Koch's Postulates



Koch's Postulate & Experiment

Have you fulfilled all of Koch's postulates in this experiment?

We can see from diseased plants found very many types of microorganisms (or microbes), whichever is the disease caused by the protagonist? Or there are other reasons? How to judge it does not cause Miscarriage of justice, Koch's hypothesis (Koch's postulates; also known as Koch's postulates Koch's rules) for the public Sickly psychologists (including human beings, animals and plants) are recognized as determine the cause of the most reliable method. There are many experiments Plant Pathology is Koch's postulates as the cornerstone of change discussed various factors and therefore the rule Plant Pathology is an important concept, learn from symptoms for the beginning, and then learn pathogens separation, cultivation, preservation And identification of plant diseases, vaccination and learning techniques, the actual operation is complete Koch's postulates.

The steps of Koch's Postulates are utilized for this experiment such as (Manheimer, 2001):

The suspected causal agent (bacterium or other microorganism) must be present in every diseased organism (e.g., a plant) examined.

The suspected causal agent (bacterium, etc.) Must be isolated from the disease host organism (plant) and grown in pure culture.

When a pure culture of the suspected causal agent is inoculated into a healthy susceptible host (plant), the host must reproduce the specific disease

The same causal agent must be recovered again from the experimentally inoculated and infected host, i.e., the recovered agent must have the same characteristics as the organism in step 2.

Did any other plates contain more than one microorganism? If so explain how this may have occurred?

Bacterial diseases are difficult to control and can be a limiting factor on tomato production. Bacterial spot of tomato, caused by Xanthomonas axonopodis pv. vesicatoria (Doidge) Dye, is extremely difficult to control under moist, warm conditions, which can occur. The bacterial spot pathogen has a higher optimum growth temperature (24 to 30°C) than the optimum growth temperature of the bacterial speck pathogen (18 to 24°C). When the weather conditions become moist and cooler than normal, bacterial speck, caused by Pseudomonas syringae pv. tomato (Okabe 1933) Young, Dye & Wilkie 1978, becomes the predominant bacterial disease. The bacterial spot pathogen has a higher optimum growth temperature (24 to 30°C) than the optimum growth temperature of the bacterial speck pathogen (18 to 24°C). Bacterial disease development is favored by high rainfall, and by low-pressure disturbances with high wind velocity. The bacteria penetrate plant tissue through wounds created by wind-driven sand, insects, or other mechanical means such as stringing, pruning, and harvesting. Severe defoliation and fruit spotting result in significant yield loss.

Copper combined with mancozeb is the standard pesticide treatment used for managing bacterial diseases on tomato. When environmental conditions are marginal for disease development, copper + mancozeb provides adequate control, but when environmental conditions favor disease development and inoculum levels are high, the standard treatment becomes considerably less effective . With the presence of copper-resistant strains of these bacterial pathogens, copper-based control measures become less effective (Fig. 1) (Dietrich, 1996).

Fig. 1. Lesions of bacterial spot (Xanthomonas axonopodis pv. vesicatoria) on tomato with copper residue

An experiment should have only one factor varied at the time ...