2 fertilizer.  Symptoms: Rice blast affects the levels on which it cause diamond shaped white to grey lesions with dark green to brown borders surrounded by a yellowish halo, the lesions may enlarge, coalesce and kill entire leaves. Blast also affects the leaf collar, which it may kill and the stem nodes and occasionally internodes which at heading, may results in production white panicles or breakage of the stem at the infected node. This is usually the most destructive symptom of the disease and is called the neck blast or panicle blast pathogen has been known as Pyricularia oryzae . Recurrence of the pathogen:  The pathogen ove...

B.Sc.Ag. (Hons) Part-III      Bacterial leaf blight of rice. https://cststudy.blogspot.com  Bacterial leaf blight of rice   Occurrence/distribution:  The most common BLB of rice caused by Xanthomonas oryzae. BLB   of rice are probably world in distribution.  Symptoms:  The symptoms appear on leaf blade and sheaths as small linear, water-soaked areas   that soon elongated and coalesce into irregular, narrow, yellowish or brownish stripes. Severe   infection cause leaves to turn yellow and die from the tip to downward. They also retard spike   elongated and cause blishing. Small lesion from on the karnels as well.  Recurrence of the disease:  The disease develops mainly in rainy, dam wheather. The bacteria over wintering on the seed and crop residuces and are spread by rain, direct contact an insect.  Control measure:  The main control measures are us...

B.Sc.Ag. (Hons) Part-III      Tungro disease of rice. https://cststudy.blogspot.com Tungro disease of rice   Distribution:  Tungro is the most serious viral disease of rice in south and south-east Asia from   Pakistan to the Philippines. Virus & vector:  Tungro ( Yellow-orange) is the result of concurrent infection by two viruses,    the single stranded RNA virus, rice tungro spherical waika virus ( RTBV) and the double   stranded RNA virus. Rice tungro Baciliform badnavirus ( RTBV). Both viruses are transmitted   by several leaf hoppers, particularly.   Nephotettix viruscns in the semi-persistent manner. Symptoms:  Tungro infected rice plants are stunted and show mottling and yellow orange   discoloration of the leaves. The typical tungro symptoms can be caused by RTBV, but they are    intensified by the presence of RTSV. RTSV often occurs along...

B.Sc.Ag. (Hons) Part-III     Brown spot disease of rice. https://cststudy.blogspot.com/ Brown spot disease of rice   Causal organism:  Helminthosporium oryzae or Bipolaris oryzae.  Distribution:  The disease has been reported from all the rice growing countries of the world. Symptoms:  All parts of the plants are being infected except roots. Sometimes the necrotic   lesions are found to the present even on the first emerging leaves. In severe cause, the seedling   are blighted and become dead. The most characteristics symptoms of the disease is the development of dark brown spot on the upper surface of the leaf lamina. The spots are developed on the leaf blade and leaf sheath. The spots are various shapes and sizes. They are isolated dark-brown oval and scattered through out the leaf blade and leaf sheath. The spots developed also on leaf sheath and culm below the ear. The base of the panicle becomes...

B.Sc.Ag. (Hons) Part-III     Stem rot of rice. https://cststudy.blogspot.com Stem rot of rice   Causal organism:  Sclerotium oryzae.     Distribution:  The disease has been reported from all rice growing countries such as Japan, Chaina, Philippines, Srilanka, Italy, Brazil, USA, etc. The sclerotial stage of stem rot of rice was first described by cattaneo from Italy in 1876. In India, the disease was first reported by shaw from Bengal in 1911. Symptoms:  The disease is commonly found in the transplanted crop in the month of July-September. First of all small dark lesions are developed on the outer leaf sheath at the water line. Later on this lesions gradually make their appearance on the inner leaf sheaths and the culm. The affected and numerous small dark brown sclerotia are formed in the tissues of leaf sheath. In later stages, the mycelial mats and the sclerotia are copiously formed inside the culm also. Rotting...

B.Sc.Ag. (Hons) Part-III     Foot rot of rice. https://cststudy.blogspot.com Foot rot of rice     Causal organism:  Fusarium moniliforme.    Distribution:  The foot rot of rice caused by Fusarium moniliforme was first reported form Italia in 1877. From Japan the disease was first described in 1898 and was known as bakanae disease. The pathogen is world wide distribution. Symptom:  The disease affects the host mainly in the seedling stage and symptoms are clearly   seen in the nursery. Sometimes the grains fail to germinate or the seedlings fail to emerge above   the soil. The most conspicuous and detectable symptoms of the disease appear in the seedling.   The affected seedling become  thin, pale and tall, such symptoms appear from the sixth days    after sowing in wet nurseries and continue upto 6 weeks. As soon as the symptoms appear the   seedling wilt...

B.Sc.Ag. (Hons) Part-III     Black/stem rust/rust of wheat. https://cststudy.blogspot.com/ Black/stem rust/rust of wheat   Causal organism:  Puccinia graminis tritici. Symptoms:  Black rust is first marked by an eruption of elongated brown pustale on the stalk, leaf sheaths and leaves. These pustules may be quater of an inch or more in length and frequently run into one another. They very soon brust, exposing a brown powder consisting thousands of uredospores. Later on teleutosoric developed. The teleutospores are often produced in the same sorus as he uredospores and as they are darker in colour, one can see he pustules gradually changing from brown to black as the season advances. Recurrence of the pathogen:  The pathogen are air borne. The pathogen pass their life cycle on    two different hosts, wheat and barberry, which are abundantly found in hilly region. The summer heat in the plains that follows the wheat ha...

B.Sc.Ag. (Hons) Part-III      Powdery mildew of wheat. https://cststudy.blogspot.com  Powdery mildew of wheat   Pathogen: Erysiphe graminis DC var tritici. Systematic position of pathogen:     Class- Ascomycetes                                                            Order- Erysiphales                                                            Family- Erysiphaceae  Distribution:  The powdery mildew of wheat is commonly found in those region, where there is enough of moisture during showing time. This disease has not or little importance in the plains of India. This disease is commonly found in the lower hi...

B.Sc.Ag. (Hons) Part-III     Covered smut of barley. https://cststudy.blogspot.com Covered smut of barley   Pathogen:  Ustilago hordei (pers.) Langerheim. Systematic position:    Class-    Basidiomycetes                                          Order-   Ustilaginales                                          Family- Ustilaginaceae  Distribution:  The covered smut of barley is world wide in its distribution. It is found all those   countries where the barley crop is grown. It is a common disease of barley in northern India. Symptoms:  As soon as the ears of the infected plants emerge out, the first symptoms may easily be seen. The smutted or blackened ears come out of the...