Class 11 Floriculturist Chapter 6 Insect Pests, Diseases and Weed Management

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Class 11 Floriculturist Chapter 6 Insect Pests, Diseases and Weed Management

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Also, you can read the NCERT book online in these sections Solutions by Expert Teachers as per Central Board of Secondary Education (CBSE) Book guidelines. AHSEC Class 11 Floriculturist Textual Solutions are part of All Subject Solutions. Here we have given AHSEC Class 11 Floriculturist Textbook Solutions English Medium for All Chapters, You can practice these here.

Insect Pests, Diseases and Weed Management

Chapter: 6

A. Fill in the Blanks: 

1. Tapping of branch on white sheet of paper may detect _______________  and ______________ incidence. 

Ans: Mites, thrips.

2. Eradicating and treating sources of inocula in the field is also an important  ______________ measure. 

Ans: Preventive.

3. All insects belong to the class ______________. 

Ans: Insecta.

4. Insect body comprises three main segments, i.e., ______________, _____________ and _______________. 

Ans: Head, thorax and abdomen.

5. Greek word pteron means ______________. 

Ans: Wing.

6. Termite belongs to order _______________. 

Ans: Isoptera.

7. Larvae of caterpillar belong to order ________________. 

Ans: Lepidoptera. 

B. Multiple Choice Questions:

1. The damaging stage of insects belonging to dipteral family is _____________. 

(a) Larva. 

(b) Adults and maggots. 

(c) Caterpillar. 

(d) Grub.

Ans: (b) Adults and maggots.

2. Caterpillar has sucking-type of mouth parts, which are known as _____________. 

(a) Homoptera. 

(b) Halter.

(c) Balancer. 

(d) Haustellum.

Ans: (d) Haustellum.

3. The irregular tunnel-like structure over the leaf surface is observed due to the feeding of _____________.

(a) Larva.

(b) Maggots.

(c) Caterpillar.

(d) Grub.

Ans: (b) Maggots.

4. Abnormal growth or gall-like structure on the leaves are the damaging sign of _____________. 

(a) Larva. 

(b) Maggots.

(c) Mites.

(d) Grub.

Ans: (c) Mites.

C. Subjective Questions:

1. What is insect pest control?

Ans: A thorough knowledge of morphology, nature of damage, vulnerable stage of pest, damaging stage, pre-disposing factors, susceptible stages of host, natural enemies and predators help in preventing and controlling them effectively. All insects belong to the class Insecta. Their body is segmented and mostly comprises three main segments, i.e., head, thorax and abdomen. Insects have two pairs of wings and three pairs of legs. According to the structure of the wing (pteron), they are classified into different orders, such as Coleoptera, Diptera, Hemiptera, Hymenoptera, Isoptera, Lepidoptera and Orthoptera, etc. All these insects belonging to different orders may have different life cycles with different damaging stages and nature of damage. With a view to accomplish better pest management, all these factors are important, but the most important is how (nature of damage) and when (damaging stage) they attack the host.

2. How are insect pests controlled traditionally?

Ans: Traditional control of insect pests is mainly done through cultural methods, which are environment-friendly and do not involve chemical use. 

These methods include:

(i) Tillage: Ploughing or flooding during summer season exposes hibernating stages of insect pests inside the soil. Stages, like eggs, larvae, pupae of some insects are found hidden deep inside the soil. These are exposed to their natural enemies and the hot Sun due to tillage operations.  

(ii) Clean cultivation: Weeds and bunds of the field are important foci for hibernating insect pests. Through cleaning of bunds and regular removing of weeds, pest population is minimised. Crop residues of previous crops must be destroyed.

(iii) Crop isolation: Crop of the same group or same families, if grown close by, increases the availability of host and this may increase the pest population. If the crop is isolated at a sufficient distance, the movement of pests from one field to another can be avoided, so their control becomes easier.

(iv) Altering sowing or planting time: This is a dodging strategy by which the host or its suitable stage is made unavailable for the pest, required for infestation.

(v) Crop rotation: Long crop rotation minimises the invasion of host-specific insect pests. 

(vi) Eradication of alternate hosts: Weeds or other plants harbouring insect pests in the absence of the major host, if these are removed, break the chain of host availability and control the pest population.

(vii) Planting trap crops: Trap crops of less economic value are planted before planting the main crop to attract insect pests towards it and the crop along with pest is destroyed completely before the insect reaches the reproductive phase.

(viii) Exclusion of infested plant or part: Removal and destruction of infested plants and their parts reduce population and foci of pest in the field.

3. Describe Integrated Pest Management.

Ans: Integrated Pest Management (IPM) is essential to deal with certain diseases, like wilts, and insect pests, such as green worms and spotted worms, by a number of approaches. The disease and insect pests, if not handled in time, can cause huge losses to the crop. Chemicals used against such pests not only have limitations but might have side effects on the plant. Frequent application of insufficient doses of such pesticide builds resistance within the organism. Excessive use has residual effect in the crop, which also becomes a major cause of pollution. Pesticides also inhibit pollinators and predators in the field, which results in reduction of yield.

IPM includes involvement of measures, such as cultural, physical, mechanical, chemical and biological methods against pests.

4. Write about the following nature of damages:

(i)  Chewing and cutting tissues of the host.

Ans: These insects have biting and chewing type of mouth parts and may cut, chew and bite the tissues of the host. Infestation of such insect pests is confirmed through this type of damages found on various parts of the host. Mostly larvae and in some cases, adults are responsible for such damages. 

Larvae of the Lepidoptera (caterpillars) and the Coleoptera (grubs) are well-known damaging stages that cause such type of damage. Maggots and immature stage flies feed on flowers of chrysanthemum and many other plants. Sunflower maggots infest the stem and cause collapse of the plant. Larvae of painted lady butterfly, yellow woolly bears, checker spot butterflies, diamondback moth, etc., cause such damage to ornamental crops severely.

(ii) Boring.

Ans: Infestation of these pests can be identified by the presence of holes and bores that they make in several plant parts. Beetles, weevils, grubs, caterpillars and maggots are well known that bore into the host and feed on internal tissues. Caterpillars of armyworm bore into flower buds and feed inside. Flowering crops, such as China aster, chrysanthemum, dahlia, delphinium, iris, phlox and salvia, etc., are attacked by  most of the borers. Burdock borer (moth), iris borer, stalk borer and European corn borer are common borers found in ornamentals.

(iii) Mining leaves.

Ans: Larvae (maggots) of certain leaf minors by mining get inserted between the upper and lower surface of the leaf. Irregular tunnel-like structure over the leaf surface is observed due to the feeding of inside tissues. Such infestation may be observed in ornamentals, such as chrysanthemum, dahlia, dianthus, salvia, verbena, etc. This can be identified by the creamy-yellow lines formed on the leaves due to tunneling. 

(iv) Galls or hypertrophied structure.

Ans: Sometimes, mites suck cell sap and produce abnormal growth of pimple-like structure on the leaves. Tiny wasps also sometimes produce galls on leaves, stems and twigs of roses and other plants. 

D.  Match the Columns:

 Ans:

A. Fill in the Blanks: 

1. An interaction between susceptible host and virulent pathogen in favourable environment is known as _______________. 

Ans: Disease.

2. An integrated approach used for avoiding and controlling the diseases is termed as _______________.

Ans: IDM.

3. Chemical or combination of chemicals found lethal to fungi and escapes the host from infection is called _______________. 

Ans: Fungicides.

4. Affectivity of fungicide when translocated to the whole system of plant irrespective of the place of application, is called ________________. 

Ans: Systemic fungicide.

5. Affectivity of the fungicide when restricted to the area of application is called ________________. 

Ans: Contact fungicide.

6. The mechanism of controlling the growth of microorganism through another microorganism is called _______________.

Ans: Antagonism.

B. Multiple Choice Questions: 

1. Disease occurs only when there is _______________. 

(a) Virulent pathogen.

(b) Susceptible host. 

(c) Favourable climate. 

(d) All of the above.

Ans: (d) All of the above.

2. Fungi which have antagonistic properties against many fungi are _______________. 

(a) Trichoderm aherzianum.

(b) Trichoderma viride. 

(c) Both (a) and (b). 

(d) None of the above.

Ans: (b) Trichoderma viride.

3. Neem seed oil can be used effectively against ________________. 

(a) Anthracnose. 

(b) Charcoal rot. 

(c) Both (a) and (b). 

(d) None of the above.

Ans: (c) Both (a) and (b). 

C. Subjective Questions:

1. Describe fungicides and their types.

Ans: Fungicides and Their Types:

Fungicides are the chemicals that control the fungal disease by killing or inhibiting the growth of the disease-causing fungus.

Types of Fungicides:

(i) Protective fungicide: These fungicides remain on the surface of the host and prevent the germination of fungal spores. These are also known as contact fungicides.

(ii) Curative fungicide: These fungicides stop or completely destroy the development of fungus after infection has taken place. These are also called systemic fungicides because they are absorbed by the plant and moved through tissues .

2. Describe different methods of fungicidal application.

Ans: Different methods of fungicidal application are:

(i) Soil drenching: In case of soil-borne infection of fungi (wilt, damping off, root rot) or nematodes (root-knot), fungicide or nematicide should be applied to the soil. Such fungicides are carbendazim, formaldehyde, etc. 

(ii)  Seed treatment: To avoid infection from the soil, as well as, from the seed, the easy way is seed treatment. Generally, seeds are treated at the rate of 2.0–2.5 g fungicide/kg of seed. Seed dressing drum or earthen  pitcher can be used for treating the seeds. Fungicides used are Carbandazim, Carboxin, Oxathin, etc.

(iii) Pasting to affected parts: In case of scorching Sun or in gummosis, the affected parts, such as stem, are pasted with Bordeaux paste.

(iv) Foliar application: Aerial parts affected by foliar diseases can be controlled through foliar sprays of fungicidal formulations. Specialised sprayers are available for treatment. Generally, fungicides are sprayed with compatible insecticides, so it reduces the cost of application. These fungicides are sulphur, copper oxychloride, Maneb, Zineb, Nabam, etc.

(v) Dip method: In this method, seedlings and cuttings are dipped before planting in the fungicidal solution for certain period to avoid infection, e.g., Benlate, Captafol, Carbendazim, Maneb, Sulphur, Zineb, etc.

3. Describe different cultural methods of disease control.

Ans: The different cultural methods of disease control are:

(i) Tillage: Soil-borne fungi, bacteria and nematodes, serving as sources of infection, perpetuate in the soil. When the soil is ploughed, they get exposed to high temperature of the Sun. This reduces their population or activity within the soil.

(ii) Field sanitation: Plant pathogen (fungi, bacteria, and virus) survives on previous crop residues and weeds in the field may serve as a major source of inoculums. Clean cultivation means removal of crop residues and keeping the bunds clean so that the pest population is minimised in the field. Plant disease can be controlled by regular destroying of the diseased plant or weeds, which disrupt the disease cycle, and thus, prove as an effective source of control. 

(iii) Crop rotation: The availability of susceptible hosts in every season or consecutive years increases the survival and persistence of diseases. Crop rotation with different crops or families breaks their persistence. Starvation of pests due to unavailability of susceptible hosts for a long time makes it difficult for pests to survive.

(iv) Resistant varieties: Resistant varieties of flower crops have provided one of the most successful approaches to control plant pathogens of many crops, especially those which cannot be controlled by any other means. Some cultivators are resistant to a particular disease and are inherently less damaged than other genetically related plants growing in the same area.

(v) Alteration in sowing time: Manipulation of sowing time and selection of early or late varieties also dodge pathogens. Certain diseases, like early blight, late blight, etc., are time-bound and require a particular stage of growth of the plant to infect. Unavailability of susceptible stages fails to infect.

(vi) Seed treatment: Most of the seed and soil-borne diseases, such as damping-off, wilt, rots, dieback, anthracnose, etc., attack the crop through seeds or soil. Seed treatment reduces the chances of infection.

(vii) Crop density: High density of crop favours incidence of many diseases. Infections can move easily from a diseased to a healthy plant in a dense field. It is, therefore, desirable to plant the crop at required spacing.

4. Describe bio-control of disease and antagonism.

Ans: This is the most common method adopted nowadays as a biological control against many soil-borne diseases. Fungi Trichoderma herzianum and T. viride, and bacterium Bacillus subtilis have antagonistic properties against many fungi causing wilt and rot. Extracts of some plants are also well-known for their fungicidal properties. These are being used since a long time as pesticides. The extracts may be applied as soil or seed treatment or as sprays.

D.  Match the columns:

Ans:

A. Fill in the Blanks:

1. Undesirable plant in the field that is responsible for economic losses to the human is called a _______________. 

Ans: Weed.

2. Weeds are harmful as these compete with the ______________ for nutrients, water, light and space. 

Ans: Main crop.

3. Blue grass and chick weed are commonly seen in _____________ soils. 

Ans: Nitrogen-rich soil.

4. Spurge pusley and knot weed show the presence of ______________ in soil. 

Ans: Nematode.

5. Young shoots of _______________ can be used against asthma and blood disorders.

Ans: Chick weeds.

B. Multiple Choice Questions:

1. Leguminous weeds are commonly seen on ________________. 

(a) Soil rich in nitrogen content. 

(b) Soil is poor in nitrogen content. 

(c) Soil rich in phosphorus. 

(d) Soil rich in calcium.

Ans: (b) Soil is poor in nitrogen content. 

2. Examples of weed that can be used as myco-herbicide ________________. 

(a) Phytophthora sp. 

(b) Colletotrichum sp. 

(c) Both (a) and (b). 

(d) None of the above.

Ans: (c) Both (a) and (b). 

3. Herbicides which are applied after weed emergence are called _______________. 

(a) Pre-emergence herbicides. 

(b) Post-emergence herbicides.

(c) Pre- planting herbicides. 

(d) None of the above.

Ans: (b) Post-emergence herbicides.

C. Subjective Questions:

1. What are weeds and their various types?

Ans: An undesirable plant in the field that is responsible for economic losses to the human is called weed. Weeds appear suddenly in the field without any planting or sowing. Weed propagules remain viable for a long time and survive in the field even under odd conditions.

Their various types are: 

(i) Annual weeds.

(ii) Biennial weeds.

(iii) Perennial weeds.

2. Describe pre-emergence and post-emergence herbicides.

Ans: Pre-emergence herbicides: These are applied to the soil immediately after sowing the seeds before crop emergence. These herbicides are of selective type, i.e., safest for the crop. Flumioxazin, Isoxaben, Napropamide, Oryzalin (Surflan), Oxadiazon, oxyfluorfen, Pendimethalin, Prodiamine and Trifluralin are included in this group. 

Post-emergence herbicides: These herbicides are applied when weeds and crops have emerged, usually two to three weeks after emergence. These are selective herbicides and used for a narrow range of weeds. Broad-leaved weeds can be controlled through herbicides containing phenoxy group, e.g., 2, 4-D. Non-selective herbicides are those containing Glufosinate, Diquat, Glyphosate and Pelargonic acid, and plant oils, such as eugenol. 

3. Describe selective and non-selective herbicides.

Ans: Selective herbicides: These herbicides are used against specific groups of weeds and do not prove harmful for other crops. Pendulum, Surflan, Treflan, etc., 2, 4, 5-T, 2, 4-D, etc. kill broad-leaved weeds but do not harm monocots, while Fusilade (fluazifop) controls monocot weeds and not broad-leaved plants.

Non-selective: These are the herbicides that prove lethal to almost all monocots and dicots that come in its contact, e.g., diquat, glyphosate.

4. What are the different methods of weed control?

Ans: The various methods of controlling weeds are as follows:

Mechanical and physical methods:

(i) Mowing the weed: Mowing consists of superficial trimming of succulent and herbaceous weeds. This inhibits the formation of seeds on weeds. Mowing is practised to keep the growth of weeds under check, specially in lawns. It should be followed by other methods of weed control, otherwise it spreads branching of perennials, and so low-growing weeds become a problem. 

(ii) Mulching the field: It is a practice of covering the open soil in between the rows and plants of the crop. The soil is covered by organic matter, crop residues, polythene or paper. Cover with mulch inhibits sunlight to the exposed areas between the crops. Due to darkness, the weeds are unable to germinate. 

(iii) Hoeing: This practice is effective in controlling weeds in row crops. It has been a widely used weeding tool for centuries. 

(iv) Hand weeding: It is effective against annual and biennial weeds. Hand weeding is done by pulling out weeds from the field with the help of a khurpi. This facilitates the loosening of soil and improves its drainage and aeration.  

D. Match the Columns:

Ans:

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