If you don't mind me asking, for what reason do you feel the need to hand pollinate your corn? Corn is a self-pollinating plant that does a very good job of it on it's own if it's planted correctly. It should be planted in blocks of several rows 2-3 feet apart and about a foot between plants.

Greg
Nevada

DL:

The answer to your question is that the silks are best pollinated as soon as they appear. This is what happens naturally if all goes well. Silks appear over a fairly long period, at least 7 days probably more in most cases.

I do agree with Greg. If your planting is big enough hand pollinating is not needed. I'm not sure you can do much good even in a small planting. No one knows if they did any good without a fair unpollinated comparison.

I've had no problems with pollination in plots about three rows by 15 ft.

And just because the silks have emerged, it doesn't mean that they are ready for pollination. The silks can usually be trusted to come into maturity at the same time as the pollen bearing flower, the tassels. Those stigmatic tubes (the silks) must reach a certain stage before a ripened pollen grain can germinate on the surface and set the sperm loose to travel down that tube to the awaiting ovary.

Corn and other wind pollinated plants rely on this timing, as well as plenty of climactic cooperation. Regardless, if the female organs haven't ripened, no amount of pollination can make them set fruit.

DL,

I usually cut off a few tassels and "drag" them across the silks, shaking them slightly as I go. I'll do this every other day over a period of two weeks, as the silks servicing the kernels at the tip of the ear take longer to emerge. This supplemental hand assist usually results in full kernel development.

Raybo

I shake the stalks and let the fine dust fly on usually the second, third, and fourth day that the silks appear. I do this just for insurance. Every other year there is field corn over the fence and I try to get mine pollinated quickly on the planting that matches the field corn.

Apparently the best time to hand pollinate is in the morning from 10 am to noon or so. That's when the pollen is most available. When I try it in the evening I'm not seeing any pollen come out of the tassles. I have a very small plot so hand pollinating is required.