Theory Note B. Sc (Agril.) Course No. Pl.Path.5.4 DISEASES OF FIELD AND HORTICULTURAL CROPS AND THEIR MANAGEMENT-I(CREDIT 2+1) Semester-V Compiled and Edited by DR. D.M.PATHAK ASSOCIATE PROFESSOR AND HEAD DEPARTMENT OF PLANT PATHOLOGY COLLEGE OF AGRICULTURE NAVSARI AGRICULTURAL UNIVERSITY CAMPUS BHARUCH -392012 Course Title: Diseases of Field and Horticultural Crops and Their Management- I Course No. Pl. Path. 5.4 Course Credit: 2 + 1 = 3 SYLLABUS Theory: Economic importance, symptoms, etiology, epidemiology, disease cycle and integrated management of diseases of Groundnut, Sesamum, Castor, Cotton, Bajra, Finger millet, Sorghum, Maize, Rice, Pigeon pea, Soybean, Black gram, green gram, Tobacco, Coconut, Pomegranate, Tea, Coffee, Banana, Papaya, Tomato, Okra, Brinjal, Cluster bean, Beans and Colocasia. Practical: Identification and histopathological studies of selected diseases of field and horticultural crops covered in theory. Field visit for the diagnosis of field and horticultural crop diseases.Collection and preservation of plant diseased specimens for Herbarium. Suggested readings: 1. Sanjeev Kumar (2016). Diseases of Field Crops and Their Integrated Management. New India Publishing Agency, New Delhi – 110 034 2. Shahid Ahamad and Udit Narain (2007). Ecofriendly management of plant diseases. Daya Publishing house, New Delhi – 110 035. 3. Rangaswami, G. and Mahadevan, A. (2008). Diseases of crop plants in India. PHI Learning Pvt. Ltd., New Delhi – 110 001. 4. Sanjeev Kumar (2015). Diseases of horticultural crops: Identification & management. New India Publishing Agency, New Delhi – 110 034. 5. Singh,R. S. (2018). Diseases of fruit crops. MEDTECH A division of Scientific International Pvt. Ltd. New Delhi – 110 002. 6. Sharma,I. M. and Gautam,H. R. (2017). About diseases of horticultural crops. Neoti Book Agency Pvt. Ltd., New Delhi – 110 002. 7. Gupta, S. K. Sharma, R. C. and Monica Sharma (2017). Disease of Vegetable Ornamental and Spice Crops. Scientific Publishers (India) P.O. Box. 91, Jodhpur – 342 001. 8. Singh R. S. (2014). Plant Diseases. OXFORD & IBH Publishing Co. Pvt. Ltd. New Delhi - 110 049 9. Singh, R. S. (2016). Diseases of vegetable crops. CBS Publishers & Distributors Pvt. Ltd. Delhi – 110 092. 10. Singh, R. S. (2017). Diseases of Fruit Crops. OXFORD & IBH Publishing Co. Pvt. Ltd. New Delhi - 110 049 11. Steven, T. Koike, Peter Gladders and Albert O. Paulus. (2017). Vegetable Diseases. CRC Press, Taylor & Francis Group, Boca Raton, FL. Introduction: Among various causal agent of plant disease, fungi were the first to be recognized. The contagious nature of wheat smut was shown by Prevost in 1807. From this basic report, many others reported fungal diseases of crops. But systematic investigation o the pathogenic nature of plant diseases goes to the great German scientist Anton de Berry (1831- 1888) who is considered as father of plant pathology. Of the 30,000 plant diseases recorded from different countries about 5,000 diseases are present in India. There are no dependable survey of number of humans living on earth. The world population was 6.2 billion in 2000 and expected 7.1 billion by the year 2010. Currently it increased by 1 billion every 11 years. In which 50-80% of the population is engaged in agriculture. Even though 2 billion people suffer from hunger or malnutrition. To feed this people and the additional millions to come in next few years all possible methods of increasing world food supply are being pursued including crop protection i.e. disease management. It is estimated that the total annual production for all agricultural crops world wide is about $ 12000-13000 billion. Of this, about $ 500 billion worth of produce is lost annually to diseases, insects and weeds. Approximately 26 $ billion is spent annually for pesticides alone fungicides, insecticides and herbicides. In United States alone each year crop worth 9.1$ billion are lost to diseases. Significance of plant diseases: Plant diseases are important because they cause economic losses to growers. It may affects: 1. Plant diseases may limit the kinds of plants and industries in an area. 2. Plant diseases reduce the quantity and quality of plant produce. 3. Plant diseases may make plant poisonous to humans and animals. 4. Plant diseases may cause financial losses. What is Plant Pathology? Plant Pathology is the study of the microorganisms and of the environmental factors that cause disease in plants, of the mechanisms by which these factors induce disease in plants, and of the methods of preventing or controlling disease and reducing the damage it causes. When we consider plant is healthy? When plant carry out its physiological functions to the best of its genetical potential. Functions: Photosynthesis Translocation - Apoplast and symplast Metabolism Storage of photosynthetic products Reproduction- seed, flowering and fruiting Pathogenic microorganism that is the biotic agents generally referred as pathogens usually cause disease by Disturbing the metabolism of plant cell By production of enzymes, toxins, growth regulators and other secretions and there by absorbing food stuffs from host cell for their own life. Microorganisms: Fungi (Eukaryotes) Bacteria (Prokaryotes) Mollicutes: RLO- Rickettsia like organism- Fastidious Vascular Bacteria causing stunting yellowing and proliferation. MLO – Phytoplasma , SLO Viruses: Mosaic, yellowing and leaf curl Viroid: Smallest entity have only infectious RNA and no protein. Nematodes Flowering plant parasite Protozoa Algae Terminology Plant Disease: Any malfunctioning of host cells and tissues that results from continuous irritation by a pathogenic organisms or environmental factors that leads to development of symptoms. Infectious disease: Those diseases that results from infection of plant by a pathogen. In such disease pathogen can grow and multiply rapidly on diseased plants. Symptoms: The external and internal reactions or alteration of a plant as a result of disease. Sign: It is the characteristic of causal organism which will indicate the presence of causal organism. Pathogen: An entity that can cause the disease. Parasite: An organism living upon or in another living organism (the host) and obtaining its food from the invading host is called a parasite. Parasitism: Parasitism is a non-mutual relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Host: A living organism containing or invaded by a parasite, which obtains its nutrients from the organism. or a plant that supports the growth and development of the parasite that has infected it. Infection: The initiation and establishment of a parasite within a host plant. Obligate parasite: A parasite that can grow only on living organisms. Propagule: One unit of inoculum of any pathogen is called a propagule. Inoculum: The pathogen(s) that lands on or is otherwise brought into contact with the plant is called the inoculum. Primary inoculum: An inoculum that survives dormant in the winter or summer and causes the original infections in the spring or in the autumn is called a primary inoculum. Primary infections: The infections causes by primary inoculum is called primary infections. Secondary inoculum: An inoculum produced from primary infections is called a secondary inoculum. Secondary infections: The infections causes by secondary inoculum is called secondary infections. Alternate host: Plants not related to the main host of parasitic fungus, where it produces its different stages to complete one cycle (heteroecious). Alternative host: A plant other than the main host that a parasite can colonize; alternative hosts are not required for completion of the developmental cycle of the parasite. Collateral host: The wild host of same families of a pathogen is called as collateral host. Epidemiology: The study of the inter relationships between a given pathogen, the environment and groups or populations of the relevant hosts. 1. Pearlmillet/Bajra (Pennisetum typhoides L.) Pearlmillet/Bajra is one of the common millets that serve as the poor man's food grain in India, Pakistan and some part of Africa. In India it covers an area of about 10 million hectares, distributed almost over the entire country. It comes up well in any kind of soil and for this reasons poor soils not fit for growing rice, wheat& Sorghum usually are used to grow. It is grow extensively in Tamil Nadu, Gujarat, Rajasthan, Madhya Pradesh and Uttar Pradesh. About twenty diseases of this crop are known, only a few are important. 1.Ergot C.O. : Claviceps fusiformis Subdivision : Ascomycotina Order : Sphaeriales Family : Clavicipitaceae Occurrence & Economic importance: This disease is reported from many parts of Africa & India. In our country, it was first time reported from Satara area Maharashtra in 1956 in epiphytotic form. More severity is due to introduction of new hybrid HB-l, 2. It is also found in Delhi, Rajasthan, Karnataka, Tamil Nadu and Gujarat. During 1967-68 it has broken out in epiphytotic form affecting most of the newly introduced hybrid bajara varieties in all areas. Loss in hybrid varieties 58-76 %. This fungus produces ergotoxin/ergotin (alkaloid), which is poisonous to animals & human beings. Symptoms: The disease occurs only at the time of flowering. Small droplets of a pinkish or light honey colored dew like substance exudes from infected spikelet. Later these droplets become darker, coalesce and cover larger area of the cob. A few to many such spikelets may be found in a group which darken with age, and small greyish or dark brown sclerotia are formed. These sclerotia replace the ovary or grain and are about 0.5-1 cm in length 1-2 mm in diameter, are hard and woody, during harvesting and threshing sclerotia get mixed with grains. The fungus attacks the ovary and grows profusely producing masses of hyphae to form the Sclerotium. Small conidiophores on which conidia are produced formed from the hyphae. The conidia are hyaline, one celled and lunate. The honey dew like droplets in the affected ears are full of conidia. The sclerotia germinate in about a month's time producing one or two stripes on which the asci are produced.