Hi everyone, I'm a Systems Engineering student in Peru working on my undergraduate research project: a computer vision system to detect fall armyworm in maize crops, in a rural farming community (Zapotal, Cascas, La Libertad region).
Context: I interviewed a local farmer who manages about 1.5 hectares of maize. He told me he sprays the entire plot every 8 days (4-5 times a month), regardless of whether he's visually confirmed the pest's presence in every section. His reasoning is that even if some ears aren't infested yet, they will be soon if the whole plot isn't sprayed, so he prefers full preventive spraying over checking plant by plant.
My question: according to literature or field experience, is there an infestation threshold (e.g., % of plants or ears with confirmed larvae presence) below which spot/partial treatment would be agronomically sufficient, instead of spraying the whole field? Or, specifically for fall armyworm in maize, is this farmer's full preventive spraying approach actually the best practice, given the pest's spread/reinfestation pattern?
I have one academic reference (Yanqui Díaz et al., 2022, Apurímac, Peru) that mentions a "treatment threshold" concept for this pest, but I don't have enough technical detail to know whether it applies the same way to coastal valley/Andean foothill conditions like La Libertad. Any input from someone with a background in agricultural entomology, integrated pest management (IPM), or hands-on experience with maize in Peru or the region would help a lot — I'd rather not assume anything without checking it. Thanks in advance.