Namaskar from soulofkrishi. We are going to present you three part videos on distinguishing plant symptoms.
Plants when they face any kind of problems, be it nutritional deficiencies or toxicities or attack by pests and diseases or faced with environmental stresses or climatic vagaries like cyclone, lightning etc plants produce typical symptoms on their parts like leaves, flowers, fruits, branches and stems Many times these symptoms overlap each other. Therefore farmers face difficulty in identifying the reasons for such symptoms in order to take corrective measures. Hence we brought before you these three videos one after the other to help you in identifying these problems by examining these symptoms in the field so that corrective measures can be taken up.
In the first video we shall show you how to Distinguishing Disease and Insect Problems from Nutritional and Environmental Stresses by observing the type and pattern of symptoms directly in the field.
When we see symptoms on crops in the field we often get confused whether the symptoms are due to nutrient deficiency or due to diseases or even pest attack. For example leaves may show chlorosis. If it is interveinal chlorosis then it may be deficiency of zinc. If the chlorosis is veinal chlorosis then it may be a disease like yellow vein mosaic disease a viral disease. Similarly if only the older leaf margins are showing necrosis then it may be due to potassium deficiency and if such symptoms are seen in both old and young leaves then it may be disease like panama wilt.
Visual symptoms are very important tools to identify the problems before taking up correct measures to overcome the problems. But farmers many times are confused because many symptoms appear externally similar to each other. To help farmers in correctly identifying the exact problem We from soulofkrishi are going to suggest easy tips to differentiate between these symptoms.
So the question is what do farmers need to observe in the field to diagnose the symptoms? They have to Go very close to plants and see whether leaves are affected or flowers or fruits or even the stems? After seeing the symptoms closely they have to describe the symptoms as for as possible with correct terminologies or even with local terminologies. Then farmers should observe the changes in colour, shape, size of affected parts and the overall growth of the plants. Make a still close observation whether any fungus or insect presence can be seen or felt.
In the second step observe the complete plant from a little distance and see which part of the plant is expressing the symptoms and see in which growth stage this symptoms have occurred like planting stage, growing stage, flowering stage, fruiting stage or harvesting stage. Observe the complete plant or tree. Pinpoint where the symptoms are appearing like specific leaf, specific fruit stage and so on. Further observe how the symptoms are spreading from early stage of plant to late stage of the plant or from one plant to other plant in a circular shape or in one direction or randomly etc. You should also see how is the severity of the problem whether it requires immediate attention or we can wait for a day or two to see further progress in the symptoms.
Then come out of the field and observe from a distance the overall plot or field and see how many plants are affected, whether the effect is in edges or in patches or in random then think whether it is due to age of plant or due to varietal characters?
Finally you have to discuss with your adjacent farmers, friends and extension workers like
if it is also in their field, or
is it occurring every year or for first time,
whether it is a problem related to the soil type, or
climate and other such details.
And even the history of chemicals used by the farmers whether it is caused due to those chemicals?
With these information we can decide about the symptoms and causes of such symptoms.
Generally five types of symptoms are seen on plants. They are yellowing or Chlorosis, Lack of growth and bushy appearance in young shoots, death of tissue or necrosis, deformation, cracking or stunting and colour change to red, pink or violet. All are caused due to specific problems.
When we see these symptoms first we should find out whether the symptom is due to biotic factor like fungus, bacteria, virus or insects or the cause is due to other abiotic factors like nutrient deficiency, chemical toxicity, climate, storm or cyclone, temperature and any such factors.
If the symptoms are due to biotic factors then we can see Presence of fungal spores, powdery or downy growth, depressions, shape changes, an insect, cast skins, powdery material like frass, etc. on the affected part of the plant. Such symptoms spread progressively in a plant and spread to other nearby plants. Even such symptoms may appear only in one or two plant species and not on other plants nearby.
If symptoms are due to abiotic factors then you will see Physical evidence not usually on the plant (i.e. wind hail, sun burn, herbicide damage, etc). Further you will not see it spreading to any other plants and it affects all plants in the area irrespective of plant species.
If symptoms are due to deficiency of any nutrients then the symptoms will be uniform throughout the field and not sporadic or in patches as in case of diseases. These symptoms particularly appear on specific plant part in all the plants. But due to these symptoms the plants do not die due to deficiency. And finally the problem can be corrected with the application of that particular deficient nutrient
If symptoms are due to excess application of any chemical including nutrients then the symptoms appear in places where the toxic chemicals are used in the field and symptoms are seen only on sprayed parts or whole of the plants. It does not spread to other parts of the plant or in the field. Plants may die because of toxic effect. If plants recover from toxicity then the recovered plants do not show any symptoms.
If on the other hand the symptoms are caused due to diseases then such symptoms are not uniform throughout the field, but seen here and there in the field and such symptoms can be seen on any part of the plant unlike specific part as in case of nutrient deficiency. Such symptoms are caused due to pathogens which sometimes can be seen on plants and If not controlled the plant mostly dies due to disease
Unlike these three types of symptoms, if the symptoms are caused due to environmental effect then such effects are uniform throughout the field and such effects are seasonal. Environmental effects symptoms appear on the whole of the plants or sensitive parts like flower, fruits. Even plants may die because of effect
With these tips we will be able to categorize various plant symptoms in to different causes , that are, deficiency, toxicity, disease/insect and environmental causes. Once we have categorized the symptoms then we should go deeper to know the real cause for taking up corrective measures.
In our next video we will show how to exactly identify nutrient deficiency symptoms, toxicity symptoms, and environmental effects.
Should you require further clarification please contact soulofkrishi.com
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Thank you Namaskar
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