If you grow Bt corn don't imply that it is organic because the organic buyers, for the most part, avoid GMO's like the plague and if they found out your spray free corn is Bt they may avoid your produce like the plague in the future. if your customer base does not care about GMO's than you likely will not lose customer trust.

You can also try corn oil in the silks as a worm preventative. Johnny's Seeds sells a contraption called Zea-later that applies corn oil to the silks which in turn smothers the first instar earworms.

Or do what I did and stop growing sweet corn and grow more lucrative crops that take up less space

I have only grown BT sweetcorn for the last 4 years. The triple sweet gene makes it the sweetest and most flavorful corn on the market. You can buy it without the BT gene if you like...I have never received more positive compliments from my customers. It is 100% corn borer free. No smuts no lodging no broken stalks or stalk rots. You should not get any earworms except some survive eating down the silk tunnel and die by the time they get to the first tip kernel. The plants are attacked by fall armyworms which we don't see until September in NJ because the BT toxin is not very strong. I don't have to apply any pesticide to BT corn June thru labor day and by not spraying every three days like you do with regular sweetcorn the beneficial pests take over and control the other pests in corn... Bob.