I understand that this is situation regarding cross-pollenation:-
There are three main different types of sweet corn generally available in the UK for culinary use, and they can come in early, mid-season or late varieties. These are:-
Extra tender and Sweet (tendersweet) F1. The sweetest type with softer kernels. The catalogues claim that isolation of this type from other types of sweet corn, is not required. Therefore, you do not need to worry which types of sweet corn are planted in the neighbourhood. Once picked, the sugars do not change to starches as quickly as the older varieties of sweet corn. Also can be quick to mature and should be ready to harvest in September in the North of the UK, and this is the type that I would recommend.
Suggested varieties of Extra Tender and Sweet (tendersweet)
Swift F1. Very early, very sweet and tender.
Lark F1. Mid season, very sweet and tender.
Supersweets F1. A sweet type but more chewy. The sugar content of this type can be 2 or 3 times that of standard sweet corn. Once picked, the sugars do not change to starches as quickly as the older varieties of sweet corn. They do not have the creamy textures of standard sweet corn. Isolation of this type is required from standard sweet corn varieties or the kernels will become tough and starchy in both types. A soil temperature of more than 13 C is required for germination.
Suggested varieties of Supersweets.
Extra early sweet.
Traditional open pollinated or Standard varieties. Can contain up to 6% sugar but are slow to mature and not really suited for the North of the UK. In addition, any sweetness will quickly turn to starch as soon as the cobs are picked. If there is cross-pollination with maize or pop corn, standard varieties will become tough and starchy.
I stick with the tendersweet type, so do not have to worry about cross contamination from adjacent plots.