In our list of pests and diseases of crops we add corn. Given its agronomic importance, it is essential to know what problems we face and what weapons we have. A single mistake can reduce or even end all the production we have of corn, so prevention and quick action is very important. These are the main pests and diseases of corn.
CORN PESTS AND DISEASES
Note: it is preferable to check the active subjects in order to see if they are approved by the ministry of agriculture of each country.
We are going to analyze corn pests and diseases . Identification and treatments.
Gray worm (Agrotis Segetum, Agrotis ipsilon, Agrotis exclamationis)
The gray worm are larvae of various butterflies that are part of the Noctuidos. They are between 4 5 cm in size, curling up when they notice the contact of a possible predator. They have a greyish color, and in the case of the Agrotis ipsilon it has black stripes on its rings.
The damage it causes on the corn crop is related to the larvae bites. They cause a generalized wilting of the central leaves in the young plant, spreading over time to the rest of the plant. A strong attack considerably reduces the volume of plants in a plantation.
The fight against the Gray Worm consists of the application of insecticides (10% w / v (100 g / l) of Lambda cyhalothrin, etc.) which in the latter case consists of a foliar spray in concentrations of 0.01-0, 02 %
Corn borer ( Sesamia nonagrioides): this Sesamia caterpillar feeds on both the ear and the stem of the corn, eating inside the peduncle that supports the plume (male flowers), causing it to fall, and therefore, stopping fertilization . Corn production drops sharply. In general, in adult plants there is a certain resistance to boring, only achieving a reduction in production and quality. In the case of young plants, a severe attack can completely damage the crop.
Treatment against corn borer consists of the application of insecticides (10% w / v deltamethrin in doses of 0.125 L / ha, 48% chlorpyrifos in normal spraying, 15-20 cc / 10 L water).
Seeded fly (Phorbia platura)
This dipteran insect measures around 0.4-0.6 cm and is attracted to humid, cool or carved areas. The larvae of the seed fly develop in the cavities of the soil. This fact generates problems in the sown grains. These appear empty or with galleries excavated by the larva. In the event that it germinates, the plant appears deformed or with little vigor, because the roots are affected by the larva. 0
For the control of the sown fly in the corn crop, it is necessary to apply insecticides (10% w / v (100 g / l) of Lambda cyhalothrin, etc.) with an application of 0.01-0.02 % of product.
Screwworm ( Elasmopalpus angustellus)
The adult corn screwworm has a wingspan of between 21 and 25 mm. The wings of the adult are grayish in color in the female and light shades in the male. The larvae can measure up to 20 mm long, they are dark gray with black tones on the head.
The damage caused by the screwworm in the corn crop is based on the perforation of the stem. Uniform perforations can be observed in the leaves.
Corn caterpillar (Heliothis armígera): damage caused by the corn caterpillar is caused by larvae bites on stems and fruits. A severe crop attack causes a complete mowing of the corn. The caterpillar makes the laying, in isolation, on the underside of the leaf.
The solution to the corn caterpillar consists of the application of insecticides (10% w / v deltamethrin at 0.075-0.125 L / ha, 48% chlorpyrifos in a concentration of 0.15-0.2% (150-200 cc / 100 L of water)
Corn aphid (Rhopalosiphum maidis): the corn aphid affects the crop due to the suction it makes on the plant material, specifically leaves and ears. These attacks cause chlorosis, necrosis and loss of vigor of the plant. Often times, if the attack is severe, it causes a reduction in the number of kernels on the ear. The time when the aphid makes its attack on the corn with intensity ranges from spring to early summer.
A treatment against the corn aphid consists of the application of insecticides (10% w / v deltamethrin, in concentrations of 0.075-0.125 L / ha).
Corn rust (Puccinia sorghi):
Corn rust is widespread practically all over the world. It usually appears when the corn approaches flowering. The rust disease begins on the leaves with a visible yellow coloration on both sides of the leaf (upper side and underside), which, over time, turn reddish-blackish in color. It is recognizable because a green or yellow circle or halo forms around this spot. The disease increases in canes of six months of age, in common plant and in suckers.
The treatment against rust is based more on preventing the entry of the disease than on curing it, since most fungicides are ineffective. The search for varieties resistant to the disease is recommended.
Spike smut ( Sphacelotheca reiliana): This disease causes systemic damage, which means that the fungus enters the seedlings and develops internally without showing visible or recognizable symptoms until the corn is in the flowering and production phase. of stigmata. Identification of the disease consists of inspection of the spikes. These deform and grow excessively, forming black masses instead of ears.
The treatment for the carbon of the ear consists of the application of fungicides (carboxy, 130-260 cc, etc).
Anthracnose stem rot ( Colletotrichum graminícola and Glomerella graminícola): This type of disease caused by these two agents causes stem rot and leaf blight. On the corn plant, elongated, dark-colored lesions appear, turning black. The plant suffers premature wilting and tearing of the vascular bundles, acquiring dark tones.
Stem and root rot ( Fusarium graminearum, Gibberella zeae, Scierotium bataticola, Macrophomifla phaseoli, Diplodia maydis):
this type of corn disease originates necrotrophic fungi that attack the roots and the base of the stem. It produces a root and neck rot of the plant causing a loss of spikes. It also produces weight loss of the grains.