Bt comes in 2 different forms - liquid and dust (Dipel is one brand). Each form works better in certain situations but I find that timing of application is much easier with the dust than with the liquid.

In this particular situation the dust is more effective in my opinion. Wetting the pollen or the silks might interfere with effective pollination. Dusting with dry Bt does not.

"To use mineral oil I read that you apply 5 drops to the silks after they pollinate but before they turn brown."

Do keep in mind that is only one of several methods used to control corn earworms and it does not need to be quite so specific as counting the exact number of drops used or picking the exact day of application.

When dealing with small corn crop numbers (where you aren't dealing with large numbers of plants) hand-picking the worms is easy to do and so is just popping open the ear top and dropping in a dollop of oil or Bt in any form. And last but not least, if growing only for personal use you just chop off the worm and damaged inch or 2 after harvest. It isn't as if he is going to eat the whole ear. ;-)

Dave

I doubt you will have problems with corn earworms this time of year. Unless someone has been planting corn close by, you may not even have a population of moths, yet. They will probably find your garden sometime in the future. I grew a small amount of corn like yours 2 straight years and did not have any damage. Army worms, on the other hand, are there because they are looking for the small grain growing in the area. Most farmers plant small grain later in the fall due to the army worms. They will die out sometime in October when the weather turns a little colder.

I have found that here ear worms only hit the last planting of corn usually.

Ear worms are hit or miss here; sometimes no shows, sometimes severe. I could second Wayne5's observations on late plantings, though... those have been my worst infestations, with nearly every ear infected.

When I have chosen to fight the ear worms (which is not every year), I use the Bt liquid, and a pressurized sprayer. I try to spray a solid stream directly through the silk & into the end of the ear, when the silks have begun to turn brown. The years I have done so, I have used only one application, and it was close to 100% effective. The late spraying has no effect on pollination.

Unless I intend to freeze corn on the cob, though, I generally just do as Dave suggested - pick off the worms by hand (either in the field, or as I husk) and cut off the damaged ends (I keep a bucket of soapy water beside me as I husk). Choosing varieties with tight husk cover will restrict damage to only the tip of the ear.