WHAT FARMERS CAN DO TO PROTECT YOUR MAIZE FROM FALL ARMYWORM

Another planting season is here already, farmers are getting ready to cultivate maize on their farmland, and money must be made. However the fear of fall armyworm destroying their maize field is still lurking deep down their minds. Many of them are yet to be equipped with the pest management system to help them control this insect pest from attacking their maize. With the help this article, farmers will have an insight what fall armyworm is and how they can prevent it from attacking their maize field.

FALL ARMYWORM

The fall armyworm (Spodoptera frugiperda) is a species in the order of Lepidoptera and is the larval life stage of a fall armyworm moth. The term “armyworm” can refer to several species, often describing the large-scale invasive behaviour of the species’ larval stage. It is regarded as a pest and can damage and destroy a wide variety of crops, which causes large economic damage.it was named because of the species’ ability to destroy crops. Because of its propensity for destruction, the fall armyworm’s habits and possibilities for crop protection have been studied in depth.

The fall armyworm is native to the tropical regions of the western hemisphere from the United States to Argentina. The fall armyworm is a strong flier, and disperses long distances annually during the summer months. It is recorded from virtually all states east of the Rocky Mountains. In 2016 it was reported for the first time in West and Central Africa, so it now threatens Africa and Europe.

LIFE CYCLE

The life cycle is completed in about 30 days during the dry season, but 60 days in the rainy season 80 to 90. The number of generations occurring in an area varies with the appearance of the dispersing adults. The ability to diapause is not present in this species

Egg: The egg is dome shaped, the base is flattened and the egg curves upward to a broadly rounded point at the apex. The egg measures about 0.4 mm in diameter and 0.3 mm in height. The number of eggs per mass varies considerably but is often 100 to 200, and total egg production per female averages about 1500 with a maximum of over 2000. Duration of the egg stage is only two to three days during the dry months.

Larvae: There usually are six instars in fall armyworm. Head capsule widths are about 0.35, 0.45, 0.75, 1.3, 2.0, and 2.6 mm, respectively, for instars 1-6. Larvae attain lengths of about 1.7, 3.5, 6.4, 10.0, 17.2, and 34.2 mm, respectively, during these instars. Young larvae are greenish with a black head, the head turning orangish in the second instar. In the second, but particularly the third instar, the dorsal surface of the body becomes brownish, and lateral white lines begin to form. In the fourth to the sixth instars the head is reddish brown, mottled with white, and the brownish body bears white sub-dorsal and lateral lines. Elevated spots occur dorsally on the body; they are usually dark in colour, and bear spines. The face of the mature larva is also marked with a white inverted “Y” and the epidermis of the larva is rough or granular in texture when examined closely.

Pupa: Pupation normally takes place in the soil, at a depth 2 to 8 cm. The larva constructs a loose cocoon, oval in shape and 20 to 30 mm in length, by tying together particles of soil with silk. If the soil is too hard, larvae may web together leaf debris and other material to form a cocoon on the soil surface. The pupa is reddish brown in colour, and measures 14 to 18 mm in length and about 4.5 mm in width. Duration of the pupa stage is about eight to nine days during the dry season, but reaches 20 to 30 days during cold weather. The pupa stage of fall armyworm cannot withstand protracted periods of cold weather.

Adult: The moths have a wing length of 32 to 40 mm. In the male moth, the forewing generally is shaded gray and brown, with triangular white spots at the tip and near the center of the wing. The forewings of females are less distinctly marked, ranging from a uniform grayish brown to a fine mottling of gray and brown. The hind wing is iridescent silver-white with a narrow dark border in both sexes. Adults are nocturnal, and are most active during warm, humid evenings.

In sub-Saharan Africa, where fall armyworm is currently devastating maize crops, estimates indicate 13.5 million tons of maize valued at $3 billion are at risk in 2017-2018, which is equivalent to over 20 per cent of total production for the region. Fall armyworm causes serious leaf feeding damage as well as direct injury to the ear. While fall armyworms can damage corn plants in nearly all stages of development, it will concentrate on later plantings that have not yet silked. Like European corn borer, fall armyworm can only be effectively controlled while the larvae are small. Early detection and proper timing of an insecticide application are critical.

MONITORING

The fall armyworm has the ability to develop resistance to pesticides. It spreads fasts and attacks many crops compared to other pests. Spraying of both organic or pesticides when the pest is beyond the third instar has very little effect on it. Maize growers should pay close attention to farmlands with a history of these problems. Problems are usually associated field planted after June 1. Early detection of infestations will allow for more effective control of this pest.

Maize farmers should start checking their maize farm in mid-June for fall armyworm activity. Survey 20 consecutive plants (selecting the first randomly) from at least 5 locations in the field. Small larvae cause “window pane” damage to leaves.

A few days before selling, look for large larvae in the whorls which will be pushed out when the tassels emerge. These larvae may attack young ears. Continue to check for this insect until silks begin to dry.

PREVENTION AND MANAGEMENT

Most chemicals in the market cannot kill eggs, for the pesticides to be effective, the farmer need to scout in their maize crop and spray when the pest is at the larvae stage. It is also advisable to use cheaper and less dangerous chemicals which are effective and locally available. Farmers are meant to spray their crops two (2) weeks after planting, at knee height and at tasselling stages. It is recommended to spray early in the morning or late in the evening and when it is not windy to avoid waste of pesticides.

Other pest control measures to be taken include;

• Farmers should endeavour to plant early to reduce pest incidence
• Maintain a healthy ecosystem to help in biological control as they harbour parasitoids
• Use of biological control such as natural enemies and bacterial insecticides
• Farmer should plant maize varieties that has partial resistance, but is inadequate for complete protection.
• Garlic-based biopesticides are also effective and work the same way as neem
• Use of traps can also reduce to the barest minimum the number of male moths and reduces its multiplication.