How to Identify and Scout for Fall Armyworm in your maize crop

29th May, 2020
How to Identify and Scout for Fall Armyworm in your maize crop

The Fall Armyworm is an insect that can damage your maize plants or even cause you to lose your whole maize crop.  Fall Armyworm prefers maize but can also feed on more than 80 other crops, like  wheat, sorghum, millet, sugarcane and vegetable crops. The larvae of this moth is the stage that causes damage to your maize crop.

The best way to protect your maize crop is to scout early and to treat early. This way a farmer is able to identify the pest and other diseases long before their population reaches economic injury level.

To avoid losses it is important that farmers are equipped with the right techniques to scout, monitor and control pests in their farm. Scouting is important as it helps farmers understand the state of their crop in all aspects including nutrition, pest and disease infestation and other afflictions like effects of adverse weathers like floods or even theft. 

Start scouting early in the morning before the hot sun forces the larvae to hide deep in the maize plants. Since the larvae are very difficult to find during the day be on the lookout for signs of damage. Signs of infested whorls include any fresh window panes, holes, and frass. Live larvae may be seen as we. Frass is the waste left behind by the worms.

It is advisable to start scouting as soon as the maize crop emerges. This will enable farmers to identify the fall armyworm when it is still small and easily controlled. Once the larvae get bigger, big enough that you can see them easily, they become difficult to control. Also, once maize enters the reproductive stage and starts forming ears, the larvae may bore into the inside of the ears and become impossible to control.

 Continue scouting until the crop is of shoulder height. After they are shoulder high or reach the reproductive stage, even if you find the fall armyworm larvae in your maize crop, there is not much to do to save the crop. This is why scouting early is very important.You should never scout the field when someone has just sprayed with a chemical pesticide as the chemical can cause harm to your health.

First determine the field to be scouted. The crop should have similar properties i.e planted at the same time, same form of nutrient management and other aspects. This saves you from making false conclusions from the false data brought about by the differences.

When you scout, both at the early and late whorl stages of your maize crop,  move through the field in a “W” pattern. This “W” pattern is one way to keep your scouting locations random. Walk into the field about 5 meters from any edge. Move in the “W” pattern through the field, stopping in 5 different locations. Avoid the border rows of the field when choosing locations. At each of these 5 locations you need to look at 10 plants for signs of Fall armyworm damage.

Record the number of plants you looked at and how many were damaged. Then move to the next point and do the same. At the late whorl stage, examine the newest three to four leaves emerging from the whorl. Use the data collected from this exercise to predict the percentage of the infected crop. Add the number of plants for all the stations to see out of 50 plants how many were infested then multiply that number by 2 to get the percentage of the infestation. For example: station 1 has 2 infected plants, station 2 - 0, station 3 - 4, station 4 - 1, station 5- 6 totalling to 13 infested plants, it means your maize farm has 26% Fall armyworm infestation.

This helps you make the right control method decision.The best way to manage the pest is by using an ‘Integrated Pest Management’ approach.

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