Wet, Mild Summer Increases Chance for Disease Spread in Tobacco Crops

Aug 17, 2015

Credit Todd Shoemake Flickr (Creative Commons License)

Kentucky’s tobacco farmers have had a relatively cool and wet summer, and that could be the culprit for higher crop disease rates.  

University of Kentucky Plant Pathologist Emily Pfeufer says farmers are reporting higher cases of black shank and bacteria-based diseases like angular leaf and target spot. 

"Black shanks is something we're getting more reports of," said Pfeufer. "Black shanks is called by a oomycetes Phytophtora nicotianae and we're seeing it a bit more in burley tobacco than dark tobacco.  What growers are seeing a little more frequently in dark tobacco is angular leaf spot caused by bacteria, and then we're also seeing in both tobaccos stains of target spot and frog eye." 

Although bacteria can be prevalent year-round, this year’s rainy summer opened a higher chance for spread.

“Bacteria pathogens infect through wounds or natural openings, and some wounding can be caused by wind-driven rain and we’ve certainly had our share of rain," said Pfeufer. "The rain splash is also helping the bacteria move from plant to plant and so that’s definitely played a role in some of our bacteria disease pressure.”

Disease remains one of the biggest threats to farmers and have the potential to wipe out entire yields. 

Pfeufer says there have been some reports of black shank, a root and crown rot disease found in all tobacco plants, has been found to become resistant to some protective sprays.

" But that doesn't necessarily mean reducing your use of chemicals but using more targeted fungicides that specifically target the black shank pathogen and then using those chemicals in combination with resistant varieties that we have available to us. We have good resistant burley and decent resistance in dark tobacco. But those fungicides need to be apply to the soil and worked into the ground to be most effective because they need to be taken up by the plant root."

Pfeufer also recommends farmers rotate tobacco fields and using buffer crops.  

"Growers can plant cover crops like rye, vetch or corn and then we suggest coming back with tobacco in three years so that will reduce the pressure from black shank." 

According to the US Agriculture Department, Kentucky is the highest exporter of burley tobacco which is grown in 110 out of 120 counties.