New option available for black shank control in tobacco

The Kentucky Department of Agriculture granted a Special Local Need, or 24(c), label to Syngenta Crop Protection on March 21 that allows the application of Ridomil Gold SL in the field at rates of 4 to 8 fluid ounces/A to burley and dark tobacco in setter (transplant) water.  This represents a major departure from what the manufacturer and University of Kentucky Extension has recommended to producers going back to when Ridomil was first introduced in the 1980s. What follows is the story of how we got to this point, and how we can use this new control tactic to help manage black shank on tobacco.

Work done in Grant County from 2008 to 2010 has shown that 8 fluid ounces/A of Ridomil Gold applied in setter water is as effective in suppressing black shank as 1 part/A applied broadcast to soil before planting on KT 204, KT 206, and KT 209, varieties with high (7-level or above) race 0 and race 1 resistance.  However, the setter water treatment did not perform as well as broadcast-applied Ridomil on varieties like KY 14 x L8, TN 90, or KTH 2901, which have 4-level or lower resistance to either race 0 or race 1 black shank.  We also noted that the setter-water treatment at 8 fluid ounces/A was similar to 1 part/A applied as a broadcast spray in years when disease pressure was low, but was outperformed slightly in terms of yield by the broadcast treatment when disease pressure was higher, even on a variety with relatively high resistance to black shank, KT 204. 

This newly-approved application method will not completely replace the standard, higher-rate method, based on our results.

Setter-water treatments with Ridomil will be best suited to growers using sound management practices (sanitation and crop rotation) along with one of the newer resistant varieties, and who are looking for additional protection from black shank.  In these cases, it will be possible to get adequate control of disease and also reduce fungicide costs by about $70/A.

Where disease pressure is high, particularly if limited crop rotation is being practiced, or where varieties with little or no resistance are being planted in fields at risk to black shank, broadcast-applied Ridomil at 1 part/A would be a more effective treatment.

To get the best results from Ridomil Gold SL when applying in transplant water, follow these guidelines:

1. Use good management practices and plant a variety with moderate to high resistance to race 0 and race 1 black shank.

2. Use only Ridomil Gold SL in setter water.  Ridomil Gold EC and Ridomil 2EC contain high levels of solvents and can injure or kill tobacco seedlings. Likewise, avoid generic versions of mefenoxam or metalaxyl.  Only Ridomil Gold SL is covered by the new Special Local Need Label.

3. Add 4 to 8 fluid ounces/A of Ridomil Gold SL to no less than 200 gal/A of transplant water to avoid injury to tobacco.  Use the high rate in areas with a greater risk of black shank.

4. Make 1-2 supplemental, soil-directed applications at 1 part/A if needed to provide control of disease.

5. Do not apply Ridomil Gold SL to stressed or weak seedlings, or during hot, dry conditions to avoid serious plant injury.

6. Mix thoroughly before transplanting.  Using a separate tank to pre-mix Ridomil Gold SL will help ensure thorough mixing, and also help prevent problems with other pesticides or fertilizers that may be added to the setter water.   This will also help ensure a consistent concentration of Ridomil Gold SL during transplanting, resulting in less injury potential and better control of disease.   

Phase I signups

Applications are currently available at the Carroll County Extension Office for Phase I signups. You have until 4:30 p.m. on Wednesday, March 30 to complete the application. The sign-up this time has a 25-75 percent match up to $2,500. We will be able to take receipts that are dated from Sept. 21, 2010 through the end of the program. 

The applications will be scored the evening of March 30 and letters will go out by April 1 notifying you if you have been approved for the cost-share program.

No-till drills for lease

The Carroll County Conservation District no-till drills that used to be at States Rental are now based at the Conservation District Office. Contact the District at (502) 732-6098 or (502) 732-0070 between the hours of 8: a.m. to 4:30 pm Monday thru Friday for leasing information.

Beekeepers Association

The Carroll County Beekeepers will meet Monday, April 4, at 6:30 p.m. at the Carroll County Cooperative Extension Office. The group is open to anyone who is interested in bees. There are novice to very advanced beekeepers in the club so don’t be shy.

The meeting should be over for everyone to be home so they can watch Kentucky play in the national championship game.

4-H Camp

Carroll County will be going to 4-H Camp July 18-21 this year. Cartmell 4-Hers should have brought home a flyer about camp in their Monday folders this week. The camp fee this year is $165 and must be paid before leaving for camp. I have been telling the kids that we will work with parents if they need to pay in installments for camp. Your space is not held unless you have paid for camp. Applications are currently available at the Extension Office which is located at 500 Floyd Drive. We are by the fairgrounds located behind Wal-Mart and Kroger.

CRP signups

Conservation Reserve Program sign ups continue at the Farm Service Agency through April 15.  For more information on the general Conservation Reserve Program sign up, please contact your local county FSA office or access the website at www.fsa.usda.gov. Mike Benton and his staff will answer any questions and lead you through the process.

Tim Hendrick is the Carroll County Extension agent for agriculture and natural resources. Call him at (502) 732-7030 or send e-mail to thendrick@uky.edu.