Important Maize diseases are given below:-
1. Maize Downy mildew / Crazy top: Peranosclerospora sorghi
Symptoms:
- Chlorotic streaks appear on the leaf and white fungus growth is seen on both the surfaces of leaf.
- Affected plants become stunted and exhibit bushy appearance due to shortening of internodes.
- Sometimes leafy growths in the tassel and proliferation of axillary buds on the stalk of the tassel are noticed.
Favourable Conditions :
- Low temperature (21-33˚C);High relative humidity (90 per cent) and drizzling
- Young plants are highly susceptible.
Management:
- Rogue out affected plants.
- Use resistant TNAU maize hybrid COH-6
- Soil application of P. fluorescens (or) T. viride @ 2.5 kg / ha + 50 kg of well decomposed FYM (mix 10 days before application) or sand at 30 days after sowing
- Spray Metalaxyl @ 1000g(or) Mancozeb 2g/lit at 20 days after sowing.
2.Maize Leaf Blight: Exserohilum turcicum & Helminthosporium maydis
a.Turcicum Leaf Blight Symptoms:
- The fungus affects the crop at young stage.
- Early symptoms are oval, water-soaked spots on leaves.
- Mature symptoms are characteristic cigar shaped lesions that are 3 to 15cm long.
- Lesions are elliptical and tan in color, developing distinct dark areas as they mature that are associated with fungal sporulation.
- Lesions typically first appear on lower leaves, spreading to upper leaves and the ear sheaths as the crop matures.
- Under severe infection, lesions may coalesce, blighting the entire leaf.
b.Maydis Leaf Blight Symptoms:
- Small yellowish round or oval spots appear on the leaves.
- These spots enlarge, become elliptical and the center becomes straw coloured with a reddish brown margin.
- Conidia and conidiophores are formed in the center.
Favourable Conditions :
- Optimum temperature for the germination of conidia is 8 to 27˚C provided with free water on the leaf; Infection takes place early in the wet season.
Management:
- Rogue out affected plants.
- Resistant cultivers – Deccan, VL 42, Prabhat, KH-5901, PRO-324, PRO-339, ICI-701, F- 7013, F-7012, PEMH 1, PEMH 2, PEMH 3, Paras, Sartaj, Deccan 109, COH-6.
- Soil application of P. fluorescens (or) T. viride @ 2.5 kg / ha + 50 kg of well decomposed FYM (mix 10 days before application) or sand at 30 days after sowing
- Spray Matalaxyl 1000 g / Mancozeb 2 g/liter at 10 days interval after first appearance of the disease.
3.Maize Charcoal rot: Macrophomina phaseolina
Symptoms:
- The pathogen affects the plant mostly after flowering and the disease is named as Post Flowering Stalk Rot (PFSR).
- The stalk of the infected plants can be recognized by greyish streak.
- The pith becomes shredded and greyish black minute sclerotia develop on the vascular bundles.
- Shredding of the interior of the stalk often causes stalks to break in the region of the crown.
- The crown region of the infected plant becomes dark in colour.
- Shredding of root bark and disintegration of root system are the common features.
- High temperature and low soil moisture (drought) favours the disease.
Management:
- Follow crop rotation
- Avoidance of water stress at flowering time reduced disease incidence
- Avoid nutrient stress.
- Apply potash @ 80 kg/ha in endemic areas
- Soil application of P. fluorescens (or) T. viride @ 2.5 kg / ha + 50 kg of well decomposed FYM (mix 10 days before application) or sand at 30 days after sowing.
4.Corn rust: Puccinia sorghi
Symptoms:
- On both the surfaces of the leaf, brown pustules are seen.
- These represent the uredosori of the fungus.
- The alternate host is Oxalis corniunlata.
- Cool temperature and high relative humidity favours the disease.
Favourable condition:
- Optimum temperature for the germination of conidia is 10 to 12˚C
Management:
- Destroy altrenate plant host
- Soil application of P. fluorescens (or) T. viride @ 2.5 kg / ha + 50 kg of well decomposed FYM (mix 10 days before application) or sand at 30 days after sowing
- Spray Mancozeb 1.25 kg/ha.
Source-
- TamilNadu Agritech Portal
