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The 2008 tobacco growing season is over, stripping is under way and receiving stations will be opening soon. But now is the time to start planning for next year and LaRue County farmers need to begin prepare to manage diseases in the 2009 burley crop.
Even with the drought, Black Shank was our biggest disease problem this year, but there’s no way to tell what disease pressures growers will face in the coming growing season. Much depends on the climate when dealing with diseases like blue mold and target spot. However, some problems and diseases will show up again and again once they become established in a transplant system or the field.
It is important to think about managing diseases like Pythium root rot, target spot, black shank and Fusarium wilt now and not wait until the upcoming production season. A critical step is to have or begin good sanitary practices on the farm. Many diseases seen in outdoor floatbeds or the greenhouse float system and in the field survive between crops on equipment and plant residues.
Greenhouses and outdoor float beds should be thoroughly cleaned and sanitized this fall to reduce overwintering populations of disease causing organisms called pathogens. Plant debris and trash should be buried or burned. Styrofoam transplant production trays should be carefully cleaned, sanitized as recommended (or destroyed), and properly stored before winter sets in.
In the field, especially where black shank was a problem, all crop debris needs to be turned under as quickly as possible after harvest. The black shank pathogen (as well as Rhizoctonia and Pythium) survives very well on crop residues, and stalks left in the field can be a source of inoculum that can lead to outbreaks of disease in 2009.
By plowing crop residues under in the fall, microbes in the soil will have more time to break down plant matter that harbors pathogens. This in turn will help reduce pathogen survival over the winter, and the effect will be greater than waiting until next spring to incorporate crop residue.
It’s also time to think about crop rotation. One of the best practices that we can recommend for preventing or suppressing diseases like black shank and Fusarium wilt is rotation to a non-host crop. Even though we are many months from planting, growers need to start the planning process and make decisions on field choice and potential rotation crops.
Fall is also a great time to think about variety selection and to begin planning for the production of transplants. Variety KT 206 has improved resistance to black shank (both Race 0 and Race 1) along with moderate resistance to blue mold. (Blue Mold was not a problem this year with the drought, but next year may be different). This variety has performed well in field trials during the past couple of years, and will be a good choice for growers with a history of black shank on their farms.
Other varieties with medium to high resistance to both races of black shank are KT200LC and KT 204LC. Popular variety 14XL8 has extremely high resistance to race 0 of black shank but no resistance to race 1. It is believed that both races are generally present in a field.
For more information on tobacco variety disease resistance levels, relative yields, maturity and other characteristics call or contact the Extension Service. The office also has information on tobacco disease management or other tobacco production issues.