ECHOcommunity Conversations

Army Worm Infestation in Maize Crops

To whom it may concern,

Can anyone please advise on the following, we have an army worm infestation in our maize fields in the Lower Zambezi, Zambia. We actively encourage our co-ops to practice organic farming methods but the organic pesticides we make does not kill these pests ?

Does anyone have any advise on how to control these pests ?

Best regards,

Richard

You may be able to find some useful input in this ECHOcommunity collection. We would really like to hear back from you if anything in this list of resources is particularly helpful to you.

Dear Mr. Snyder,

Thank you very much for the links below they proved to be extremely helpful.

Best regards,

Richard

I can offer a more “conventional” organic approach. In the US we use one or more of a handful of commercial products. It’s worth noting that these are bio-rational sprays (they’re all made using bacteria, fungi, or viruses that will infect the insect), and it’s entirely reasonable for a country to set up their own production. Cuba is a good model this, as I understand.

Sprays for corn work best when they’re sprayed with a boom sprayer. I acknowledge that means a tractor and sprayer and that may not apply to your farmers. One option is for one person (or everyone in a cooperative) to own one sprayer and be responsible for spraying everybody’s fields. But - it’s also possible to apply these sprays directly to each ear of corn, by hand!

These are all sprayed when the corn is in the whorl stage.

Products: the trade name is in (trade name), if it’s possible to import and purchase:

Bacillus thuringiensis aizawai (XenTariOG) : 0.5 to 2 lb/A; PHI 0d, REI 4h, Bee: L, Group 11. Use alone to control light populations or first and second instar larvae. Add a contact insecticide to control more mature larvae and higher populations. Must be ingested; apply in evening or early morning, before larvae are actively feeding. Adherence and weather-fastness will improve with use of an approved spreader-sticker. Use high rate at cool temperatures. For resistance management, may be rotated with Bt kurstaki products (Dipel).

Bacillus thuringiensis kurstaki (Dipel DFOG): 0.5 to 2 lb/A; PHI 0d, REI 4h, Bee: L, Group 11 . Use alone to control light populations or first and second instar larvae. Add a contact insecticide to control more mature larvae and higher populations. Must be ingested; apply in evening or early morning, before larvae are actively feeding. Adherence and weather-fastness will improve with use of an approved spreader-sticker. Use high rate at cool temperatures. For resistance management, may be rotated with Bt aizawai (XenTari).

Burkholderia spp. strain A396 cells and spent fermentation media (Venerate XCOG): 1 to 8 qt/A; PHI 0d, REI 4h, Bee: M.

Chromobacterium subtsugae strain PRAA4-1 (GrandevoOG): 1 to 3 lb/A; PHI 0d, REI 4h, Bee: M.

spinosad (Entrust SCOG): 1.5 to 6 oz/A; PHI 1d, REI 4h, Bee: M, Group 5 . Apply as directed spray into leaf whorls or as broadcast spray.

It’s very helpful to scout for the pests. We sometimes use traps so we can count moths. Here’s one resource: http://nevegetable.org/crops/insect-control-6

Scout whorl and emerging tassel stage corn by checking 100 plants in groups of 10 or 20 in a V or X pattern across the field. Avoid checking only field edges and select plants at random, not only where you can see damage. A plant is ‘infested’ if at least one caterpillar is found. If feeding damage is old and no larva is found, the caterpillar may have left the plant to pupate in the soil. If 15% or more of plants are infested with FAW, a control is needed.

In emerging tassels, combine counts for ECB and FAW. For example, if 10% of plants have FAW and 12% have ECB, the combined infestation is 22%, above the 15% threshold.

Mike

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Hello Richard,

Where on the Zambezi are you? I cannot offer advice on the army worms, but will pray with you for solutions! My husband Richard and I were in Zambia in 1979, at Chitokoloki, also traveled to other parts. May you find the solution to your needs and have an abundant harvest!

Pam

Hi Pam,

We currently sponsor over 15 projects in the Lower Zambezi, Zambia a very beautiful area of Zambia, sadly being decimated by drought even-though we are on the Zambezi river. Anyway don’t worry about offering advice your prayers will definitely
suffice.

Many thanks,

Richard’

This was a topic of some conversation at the ECHO meeting in Florida recently. Some areas are using a pinch of agricultural lime placed in the plant whorl to help control the worms. I don’t have direct experience with this control method. The most important thing is to start scouting early. SAWBO has a video detailing the scouting process. You can view it here: https://sawbo-animations.org/708.

I think a lot depends on how vulnerable the people are to the losses of army worm. If the people are vulnerable to losses that will cause malnutrition you better think twice about recommending only organic methodology unless you already have evidence that your organic options offer better control than chemical control. Voice of reason says that if malnutrition is possible then after applying good scouting techniques it would make sense to test the best recommended chemical controls available (regardless of your position on organic methodology) against best cultural practices and biological/organic controls you have available to you and you have the time to do given the rest of the practices that are timely on the farm. You may want to go up to 90% chemically controlled and have a smaller plot with the organic/cultural comparison if chemical control in your area has a history of being more effective. You may learn to get just as good or better control more economically on the cultural/organic control and then switch to all cultural or organic at that time.

One Israeli farmer in South Sudan, told me they increase the volume of water in the spray mixture up to 2 times but apply the same amount of chemical and get better control, thus filling the whorl and reaching more worms.

Also there is an important factor in profit per unit hour invested or product produced per unit of hour (in subsistence situations) invested and people need to pay attention to that or they minimize their ability to invest in education, health care, and improving their investment to strategically expand their income base. So if your cultural or organic control methods are so time consuming they are detracting from another important farm activity that is highly profitable or very timely you need to weigh that factor in your decision process.

Consider Dr. Ames seminal work on the substances that caused cancer.
https://www.nytimes.com/1994/07/05/science/scientist-at-work-bruce-n-ames-strong-views-on-origins-of-cancer.html

Dan

I know this was a while ago, but since FAW isn’t the type of thing to just magically go away, I wanted to share a link to this webinar put on by FAO/FTN a couple weeks ago, concerning research in the area of FAW control, I though the wasp information was particularly interesting, and hopefully this information can be useful when thinking about a “agroecological” approach to FAW infestations.

FAO Technical Network webinar on “Agroecological approaches for fall armyworm management”.

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