Common Pests & Diseases in Maize

1. Common Pests & Diseases in Maize

2. MaizeZea mays Maize is used both for human as well as animal consumption 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.

3. Pests 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

4. Diseases 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

5. PESTS Maize stem borers White Grubs Wire-worms Corn leaf aphids Red Hairy Caterpillars DISEASES Stalk & Cob rots Blights Rusts Smuts Wallaby ear Virus

6. Maize stem borerChilopartellus Order : Lepidoptera Family : Pyralidae

7. 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 daylight.  Egg stage:  Fresh eggs are cream in color and oval in shape Eggs are deposited on the upper leaf surface in clusters As eggs mature they develop three parallel, reddish-orange rows known as the ‘red bar stage’.  Eggs hatch in 3 to 5 days.

8. 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 length.  Generally occur at the last site of feeding, typically in the lower third of the stem.  Adults emerge in 7 to 10 days.

10. Nature of damage Leaves damaged by feeding Growing point damaged, resulting in dead heart Stems bored  Signs On the young plants there are rows of oval perforations in the unfolding whorl. Dead heart Lodging 

11. Factors favoring development Mild, cool seasons Continuous host presence Zero-till agriculture Lack of natural predators Damage 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 damaging.  Damage is severe if high infestation results in severe crop lodging. 

12. Management 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 - Trichogrammawasp species that parasitize eggs.  Chemical control Chemicals can be applied either as a spray or in granular form.  Host resistance – various Hybrids

13. White GrubsPhyllophaga spp. and Cyclocephala spp. (annual white grubs) Order : Coleoptera Family : Carabidae

14. 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

15. 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.

16. Damage to plants Root damage, resulting in wilting of seedlings, poor plant growth, lodging, or seedling death Signs 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.

17. Management 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

18. Wire-worms Life cycle and description Adult stage: Adult beetles are brownish to black with a hard, elongated shell 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

19. 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

20. Damage to plants Boring and feeding of plant roots. Crop lodging. Injury to base of stem Signs 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)

21. Management 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 control Seed treatment for small grains, in corn a granular insecticide can be applied in a band or in-furrow treatment at planting time.

22. Red Hairy CaterpillarAmsacta 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

23. 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 Damage Larvae feed on the epidermal layer of leaf lamina Skeletonize the leaf surface

24. Management Cultural Control Deep ploughing Early sowing Cropping patterns like Inter cropping & Crop rotation Biological Control Spray A-NPV and Bacillus thuringiensis (Bt) Release of Braconhebetor 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

25. Corn leaf aphidsRhopalasiphum 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

26. 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 Signs Yellowish mottling, turning to red Reduced ear growth

27. Management 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 Lysiphlebustestaceipes predators such as Lacewings, Lady beetles

28. Maize diseases Stalk & Cob rots Blights Rusts Smuts Wallaby ear Virus

29. Stalk and cob rots • Fusarium stalk rot (Fusariumverticillioides[Gibberellafujikuroi] and other Fusarium species) • Fusarium cob rot or ear rot (Fusariumverticillioidesand other Fusariumspecies) • Gibberella stalk rot (Gibberellazeae; Fusariumgraminearum) • Gibberella cob rot, ear rot or pink ear rot (Gibberellazeae; Fusariumgraminearum) • Diplodia cob rot or ear rot (several Diplodia species)

30. Gibberella ear rot

31. Fusarium stalk rot (Fusarium verticillioides [Gibberella fujikuroi] and other Fusarium species) it tends to be more severe in warm, dry regions. • Infected seedlings are usually stunted, and have pale green or purple leaves and poor roots. • . The discoloration may also be seen on the surface of the stalks near nodes. Stalks are weak and lodge easily.

32. How to Control? • Good agricultural practices, including crop rotation, correct plant densities and the minimisation of stress, assist in reducing fusarium stalk rot. • Use resistant hybrids to manage this disease.

33. Fusarium cob rot or ear rot (Fusarium verticillioides and other Fusarium species) • Fusarium cob rot is favoured by warm, dry weather at or after flowering • Individual or groups of infected kernels are scattered at random on the cobs but, in severe cases, the entire cob can be affected. • Whitish pink-lavender fungal growth occurs on and between the kernels, often at the tip of the cob as the result of insect damage

34. How to Control? • The practices outlined above for fusarium stalk rot, as well as the management of insect pests and proper storage of kernels, reduce the risks of mycotoxin contamination. • Use resistant hybrids where available

35. Gibberella stalk rot (Gibberella zeae; Fusarium graminearum) • This fungal disease is favoured by moist conditions. The surfaces of infected stalks are often reddish-brown, particularly around the nodes, and the tissues internally are red-pink. Stalks are weak and break easily, resulting in lodging and plant death. Later in the season, small, round, bluish-black fruiting bodies may be found around the nodes of dead stalks

36. How to Control? • Use crop rotation (avoiding maize-winter cereal rotations), good agronomic practices to minimise stress, and/or resistant maize hybrids to combat this disease

37. Gibberella cob rot, ear rot or pink ear rot (Gibberella zeae; Fusarium graminearum) • Gibberella cob rot is favoured by cool, moist conditions at flowering The most common symptom is a reddish-pink or whitish-pink fungal growth that appears at the tip of the cob and grows down. Husks tend to bind to the kernels and there may be black fruiting bodies on external husk leaves. Infection occurs from windborne spores, which grow down the silks at flowering.

38. How to Control? • The use of good agronomic practices, resistant hybrids, prompt harvesting and proper storage minimise the risk.

39. Diplodia cob rot or ear rot (several Diplodia species) • Most of the species that cause diplodia cob rot are also capable of causing seedling death, stalk rot, and/or leaf spot, though cob rot is the most significant disease. • Wet weather favours infection of cobs and leaves. • If infection occurs after flowering, the husks covering the cobs are bleached. Cobs are usually shrunken, lighter than normal and covered in a white-grey fungal growth.

40. How to Control? • The only known management options to hasten residue breakdown are crop rotation and agronomic practices.

41. Blights • Turcica leaf blight or turcicum leaf blight (Exserohilum turcicum) • Maydis leaf blight (Bipolaris maydis)

42. Turcica leaf blight or turcicum leaf blight (Exserohilumturcicum)

43. It is favoured by warm weather when leaves are wet from dew or rainfall for extended periods. • Long, spindle-shaped, greyish-green, water-soaked spots develop on leaves and later turn light purplish-brown or grey. After flowering, the disease can develop rapidly, resulting in blighting of infected leaves.

44. How to Control? • Use less susceptible hybrids and do not practise maize monoculture. Eliminate volunteer maize. • Early plant can reduce the risk of this disease. • Control with fungicides is not economical.

45. Maydis leaf blight (Bipolaris maydis)

46. Infection and disease development is favoured by warm, showery, humid weather • Symptoms can vary depending on the hybrid. • Spots range from tan, elongated spots up to 40 mm long and 6 mm wide with parallel sides to tan, spindle-shaped or elliptical spots up to 25 mm long and 12 mm wide. • Spots often have dark red-brown margins and/or a narrow yellow halo. This fungus can be seedborne and cause seedling rot.

47. How to Control? • Plant resistant hybrids to combat this disease.

48. Rusts • Common rust (Puccinia sorghi) • Polysora rust, or tropical rust, or southern corn rust (Puccinia polysora)

49. Common rust (Pucciniasorghi)

50. The disease is recognised by the abundant oval-elongate, red-brown pustules up to 2 mm long, which erupt through both leaf surfaces in scattered groups. • This distinguishes common rust from polysora rust, which has little development of rust pustules on the lower leaf surface. • The pustules contain numerous powdery spores that can be spread long distances by wind.