Sunburn, Sunscald

Wide parts of tissues turning brown and gradually drying up (figures 1 and 2) are observed on some growing tobacco leaves, particularly exposed to sunlight during periods of extreme heat. These leaves are very succulent, and when they are exposed to very low relative humidity and high temperatures, they will partially wilt and dry up especially on the leaf margins and at the tip. This phenomenon is usually observed in a quite small number of leaves.
 
This non-parasitic disease (sunburn, sunscald) could also be favoured by root injuries related to tillage and occur more easily in soils that favour asphyxia, thus it reminds of waterlogging (drowning). The symptoms may be confused also with damage caused by bugs.