This answer were fing on 420magasin forum :
By the time you notice a stalk borer problem it's too late to save the plants in most cases. Your best bet is remove infested plants and kill the stalk borer as it can move on and attack other plants. It also reduces the number of stalk borers that survive to lay eggs later. It is possible to cut into infested stems with a very sharp knife to kill the stalk borer and then bind the plant and hope it survives (there isn't much to loose by trying).
Problems are more likely to occur in garden with adjacent grassy, weedy areas. Control weeds to help reduce the risk of stalk borer infestations. If this isn't possible, keep weeds cut short, especially in the spring when stalk borers are looking for feeding sites, and late summer/early fall when adults are laying eggs. Insecticide treatments is not suggested. Stalk borer problems are too sporadic making it difficult, if not impossible, to predict which plants will be attacked and when.