Published at the Chat 'n Chew Cafe, July 2000

Scrambled Silks, Anyone?

R.L. (Bob) Nielsen
Agronomy Dept., Purdue Univ.
West Lafayette, IN 47907-1150
Email address:

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This article is admittedly fearmongering on the part of your friendly neighborhood corn specialist, but I figure it is my prerogative and responsibility to do so when I believe conditions are ripe for the development of a potential crop problem. If the problem does not occur, then growers will be relieved and they will forget I said anything about it. If the problem does occur, then I will look pretty smart for having forecast its development.

Click for larger imageThe potential problem of which I speak is a phenomenon traditionally called 'silk balling'. I prefer the name 'scrambled silks' because I think it is more descriptive. The problem is one in which silk elongation, prior to their emergence from the husk leaves, is interrupted or altered, resulting in a mass of scrambled silks near the tip of the cob that never fully emerge from the husk. Obviously, any silks that fail to emerge from the husk will not exposed to any pollen and consequently will not contribute to the formation of kernels on the cob. The net result is some degree of barrenness on the cob and, consequently, lower yield.

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Scrambled silks is a relatively infrequent problem and its causes are not well understood. Some believe that the occurrence of cool nights (low 60's or cooler) prior to silk emergence plays a role in the development of scrambled silks. Others believe that rapid changes in temperature patterns (e.g., very warm to very cool) prior to silk emergence encourages the problem. Hybrids with naturally tighter husks seem to be more susceptible to developing scrambled silks.

Given these opinions on temperature factors that may contribute to the problem, one could speculate (some would say fearmonger) that recent unusually cool nights throughout the central and northern parts of Indiana, plus the current forecast for more of the same, may lead to an increased occurrence of scrambled silks this year.

Click for larger imageUnfortunately, there is nothing you can do about preventing or avoiding the problem. Nonetheless, it would be prudent to walk some of your fields during or after pollination and look for evidence of the problem. Typically, the severity of the resulting poor kernel set is low and concentrated near the tip end of the cob. However, I've seen situations in the past where scrambled silks resulted in severe barrenness in nearly 1/3 of the plants in a field.

If you don't have time to walk your fields right now, any affected plants will likely raise red flags later on in the grain filling process. By this, I mean that any plants severely afflicted with barrenness will eventually develop purpling or reddening of leaf midribs, leaf sheaths and other plant parts.

Click for larger imageThe reasons for this discoloration are similar to those for purple corn earlier in the growing season. An otherwise healthy plant whose ear is highly barren of kernels is a plant that is overproducing photosynthate (source) relative to the demands of existing kernels (sink). The excess sugars in the leaves and stalk trigger the formation of anthocyanin pigments in the plant tissues, especially in those hybrids with quite a few of the purpling genes. The similarity to early season purple corn is in the connection between excess plant sugars and anthocyanin production. Early in the season, excess plant sugars often result when root development is hindered for some reason.

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Corn Growers GuidebookFor other information about corn, take a look at the Corn Growers Guidebook on the World Wide Web at

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