Integrated Pest Management and Striga

In November, the project I am linked with held a seminar to discuss two maize pest problems faced this season: Fall Armyworm (FA) and the Black Ant (BA). An entomologist based in the US and working on the project conducted the seminar and it was extremely informative and interactive.

Macondo and our demonstration plot was spared of these pests because we planted early and were therefore able to harvest early. Surrounding areas were hit as were many other maize growing areas in the country. The FA takes over fast and 2016 was the first recorded outbreak in Ghana. BA is endemic to Ghana but has become a problem because colonies have become too large and although carnivorous, have started to eat the maize plants when its usual food is sparse. As for the BA, although the ants were ever present in Macondo, there were no reports that I heard of affecting yields.

 

Fall Armyworm

As this year was the first outbreak ever, the theory is there will not be an outbreak next season but farmers will overspray for fear there will be and/or ‘just in case’. Although the FA’s first recorded outbreak was this year, it is unknown how long the pest has actually been in Ghana. And because this year was the first outbreak, there is no data on it’s flight pattern (it is a moth but damage is caused when it is a worm), where it started or where it went, its life cycle here, etc. The African Armyworm is not a problem as it is highly regulated, having an outbreak about every twenty years or so.

Note the identifiers of the FA: inverted Y on the head and four dots on the last segment.

It is with events like the FA that government and private institutions can work together to collect data and learn more about such insects. In the case of the FA for starters, Dr Dan said to track adults (i.e. the moth) and learn when they lay. The immediate benefits of having this knowledge is knowing when larvae are as small as possible and most vulnerable thus allowing us to use ‘softer’ chemicals.

 

Black Ant

Dr Dan opened on the BA with an interesting thought that shaped the rest of the conversation regarding this particular problem: The BA may not necessarily be our enemy. As mentioned earlier, the BA is usually a carnivore. It has been attacking maize because there is a shortage of its usual food supply (probably caused by the population explosion – vicious cycle!).  This means BAs are hungry so maybe, maybe, they would eat the FA. Thus becoming a non-pest and more so, our friend. Another, [potentially] simple solution is habitat modification. It is known that BAs do not like shade. So planting trees and shrubs to create a natural border around one’s field should prevent BAs from crossing into the maize field. Another solution is to use a bait but this is complex and would need to be developed. Again, another opportunity for government institutions and national and international research institutions to work together to identify and create the bait.

ba
Black Ant

I can sit here and list possible solutions and make it sound somewhat easy but in reality, no matter how simple the solution, it does not mean farmers will adopt it. For example, another easy solution is mulching. This would create that much hated shade and at the same time improve soil health. However, trying to get the farmers of Macondo to mulch sounds highly unlikely to me. For one, burning corn/maize/millet/sorghum/rice stalks after harvest is very common and for decades now the government and national and foreign institutions have tried to change this behavior and all to no avail. These stalks would be the primary mulch source and teaching farmers why it is better to leave that part of the plant on the soil, year after year was not enough. If they are not willing to do less work (i.e. not setting a fire and managing it) why would they do more work of either making mulch out of compost or finding another soilcover source?

 

Striga

20161007_105038
Deceptively pretty Striga. Its roots grow at the base of the maize plant, essentially stealing water and nutrients meant for the corn.

We wrapped up the session with an impromptu rapid fire session on Striga, which is a weed. Dr Dan ran the session more like a workshop where the participants brainstormed solutions. We were broken into four or five groups and we were able to come up with an array of tactics, with many that if combined, could be more effective. Striga is a huge problem, all across Ghana and beyond. It has aggressive roots that grow alongside maize roots, essentially stealing the nutrients from the crop. Some suggestions ranged from planting earlier to basically get a head start on growth to manual weeding, which is very labor intensive (as I experienced with the Macondo demonstration plot). These are worth mentioning as they could be done alongside more complicated ones, like working on soil fertility, which would take a few years before seeing any benefits (whether striga related or not). The theory behind this is that if the soil is healthier, striga will not attach itself so strongly to the maize roots, giving it room to breathe and eat.

Another solution I really liked was crop rotation and leaving fields fallow. In northern Ghana, we only have one growing season so none of this sounds appealing at all. But maybe a three year demonstration plot could be done. Where one field would be used as the example of the land belonging to one farmer. The field would be divided into three, with two complementary crops grown, for example soya beans and maize. The third portion would be left fallow. The next year the same crops would be rotated and then again in the third year. Soil records could be kept to see if any difference in fertility was made, data collected on a sample number of striga plants found in each section year after year, etc. The point I am trying to prove is that there are so many options that need to be looked into as striga is very devastating and chemicals should not be the go to, primary option.

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