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Thursday, July 31, 2014

Hollow husk a growing problem in hybrid corn

Monday, March 26, 2012

Recently in the field, we have seen some strange looking ears of corn.

The ears of corn look malformed. Some ears have fully developed kernels in some spots, and have other spots where there is no kernel development. The ears are shorter and the tip of the cob may be stunted.

This can be distressing and troubling to many farmers. This problem is called arrested ear development, or in layman's terms, hollow husk. This is a physiological disorder that can, in some cases, severely affect yield. Some farmers have had whole fields where the ears are malformed and have lost over 80 percent yield.

There are a number of factors that can cause arrested ear development such as stress to the plants and the application of nonionic surfactant adjuvants.

Reports of arrested ear development seemed to spike during the 2007 growing season and the reports seemed to coincide with increased foliar fungicide applications that were applied about one week before pollination started.

The researchers at Purdue set out to figure out what was going on. The researchers discovered that when they applied a nonionic surfactant prior to tasseling without a foliar fungicide, they could cause arrested ear development. The highest risk of arrested ear development seemed to occur when the plants were treated one to two weeks prior to pollination. Ear development can be seen to be effected as little as seven days after an application.

Arrested ears show abnormal development at the tips of the ears while the base of the ear may seem normal. The ear will be shorter, have significantly fewer kernels, and have a dried stunted tip. In a severely arrested ear, the kernel development and the cob development may cease entirely.

The husk also shows some symptoms early on and the symptoms can increase as the grain fill progresses after pollination. Arrested ear husks look more slender and the tip may be pointed due to an underdeveloped ear shot. The husk will have the same number of leaves and the length of the outer husk leaves remain about the same. The husks will feel hollow when squeezed.

This is where the layman's term, hollow husk, comes from.

The inner leaves of the husk will have a crinkled appearance and are shorter than normal. The silk of an arrested ear will be greatly reduced or may be nonexistent in a severely arrested ears. This is due to the underdeveloped kernels, shape, and tightness of husk leaves.

The leaves themselves show very little symptoms until grain fill when the leaves may turn purple or even red. The stalk may display the purpling too. This coloring is due to a higher sugar content in the leaves because the plant is developing fewer kernels. However, red leaves can also be a sign of poor kernel set, not just arrested ear development.

Arrested ear development can be reduced or eliminated by not spraying any chemical containing a nonionic surfactant during the growth stage of V10-VT which is about two weeks before pollination to tasseling. Many chemical labels recommend not to use products during stages V8to VT. Read the labels carefully.

More research is continuing to determine which nonionic surfactants sprays present the highest risk. More information is available in the publication Arrested Ear Development in Hybrid Corn, Publication number BP-85-w. For more information about arrested ear development please contact Ann Delchambre 765-653-8411 or email adelchambre@purdue.edu .

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