Tan oval spots with dark borders climbing up my maize leaves, what is it?

Small to medium tan or buff coloured oval to rectangular spots with darker brown borders, increasing in warm humid weather and different from the long cigar lesions of turcicum, are more typical of maydis or southern leaf blight, another common leaf disease in maize. The two leaf blights are managed in similar ways, but please send a photo to your KVK or agri officer to confirm, since correct identification helps choose a resistant hybrid. Cultural steps that help are growing tolerant hybrids, rotating away from continuous maize, ploughing in or removing old residue where the fungus survives, and avoiding very dense planting that traps humidity. If the spots are spreading up toward the cob leaves before grain filling and a spray is justified, recommended actives include mancozeb or a recommended option, but follow the label dose, the pre-harvest interval and the local KVK recommendation and rotate modes of action. Keeping the leaves around the cob healthy is what protects your grain filling.