1 Detection vs. diagnosis – Definition and Differences

Transcript

Hello everybody!! I welcome to the course Detection, Diagnosis and Plant Disease management. The first talk in the discourse will be dealing with detection versus diagnosis there are certain differences between these two terms and we’ll try to understand the differences of these two terms we all know that healthy plans are required to feed the world but unfortunately plant suffers from varieties of plant pathogens and that is why course is necessary to go for detection and diagnosis of plant pathogens healthy crops are essential for safe healthy and sustainable farming that contribute to the quality of food and life reliable Diagnostics for the timely detection of plant pests and diseases provide the basis for healthy crop production this is how Diagnostics help controlling risk and provide security during crop production now let us try to understand what is a plant disease any disturbance of a plan that interferes with its normal growth and development can be called as plant disease plant disease can be caused by either by at occasions or a biotic causes and plant diseases caused major production and economic losses in agricultural industries globally early information on crop health and disease detection can facilitate the control of diseases as well as minimize economic losses that is why it is highly important to detect and diagnose the causal result of disease and that is so that we can facilitate that control of the disease and thereby minimize loss to the growers how detection is different from diagnosis in practice to detect a problem is to objectively observed symptoms caused by the problem whereas to diagnose a problem is to ascertain the specific pathological condition that is causing the problem so this is the basic difference between the detection and diagnosis identification of disease-causing agent may take a week or more time the following expects are important during identification that is to use the power of observation and ask questions related to the disease in order to eliminate or identify possible causes of the problem and also to consider various environmental and cultural factors that are associated with the plants that are suffering from a particular disease as a result of the questions and of the resistance of the diagnostician he or she may be able to identify a disease and this is causingasn’t or he be able to narrow the problem down to several possibilities which will require further study in the laboratory or even the diagnose station may be completely baffled by the problem it may be if it is a new problem or an emerging problem so to diagnose or detect before going for detection and diagnosis of the plant disease it is absolutely important to know what is normal for that particular plant for example in case of certain plant the proper identification of the plant type is highly important secondly recognizing healthy appearance of the plant is also to be in the back of the mind for the diagnostician to distinguish it from a normal and diseased plant for example some of the plants they have some genetically variation in the manifestations of their leaf color or in the flower color or in the leaf structure and these manifestations this is not considered to be abnormal as these manifestations are inherent characteristics of the plant itself for example yellow coloration in the leaf in many plants then leaf distortion in the colocasia plants and color breaking in tulip flowers so these are normal 4d plant species and it should not be considered as a disease plant so identification characteristic symptoms for plant diseases are basically based on under development of tissues or organs over development of tissues or organs necrosis or death of plant parts or alteration of normal appearance all these are characteristic symptoms of disease then again there is a two term sign and symptoms and these symptoms are basically changes in the plant’s appearance in response to a pathogen that deviates from its normal appearance for example common bacterial blight symptoms include brown necrotic lesions surrounded by a bright yellow halo at the leaf margin or interior of the leaf on bean plants at the same time dizzy signs are the structures of the plant pathogen visible on the infected plants for example fruiting bodies of fungus such as powdery mildew on leaf is the parasitic fungal disease organism itself so this is the basic distinction between sign and symptoms as where the sign manifestation of sign is the presence of structures of the pathogen whereas symptoms is the change or deviation from the normal appearance of the plant or plant part the fungal disease science includes say for example leaf rust stem rust in sclera tinea white mole or in powdery mildew in all these diseases one can have manifestation of the presence of the fungal structures for example on leaf rust these early pustules of the rust pathogens then in case of squirting near white mold we can see the presence of fungal on the beans then fungal diseases symptoms includes bird’s eye symptom on berries wilting of plants leaf spot chloro sill closes in all these cases we see the just the symptoms on the leaf or other plant part but not the Paterson itself or Paterson structures itself so this is the basic difference between science and symptoms and here are some of the manifestations of fungal diseases signs and symptoms similarly there are signs and symptoms also present for bacterial disease normally Bechtol disease signs are difficult to observe but it can include bacterial coos water-soaked lesions bacterial streaming from cut stem and so on since bacteria are very smaller in size one cannot see bacterial cells with normal eyes and that is why some characteristic symptoms like bacterial poos water-soaked legions bechtel streaming can be considered as signs of bacterial disease whereas typical bacterial symptoms include leaf spot with yellow hello fruit spot canker crown gall all these part of bacterial disease symptoms similarly for viral disease since virus also we cannot see with our naked eye so there won’t be any signs of viral structures or viruses that will be able to make it out with our naked eyes but definitely viral disease symptoms can be very well identified based on the mosaic type of symptoms crinkle leaves yellowed leaves plant stunting these are some of the characteristic symptoms of viral disease at the same time a plant may be affected by more than one viruses and it can cause variation in the symptom production in the same plant species so one has to have thorough understanding of these signs and symptoms that are produced by different plant pathogens on a particular plant species to correctly identify the pathogen at the very beginning say for example in peach shielding when it is infected by three different combination of viruses of the same plant species they produces different symptoms on the same host for example if the left one implant is of Beach is infected by prune dwarf virus as well as pruners necrotic ringspot virus whereas the prune dwarf virus infection is in the middle and in the right hand plant it is infected by pruners necrotic ringspot virus so different viruses can have different symptoms produced on the same host and if this combination of more than one virus infection then it may lead to again production of entirely different type of symptoms so all this has to be kept in mind for the diagnostician or the plant pathologist who is at the investigating level to determine the signs and symptoms along with the cause possible causal agent that may be associated wind up the pathogen a host and with this we have come to an end of the first talk of the week and till we meet in the second talk have a good time.

Thank You