Herbicides and Pesticides MCQ Quiz in मल्याळम - Objective Question with Answer for Herbicides and Pesticides - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

The Correct Answer: 3) Monocot flowers possess no nectaries

Key Points

• Perfect flowers (those that contain both male and female reproductive structures) in the plant world fall into one of two categories: monocots or dicots.
• Number of Cotyledons: The fundamental difference between monocot and dicot flowers concerns the number of cotyledons (seed leaves) in the plant embryo: monocots have one, while dicots have two.
• Floral Parts: Monocots typically have flower parts in multiples of three (3, 6, 9, and so on), while dicots usually have flower parts in multiples of four or five.
• Nectaries: Monocot flowers often lack nectaries, the structures that produce nectar in many flowering plants. This is not always the case, however - certain monocots do have nectaries.
• Vascular Tissue: Vascular tissue in monocot stems is scattered randomly, while in dicots it is organized in a ring.
• Root System: Monocots usually possess a fibrous root system, whereas dicots typically have a singular main root known as a taproot with many minor lateral roots branching off from it.
• Leaf Venation: Monocot leaves usually show parallel venation (the veins run alongside each other from the base to the leaf apex), while dicots exhibit net or reticulate venation (the veins branch and rebranch within the blade).
• Pollen Grains: The pollen grains of monocots have one furrow or pore, so they are monosulcate. On the other hand, the pollen grains of dicots mostly have three pores or furrows and are thus tricolpate.

The correct answer is Ephedrine.

• Ephedrine is not a pesticide.
• Pesticides are chemical substances that are meant to kill pests.
• In general, a pesticide is a chemical or a biological agent such as a virus, bacterium, antimicrobial, or disinfectant that deters, incapacitates, kills, pests.

Key Points

• Ephedrine is a prescription medicine used to treat the symptoms of low blood pressure during anaesthesia (Hypotension).

Important Points

• Types of Pesticides are:
  • Insecticides  (insects)
  • Herbicides  (plants)
  • Rodenticides (rats & mice)
  • Bactericides  (bacteria)
  • Fungicides  (fungi)
  • Larvicides  (larvae)

 

The correct answer is 2 kg/ha.

• The major monocot weeds that occur in mango orchards are Cynodon dactylon and Cyperus rotundus.
• Dicot weeds are Bidens pilosa, Tridax procumbens and Phyllanthus maderaspatensis.

 

1. ​Chemical control:

• ​Herbicides have been used to some extent in mango to control weeds.
• Application of Paraquat (3 kg a.i./ha) or Diuron as pre-emergent treatment at 6.67 and 8.9 kg/ha gives good control of weeds in mango.
• Or Bromocil and Dalapon were also effective for controlling dicot and monocot weeds respectively.
• One spray of Atrazine or Diuron at 2 kg a.i./ha as pre-emergent treatment to soil and one spray of Paraquat as post –emergent spray on weeds at 3 kg a.i./ha found effective for controlling both monocot and dicot weeds in 1 - 5 years old mango orchard.

The correct answer is 1 and 2.

Key Points

• 2, 4-D (Dichloro phenoxy acetic), is a chemical.
  • It is used to destroy broadleaf weeds.
  • 2,4-Dichlorophenoxyacetic acid is a widespread systemic herbicide utilized in the management of weeds with broad leaves.
  • A chemical that kills the weeds is known as weedicides.
  • 2,4-D is a widely used herbicide that has been widely used since the 1940s to control weeds. It is used in many places, including turf, lawns, right-of-way, aquatic sites, forestry sites and a variety of farms, fruit and vegetable crops.
  • It can also be used to regulate the growth of citrus plants.

Additional Information

• Chemicals that control weeds are called weedicides.
• Insecticides are used to control the pest.
• Weeds grow in crops and make the crop weak by competing for nutrients, moisture, air, light, and space, etc.
  • Weeds become the shelter of harmful pests and diseases and severely affect the yield and quality of the crop.
  • Therefore, weed control is done in time to get the maximum yield of wheat.

The correct answer is Simazine.

• Pre-emergence herbicides: This type of herbicide kills weeds before they sprout.
• Pre-emergence herbicides prevent germinated weed seedlings from becoming established either by inhibiting the growth of the root, the shoot, or both.
• The time of application of pre-emergence herbicides is 1-4 days after sowing.
• Preemergence herbicides are Simazine, Atrazine, Butachlor.
• Simazine is a pre-emergence herbicide used to selectively control a wide variety of annual and perennial grasses and broadleaf weeds. 
• It has found much success in croplands to keep target weeds off of fruits and vegetables in orchards.

Brown planthopper (Nilaparvata lugens): Both nymph and adult cause damage by sucking the plant sap from leaves which turn yellow. Under the favorable condition of high humidity, high nitrogen application and no wind, the population increase and due to severe damage hopper burn is obtained in various localities. The insect also transmit Grassy stunt virus disease of rice.

The correct answer is 2, 4-D.

Key Points

• The compound 2,4-dichlorophenoxyacetic acid, or 2,4-D, is an herbicide used to kill any dicot plant tissue.
  • The substance is a synthetic auxin, a type of plant hormone that is absorbed by plant leaves.

Additional Information

• Auxin is a group of several natural (and artificial) plant hormones; the most common and physiologically important auxin is indole acetic acid (IAA).
• Cytokinins are a class of plant hormones that promote cell division, or cytokinesis, in plant roots and shoots.
• Abscisic acid (ABA) is a plant hormone that regulates many aspects of plant growth, development and stress responses.
  • ABA-deficient mutants from various plant species display reduced seed dormancy and wilting phenotypes, highlighting that these important ABA functions are conserved across the plant kingdom.

The correct answer is Fenpropathrin.

• Shoot and fruit borer management:

1. Spray Bt formulations of B. thuringiensis var. kurstaki such as Dipel @ 1.5 to 2 ml /L of water.
2. Spray insecticide starting from one month after planting at 15 days interval.
3. Fenpropathrin 30 EC 250-340 ml or Thiodicarb 75 WP 625-1000 g Flubendiamide 20 WG, 375 g with 500 – 750 L water/ha.
4. Carbaryl 50 WP 2 kg + Wettable Sulphur 50 WP 2 kg, Endosulfan 35 EC 1.5 L + Neem oil 1.5 L, Quinalphos 25 EC 1.5 L + Neem oil 1.0 L, NSKE 5%, Azadirachtin 1.0% 1.0-1.5 L.​

 

• ​Stemborer management:

1. ​Spray insecticide starting from one month after planting at 15 days interval.
2. Carbaryl 50 WP 2 kg + Wettable Sulphur 50 WP 2 kg, Endosulfan 35 EC 1.5 L + Neem oil 1.5 L, Quinalphos 25 EC 1.5 L + Neem oil 1.0 L, NSKE 5%, Azadirachtin 1.0% 1.0-1.5 L.
3.  Fenpropathrin 30 EC 250-340 ml or Thiodicarb 75 WP 625-1000 g.
4. Avoid using synthetic pyrethroids as they cause resurgence of sucking pests.

The correct answer is (a) - 3, (b) - 4, (c) - 1, (d) - 2.

Key Points

• Pyrethrins
  • They are a class of organic compounds.
  • It is normally derived from Chrysanthemum cinerariifolium, which targets the nervous systems of insects.
  • Pyrethrin occurs in chrysanthemum flowers naturally.
  • It is often considered an organic insecticide when it is not combined with piperonyl butoxide.
• Organo phosphates
  • They are a class of organophosphorus compounds with the general structure O=P (O double bond P).
  • It is considered an ester of phosphoric acid.
  • They are commonly used as flame retardants, plasticizers and additives to engine oil.
  • It is also used in industries such as textiles and furniture.
• Pheromones
  • It is an excreted chemical factor that triggers a social response in members of the same species.
  • They are chemicals that act like hormones outside the body of the secreting individual.
  • There are many types of pheromones, such as
    • alarm pheromones
    • food trail pheromones
    • sex pheromones
• Juvenile Hormones
  • They are a group of acyclic sesquiterpenoids.
  • It regulates many aspects of insect physiology.
  • Vincent Wigglesworth discovered Juvenile Hormones.
  • These hormones regulate development, reproduction, diapause, and polyphenisms.
  • Juvenile Hormones were formerly called neotenin.
  • These hormones are secreted by a pair of endocrine glands behind the brain known as corpora allata.

Additional Information

First Generation Pesticides	Pyrethrins
Second Generation Pesticides	Organo phosphates
Third Generation Pesticides	Pheromones
Fourth Generation Pesticides	Juvenile Hormones

Paraquat is a non-selective contact herbicide. It kills a wide a range of seasonal grasses and broad-leaved weeds and the tips of established perennial weeds.

Alachlor is a selective systematic herbicide. It is an odourless, white solid. It is used to control annual grasses and broadleaf weeds in crops.

Atrazine is a selective herbicide. It is used pre- and post-emergence. It is used in broadleaf weeds in crops such as maize (corn) and sugarcane and on turfs.

Butachlor (Machete) is a selective pre-emergence herbicide. It is used in seedbed and transplanted rice for control of Echinochloa spp. and most other annual weeds.