UNIT VII

Question 1

It is a plant growing out of place

Answer 1

Weed

Question 2

Weeds can be classified into 4 categories, what are they?

Answer 2

1. Growth Habit
2. Lifespan
3. Body Texture
4. Habitat

Question 3

Name the three types of weeds based on growth habit.

Answer 3

1. Vines
2. Shrubs
3. Trees

Question 4

Name the three types of weeds based on lifespan.

Answer 4

1. Annuals
2. Biennials
3. Perennials

Question 5

Name the two types of weeds based on body texture.

Answer 5

1. Woody
2. Herbaceous

Question 6

Name the three types of weeds based on habitat.

Answer 6

1. Terrestrial
2. Epiphytic
3. Aquatic

Question 7

Classification of weeds based on gross morphology.

Answer 7

1. Grasses
2. Sedges
3. Broadleaf

Question 8

What families do grasses belong?

Answer 8

1. Graminaceae
2. Poaceae

Question 9

To which family do sedges belong?

Answer 9

Cyperaceae

Question 10

To what families do broadleaves belong?

Answer 10

1. Monocotyledonae
2. Dicotyledonae

Question 11

They are weeds, which are highly competitive and persistent; they reduce crop yields even at low densities and are difficult to control.

Answer 11

Noxious Weeds

Question 12

These type of weeds have fully expanded leaves, the leaves have netted venation.

Answer 12

Broadleaves

Question 13

These weeds bear a close resemblance to the grasses and can be distinguished by a thin triangular stem. They have an absence of nodes and internodes, ligules, the fusion of leaf forming a tube around the stem.
Perennial versions of these weeds have underground tubers or rhizomes.

Answer 13

Sedges

Question 14

These weeds range from small, twisted, erect or creeping annuals or perennials. Stems are called culms and with well-defined nodes and internodes, while the leaves are alternately in two rows from the nodes.

Answer 14

Grasses

Question 15

What are the 3 types of aquatic weeds?

Answer 15

1. Emergent
2. Floating
3. Submerged

Question 16

What type of aquatic weed has the upper portion is above water but roots are anchored to the ground.

Answer 16

Emergent

Question 17

What type of aquatic weed has all parts are under water?

Answer 17

Submerged

Question 18

What type of aquatic weed has the upper portion is above water but roots are not anchored to the ground

Answer 18

Floating

Question 19

It is a mechanism through which a species survives unfavorable conditions including control operations. It refers to the rest period of the seed.

Answer 19

Seed Dormancy

Question 20

What are the mechanisms of dormancy?

Answer 20

1. Physical/Structural Mechanism
2. Physiological Mechanism

Question 21

Which mechanism of weed seed dormancy refers to the impermeability of the tissue surrounding the seed or embryo to water and/or oxygen.

Answer 21

Physical/Structural Mechanism

Question 22

This type of mechanism of weed seed dormancy can be caused by an immature embryo or by the the presence of inhibitors?

Answer 22

Physiological Mechanism

Question 23

It is the lapse of time required for the seed to overcome its physiological barrier for germination.

Answer 23

After ripening

Question 24

What mechanism in the hilum can also control limitation of water
imbibitions in hard seeds.

Answer 24

A hygroscopically activated valve

Question 25

This dormancy in weed seeds is acquired as the seed or organ develops or matures.

Answer 25

Primary, natural, or innate seed dormancy

Question 26

This dormancy in weed seeds is due to unfavorable conditions.

Answer 26

Secondary or Enforced Dormancy

Question 27

It is a method of breaking seed dormancy wherein the seeds are exposed to a lower temperature.

Answer 27

Stratification

Question 28

Give the 3 methods of Weed Control

Answer 28

1. Mechanical Weed Control 2. Chemical Weed Control 3. Biological Weed Control

Question 29

Weeds are controlled using a rotating hoe (rotary or conical weeder) to cultivate, uproot and bury emerging young weeds between rows of rice plants.

Answer 29

Mechanical weeding

Question 30

Why do we need to control weeds?

Answer 30

* prevent yield loss * maintain quality & market price of produce * prevent build-up of weed seeds in soil * prevent weeds that attract rodents, insects, and diseases * prevent clogging of irrigation channels * reduce time and cost in land preparation and weeding operations

Question 31

This type of weed control uses chemicals called herbicides to kill certain plants or inhibit their growth.

Answer 31

Chemical Weed Control

Question 32

It is the resumption of growth.

Answer 32

Germination

Question 33

How many stages of germination are present? Please enumerate.

Answer 33

1. Imbibitions 2. Period of rapid metabolic activity 3. Emergence of root 4. Emergence of shoot 5. Period of independent growth

Question 34

This phase is purely a physical process. It involves the absorption of water by starch and can take place in living and dead seeds.

Answer 34

Imbibitions 1

Question 35

This phase is physiological and water is absorbed by the embryo. It marks the initiation and progress of starch hydrolysis

Answer 35

Imbibitions 2

Question 36

During this period, cell division and cell elongation proceed at a fast rate supported by a rapid synthesis of materials.

Answer 36

Period of Rapid metabolic activity

Question 37

What are the factors affecting the Growth of Weeds?

Answer 37

1. Light 2. O2 3. Temperature 4. Moisture 5. Carbon Dioxide

Question 38

What are the major factors influencing Flowering and Seed Production?

Answer 38

1. Photoperiod/Daylength 2. Vegetative Growth 3. Temperature 4. Growth regulators

Question 39

This determines the spread of the weed. Adaptive structures and proper habitat as well as activities of man contribute to it.

Answer 39

Dispersal of Weed Propagule

Question 40

It is the term used to refer to the structure, usually single-seeded together with accessory parts, that is dispersed or separated from the mother plant and whose function is to perpetuate its kind in other areas.

Answer 40

Dispersal Unit

Question 41

What are the agents of weed dispersal?

Answer 41

1. Man 2. Animals 3. Wind 4. Water

Question 42

In ancient times, the Chinese discovered that increasing ant populations in a citrus groves helped decrease destructive populations of what insect pests?

Answer 42

1. Large Boring beetles 2. Caterpillars

Question 43

These insects feed directly on the weed roots causing injury which allows bacteria and fungi to penetrate.

Answer 43

Beneficial Nematodes and Insects

Question 44

What is the term used for insects, pathogen etc. and other animals that are used to control weeds?

Answer 44

Bioagent

Question 45

This weed control method can reduce weeds but not totally eradicate the entire weed population.

Answer 45

Biological control

Question 46

What are the 2 methods used in Biological Control of Weeds?

Answer 46

1. Augmentation of Natural Enemies 2. Biological Herbicides

Question 47

This method in Biological Weed Control includes the periodic release and/or distribution of natural enemies.

Answer 47

Augmentation of Natural Enemies

Question 48

A new approach to biocontrol of weeds has recently been pioneered in Arkansas with the application of a spore suspension of an endemic fungus.

Answer 48

Biological Herbicides