Pests of Maize by KasunDT

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Faculty of Agriculture
Rajarata University of Sri Lanka
                                   Kasun Hettige
                     Zea mays
•Maize is used both for human as well as animal
•Maize, commonly known as corn, is a cereal grain
•It belongs to the grass family
•There are many pests & diseases imposes to the
maize cultivation.
•In here, we discuss about the common pests &
diseases for the maize cultivation.

                       Kasun Hettige
Pests can be divided into 2 categories according to
the damaging nature;
•Pests affecting the plant
Ex- Maize stem borer
•Pests affecting the grain
Ex- Corn earworm

In here, talk about
   •Life cycle
   •Damage &
   •Management of pests
                          Kasun Hettige
Diseases can be divided into 4 categories according
to causative agents;
•Bacterial Diseases - Bacterial leaf blight and stalk rot
•Fungal Diseases – Rusts & Smut
•Nematodes, Parasitic – Lesions, False root-knot
•Virus Diseases - Maize wallaby ear

In here, talk about
   •Symptoms &
   •Control methods of diseases

                          Kasun Hettige

Maize stem borers
White Grubs
Corn leaf aphids
Red Hairy Caterpillars

                    Kasun Hettige
             Maize stem borer
                 Chilo partellus

Order : Lepidoptera
Family : Pyralidae

                      Kasun Hettige
                Maize stem borer
Life cycle and description
Adult stage:
•Adult moths are white to straw colored and are about
20mm in length.
•Moths have a large mouthpart similar to a snout.
•Moths are nocturnal, hiding in vegetation during
Egg stage:
• Fresh eggs are cream in color and oval in shape
• Eggs are deposited on the upper leaf surface in
•As eggs mature they develop three parallel, reddish-
orange rows known as the ‘red bar stage’.
•Eggs hatch in 3 to 5 days. Hettige
Larval stage:
•When larvae first emerge they are reddish in color
•Change to dull white with prominent brown and black
spots on each body segment.
•Immature larvae feed in the whorl while mature larvae
bore into the stem.
 Pupal stage:
•Pupae are dark brown in color and about 25mm in
•Generally occur at the last site of feeding, typically in
the lower third of the stem.
• Adults emerge in 7 to 10 days.
                         Kasun Hettige
Kasun Hettige
Nature of damage
•Leaves damaged by feeding
•Growing point damaged, resulting in dead heart
•Stems bored
•On the young plants there are rows of oval
perforations in the unfolding whorl.
•Dead heart

                      Kasun Hettige
Factors favoring development
•Mild, cool seasons
•Continuous host presence
•Zero-till agriculture
•Lack of natural predators
Mechanism of damage:
•Destruction of the growing point in the whorl leads to
dead heart and yield loss.
•Tunneling and girdling of the stem near ground level
prone to lodging.
When damage is important:
•Second and third generations are generally most
•Damage is severe if high infestation results in severe crop
                          Kasun Hettige
Cultural control
•Early planting can help avoid peak periods.
•Planting early maturing varieties also reduces the number of
pest generations per crop.
•Harvesting early can reduce yield loss due to lodging.
•Management of infected stalks left in the ground
Biological control
Natural parasitoids - Trichogramma wasp species that
parasitize eggs.
Chemical control
Chemicals can be applied either as a spray or in granular
Host resistance – various Hybrids

                           Kasun Hettige
                 White Grubs
Phyllophaga spp. and Cyclocephala spp. (annual white grubs)

Order : Coleoptera
Family : Carabidae

                          Kasun Hettige
                        White grubs
Life cycle and description

Adult stage:
•Adult beetles are pale yellow to dark brown
•Legs are dark brown

 Egg stage:
•Freshly laid eggs are oval, white
•Mature eggs are brownish-black
•Eggs are deposited singly in the soil surface
•Hatch in 1-2 weeks
                             Kasun Hettige
Larval stage:
Larvae are creamy white and C-shaped
Mature larvae appear slightly swollen and semi-transparent.
Larvae have prominent brown heads
Larvae undergo three instars stages
Feed on roots of crops & the organic matter in the soil

Pupal stage:
Pupae are soft and white to yellowish in early stages
Gradually becoming brown
Pupal development takes 30 to 40 days.

                          Kasun Hettige
                    Damage to plants
Root damage, resulting in wilting of seedlings, poor
plant growth, lodging, or seedling death
•Wilting seedlings.
•Poor crop stands.
•Tilted, curved, or lodged plants.
•Uneven growth.
•Dead heart.
Factors favoring insects / pest development
•Shallow, matted root systems.
•Soft, well-drained, and slightly acidic soil.
•Crops following pasture.
•Zero-tillage agriculture.   Kasun Hettige
•No effective treatment is available if a grub problem
is identified after corn emergence
•Soil insecticides such as Aztec,Capture,Lorsban
•Plowing destroys many larvae, pupae, and adults in
the soil by exposes the insects to predators
Biological Control
•Natural enemies include parasitic wasps
•Also, Cordyceps fungus infects the grubs

                        Kasun Hettige
Life cycle and description
Adult stage:
•Adult beetles are brownish to black with a hard, elongated
•Adults make a clicking noise when pressed on the dorsal side
•As a result they are often known as ‘click beetles’.

Egg stage:
•Eggs are tiny, round, and pearly white
•Deposited in moist soil in grassy areas
                             Kasun Hettige
Larval stage:
•Larvae are known as wireworms
•Initially wireworms are white & soft
•Mature larvae are shiny, smooth, deep yellow or brownish

Pupal stage:
Pupae are white, soft and located in the soil

                          Kasun Hettige
Damage to plants
•Boring and feeding of plant roots.
•Crop lodging.
•Injury to base of stem
•Patchy seedling emergence.
•Wilting and tillering of seedlings.
•Lodging of older plants.
Factors favoring insects / pest development
•Mild weather during the cold season
•Moist soil.
•Grassy or weedy fields attract adults to oviposition
•Poorly drained soils (for some species)
                             Kasun Hettige
•Thorough cultivation makes conditions unfavorable
to the egg laying adults
•Exposes all stages of the pest to weather and
natural enemies
•Apply beneficial nematodes to attack and destroy
pests in the soil
•Soil insecticides which are labeled for wireworm
•Seed treatment for small grains, in corn a granular
insecticide can be applied in a band or in-furrow
treatment at planting time.
                       Kasun Hettige
             Red Hairy Caterpillar
                   Amsacta mooreii
Life cycle and description
Egg stage:
•Creamy yellow in color
•Hatch in 3-4 days
Larval stage:
•Reddish brown color
•Black anterior and posterior bends
•7-8 instars

                           Kasun Hettige
Pupal stage:
•Takes place in the soil
Adult sage:
•Moth with white colored wings & black markings
•Fore wings have a red line on its anterior margin
•Hind wings have black dots
•Female is larger in size than male moth

•Larvae feed on the epidermal layer of leaf lamina
•Skeletonize the leaf surface

                            Kasun Hettige
Cultural Control
•Deep ploughing
•Early sowing
•Cropping patterns like Inter cropping & Crop rotation

Biological Control
•Spray A-NPV and Bacillus thuringiensis (Bt)
•Release of Bracon hebetor two times at 7-10 days interval
•Conserve dominant predators like Coccinella spp.
•Conserve the bio control population of spiders, praying
mantis, ants, dragon flies, lady bird beetles

                            Kasun Hettige
                 Corn leaf aphids
                  Rhopalasiphum maidis
Life cycle and description
•The small, greenish blue adults
•Females do not lay eggs but give birth to nymphs
•Skins give the colonies a whitish to blackish appearance

                            Kasun Hettige
Nature of damage
•Plants affected by this pest may become stunted
•show a yellowish mottling, and turn reddish as they mature
•Young plants that have been infected seldom produce ears
•Yellowish mottling, turning to red
•Reduced ear growth

                            Kasun Hettige
•Insecticide sprays will not prevent virus
transmission, but can reduce population levels
• There are no established thresholds for aphids on
field corn. Only on rare occasions do aphids reach
damaging populations
•Obtaining good coverage of the plant
•Oil and soap sprays are acceptable for use on
organically grown crops
•Biological Control –
parasite Lysiphlebus testaceipes
predators such as Lacewings, Lady beetles
                         Kasun Hettige
Kasun Hettige

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