Field Notes, June 28, 2010, Cercospora, chinch bugs

We used to call this disease Narrow Brown Leaf Spot, but because of its confusion with Brown Spot and the devastating impact it had several years ago we now refer to it as Cercospora.  Cercospora is the genus name of the fungus that causes the disease.  These symptoms tell us infection has already occurred, but is not the yield limiting phase of the disease.

This is  a close-up of some of the same leaves shown in the first photograph.  One major characteristic of this disease is the linear brown spots on the leaves.  They follow the veins of the leaves.  The phase that causes the most yield damage is the net blotch phase that shows up on the sheath of the flag leaf and on the stem.

Most of the time chinch bugs are a pest when they feed on young seedlings in rice fields that are not flooded.  Once the fields are flooded we usually forget about chinch bug injury to rice.  In this case seedling rice was being flooded late in the year and chinch bugs were reducing stand.  We expect the flood to take care of the problem.


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