This last step will prevent the spores from being released to infect later plantings.

Corn earworm.

Insects: Many species of insects are known to attack and damage sweet corn at all stages of its growth. Those that attack the plants early are more apt to cause serious damage, and they need to be dealt with promptly. These include the southern corn rootworm, cutworms, white grubs, wireworms and flea beetles. You can get some protection against the rootworms, wireworms, and grubs by using seed treated with a combination fungicide-insecticide. Cutworms and flea beetles may require an application of insecticide for control.

Insects attacking sweet corn later in its growth are corn borers, army-worms, aphids and the corn earworm.

Several insecticides are available to control them. Recommendations for specific compounds to use and rates of application can usually be obtained from a reputable garden supply center.

Once the sweet corn becomes established and attains most of its plant growth it can withstand a surprising amount of insect feeding without drastic loss of yield. Earworms that begin feeding on the silks and burrow into the ear tips are difficult to control. Unless the infestation is extremely high and damaging, most damaging, gardeners choose to ignore the worm at the tip of the ear, merely clipping off the ear tip and any damaged kernels when the corn is husked.

Most State agricultural experiment stations publish current recommendations for controlling insects on sweet corn. These bulletins and circulars can be obtained by writing to your State Agricultural Extension Service.

Harvesting

Sweet corn should be harvested when the kernels are in the milk stage. At this stage the silks are brown and dry beyond the end of the husks and the ear has enlarged enough to fill the husks tightly to the tip. The kernels are about as large as they will become, but they are still soft, tender and filled with an opaque milky juice.

With some experience the optimum maturity for harvest can be recognized by sight and feel. The husks should never be disturbed to peek at the corn as this will permit insects and birds to invade the ear.

Another way to estimate harvest time is to note the date of silk emergence on the earliest plants in a row, then harvest those ears 17 to 24 days later. The number of days from silk emergence to prime harvest will vary according to weather conditions. If days and nights are exceptionally warm, prime maturity may be reached 17 or 18 days after silking. If cooler weather prevails during this period, it may require 22 to 24 days. After picking a few ears, you usually can make an accurate determination about harvesting the remainder of the corn at its prime maturity.

Sweet corn passes through its prime maturity very quickly. With uniform hybrid varieties the harvest of a single planting will last only about 4 to 5 days. If harvest is delayed the kernels become tough, starchy and lose their sweet flavor.

Sweet corn also loses its quality rapidly after it has been picked from the plant. For best quality, the corn should be picked early in the morning and refrigerated immediately. The sooner it is prepared for serving the better, but it can be held in a refrigerator (35 to 40 F) for 2 to 3 days with only a moderate reduction in eating quality.

To harvest corn, break the ear shank as close to the ear as practicable without breaking the main stalk or tearing the entire shank from the stalk. Grasp the ear with one hand near its base and bend it sharply downward or to one side with a rotary motion of the wrist. The inexperienced may need to use both hands; hold the shank with one hand and use the other to snap the ear off. With practice and a strong grip, the ears of most varieties can be snapped off with one hand.

Fully mature and well-developed ears of sweet corn.

Many of the modern hybrids under optimum fertility and growing conditions will produce two nice ears per plant. The top ear will be the dominant one, and it will reach prime maturity a day or so ahead of the second ear. Under such conditions a 100-foot row should yield 100 to 120 nice ears.