COLUMN: Manage disease in end-of-season tobacco harvest

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By Bryce Roberts

With the 2012 tobacco growing season coming to an end, growers are working hard to get their crops into the barns. On one hand, the dry conditions of this past summer have kept leaf diseases like frogeye and target spot in check and we have not seen any blue mold. On the other hand, we saw more black shank and Fusarium wilt than we have for the past three or four years.
Looking forward to the next growing season, it’s hard to say what will be the big disease issue. So much depends on the climate when we are dealing with diseases like blue mold, target spot and frogeye. We do know however; that some problems will show up again and again once certain pathogens get established in float beds or the field.
We need to begin thinking about diseases like Pythium root rot, target spot, black shank and Fusarium wilt and how to get a head start on managing them next season.
A critical step you can take is to evaluate your sanitary practices on the farm. Many diseases we’ll see in the float bed system and field survive between crops on equipment and plant residues. You should thoroughly clean and sanitize greenhouses, trays and outdoor float beds in the fall to reduce overwintering pathogen populations. Make sure to bury or burn plant debris and trash.
In the field, especially where black shank may have been a problem, it’s important to turn all crop debris as quickly as possible after harvest. The black shank pathogen survives very well on crop residues and stalks left in the field can lead to future disease outbreaks. By plowing those crop residues under in the fall, you will allow the soil microbes more time to break down plant matter and reduce survival of the pathogen.
One of the best practices for preventing or suppressing diseases is rotation to a non-host crop. Even though we are many months away from planting, you can start the planning process and make decisions about field choice and potential rotation crops. Fall is a great time to think about variety selection and begin planning for transplant production. Varieties such as KT 210, KT 206 and KT 209 continue to perform well against black shank, and KT 210 offers a good combination of black shank and Fusarium wilt resistance. We should also see a wider availability of KT 212, an early-maturing variety that is similar to 14 X L8, but with moderate resistance to race 1 black shank.
Feel free to contact me at your Spencer County Cooperative Extension Service at 477-2217 or you can email me at broberts@uky.edu.  You can visit the Spencer County Extension Services’ website at www.spencerextension.com.
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