Pests and diseases (Maize)

1. Stem Borer (Busseola fusca, sesania colanistis, eldana sacharina). The insects are transmitted to the plants by butterflies, which lay eggs on corn in dry season. Damages inflicted to plants by these insects are remarkable from the holes they make in seeds, with leaves completely eaten up and galleries in stems, the whole surrounded by excrements of the insects.

Symptoms of maize stalk borer, Busseola fusca, damage on leaves: (A) characteristic “window panes,” (B) shot holes where tissue has been eaten away, and (D) dead

heart. Symptoms of damage to stems and cobs: (C) galleries filled with frass, (E) cobs showing frass, and (F) deposits and empty grains.

The following measures are recommended to fight against the disease: early planting, rotation of crops, pile up the stems in compost or apply Dursban 48%.1, 5l/Ha or beta-cyfluthrine 2,5% in 10 l of water /acre.

2. Maize streak virus; this disease

is transmitted by an insect called Cicadulina rubila. The disease is noticed by visible traces on leaves. The virus causes a white to yellowish streaking on the leaves. The streaks are very narrow, more or less broken and run parallel along the leaves. Eventually the leaves turn yellow with long lines of green patches. Plants infected at early stage usually do not produce any cobs.

Symptoms of Maize Streak Virus

To fighting against the disease, it is recommended to early plant the entire field, pull up possible infected seedlings, which could transmit the disease.

3.  Leaf spots: this disease is transmitted by a fungus called “Helmnthosporium turcicum “. This disease attacks the leaves of corn and it is seen by many large oval spots on them. It is frequent during rainy seasons

Symptoms of maize leaf spots

The following measure fight against the disease: early planting using resistant varieties and treated with Thiran and Benomyl before planting. It is recommended to compost the stems away from the field.

4. Fall Army worm

Fall armyworm (FAW) - Spodoptera frugiperda, is a pest that can cause significant damage and crop yield losses, if not well managed. Maize is its preferred host and a major staple crop for smallholders. In addition to maize, the pest has also been detected on an increasing number of other crops (e.g., sorghum and sugarcane).

 

                              

Fall Armyworms and their damage on maize leaves         Fall Armyworm with “Y”shape  between eyes

Prevention

• Deeply ploughing the soil with the aim of discovering, removing or burying the fall armyworms,
• Always weeding the plantation whenever weeds have emerged and keeping clean the plantation contours,

• Removing the plants residues in the field after the harvest,
• Boosting the plants resistance by applying well decomposed manure, recommended inorganic fertilizers and irrigation,
• Crop rotation of cereals with legumes (beans, soybeans,..) or tubers (potatoes, sweet potatoes),
• Regular surveillance of the plantation (at least three times a week) and check whether there is no Fall armyworm outbreak. Once you realize that there Fall armyworms are available, you should inform the concerned people (farmer promoters, facilitators and extension workers at Cell, Sector, District and RAB…)

Control

• Collecting fall armyworms and killing them,
• Using pesticides like:

• Cypermethrin 4%+profenofos 40% (example: roket, target, cypro, jaket,…)   at 1-2 ml of pesticide in1l of water,
• Lambda-Cyhalothrin 50g/l, at 1-2 ml in 1l of water,
• Pyrethrum 5% EWC, at 8ml in 1l of water,
• Acetamiprid 20g/l + Lambda-Cyhalothrin 16g/l, 4-6ml in 1l of water,
• Imidacloprid 200g/l at 1ml in 1l of water.

5. Maize Lethal Necrosis Disease

Maize lethal necrosis disease is caused by co-infection of maize by Maize chlorotic mottle virus (Machlomovirus: Tombusviridae) and Sugarcane mosaic virus (Potyvirus: Potyviridae) or sometimes another cereal virus of the Potyviridae group.

Symptoms

Maize chlorotic mottle virus (MCMV) causes a variety of symptoms in maize depending upon genotype, age of infection and environmental conditions. They range from a relatively mild chlorotic mottle to severe stunting, leaf necrosis, premature plant death, shortened male inflorescences with few spikes, and/or shortened, malformed, partially filled ears (Castillo and Herbert, 1974; Castillo Loayza, 1977; Niblett and Caflin, 1978; Uyemoto et al., 1981).

   

Symptoms of MLN disease

Prevention and Control

• Seed should not be recycled; farmers should plant certified seed only. Those seeds are available in agrodealers’ shops;
• The best approach for the management of MLND is to employ integrated pest management practices encompassing cultural control such as closed season, crop rotation and crop diversification, appropriate spacing, fertilizer application, weeding etc…
• Uprooting infected plants and bury them in 1m deep hole,
• Do not grow maize nearby an infected maize plantation,
• Crop rotating maize with other non cereal crops,
• Grain and cobs that are rotten should not be fed to humans or animals. These should be destroyed by burning,
• Domestic regulation can be put in place to prevent the movement of maize products from affected areas to disease-free regions.