What Causes Barren Corn?

Drought

• Dry conditions early in the plant's life can reduce or even prevent pollination. Bruce L. Vasilas and Richard W. Taylor, of the University of Delaware, explain that this problem arises from the "physical separation of male and female flowers on the plant." The tassels bear pollen, but dry conditions can kill the tassels. Dry silks produce little or no pollen, and without adequate pollen, the plant will be barren.

Corn Leaf Aphids

• Another problem with pollination, and thus with corn yield, is the corn leaf aphid. This relatively common pest produces a secretion called honeydew, which can gum up the tassels and inhibit pollen production. Ric Bessin, University of Kentucky entomologist, explains that corn leaf aphids usually infest plants late enough in their growth that they do not interfere with yield. They cause barren corn only when the infestation is severe enough and early enough to prevent pollination.

Other Pests

• Other pests can affect corn tasseling, which can inhibit pollination if it occurs early enough in the corn pollination process. In a lengthy report on corn problems for the University of Florida's IFAS Extension, David Wright and Jim Rich mention several pests that can be responsible for tasseling problems: cucumber beetles, Japanese beetles, grasshoppers and European corn borers. A University of Georgia study by Dewey Lee et al., also states that corn earworms and western corn rootworms are to blame.

Diseases

• Not all corn pests are insects. Diseases, both bacterial and viral, can inhibit tasseling. Both the studies by Wright and Rich and by Lee et al., point to anthracnose, which can bleach or dry tassels, and crazy top virus, which causes leaves to develop instead of pollen-producing tassels. Drought stress can exacerbate these problems.

Other Environmental Factors

• Some horticulturists blame environmental factors, in addition to drought, for barren corn. Wright and Rich point to boron deficiency, which can prevent tassels from emerging. Lee, et al. suggest that deficiencies in either phosphorous or nitrogen can also impair the development of corn silks. They also blame a condition called "silk balling," which results from sudden cool temperatures during tassel development, though this is more prevalent in some hybrids.