Question

give the disadvantages of weeds ​

Answer 1

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✳️dissadvatages of weed:

- Weeds reduce the economic yield by competing for water, nutrition, light,space and air with main crop.

-Weeds create difficulty while carrying outcultural practices like hoeing,irrigation and harvesting in the field.

-some weeds due to their rhizomes in soil like baru grass (Sorghumhalepense) and knots of motha (Cyprus rotundus) resist their eradication.

Weeds like ltsit (Trianthema portulacasirumi) and chulai (Amaranthusviridis) have very high rate of seed production.

- Several weeds act as alternate hosts to many serious pests and diseases.They may harvour insects-pests and act as secondary hosts for spread ofseveral diseases. For example, Cynodon dactylon (doob grass) and Cyprus

rotundus (Motha) are alternate hosts of grass hopper. Similarly, 'wild senji'and 'maina' are hosts of aphids. Parthenium hysterophorus (congress grass)acts as alternate host for mealy bug

Answer 2

Answer:

following are the disadvantages of weed.

Explanation:

1. Reduction in crop yield:- Weeds compete with crops for water, nutrients and light. Being hardy and vigorous in growth habit, they grow faster then crops and consume large amount of water and nutrients, thus causing heavy losses in yields.

2. Increase in the cost of cultivation:- Tillage operations are done to control weeds and it is generally estimated that on an average about 30 percent of the total expenditure for crop production is on tillage operations and more labour is employed for weeding. This results in increasing cost of cultivation and reducing the margin of net profit.

3. The quality of field produce is reduced:- When the crop is harvested from a weedy field the seeds of weeds get mixed with the main crop which results in lowering the quality of the produce .e.g. seeds of weeds in wheat, gram etc. Similarly, bundles of many leafy vegetables like methi or palak contain green plants of weeds. They fetch lower prices in the market.

4. The quality of the livestock products is reduced. Certain weeds eg. Hulhul when eaten by milch cattle impart an undesirable flavour to milk. Similarly weeds like gokhru get attached to the body of the sheep and impair the quality of wool. Certain poisonous weeds like Datura may cause death of cattle if they are unknowingly eaten by cattle.

5. Weeds harbour insect, pests and diseases:- Weeds either give shelter to various insects, pests and diseases or serve as alternate hosts.

6. Weeds check the flow of water:- Weeds block drainage and check the flow of water in irrigation channels and field channels thereby increasing the seepage losses as well as losses through overflowing. The irrigation efficiency is also reduced.

7. Weed secretions are harmful:- Heavy growth of certain weeds like quack grass or motha lower the germination and reduce the growth of many crop plants. This is said to be due to the presence of certain phytotoxins in these weeds.

8. Weeds are harmful to human beings:- certain weeds cause irritation of skin, allergy and poisoning in human beings.

9. Weeds cause quicker wear and tear of farm implements; they get worn out early and cannot work efficiently unless they are properly sharpened or mended.

10. Weeds reduce the value of the land:- Agricultural lands which are heavily infested with perennial weeds like kans always fetch less price, because such lands can not be brought under cultivation without incurring heavy expenditure on labour and machinery.