AGRI 42 LAB

Question 1

Difference between sign and symptoms & example

Answer 1

Symptom:leaf spot, yellowing, wilting, stunting

Sign: sclerotia, mycelia, bacterial ooze, fruiting bodies

Question 2

Explain the disease triangle

Answer 2

Check the module

Question 3

Disease of Corn (fungi)
with scientific name

Answer 3

Leaf blight-Bipolaris maydis
Leaf rust-Puccinia polysora
Downy Mildew-Peronosclerospora philippinensis
Sheath blight-Rhizoctonia solani
Corn smut-Ustilagomaydis
Ear rot-Diplodia maydis or Diplodia macrospora

Question 4

DISEASES OF CORN (Bacteria)

Answer 4

Bacterial stalk rot-Erwinia carotovora

Question 5

DISEASES OF CORN (Virus)

Answer 5

Corn mosaic-Maize mosaic virus

Question 6

Weed classfications and give examples

Answer 6

oBased on morphology- broadleaf, sedges, grass
oBased on habitat- Dryland & Wetland
oBased on life cycle- Annual & Perrenial

Question 7

MAJOR WEEDS ASSOCIATED WITH CORN
(Grasses)

Answer 7

Dactylocteniumaegyptium: annual
~crowfoot grass, damongbalang, krus-krusan, sabong-sabongan
-Eleusine indica: annual
~goosegrass,bakis-bakisan, kabit-kabit, sabong-sabongan
Paspalidiumflavidum: annual
~paspalidium
Rottboelliacochinchinensis: annual
~itch grass, aguingay, sagisi, marapagay
Imperata cylindrica: perennial
~cogon,kogon

Question 8

MAJOR WEEDS ASSOCIATED WITH CORN
(Sedge)

Answer 8

Cyperus rotundus: perennial
~purple nutsedge,mutha

Question 9

MAJOR WEEDS ASSOCIATED WITH CORN
(Broadleaves)

Answer 9

Ageratum conyzoides: annual
~tropic ageratum, bulak-manok, damong mabaho
Celosia argentea: annual
~celosia

Cleome rutidosperma: annual
~spindletop, apoy-apoyan, sili-silihan

Euphorbia hirta: annual
~garden spurge, tawa-tawa, gatas-gatasan, boto-botonis, luhang birhen

Heliotropiumindicum: annual
~indianheliotrope, buntot-leon, higad-higaran, trompa elepante

Ipomoea triloba: annual
~three-lobed morning glory, kamo-kamotihan, kamuti-kamutihan, kupit-kupit

Portulaca oleracea: annual
~common purslane, olasiman

Synedrellanodiflora: annual
~synedrella,fantakuen, kalintuhod

Amaranthus spinosus: annual
~spiny amaranth, kulitis, bayambang, uray

Mimosa pudica: perennial
~sensitive plant,makahiya, torog-torog, huya-huya, babain, malamarine

Question 10

CLASSIFICATION OF INSECTS BASED ON MOUTHPARTS

Answer 10

oSucking
oChewing
oBoring

Question 11

Insect damage results to curling, necrosis, drying of tissues and sometimes death of shoots & stems

Answer 11

Sucking Insects

Question 12

Damages: Folding of leaves, oinholes, huge holes, defoliation, feeding on the undersurface of the leaves

Answer 12

Chewing insects

Question 13

Many tassels, silks and ears drop prematurely during severe infestations
-Stems heavily affected dry up, leading to death of the crop

Answer 13

Boring insects

Question 14

Damages: stunting; pre-mature dying of leaf, tassel or ear; sooty molds;
may transmit virus
Corn stages affected: early whorl to silking

Answer 14

Rhopalosiphummaidis
(Corn aphid)

Question 15

Damages: loss of plant vigor; formation of honeydew droplets on leaves; may transmit virus; drying up
Destructive stage: nymph
Corn stages affected: seedling to late whorl to reproductive (if infestation is heavy)

Answer 15

Peregrinus maidis
(Corn planthopper)

Question 16

Damages: Loss of plant vigor; stunting; may transmit virus
Destructive stage: nymph and adult
Corn stages affected: seedling to late whorl to reproductive (if infestation is heavy)

Answer 16

Proutistamoesta(Common grass derbid)

Question 17

Damages: leaf feeding lesions; curling & breaking of young leaves; stunting; drying & rotting of central shoots
Destructive stage: larvae
Corn stages affected: emergence to early whorl to

Answer 17

Atherigonaoryzae(Corn seedling maggot)

Question 18

Damages: shotholes; cut silks; holes at opening of corn ears; damaged emerging tassels
Destructive stage: larvae
Corn stages affected: early whorl to hard dough

Answer 18

Helicoverpaarmigera(Corn earworm)

Question 19

Damages: shredding of leaves due to feeding of soft tissues, but not veins & midribs; cut corn silk during flowering
Destructive stage: larvae
Corn stages affected: One leaf stage to silking

Answer 19

Chrysodeixiseriosoma[=chalcites] (Corn semilooper)

Question 20

Damages: scraping of leaf tissues; cut stem, leaves, including veins; defoliated plants
Destructive stage: larvae
Corn stages affected: Emergence to early whorl

Answer 20

Spodoptera litura(Common cutworm)

Question 21

Damages: scraping of leaf tissues; cut stem, leaves, including veins; defoliated plants
Destructive stage: larvae
Corn stages affected: Emergence to early whorl

Answer 21

Spodoptera frugiperda(Fall army worm)

Question 22

Damages: stunting; root eaten up causing wilting to death
Destructive stage: larvae
Corn stages affected: emergence to early whorl to reproductive (if infestation is heavy)

Answer 22

Leucopholisirrorata(June beetle, toy beetle, white grubs)

Question 23

Damages: stunting; root pruning; irregular feeding on your leaves; wilting to death
Destructive stage: nymph and adult
Corn stages affected: emergence to whorl

Answer 23

Gryllus bimaculatus(Common black cricket)

Question 24

Ostrinia furnacalis (Asiatic corn borer)
Damages: pin-hole to match-head size lesions on leaves; broken stalks; pre-mature drying of whole plant or ear
Destructive stage: larvae
Corn stages affected: seedling to maturity

Question 25

๏living organisms
๏beneficial
๏found in nature
๏are able to:
✓kill
✓weaken
✓reduce reproductive potential

Answer 25

Natural Enemies…

Question 26

Natural enemies include:

Answer 26

✓predators
✓parasitoids
✓microbial agents

Question 27

๏insect pathogens
๏natural enemies of plant pathogens

Answer 27

MICROBIAL AGENTS