The recent excessive rainfall in potato fields can cause anaerobic conditions, making potatoes susceptible to bacterial soft rot, lenticels openings, and blackheart among other problems. Excess water causes cells to deteriorate and make seed pieces weak or even prevent them from establishing a healthy canopy. If there are tubers setting, these tubers will be unable to obtain sufficient oxygen causing the lenticels to open to obtain oxygen. When this happens it allows bacteria to enter. Once bacteria are present in the lenticel they can multiply and cause rotting of the tuber or the bacteria can enter a latent phase. Lenticel spot is a result of the latent phase which is typically the result of the lenticel closing and a corky layer being formed over the bacteria. Lenticel spot typically starts in the field and is enlarged in the storage and packaging process. Anaerobic conditions can also lead to blackheart. During tuber development, conditions that favor low-oxygen availability can lead to the development of blackheart. A water film surrounding the tuber (oxygen diffuses slowly through water) and water-logged soils also will favor blackheart development. Blackheart development is intensified when the temperature is high because respiration rates of potato tubers are greater in high temperatures, while lower temperatures need a longer period of time for symptoms to develop.

We are interested in obtaining samples of bacterial rots to characterize what types are present in potato tubers. If you suspect bacterial rot, please contact me or send me a sample of a few tubers. Or go to PotatoDr.com if you want to send me a picture of a questionable potato.