eChapters

Introduction

We, the participants of ITAF 2023 along with Dr. B. R. Chavan and Dr. Prashant Bodake visited Farm Song Nam under the guidance of Asst. Prof. Dr. Naphat Panthukumbol and Dr. Sorawit Powtongsookon 18/10/23 at 01:00 pm. This research station is under NSTDA (National Science and Technology Development Agency). The purpose of the visit was to learn about the latest developments in aquaculture technologies.

Dr. Sorawit explains that this system is able to monitor water quality, floc sedimentation, the current age of shrimp, quantity in the pond, total weight, density, size, total amount of water used, pond volume, and volume of water in the pond at a time. This system is equipped with cloud backup that can store all recorded pieces of information. After monitoring, the available information is automatically uploaded to the cloud and accessible through mobile by simply visiting the website. The key feature of Aqua-IoT is the integration of key data– physical, chemical, and biological water qualities and weather – into one single dashboard that enables users to understand the relationship between the data, analyze the data, and make informed decisions.

Introduction

We, the participants of ITAF2023 with Dr. B. R. Chavan and Dr. Prashant Bodake, visited Boonsawang Co. under the guidance of Asst. Prof. Dr. Naphat Panthukumbol and Mr. Suthi Mahalao on 18/10/2023 at 09:00 am. Boonsawang Co. in Chonburi, owned by Suthi Mahalao, also exports fry to Vietnam, Malaysia, Singapore, Taiwan, Australia, and Israel. In addition, Suthi runs his sea bass farm and is a feed distributor to farms in the province. The purpose of the visit was to learn about the seabass culture system and get familiar with technical aspects. The farm occupies an area of 10 hectares and is covered in 11 ponds. The farm is aimed to grow from fry to marketable size seabass. The single crop duration is divided into 4 periods.

We, the participants of ITAF2023 visited The ocean farm under the guidance of Asst.Prof.Dr.Naphat Panthukumbol and Dr.Somrat Taweedet on 17/10/23 at 3:00 pm. The farm is certified by fisheries department and is located in Chonburi Province. The purpose of visit was to learn about the nursery rearing of shrimp and use of frozen artemia.

1) Nursery rearing details

The cultured species was Litopenaeus vannamei. Rearing was done from nauplii to PL15 stage. The farm is producing 2 variants named- ‘The ocean hero’ which is disease resistant and ‘The ocean speedy’ having high growth rate. They are procuring nauplii from Phuket. Then double certification from DOF and Burapha university lab is done to ensure SPF stock. The purchasing price of nauplii is 12,000 baht/ million nauplii and transportation done by plane. The culture period of shrimp is around 21 days.

On 17 October we visited the Institute of Marine Science, Burapha University (BIMS), THAILAND at 9 a.m. The institute is situated in Bangsean. BIMS is a marine research institute of Burapha University. They have 6 organizations: Marine Research Department, Marine Aquarium Department, Marine Museum Department, Academic Service Department, Office of the Director and Research Station.

They have shown us their Life Support System of Public Aquarium and coral propagation and conservation.

1) Public aquarium

We have seen the Life Support System of Public Aquarium i.e. Filtration System, which involves the complex systems and technologies used to maintain the health and well-being of marine life in public aquariums. This is crucial for keeping the animals and ecosystems on display healthy and sustainable. The display tank has having 10,00,000-liter capacity.

We, the participants of ITAF2023 visited Sriracha fisheries research station under the guidance of Asst. Prof. Dr. Naphat Panthukumbol and Dr. Somrat Taweedet on 16/10/23 at 08:00am. The research station is under faculty of fisheries, Kasetsart university in Chonburi Province. The purpose of visit was to learn about the mussel aquaculture and Integrated Multi- Trophic Aquaculture (IMTA).

1) Mussel aquaculture

Cultured species was Perna viridis( Green mussel ). Almost all rafts were owned by fishermen and 10 rafts were under the management of sriracha fisheries research station. The cost of production was 100 baht /acre. Simple method of culture is practiced by installing rafts before breeding season and allowing the natural spawn to attach. The harvesting size of mussel is 8 cm. Observed growth rate is 1cm/ month. Other maintenance includes repairing of ropes ,buoys etc. during off-season. Farmers face many constraints like plankton bloom, waste water discharge, predation by sting ray,parasitism during summer months.

Frog farming in Thailand started 20 years ago. The frogs commonly found and farmed in Thailand are the local species, Rana tigerina and Rana rugulosa. The first imported bullfrog, Rana catesbeiana was introduced in 1980 and is popular in the northern part of the country. Rana tigerina is olive brown in colour which is about 15cm long when fully grown. The adult weighs about 300g. Rana rugulosa is another local species that is olive-brown in colour with a dark head. It is about 13cm long when fully grown and weighs about 270g. The imported species, Rana catesbeiana is olive-brown to green in colour. It is 17 cm long when fully grown and weighs around 459g.

On the morning of 13 Oct 2023 morning (9:30 am - 12:00 pm), ITAF participants visited snake-skin gourami local farms in Samut scorn province. Snake-skin gourami is one of the best delicacies in Thailand which has large demand in local and international markets. Snake-skin gourami can breed after reaching 100-200 gms ( 2 months). The culture period of snake- skin gourami is 9-10 months. In snake- skin gourami males have a large body and long dorsal fin than females.

Farm 1

Snake-skin gourami culture is done in 30 rai ( 1 rai= 1600 m2) area of the farm. The depth of the pond is 1.5m. A single crop is taken in one year. 50,000 no. of fry are stocked in 30 rai area. Feeding areas are constructed by the net embankment where feed is given to fish harvesting is done after 8-9 months. The cost of production for one crop is 2 million/year in that they produce 30-40 tonnes /30 rai, which is almost 3 million / year.

We visited the CPF (Thailand Public Company limited) in Samutsakorn on 12/ 10/23 at 1:30 pm. The purpose of the visit was to know about the feed ingredients and production process.

1) Overview

Product like shrimp feed and fish feed are prepared by the company. Company was spread in 61 Rai( 24 acre) area. 400 employees are working in the company.Working hours is 3 shift / day and working days – 6 days / week.Shrimp feed unit have the capacity of 13,000 T/M and actual production was 7000 T/M. 8 line pellet machine was used for this purpose. Fish and frog feed unit have capacity of 11,000 T/M and actual production 7000 T/M. 6 line extruder machine was used.

The ITAF participants visited the Anuban Tilapia Floating Cage Culture on the Canoy River situated in the central part of Thailand on 11/10/2023 at 1:30 p.m. The purpose of the visit was to learn about the floating cage culture on a large scale.

Construction Details

The farmer had a total 500 number of cages divided into 5 units i.e. 1 unit contains 100 cages. The dimensions of the floating cage are 7m in length, 5m in width and 2m in depth having an area of 70 m3. The fabrication of the cage was done by using the GI pipes attached to the barrels for buoyancy. The double HDPE netting was done from five sides and on the upper side bird net was fixed as a biosecurity measure. The construction cost of the cage was 140000 baht /cage.

Construction details

They had a total of 36 tanks, and most of them were made of tin. Each tank had a diameter of 6 meters, was 1.2 meters deep, and could hold up to 30 tons of water. Inside these tanks, there was a plastic lining. Additionally, there were 4 to 5 tanks made from bamboo. Bamboo tanks have a shorter lifespan, lasting 1 to 2 years, while tin tanks can last for 8 to 10 years.

Culture details

The species that was cultured over there was Red tilapia. Culture practice was intensive. The nursery-rearing period was 70 days. In the first step, fish were raised from 0.5 grams to 10 grams in a separate tank for 35 days. The second step involved the growth of fish from 10 grams to 30 grams for the next 35 days in another separate tank. The fishes were bought from outer sources and they were all male fishes.

We visited The Model Sea Farm Project under the Royal Initiative of Her Majesty Queen Sirikit on 10/10/2023 at 1 pm It is a government farm located at Phetchaburi Coastal Aquaculture Research and Development Center. The purpose of the visit was to learn more about seaweed production and zero waste aquaculture system.

1) Sea ranching

Species used for sea ranching was Banana shrimp (Fenneropenaeus merguiensis). 2 months old shrimps were collected from tank and used for ranching

Overview of Inland Fisheries Status

In Thailand, inland capture fisheries are carried out mainly in rivers, lakes, swamps and reservoirs. These fisheries are an important source of animal protein for the rural people. Since 2005, production from inland capture fisheries has increased by almost 13 percent. Gillnets, longlines, hook-and-line, scoop nets, cast nets, and lift nets are some of the fishing gears being used. Among these fishing gears, gillnets are the most popular and efficient, particularly in swamps and reservoirs. Thai silver barb, snakehead, walking catfish, local carps, and Nile tilapia are caught. Nile tilapia, hybrid catfish, silver barb, snakeskin gourami, giant river prawn, striped catfish and striped snake-head contributed 95 percent in quantity and 92 percent in value in fresh water aquaculture.

The Aquatic Resources Research Institute (ARRI) was established to conduct research & answer important impending questions associated with the nation’s aquatic resources, like conservation of marine organisms, marine science, oceanography, aquaculture, biotechnology etc. It also works for transferring or sharing the knowledge to public, for guiding towards sustainable development.

Sichang Marine Science Research & Training Station: (SMaRT) Chonburi Province

Thailand This is another unit of the ARRI. It was established in 1979, in Chonburi Province Thailand.

Introduction

Ammonia, nitrite and nitrate are considerable in the water quality management because they can be produced a toxic depending to their form and concentration. The solubilities of nitrogen contain in water at different temperatures and pressures. Nitrogen is a basic growth substance and an important element in aquatic ecosystems as well as in the pond water. It exists variously forms in water and manly classified in organic and inorganic.

Introduction

Ammonia is the major end product in the breakdown of proteins in fish. Fish digest the protein in their feed and excrete ammonia through their gills and in their faces. The amount of ammonia excreted by fish varies with the amount of feed put into the pond or culture system – increasing as feeding rates increase. Ammonia also enters the pond from bacterial decomposition of organic matter such as uneaten feed or dead algae and aquatic plants.

Introduction

Water is the chief factor in fish farming. Water carries oxygen, eliminate metabolic waste products, through its physical and chemical composition, determine the success of production. The major constraint is that the waste organic matter released into water.

Measurement of pH, temperature, conductivity, salinity, transparency, turbidity and solids are important parameters to play role in water quality. pH in water changes during the day and night in response to photo-synthesis which is supported by the sun light intensity. Temperature is a physical parameter which effected on fish growth as resulting of many bio-chemical processes. It changes with the time depending on air temperature surrounding site.

Introduction

In the ever-evolving realm of fisheries and aquaculture, the infusion of molecular technology has become a beacon of hope, transforming the way we diagnose diseases and identify pathogens. Imagine it as a kind of genetic detective work that not only helps us understand the health of aquatic life but also empowers us to protect it. It all begins with the delicate dance of DNA extraction, a bit like teasing out the secrets locked within the cells of aquatic organisms. This biological treasure map, once unveiled, guides us through the labyrinth of diseases. Enter the PCR protocol for Carp Edema Virus (CEV) detection—a sort of molecular magnifying glass that allows us to zoom in on specific genetic footprints of trouble. It’s like deciphering a genetic code, helping us pinpoint potential issues swiftly.

Introduction

Subculture is key skill in bacteriological laboratory allowing us to colony propagate a pure culture in single colony. Pure cultures are essential for characterization such as identification using biochemical test or antimicrobial susceptibility testing.

Protocol

1. Label your fresh blood agar plate.

2. Select a single colony to subculture (colonies grows by clonal expansion; each colony should be a pure strain.)

3. Use the colony you have just picked to make the 1st streak on your fresh plate.

We performed a detailed hands-on practical on ‘Shrimp Health Examination’ at the Pathology Necroscopy room on 29th September 2023. Several activities regarding the health examination of shrimp were performed. It included, the collection of blood from an in-between portion of pereiopods and pleopods, also making blood smears on a glass slide, staining, and observation of blood cells under a microscope. Collection of samples from hepatopancreas for microbial culture to know the presence of any pathogen present. Collection of body part samples like gill, pleopods, and telson to observe the presence of external parasites. The species used health examination Whiteleg shrimp (Litopennaenus vannamei).

Introduction

In this microbiology report, we delve into the intricate realm of bacterial isolation and identification, exploring the fundamental processes that unlock the mysteries of microbial worlds. From the methods employed for isolating bacterial strains to the intricate techniques of identification, this report aims to provide a comprehensive understanding of the crucial role microbiology plays in unraveling the secrets of these microscopic organisms. Join us on a journey through the principles and applications that form the backbone of bacterial isolation and identification in the fascinating field of microbiology.

Introduction

The study of fish health is crucial for understanding aquatic ecosystems and ensuring the well-being of aquatic species. This report provides a detailed account of a hands-on activity involving necropsy and health examination of fish. Through this practical experience, we aimed to gain insights into the common ailments affecting fish populations and develop skills in identifying pathological conditions.

The necropsy process involves the post-mortem examination of fish specimens, enabling us to observe and analyze internal organs, tissues, and external features. By combining practical techniques with theoretical knowledge, we seek to contribute to the broader understanding of fish health and disease.

11.1 General

The world is currently facing a critical turning point in its pursuit of sustainable energy solutions. With the global population growing and concerns about climate change increasing, it is crucial to move away from finite fossil fuels and towards renewable alternatives. One promising contender in this field is biodiesel, which has the potential to power our future while also reducing environmental impacts. At the heart of biodiesel production lies the complex process of oil-based biomass processing. This involves extracting valuable oils from various sources and using them to create renewable and eco friendly fuel. Oil-based biomass processing is a dynamic intersection where innovation meets necessity, combining chemistry, engineering, sustainability, and environmental consciousness. It is an intricate and multifaceted endeavor requiring careful attention to detail and a collaborative effort to succeed.

Transforming organic materials, such as agricultural residues, food waste, or biomass, into valuable bio-based products is crucial for waste management. This process, called biochemical conversion, employs various enzymatic, microbial, or chemical reactions to break down complex organic compounds into simpler molecules like sugars, fatty acids, and amino acids. These intermediates can then be further processed into biofuels, pharmaceuticals, and other bio-derived materials, making this process promising for sustainable energy and resource management. Biochemical conversion typically includes pretreatment, enzymatic hydrolysis, fermentation, and purification. It offers a sustainable alternative to conventional fossil fuel-based production methods, reducing environmental impacts and dependence on non-renewable resources.

9.1 Introduction

Biomass conversion is a transformative process that harnesses the energy and chemical potential of organic materials derived from living organisms. It encompasses various methods of converting biomass, including agricultural residues, forestry by-products, algae, and even waste materials, into valuable products such as biofuels, chemicals, and energy. This process is a cornerstone of sustainable resource utilization and plays a critical role in addressing environmental concerns, reducing reliance on fossil fuels, and promoting a circular economy. Biomass conversion methods range from biochemical processes like fermentation and anaerobic digestion to thermochemical processes such as combustion, pyrolysis, gasification, and liquefaction. Each method employs distinct conditions, catalysts, and technologies to break down complex biomass structures and convert them into desired products.

8.1 General

Pyrolysis is a process that utilizes heat or fire to separate biomass, derived from the ancient Greek words “pyro” meaning fire, and “lysis” meaning separation. A thermochemical conversion process transforms biomass into a useful intermediate liquid product. This product can then be converted into a hydrocarbon biofuel, oxygenated fuel additive, or a petrochemical substitute. Pyrolysis shares similarities with other thermochemical processes such as cracking, carbonization, torrefaction, destructive distillation, dry distillation, and thermolysis. However, it is not related to gasification, which involves chemical reactions with a gasification medium.

Gasification is a process that turns materials containing carbon, like wood, crops, coal, or waste, into a type of fuel called producer gas or syngas. This is done by heating the carbon-rich material with a controlled amount of oxygen at high temperatures. Gasification is a type of partial oxidation, which means using less oxygen than needed to burn the same amount of fuel. Knowing the necessary amount of air for the conversion process is important to run a gasifier correctly. This requires understanding the stoichiometry based on the composition of the biomass. A chemical formula for the biomass can be calculated by analyzing the elements present, which serves as the basis for estimating the air-fuel ratios through stoichiometric calculations. Gasification only uses 25 to 40% of the theoretical oxidant, producing heat for fuel conversion. In gasification, the main combustible products are carbon monoxide and hydrogen.

The utilization of biomass presents a promising avenue for addressing the challenges of resource scarcity, waste management, and environmental sustainability. This book chapter delves into the multifaceted applications of biomass, with a particular focus on the processing of straw, a versatile agricultural residue. From providing essential bedding material for animals and enhancing agricultural practices to playing a pivotal role in horticulture, cushioning, mulching, and composting, this chapter examines the diverse roles that processed straw assumes. Furthermore, it explores its significance in paper and cardboard manufacturing and its emergence as a renewable fuel source, underscoring how thoughtful biomass utilization paves the way toward a more environmentally conscious and resilient future.

5.1 Introduction

The densification of biomass involves transforming loose and low-density organic materials, such as wood residues, agricultural waste, and plant-based materials, into compact and energy-dense forms. This process is necessary because natural biomass can be challenging to handle, transport, and store. Densification uses mechanical, thermal, or chemical processes to increase the material’s density and energy characteristics. The resulting products, such as pellets, briquettes, or cubes, offer several advantages, including higher energy content per unit volume, efficient storage and transportation, reduced moisture content, and improved combustion efficiency. These products are utilized in various industries, including energy production, residential heating, waste management, and industrial applications. Biomass densification promotes sustainable practices by effectively utilizing biomass resources, reducing waste, and promoting the use of renewable energy sources while mitigating environmental impacts.

4.1 Introduction

Baling biomass is a crucial technique in efficiently managing and utilizing agricultural crop residue. This chapter explores the process of baling, which involves compacting biomass materials into standardized bundles for easier handling, storage, and transportation. From agricultural residues to forestry waste, the chapter delves into various types of biomass suitable for baling, the equipment used, and the benefits of this technique. It also discusses the environmental impact, economic considerations, and emerging trends in baling methods. Through in-depth analysis and practical insights, this chapter offers a comprehensive understanding of how baling contributes to sustainable biomass management and resource optimization.

3.1 Overview

3.1.1 Rice straw: What is it?

When harvesting paddy rice, rice straw is produced as a by-product. Approximately 0.7-1.4 kilograms of rice straw can be obtained for each kilogram of milled rice, depending on the variety, moisture content during harvest, and cutting length of the remaining plant stems. The rice straw is separated from the grains after the plants are threshed manually using stationary threshers or with modern combine harvesters, as shown in Figure 3.1.

Rice straw is a type of lignocellulosic biomass comprising cellulose, hemicelluloses, and lignin. Figure 3.2 illustrates that pretreatment can be used to separate these components. Unlike lignin, which is found in the cell wall, cellulose and hemicellulose are organic fibers.

Biomass, a diverse and renewable resource, holds immense potential as a source of energy, feedstock, and environmental solutions. However, effectively harnessing its benefits necessitates a systematic approach. This chapter introduces the concept of Biomass Management Techniques as a pivotal framework for optimizing the utilization of biomass resources. With a focus on sustainable practices, this chapter delves into various techniques to handle, process, and utilize biomass efficiently. From collection and transportation to storage, conversion, and beyond, Biomass Management Techniques encompass a wide array of methods that ensure the seamless integration of biomass into energy generation, industrial processes, and environmental conservation.

1.1 An overview of biomass

Biomass is an abundant and renewable energy source that has the potential to meet the growing need for clean and sustainable energy solutions. This chapter provides an overview of biomass, its potential, and conversion technologies, which include various techniques for transforming biomass into useful forms of energy such as heat, electricity, and biofuels.

Biomass is an organic substance that can be obtained from agricultural crop waste, forest waste, animals, and microorganisms. It can be used as an energy source or a primary material in various applications. The energy in biomass is derived from photosynthesis, in which plants convert sunlight, carbon dioxide, and water into organic matter.

India’s agricultural accomplishment is a global success story

Post Green revolution; Some of the most pertinent questions that humanity faces

Can we sustain our food production ecosystem, while feeding 9 billon people?

Can we improve farm economics without reversal of soil biodiversity loss and carbon content?

Can agriculture play an important role in reducing carbon footprints and mitigating the current climate crisis?

Answers to abovementioned questions do not lie in the currently dominating chemical intensive farming practices, which rely too heavily on

Introduction

It is becoming increasingly difficult to find workers to work in agriculture.

Younger generations do not want to work in plant protection.

We can see that the average age of farmers is getting older.

This leaves the fields unprotected from disease and insects and greatly reduces yields.

Fortunately, this gloomy situation has changed since 2015 thanks to modern technology.

Digital tools are among the most innovative crop protection tools in modern agriculture.

Changes in philosophy about plant disease management

To achieve reasonable and sustainable results crop disease management philosophy should shift focus from

Management of pathogens (or insect vectors) to managing host plants.

A single goal of high productivity to multiple goals of high yield, efficiency, quality and safety.

Disease Control vs. Disease Management

The word control evokes the notion of finality, the final elimination of problems .

It is impossible to exclude , eliminate or prevent diseases.

Control is ecologically and practically not possible.

Although disease control is an established and widely understood concept, there are compelling reasons to replace control with management .

Introduction

Genetic engineering is the process of using molecular techniques to add, modify and delete genes of interest to the DNA strands of recipient cells or recipient plants. Genetic engineering is also called genetic technology, transgenic technology, transformation technology and recombinant DNA technology. Genetic engineering consists of tools and techniques used to study, identify, or modify the genes of living organisms. It is also defined as a technique for developing transgenic organisms. The key points of genetic engineering are briefly listed below.

1. Markers: Easily identifiable features are called markers or marker features.

2. Types of marker

These markers are three types

2.1.Morphological markers: These relate to the size, shape, color and surface area of different parts of the plant.

2.2.Biochemical markers: Such markers refer to changes in protein structure. For example, isozymes and storage proteins.

Introduction

Most common improvement of host resistance to almost any pathogen is brought about by improving the genetic resistance of the host, that is by breeding and using resistance varieties.

Genetic engineering technology made possible the isolation of individual resistance (R) genes from resistant plants and the transfer of such genes into susceptible plants in which they induce the hypersensitive resistant response.

Thus, genetic engineering technology combined with Conventional plant breeding, will provide one of the most effective tools for controlling plant diseases.

Genetic variations

Genetic variation is the presence of differences in gene sequences between individual organisms of a species.

Enables natural selection, one of the major forces driving the evolution of life.

When an individual’s offspring exhibit mutations in the traits of their parents, such offspring are called variants.

1. Genes and Disease

When various plants such as rice, wheat, tomato and apple are infected with pathogens and cause disease, pathogens are generally different for each host plant type.

Venturia inaequalis, the fungus that causes apple scab, only affects apples. Fusarium oxysporum f. sp. lycopersici which causes tomato wilting, only affects tomatoes and so on.

It is the presence in the pathogen of one or more genes of pathogenicty, specificity, and virulence to the respective host that enables disease development in the host.

Introduction

Plant pathogens include fungi, bacteria, viruses, viroids, phytoplasma, and nematodes.

They have evolved different strategies for invading, feeding on, and reproducing inside plants.

Biotrophic pathogens require living tissue to grow and reproduce.

Necrotic pathogens kill host tissue at the onset of infection and feed on the dead tissue.

Viruses generally require living tissue for survival.

Philosophy of defence in plants

Plants cannot move and must resist or tolerate co-located pathogens.

Plants have evolved very powerful preformed defense systems in the form of structural and toxic barriers.

Plants cannot keep intruders out, they can only limit (contain) them.

Plants can tolerate more nutrient runoff. They often sacrifice a piece of tissue to contain pathogens.

Enzymes, toxins, growth regulators, and polysaccharides are much more common and perhaps more important in the development of plant diseases. The pathogen produce these substances when grown on certain substrates (inducible). Let’s talk carefully one by one

Enzymes in plant diseases.

Toxins in plant diseases.

Growth regulator in plant diseases.

Polysaccharides in plant diseases.

Host -Pathogen Interaction

Most often, plants become diseased when attacked by living (biotic) or affected by non-living (abiotic) pathogens.

In the first case, at least two components viz., host and pathogen must come into contact and interact for plant disease to occur.

Then, for disease to develop, a third factor, a favorable range of environmental conditions, must also occur.

The interaction of the three disease factors was often visualized as a triangle called the “Disease Triangle".

Each side of the triangle represents one of three components.

Disease development depends on three factors: host, pathogen, and environment.

Host must be susceptible.

The pathogen must be virulent to cause disease.

The environment must be conducive to disease development.

Role of environment on disease development 

Environment

Plant diseases are a recurring threat. Everywhere they appear in a certain cycle. Chains of infection (pathogenesis) initiated by primary inoculums comes spontaneously at the end of the harvest season or at host death due to the production of various types of pathogenic reproductive organs/propagules. These propagules must find ways to bridge the gap between harvest times to ensure continuity of infection. Therefore, plant pathogen survival is a critical step in a successful pathogen disease cycle. Pathogen spread is another important phenomenon in plant disease recurrence and epidemiology. Effective spread/diffusion of virulent propagules is critical for initiation of chains of infection and further progression of the disease in time and space.

1. Growth of plant pathogens

Various plant pathogens, namely fungi, bacteria, nematodes, viruses, viroids, mollicutes, fastidious bacteria, and protozoa, grow in different ways.

1.1 Fungi and parasitic higher plants

Fungal pathogens and parasitic higher plants usually invade and infect tissues by growing on or in them from the first point of inoculation.

Most of these pathogens, whether they cause small lesions or large infected areas on the plant, grow, branch, and spread to more and more plant tissues until the infection stops spreading or the plant dies.

Plant Pathogen

Pathogen is an inducer of disease.

A pathogen can therefore be defined as any factor that induces unresolved impairment or disruption of one or more important plant functions.

Some plant functions such as nutrient uptake, are highly localized. Others, such as respiration, occur in all living tissues. Still others, such as photosynthesis and photorespiration, are extensively coordinated. Pathogen effects therefore range from very local to very general.

History of plant pathology records chronological account of important events, contributions of persons who significantly influenced the thinking of their era and interpretation of the observed facts or phenomenon over a period of time. Historical writings help us to understand systematic development in plant pathology, and there problems faced by certain outstanding workers whose view points were unacceptable to majority of opinion makers, simply because it was new and against the established norms of the day. History of plant pathology is a must read for the students of this discipline. The historical accounts will unfold the stories that may motivate the new generation to think and interpret the findings in their own way, without fear of established theories and dogmas carried from the past.