I noticed just the other day that most home garden sweet corn is either right or already silking. Silking in the world of corn is when very fine shiny, thread-like fibers grow out the tip-end of the ear of corn. Thus the warning about the corn earworm.
You see, the ever dreaded corn earworm is a prevalent pest that just loves some sweet corn. Adults are light tan moths with 1-1/2 to 2 inch wingspans while the actual earworms are variable in color.
They are found feeding most of the time in the corn ear tips. The larvae are cannibalistic, rarely is there more than one per ear of corn. Oh don’t we just hate that. Poor little critters will fight to the death defending an ear of corn.
The Pupae overwinter in the soil with the adults emerging in the spring. These critters are known to travel long distances to feast upon sweet corn. Females lay eggs on undersides of leaves or tips of corn ears, with the eggs hatching in 2-10 days and larvae feeding for 2-4 weeks. The little boogers get a belly full then leave the ear and drop to the soil to pupate. Yes, to start the process all over again, with adults emerging in 10-25 days. There can be 1 to 4 generations per year. Yeah, such joy.
The larvae start out feeding on fresh silks and then move down the ears eating the kernels and leaving trails of well you know, stinky.
Conventional: use an insecticide containing either bifenthrin, cyfluthrin, or permethrin. Mix the insecticide in a sprayer with water (according to the insecticide label) and apply.
Direct the spray at the center third of the plant which is where the corn ears can be found and thus need protecting. This preventive program should begin when 10% of the ears are silking. Repeat sprays at three to five day intervals until 90% of the silks have wilted (turn dark brown) this should give good control. One gallon of finished spray should treat 150 to 200-row feet of sweet corn.
Organic: use an organically approved insecticide containing either pyrethrins, spinosad, or neem making sure to follow the directions previously mentioned.
It is very, very important to protect the ears of corn during early-silking and continuing until the silks turn a dark brown.
You will not get 100% control of these critters but don’t fear. All is not lost. Just take a knife and cut out the bad part of the corn before cooking. The remaining ear of corn will be clean and edible.