Field Notes, July 19, 2010, Glyphosate Injury, Sheath Blight, Brown Spot

Glyphosate Effects on Rice Panicles

 

When glyphosate drifts on to rice when rice is in the boot stage symptoms are seldom noticed until the crop begins heading.  In this case drift was suspected on several ages of rice.  When stems of plants in early boot were split these deformed panicles were found.  Note that in the panicle at left one kernel is developing normally while all others are not.

Herbicide Injury to Rice Growing Points

 

Again splitting stems exposed dead or severely injured growing points of these rice plants.  Herbicide injury is suspected.  Plant samples were taken to try to determine the causative agent.  Glyphosate and Newpath are the current suspects.

Brown Spot of Rice

When I first saw the sypmptoms shown here and the pattern in the field I thought gramoxone had drifted on the field.  That was quickly eliminated when a survey of surrounding vegetation showed no injury.  History of the field provided a clue.  The farmer had laser leveled the field in the spring.  Brown spot is a disease often assoicated with nutrient deficiency and that is the likely cause here.

Sheath Blight on Rice Panicles

 

When sheath blight of rice is severe it moves up the plant rapidly.  From the flag leaf sheath it will then infect the panicles resulting in one of the most severe forms of the disease.  When this level of disease is prevalent in a field major yield reductions can be expected.  Fungicides applied earlier could have prevented it.

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