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Careers in mycology and plant pathology
A PLANT pathologist is a scientist who specializes in plant health management. The task of keeping plants healthy needs a knowledge of organisms and agents that cause disease in plants and affect the growth, yield or quality of the harvested product.
Plant pathologists also need to acquire the basic know-how of related disciplines such as biochemistry botany, ecology, epidemiology, genetics, microbiology, molecular biology and physiology. They learn to control diseases by biological, chemical or cultural means or by combination of all these methods. They find employment in colleges and universities, provincial and federal government agencies, industry or foreign services and as private consultants
Plant pathologists, like any other doctor, examine diseased plants with the help of special diagnostic tests and techniques, determine the cause of the disease and then suggests the remedial measures. This information helps farmers, growers and land owners to control disease in their plants. The diagnosis mostly involves the use of microscopes as well as extensive cultural studies and investigations.
A plant pathologist works with living things: Before new varieties are released by governmental institutions or commercial seed companies, these are tested by the plant pathologists in field experiments. Under observation the test trials are carried out for appearance of any signs or symptoms of disease or assessment of resistance to disease.
Plant may react to the agent of disease in different ways. Therefore, the symptoms and effects on plant growth for a certain disease are analyzed very carefully. Experiments for screening of suitable varieties are often carried out in the green houses as it allows growth under controlled environment than is available in the field.
Hands-on study: Thousands of synthetic organic chemicals are released in the market every year for the control various ailments in plants. A trained plant pathologist are skilled to identify promising new fungicides or biocides from wide array of chemicals is required for further screening to quantify the dosages of these chemicals keeping in view the biosafety measures.
Agricultural produce like grains, fruits, vegetables also get attack of disease after harvest. These are kept in incubation chambers under appropriate conditions and the infection process is studied. Plant Pathologist determines how, air, temperature and moisture, affect the disease development.
There is another category of experts called field pathologists who examine the condition of diseased trees by several methods. For example many of them wilt and other diseases are caused due to the lack of moisture and hence information about moisture level and conduction in trees helps in diagnosis and treatment of infected trees.
State-of-the-art: Students of Plant Pathology are often seen doing inoculations on to petri plates with materials/tissues taken from diseased plants. This is a crucial step in the process of identifying the causal organism.
Petri dishes containing colonies of the pathogens are examined under microscopes and photographs are made through the microscopes. This helps the experts to study the causal organisms in detail. Pure cultures are raised and identification of the causal agent is established.
Similarly phytonematologists too are pathologist trained in the study of nematodes (eelworms). They collect the soil and plant samples and identify the organisms. The number of nematodes is also determined. Nematodes are tiny organisms, which feed on plant roots. Therefore, both their number and types would indicate that how severely a plant is injured.
Learning by experiments: Pathogenic organisms can strike the plant at any stage of development. Experiments are therefore, planned and seedling diseases of various crop plants are classified and counted to evaluate the effects of disease control treatments.
A thorough examination of the soil is also characterized for fragments of infective fungi. As part of the experiments soils are inoculated with the pathogens before the crop is sown. Thus the information is obtained about conditions helpful or harmful to the fungi. Fungal structures in soil result in root infection such as cotton root rot. Sometimes crop plants are treated with certain chemicals and then exposed to a particular pathogen to measure the disease control potential of the experimental chemical.
Now sophisticated equipments, like an electron microscope, aid in the identification of certain disease-causing agents such as viruses or bacteria. Plant pathologists use this information in diagnosis of disease and in developing methods of prevention and control. Electron microscopy can be used in sophisticated lab. research. Minute structures on the surface of a spore can help in identifying and classifying organisms. The structure and length of components essential for genetic engineering, obtained from microbial cells, can be examined.
Computer technology is a necessary skill of a modern day pathologist, who keeps track of hundreds of thousands of test results. Computers can also be used to forecast the onset of disease epidemics.
Plant pathologist needs to work closely with organic chemists in the discovery and development of new chemicals for control of important plant diseases.
Keeping in view a rapidly increasing human population, a plant pathologist concentrates not only on improving the quality of food but also attempts to increase crop productivity. This requires a rigorous evaluation of commercially available fungicides for disease control, which demand technical skills in plant pathology and fungicide chemistry.
In addition to grains, fruits and vegetable, nuts are a major source of food in many countries. Therefore, plant pathologists would take special measures to keep nut trees/plant disease free. Similarly in addition to cotton and other cash crops, sugar beet and sugarcane also need equal attention of plant pathologists.
The growers of these crops therefore learn to identify disease problems in the crop fields under the watchful eye of a practicing plant pathologist. If the disease is found, control practices will be employed.
Potatoes being another staple food grown in field trials and weighed and graded. Different varieties are grown under different conditions to see how well they resist disease and how much yield they give. Tests based on lab. and field inspections are also used to develop quarantine and to ensure that potatoes planted for seed are free of disease.
Plant pathologists pay special attention to keep the environment healthy. Infected twigs and branches of shade trees are pruned either to diagnose the disease or to remove infected plant parts as a control measure. Accurate diagnosis of symptoms is important in keeping shade trees and lawn/turf grass healthy. Rain samples are regularly collected in automatic sampler to determine acid rain and air pollution. The acidity of rainfall and the number of particles entrapped with in it vary with the stages of rainfall and affect the disease incidence & epidemiology.
Aspiring plant pathologists develop experience through investigative laboratory experiments with plants. A plant pathologist normally majors in one of the branches of biological sciences and does research work in plant pathology. Although jobs are available at each level of education opportunities for doing research are greater for a person with an advanced degree.
In the class of virology, graduates learn to use serological techniques for the characterization of viruses.
Upcoming techniques like genetic engineering to develop strains with enhanced valuable traits are also becoming a part of regular activities of plant pathologists.
Tissue culture technology to provide disease free seeds and seedlings mass culturing of edible fungi to produce protein rich food are also a common practice.
Some times the classes are held in the field students are trained to evaluate cultivated varieties of wheat for resistance to rust or leaf spots. They learn how to record disease incidence and severity in field situations
The writer is assistant professor, Department of Mycology & Plant Pathology, University of the Punjab, Lahore
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