Maize Diseases, Pest Identification and Control

Pest and disease problems on a maize farm

With the introduction of resistant seed varieties to the Nigerian farming system, the devastating effect of many pests and diseases affecting maize plants significantly reduced. Diseases like downy mildew and streak are known to be the most deadly pathogens in maize production. The lack of resistance to these diseases in local maize varieties enables the pathogens to destroy the diseased farm.

The activities of insect pests severely reduce the amount of maize production. According to statistics, losses reach millions of dollars annually. Pest infestation often leaves plants vulnerable to disease infection — transmission is done through the exposure of plant tissue to pathogens or disease-carrying pests (vectors).

High moisture content in grains encourages pest and disease problems, especially in storage. Insect-resistant maize varieties are also available to farmers to reduce the number of pre-and post-harvest losses.

It is essential to know that maize has risen to a commercial crop over the last decades, on which many agro-based industries depend as a raw material. This is why research institutions in Nigeria work tirelessly to ensure that resistant varieties are bred into maize and accessible to local farmers.

Uncontrolled weed on a maize farm

The presence of weeds has proven to be another significant cause of low yield in maize production in Nigeria — because the weed plants serve as alternative hosts for pests/diseases, and they compete with maize plants for nutrients, light and water.

Weed control could be a rigorous and expensive process, but it will save you from a lot of possible havoc when you make an effort to get it done. Recently, farmers have complained that a parasitic maize weed called Striga has resulted in tremendous losses in maize production.

This article will enlighten you about common pests and diseases that could strip your farm of potential harvest if control measures are not taken seriously.

Maize Diseases

Here are the major diseases affecting maize production in Nigeria:

Maize Rust:

The fungus Puccinia sorghi causes Maize rust or common rust- it occurs every growing season. The most visible symptom is the appearance of chlorotic rust pustules on the upper, lower and midrib surfaces. The pustules are often oval and are either clustered or scattered around leaf surfaces. As the infection progresses, the pustules rupture, releasing powdery red spores. The exposed spores result in further leaf infection causing the leaves to be yellow and eventually die. The wind usually transmits disease spores.

Maize rust

Leaf Blight:

This fungus commonly causes northern leaf blight — Exserohilum turcicum. It first appears as an oval grey or light brown spot, which gradually merges, covering large parts of the leaves. The disease causes the entire plant to wither and die. The fungal spores thrive in a moist environment; water splash is a medium of transmission. The condition usually results in grain loss and animal fodder reduction.

The apparent long and narrow lesions on the leaf vein is a factor for field identification.

Leaf Blight

Maize Streak:

The bacterium Xanthomonas vasicola pv causes bacterial leaf streak disease on maise. vasculorum. Symptoms appear as tiny brown or orange lesions with wavy edges appearing between the leaf veins, midrib and leaf blades. They often appear water-soaked with bright yellow halos. Over time, the lesions overshadow the entire leaves.

High wind and moisture transmit this disease.

Maize Streak

Downy Mildew:

Downy mildew is one of the most economically significant diseases of maise. It is caused by different fungus; one of them is the Peronosclerospora sorghi. Symptoms vary depending on age, cultivar and climatic factors. However, after infection, symptoms show as early as two weeks after sowing, resulting in leaf discolouration and stunted growth. Leaves wound up becoming narrower, covered with a white, downy growth on both leaf surfaces.

Downy Mildew

Control of Maize Disease

• Plant disease-resistant varieties.
• Weed Frequently.
• Practice crop rotation with non-host crops.
• Dry seeds before sowing to reduce moisture contents enabling fungal spores.
• Use appropriate fungicides to control the severity of fungal infection.

Maize Pests

Economic important Insect pests in Nigeria are divided into three categories;

• The field pests :

These are pests that feed on and destroy the maize plants on the field. Most of their feeding activities leave the plant susceptible to diseases. Examples of field pests are; Stem borers (Chloe Partellus), Aphids, Grasshopper, Weevils, Silkworms and Armyworms. These pests cause devastating losses in maize crops.

Maize field pest

• The field-to-store pest:

These are pests that attack maise grains during transport or exportation. Maize weevil (Sitophilus zeamais) is a severe pest affecting transported maise grains. Its feeding activity can cause severe losses on both transported and stored products.

Maize store pest

• Store pests

These are pests affecting stored grains. The larvae usually mature inside the grains, chewing their way out and destroying the grain embryo. Like the field -to-store pests, the feeding activities of these pests results in severe damage to stored grains. Maize weevil and grain borers are examples of stored pests.

Corn store pest

Control of Maize Pests:

• Use Biological control measures, that is, the incorporation of natural pest enemies.
• Use of pest-resistant varieties.
• Use of suitable insecticides examples, plant-based powders.
• Employ cultural methods like handpicking, crop rotation, proper sanitation and mulching.
• Use of scarecrows and insect line drawing.

We hope this article was helpful, Visit our website www.farmsby.com for more information.