SUGARCANE CULTIVATION IN THE WORLD:

“The history of man is the record of a hungry Creature in search of food”. This was expressed by Van Loon (1921) in the Story of Mankind.

Man and his scientific pursuits- The primitive man, when his number was small, hunted for food and lived in the natural ecosystem without essentially destroying it. His eventual use of fire and the beginnings of agriculture worked as trigger factors into natural ecosystems (Billings, 1972). Man soon becomes a powerful factor in upsetting the ecosystem balance. In recent centuries, as human population increases geometrically with development, there is an increasing shift to modified ecosystems.

The most important current level of biological study in eco-pathology is the quantitative estimates of populations, communities, habitat conditions and the interactions involved. This is being recognized in non-biological circles too, since the impact of agriculture, deforestation, urbanization, industrialization and unilateral development work is being felt more keenly day by day.

Modern agriculture owes its foundation and subsequent development on the centuries of experience by farmers-the practical biologists, coupled with relevant scientific knowledge acquired and applied by biologists, chemists, physicists, engineers, etc. Enormous amount of food is being produced annually on global basis. Yet in the midst of this abundance of food, millions of people of the world still go hungry. Science has taught us how to produce plenty and science is universal. Why then this anomaly? We believe the answer can be given by the social scientists. Fact remains that man in the grater part of the world is still, “a hungry creature in research of food”.

Plants and animals are the two major sources of food; and between the two man’s dependence on green plants is predominant. Green leaf is the greatest factory on the face of the earth. In terms of energy input and value of new products created, it completely dwarfs the most gigantic installations created by man. Without this biological factory there would be no life on this planet. It is our obligation then to protect this factory and keep its auxiliary sources healthy so that the factory will operate at maximum efficiency.

Dutch amateur scientist Anton Van Leeuwenhoek (1632-1723) unfolded the microbial world, the world of living organisms beyond resolution of unaided human eyes, around in the third quarter of the 17^th century. Thus he conquered a New World of living beings, hitherto unknown to man. Thousands of bacteria are present in the human mouth. Fungi appear on old moist breads. Viruses may be transferred from plant to plant by insects and other means. Nematodes are found in all natural soils.

Although Leeuwenhoek was the first man to discover the microbial world, the people even in the prehistoric days used to derive benefits of the activities of some of the useful microbes without knowing them, e.g. conversion of starch and sugary substance to alcoholic beverage by yeast from a group of fungi. Man’s knowledge of pestilence and plant diseases can be traced back to thousands of years from now. People believed that God used to punish man from time to time through these epidemics of plants and animals so that he becomes cautious.

About two centuries after the discovery of the microbial world by Leeuwenhoek, Louis Pasteur (1822-1895) and Robert Koch (1843-1910) conclusively proved the germ theory of diseases during the middle of the nineteenth century. They established the fact that all contagious diseases of man and animal were caused by different types of microorganisms. But people were not ready to accept the fact that plants like man also suffer from diseases caused by pathogenic microbes. They continued to believe that devastation of crops by diseases like blight, smut, rusts, mildews, red rot etc. was due to the influence of evil spirit or wrath of God. More educated people however, attributed to bad weather- whatever that might mean. A few keen observers and dissidents, who detected microorganisms in the rotten tissues of red rot infected plants, suggested that plant also suffer from contagious diseases caused by pathogenic microorganisms. But they were ridiculed by a host of contemporary scientists and bureaucrats. A major catastrophe in human history had to befall on the people of a certain geographic area to dispel the arrogance of these conceited experts.

Since the birth of plant pathology as a distinct branch of biological science, the plant pathologists has been relentlessly working to determine and identify the cause of plant diseases and to assess the losses inflicted in the from of yield reductions, with a view to suggesting effective and economically acceptable methods of plant disease control.

Assessment of crop losses caused by plant pathogens is a difficult task. Losses may be quantitative and /or qualitative. Available statistics on crop losses in most cases are to a great extent approximation. Estimated losses of some crops on a global basis are shown in Table-1.

Table-1: Estimated crop loss due to disease, insects and weeds on a global basis.

A grower puts all efforts and invests his capital to raise a sugarcane crop with the high hope of reaping a good harvest. But frequently his expectations are shattered by the interventions of plant pathogens the invisible competitors. The pathogens sneak into the field and infect sugarcane crops causing scores of different types of diseases. Most of the diseases can be recognized by observing the external manifestations of the physical and physiological disorders called symptoms. Extent of losses that might be inflicted by pathogens depends on their virulence, meteorological factors favoring their activities and the state susceptibility of the plants affected. Thus depending on the intensity of disease development, these invisible competitors may damage the whole or a part of the sugarcane growers anticipated harvest.

The challenge of developing modern biology for the twenty first century needs a systemic research at least for the welfare of humanity. Present day sugarcane cultivation is more complex than what it used to be in the past. Adoption of modern technologies in sugarcane greatly improved the food supply to people in one hand and on the other hand high input agriculture created new problems to be solved by relevant scientist in the interest of sustainability of this production system. Plant pathologists are expected to play a vital role to maintain sound health and yield for plant populations through development and application of eco-friendly packages for disease control.