How to Identify and Treat Maize Diseases: Symptoms, Spread, and Control Management

Welcome to our blog on common maize diseases and their management! Maize, or corn, is a major crop worldwide but is susceptible to various damaging diseases. Maize (Zea mays L. ssp. mays) is a grain domesticated by indigenous peoples in Mesoamerica. It is grown in various environments in India and worldwide as a vegetable and starch. Maize cultivation in India can be divided into traditional and non-traditional areas, catering to commercial purposes, particularly for the poultry industry.

Understanding the causes, symptoms, spread, and effective control methods is crucial for successful maize cultivation. This article will provide concise and accessible information about these diseases, capturing your attention while delivering valuable insights. Let’s delve into maize disease management and safeguard your crop’s health and yield.

Major Common Damaging Disease of Maize/ Corn Crop

Gray Leaf Spot (GLS): Grayish-green lesions with dark borders appear on maize leaves, reducing photosynthetic efficiency and affecting yield.
Northern Leaf Blight (NLB): Elongated, cigar-shaped lesions with gray-green or tan centers develop on leaves, reducing plant vigor and yield loss.
Southern Rust: Orange to rusty-brown pustules form on leaves, reducing photosynthesis and causing premature leaf senescence.
Common Rust: Small, reddish-brown pustules appear on leaves, affecting plant health and grain quality.
Diplodia Ear Rot: Whitish mold covers maize kernels, reducing grain quality and causing mycotoxin contamination.
Fusarium Ear Rot: Pink or white fungal growth develops on maize ears, reducing kernel quality and mycotoxin contamination.
Stalk Rot: Maize stalks become weak and may collapse due to fungal infections, resulting in lodging and yield loss.
Goss’s Wilt: Dark-green to black “freckles” or “water-soaked” lesions with a bacterial ooze appear on leaves, reducing photosynthesis and yield.
Maize Dwarf Mosaic Virus (MDMV): Stunted growth, mosaic patterns, and yellowing of leaves occur due to viral infection, leading to reduced yield.
Maize Streak Virus (MSV): Infected plants show yellow streaks or mottling on leaves, reducing photosynthetic efficiency and overall yield.

How to Identify and Treat Maize Diseases

Maize Rust

Causes: Caused by the fungus Puccinia polysora.
Symptoms: Circular golden-yellow to brown raised structures (pustules) on leaves.
Spread: Favored by high temperatures (around 27°C) and humidity.
Control: The use of resistant varieties is the most feasible measure.

Maize Leaf Blights

Causes: Caused by the fungus Helminthosporium maydis.
Symptoms: Appearance of spots (lesions) on leaves, progressing upward.
Control: Fungicidal sprays like Zineb, Maneb, and Cuman can be used, but planting resistant varieties is the most effective method.

Curvularia Leaf Spot

Causes: Caused by the fungus Curvularia pallescens.
Symptoms: Small circular spots with grey centers and brown borders.
Control: Spraying with fungicides like Miltox and Copranol is possible but less economical. Planting-resistant varieties are recommended.

Brown Spot

Causes: Caused by the fungus Physoderma maydis.
Symptoms: Tiny yellowish spots on leaves turning brown.
Control: Well-planned crop rotation and use of resistant varieties.

Downy Mildew

Causes: Caused by the fungus Peronosderospora sorghii.
Symptoms: Chlorosis, stunted growth, deformed tassel, and ear.
Control: Plant resistant varieties, seed dressing with appropriate chemicals, rogue and destroy infected plants, and avoid late planting.

Maize Streak Virus (MSV)

Causes: Spread by leafhoppers belonging to the genus Cicadulina.
Symptoms: Chlorotic streaks along veins, stunted growth, poor cobs.
Control: Use streaks-resistant varieties, crop rotation, and avoid late planting.

Note: Proper disease control measures include using resistant varieties, timely fungicidal sprays, seed dressing, crop rotation, and eliminating infected plants. By implementing these preventive strategies, farmers can effectively manage and protect their maize crops from the damaging effects of these diseases.

Bacterial Stalk Rot Disease of Maize and Their Management

Bacterial Stalk Rot disease of maize, caused by Erwinia carotovora and Erwinia chrysanthemi, displays distinct symptoms. The lower internodes of the stalk become soft and water-soaked, often accompanied by a sweet fermenting odor. Wilting and leaf water loss occur, eventually causing affected plants to lodge or topple.

The ears and shank may also exhibit rot, hindering their development. Disease-resistant maize hybrids such as Ganga Safed-2 and DHM 103 are recommended to manage the disease as they have a lower incidence of disease. Additionally, it is crucial to avoid waterlogging and ensure proper drainage to prevent the disease’s spread.

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Black Bundle Disease and Late Wilt Disease of Maize and Their Management

Black Bundle Disease and Late Wilt Disease, caused by Cephalosporium maydis and Caphalosporium acremonium, respectively, can devastate maize crops. Infected plants exhibit wilting, starting from the top leaves, eventually drying and losing color. The stalks also lose their healthy green color, turning purple to dark brown in advanced stages. Splitting open diseased stalks reveals brown vascular bundles.

Affected plants produce ears with undeveloped, shrunken kernels, often resulting in significant crop loss. Farmers can employ control measures to manage these diseases, like using resistant varieties, practicing crop sanitation and rotations, preventing water stress during flowering, and applying seed treatment with Thiram or Captan. These strategies help protect maize crops and maintain optimal yields.

Charcoal-Rot Disease of Maize and Their Management

Charcoal-Rot Disease, caused by the organism Macrophomina phaseolina, displays distinct symptoms during maize plant maturity, typically after flowering. Affected plants experience premature ripening, with lower internodes turning straw-colored and severe disintegration of the pith. Stalks may split longitudinally into fibrous masses, while small black sclerotia can be found in the pith and roots.

To manage the disease, it is important to provide regular irrigation, especially during flowering. Choosing resistant varieties like DHM 103 and Ganga Safed – 2 while avoiding susceptible ones like DHM 105 is recommended. Effective seed treatment using Carbendazim or Thiram can be implemented at 3g/kg of seed.

Common Rust Disease of Maize and Their Management

Common Rust Disease, caused by Puccinia sorghi, manifests as circular to elongate golden brown or cinnamon brown, powdery pustules on both leaf surfaces. As the maize crop matures, these pustules transform into brownish-black structures containing dark thick-walled two-celled teliospores.

The infection can spread to sheaths and other plant parts in severe cases. Effective management involves planting resistant hybrids like Deccan, Ganga-5, Deccan Hybrid Makka-103, and DHM-1. Early intervention with sprays such as Mancozeb (2.5g/lit) or Dithane M-45 (0.4%) at the first sign of symptoms, followed by repeat applications at 10-day intervals until flowering is recommended.

Downy Mildew Disease of Maize and Their Management

Two types of Downy Mildew are often observed: Brown Stripe Downy Mildew, caused by Sclerophthora rayssiae, and Crazy Top Downy Mildew, caused by Sclerophthora macrospora. Brown Stripe Downy Mildew primarily affects the leaves, with symptoms confined to the veins. The top leaves wilt, lose color, and become dry. Chlorotic stripes develop, extending in a parallel pattern and potentially covering the entire leaf surface in severe cases. Advanced stages exhibit necrotic stripes with a purple or reddish color, resembling burnt patches.

Crazy Top Downy Mildew first appears as rolling and twisting of upper leaves, leading to tassel malformation. The tassel becomes partially or completely deformed, forming narrow, twisted, leafy structures. Affected plants show excessive tillering, stunted growth, and chlorotic stripes on the leaves.

To manage Downy Mildew, integrated disease management strategies are crucial. These include cultural practices like crop rotation, using resistant maize varieties, and maintaining field hygiene to reduce disease incidence. Additionally, fungicidal sprays with appropriate chemicals can be applied at recommended intervals.

In case you missed it: Maize Shoot Bug Pest Management: Symptoms, Treatment, Chemical, Biological, Natural, and Organic Control

Conclusion

Effective management of common maize-damaging diseases involves understanding their causes, identifying symptoms, preventing their spread through cultural practices, and implementing targeted treatments such as resistant varieties and fungicidal sprays.