Search NC Small Fruit, Specialty Crop, and Tobacco IPM

Friday, July 23, 2010

Mystery holes on tobacco stalks

Tobacco stalk with holes.  Photo: Norman Harrell.

Wilson County field crops agent, Norman Harrell, sent me an email with the above picture attached.  A grower brought in the tobacco stalk concerned about what could be causing the holes.  I see this type of damage every year around this time, and it is not of economic concern.  Although any chewing insect (ie. crickets, beetles, grasshoppers) could potentially cause this type of injury, it's most likely due to either tobacco budworms or tobacco/tomato hornworms.  While these caterpillars typically feed on leaf tissue, they may occasionally take a bite out of the stalk.  Stalk injury like this does not impact the plant, and does not suggest that further damage is likely (unless hornworms are found when scouting).  The threshold for hornworms in tobacco is 1 inch-long or larger hornworm per 10 plants with parasitized hornworms counting as 1/5 of a worm because they eat approximately 1/5 of that of a healthy caterpillar.

Bottom line, however, is that stalk damage of this type may be caused by several insects, but is nothing to worry about!

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