SECTION B
Ques.2A. On the Basis of site of Predominance -
* Obligate weeds - grown only in association with man and his agriculture. it is never found in wild form. EG - Chinopodium album , Anagallis arvensis.
* Facultative weeds - grown both as wild and cultivated habitat. EG - Argemone mexiacana, Euphorbia hirta.
Ques2B. father of weed science - Jethrotull , in book - Horse hoeing husbandry
Ques2C. Congress grass is a common name for Parthenium hysterophorus, a species of flowering plant that is native to the American tropics but has become an invasive weed in India and other countries1. It can cause health problems such as allergies, asthma and dermatitis in humans and animals. It can also reduce crop yields and biodiversity by competing with native plants. It is believed that it was introduced to India through contaminated wheat imports from the USA in the 1950s. It can spread rapidly through seeds, which can be dispersed by wind, water, animals and vehicles.
Ques2D. 2,4-D is a type of herbicide that is used to kill broadleaf weeds without affecting most grasses¹. It is also a type of phenoxy compound, which is derived from chlorination of phenol or phenoxyacetic acid². It is also a type of synthetic auxin, which is a plant hormone that regulates growth and development.
Ques2E . Biological weed control is a method of using living organisms to reduce the population or impact of weeds. The organisms can be insects, mites, nematodes, pathogens, or grazing animals that feed on the weeds or their seeds. Biological weed control can be effective for long-term management of invasive weeds, but it may not completely eliminate them. It also requires careful selection and monitoring of the biocontrol agents to avoid harming non-target plants or animals.
Ques2F- On the basis of Importance -
1. Relative weed - eg- rice in wheat field.
barley in wheat field
2. Absolute weed - eg- Cyperus rotandus such weed are due to its characteristics.
3. Rogue weed - eg - plants of C - 306 variety grown in Raj - 40 variety of wheat crop.
4. Mimicry weed - eg - Phalaris in wheat field and wild rice in rice field.
5. Volunteer weeds - eg - green gram in wheat field on the present season crop.
weeds grown from the fallen seeds of previous or preceeding crop in field.
6. Noxious weeds - eg - Parthenium , Orobanchi
toxic to hormone & animals.
7. Objectionable weeds - eg- wild oat and oat.
which produce seeds that are difficult to separate once mix with crop seed due to its resemblance.
8. Satellite weed - eg - Avena fatua in barley.
weeds mature at same time and height along with crop and seeds are similar to main crop.
9. Exotic / Alien weed - origin out of native place.
eg- lantana camera - from USA
parthenium from USA
Phalaris minor - Medeteranean region
SECTION C
Ques3A. Allelopathy refers to the chemical interactions between plants, where one plant releases biochemical compounds into the environment that affect the germination, growth, survival, or reproduction of other nearby plants. These compounds are known as allelochemicals and can have both stimulatory and inhibitory effects on neighboring vegetation.
Allelopathy can be applied for weed management:
1. Weed Suppression: Some plants release allelochemicals that inhibit the germination or growth of competing weeds. This can be especially useful in agricultural settings where crops are vulnerable to weed competition. For example, certain cover crops are grown specifically for their allelopathic effects on weeds.
2. Crop Rotation: Incorporating allelopathic plants into crop rotation systems can help suppress weed growth during fallow periods. This can contribute to maintaining soil health and reducing the need for synthetic herbicides.
3. Mulching: Mulching with plant materials that possess allelopathic properties can help in weed control. The decomposition of the mulch releases allelochemicals into the soil, creating an inhospitable environment for weed growth.
4. Intercropping: Planting allelopathic crops alongside main crops or intercropping can reduce weed infestations. The allelopathic plants release compounds that deter weed growth, creating a more competitive environment for the desired crops.
5. Allelopathic Cover Crops: Planting cover crops with allelopathic properties as part of a weed management strategy can help suppress weed growth. Examples include rye, sorghum, and certain varieties of mustard.
6. Biological Weed Control: Understanding and harnessing allelopathy can contribute to the development of biological control methods. This may involve identifying and cultivating allelopathic plants that can be used to naturally control weed populations.
Annidation ?
Ques3 B. Characteristics of weeds -
1. Produce enormous no. of seeds. eg. wild oats (Avena fatua) produces 250 seeds / plant.
2. Thrive well even in adverse condition because they can modify their seed production and growth accordingly to available of moisture and temperature.
3. seeds remain viable for many years without loosing in viability. eg. field bind weeds (Convulvulus arvensis) for about 50 years.
4. weeds seed have tremendous capacity to dispense from on place to another by wind, water , animals and man .
5. weed seeds mimic with the crop seeds due to them size and get transported with them.
6. able to regenerate lost plant.
7. compete with cultivated plants.
8. all seeds of weeds mature simultaneously.
9. weeds have allelopathic effect on crops.
10. produces seeds in flushes.
11. seed production through apomixis, spore , etc.
12. weed seeds have dormancy either inherited or induced .
13. have short period of plant growth.
14. generally grow at faster rate and produce seeds earlier than most of crops growing in association.
Ques4A. Classification of weeds -
1. On the basis of site of Predominance -
a. Obligate weeds - grown only in assocation with man and his agriculture. it is never found in wild form. eg - chinopodium album
b. Facultative weeds - grown both as wild and in cultivated habitat. eg- argemone mixicana
2. on the basis of dependence of host plants. -
a. Total root / Holo root parasite
b. Total stem
c. Semi - root parasite
d. Semi-stem parasite
3. on the basis of botanical / Morphological characters. -
a. grasses
b. sedges
c. Broad Leaf
4. on the basis of season -
a. Kharif weeds
b. rabi weeds
c. Zaid weeds
5. on the basis of Importance -
a. Relative weed -
b. Absolute weed
c. Rogue weed
d. Mimicry weed
e. Voluntree weed
f. Noxious weed
g. Objectionable weed
h. Satellite weed
i. Exotic weed / Alien weed
7. on the basis of life cycle -
a. Annual
b. Biennial
c. Perinneal
8. Based on Soil types - (eadphic) -
a. black cotton soil
b. red soil
c. light, sandy , loan soil
d. laterite soil
9. on the basis of Origin -
a. Indigeneous
b. Introduced / Exotic
10. on the basis on Cotyledon -
a. Monocots weed
b. Dicot weed
11. Based on soil PH -
a. Acidophile
b. Basophile
c. Neutrophile
12. Based on nature of stem -
a. woody
b. semi - woody
c. herbaceous
13. Based on specificity -
a. poisonous weed
b parasite weed
14. Aquatic weed -
a. submerged
b. emersed
c. marginal
d. floating
15. on the basis of place of occurence -
a. crop plant
b. pasture lands
c. waste places
d., playground road soil
16. Based in ecological affinition -
a. wetland
b. garden land
c. Dry land
Ques4B.
Five herbicide common name and trade name -
Ques5A. Weed management refers to the strategies and practices employed to control and minimize the impact of unwanted plants, commonly referred to as weeds, in agricultural, horticultural, or natural ecosystems. Effective weed management is crucial for maintaining the health and productivity of crops, gardens, and ecosystems. Various methods and practices are used in integrated weed management approaches. Here are some common weed management practices:
1. Cultural Practices:
- Crop Rotation: Changing the type of crops grown in a specific area from season to season can disrupt the life cycle of certain weeds and reduce their prevalence.
- Cover Cropping: Planting cover crops helps suppress weeds by shading the soil, competing for resources, and sometimes through allelopathic effects.
2. Mechanical and Physical Methods:
- Hand Weeding: Manual removal of weeds by hand or using hand tools is a labor-intensive but effective method, especially in smaller areas.
- Mowing and Cutting: Regular mowing or cutting can prevent weed seed formation and reduce weed competition in lawns, fields, and along roadsides.
- Tillage: Turning over the soil through plowing or cultivation can bury weed seeds and disrupt their growth. However, excessive tillage can have negative impacts on soil health.
3. Chemical Control:
- Herbicides: Selective or non-selective herbicides are chemicals designed to control or kill weeds. They can be applied pre-emergence (before weeds emerge) or post-emergence (after weeds have emerged).
- Weed Barrier Fabrics: These are physical barriers placed on the soil surface to prevent weed growth. They are commonly used in landscaping and horticulture.
4. Biological Control:
- Introduction of Natural Enemies: Some insects, animals, or pathogens feed on specific weed species, providing a natural means of control. Care must be taken to ensure that introduced species do not become pests themselves.
5. Integrated Weed Management (IWM):
- Combining Methods: IWM involves the use of multiple weed control strategies to achieve effective and sustainable results. This may include a combination of cultural, mechanical, chemical, and biological control methods.
6. Preventive Measures:
- Quarantine Measures: Preventing the introduction and spread of invasive weeds through careful monitoring and control at borders and points of entry.
- Sanitation: Cleaning equipment, clothing, and tools to prevent the unintentional spread of weed seeds.
7. Educational and Awareness Programs:
- Farmer Education: Providing farmers and landowners with information about weed identification, life cycles, and management practices helps improve their ability to control weeds effectively.
8. Adaptive Management:
- Regular Monitoring: Regularly assessing weed populations and adapting management practices based on observed changes and effectiveness of control measures.
Ques5B.
1. Classificaiton of Herbicide -
a. Selective herbicide -
b. Non - selective herbicide
2. based on type of weed control -
a. herbicide of broad leaf
b. narrow leaf weed
c. narrow specture
d. broad spectures
3. based on translocation / movement of herbicide in plant -
a. contact
b. systemic
4. on the basis of time of application -
a. Pre-plant applied
b. pre-emergence
c. post-emergence
5. Based on residual action -
a. residual
b. non- residual / zero persistence
6. on the basis of duration of weed control -
a, Temporary soil sterilants / fumigants
b. Permanent soil sterilant
7. On the basis of methods of applicaiton -
a, Soil active /soil applied herbicide
b. Foliage applied / foliage active
c. Direct contact Application DCA
