Independent consultant, Dr Joe Huesing has over 25 years of experience in Fall Armyworm (FAW) and pest insect mitigation, integrated pest management (IPM) and pesticide regulation in both the public and private sectors, across the Americas, Africa and Asia. Over the last five years, first as lead USG scientist on the FAW Task Force, and then as an independent consultant, he has provided advice to USAID on FAW control and IPM. He was also a panellist in our first Plenary of the ASEAN FAW Action Plan. In this blog, we ask Dr Huesing to share his thoughts and tips for smallholder farmers on how to best control FAW.
Q: How important is good soil health and fertiliser, management of soil pH and good quality seed to FAW control? JH: Very important. Soil health comprising a balanced mix of organic matter and/or fertilizer containing nitrogen, phosphorous and potassium, with a properly adjusted soil pH will build a robust stand of maize. A robust stand of maize is better able to meet the yield potential of the maize variety planted. The more robust the stand, the better it is at withstanding stresses. A robust stand of maize also aids in conservation biocontrol. For example, the greater the yield in a stand, the better the relative pricing between the cost of control and yield protected. In other words, if it costs the same price to treat a 2 tonne/ha field vs a 5 tonne/ha field the yield differential between the 2T and 5T fields will be much greater for the 5 T field. Q: We hear are a lot about the importance of farmers in getting out and scouting their fields for FAW regularly. What should farmers be aware of when scouting for FAW in their fields, and is there "best practice" they should follow when doing so?
JH: The key to controlling FAW effectively is to identify the pest when it is in the first and second instar and before it moves into the whorl or the ear. At this stage the insect is quite small – it is far easier to see the damage, which is described as ‘small fresh window panes’ than it is to see the larvae because they are only millimetres in length.
The single biggest mistake that farmers and researchers make is to react to the problem too late when the larvae are too big to control easily. This leads farmers and researchers to think their treatments ‘don’t work’ when in fact it was probably a timing issue. The only way to address this is to scout early and often. In fact, in the U.S. State of Florida, where FAW is endemic, commercial farmers scout 2 to 3 times a week in high-value maize crops.
The USAID-CIMMYT resource on Fall Armyworm management practices explains more here: Fall Armyworm in Africa: A Guide for Integrated Pest Management
Q: Do farmers have to use pesticides to control FAW effectively? When does it make sense to use pesticides?
JH: The decision to treat for FAW, like all pests, is an economic decision. It is a cost-benefit decision between the cost of treatment (the pesticide plus labour) and the level of yield protected. The FAW IPM Guide for Africa provides guidelines. Britz (2020) using carefully controlled experiments showed that even a 10% FAW infestation could lead to ~13% yield losses. If pesticide and labour costs are between $10 USD and $90 USD per hectare then at a market price of ~ $ 0.21 USD it would take something on the order of 55 to 420 kg of saved yield loss to pay for the treatment. Further advice and guidelines will be published in the upcoming CIMMYT/USAID FAW Manual for Asia.
Q: Costs are always an issue for smallholder farmers who often survive on very small margins. Does managing for FAW have to be a high-cost activity?
JH: The data mentioned in the previous question show that, if properly trained, smallholder farmers can manage FAW within their means. Farmers need the knowledge to plant a robust stand of maize using the best quality seed they can find. They need to understand how to scout the field and determine when, and if they need to treat. If treatments are needed, they need to understand how to choose the safest controls that will conserve natural enemies and that are affordable. Q: You have significant experience working with farmers on the ground. Do you have three top tips to share with our farmers that they could consider when responding to the threat of FAW?
JH: First, there are many pests in maize, this is just the latest – so pay attention to all the pests. Second, learn how to scout your field properly. Third, learn how and when to choose the best treatment, when and if needed. And importantly, learn how to apply the material at the right time and at the proper rate while maintaining safety for yourself and your family. Help is available from a number of sources including CIMMYT and the private sector as well as extension staff. Don't be afraid to ask for help.