What Causes Blast in Oats?

Over the past week, I have seen pictures or samples of oat panicles where there are empty florets on the panicle.  Oat samples displaying the same symptoms have come into Manitoba Agriculture’s Crop Diagnostic Centre.  Mardi Desjardins, formerly of Manitoba Agriculture, provided the following information on Blast in Oats.

oat blast

Blast in Oats. Photo by Manitoba Agriculture (2014)

Blast in oats can be caused by stresses such as unfavorable growing conditions prior to emergence of the panicle, any time from floret initiation to panicle emergence.  It is a little different from heat sterility related to high temperatures at anthesis and “blasted” florets typically appear incompletely developed.

Factors most commonly linked to blast in oats include insufficient light due to cloudy conditions, temperature extremes, moisture stress, or physical damage from hail.  Florets begin forming several weeks prior to emergence of the panicle and if stresses occur during the development, the least developed florets at time of the stress tend to be aborted. The ones most commonly affected are those toward the base of the panicle and on inner branches of the panicle which are the youngest.  Blasted florets can however, potentially occur throughout the panicle or in a different area of the panicle.

The lower part of the panicle location in the picture above and the incompletely developed nature of the florets in the picture are classic for the environmentally caused “blast”.

Submitted by:  Mardi Desjardins, formerly of the Crop Diagnostic Centre & Pam de Rocquigny, Cereal Crops Specialist, Manitoba Agriculture

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