BY MELODY ROSE
Tobacco growers in Northeast Tennessee are urged to be on alert and make protective fungicide applications following discovery of blue mold near Abingdon, Va.
Dr. Chuck Johnson, plant pathologist at Virginia Tech University, reported fresh lesions of blue mold in a large burley field on Monday.
Growers should be on the alert and make a protective fungicide application.
Rainy weather that brought about this particular case of blue mold has subsided, but scattered thunderstorms are still in the forecast for the next few days.
It is very important to consider the following tips and recommendations since Virginia borders Tennessee, officials at the Greene County Extension Office said.
Dr. Steve Bost, plant pathologist with the University of Tennessee, recommends spraying with Actigard, Revus, Forum, and Quadris as choices.
No mancozeb products are labeled for use on tobacco in Tennessee at this time.
Dithane has not had a tobacco label for a couple of years, and Dow has no plans to add one, Bost said in a news release.
The Section 24c (SLN) labels for Manzate ProStik and Penncozeb have expired.
The registrant, Uniphos, is considering renewing the SLN's.
The Quadris label requires alternation with a non-related fungicide.
If blue mold is the only foliar disease of concern, Actigard and Revus will fill the bill.
Restrictions on the use of Actigard will come into play. The label prohibits use on young tobacco (less than 18-inch height for burley, 12-inch for dark) and on stressed tobacco.
A lot of tobacco continues to feel the effects of drowning and sunscald.
Where Actigard use is not appropriate, Revus or Forum can be used, and have immediate effect, as opposed to Actigard's five-day plant activation period.
OTHER FOLIAR DISEASES
In mancozeb's absence, only Quadris has activity against leaf spot diseases other than blue mold.
Growers who desire foliar disease control other than blue mold will be limited to one application of Quadris, since the Quadris label requires rotation with a non-related fungicide that has activity against the target disease.
The heavy rains caused some drowning, sunscald on wilted leaves, and various types of necrotic spots of a non-pathogenic nature.
The use of Quadris in such fields is not recommended unless needed for fungal leaf spot control.
These spots do not pose a threat that Quadris will alleviate, and the use of this fungicide could cause further spotting by enhancing weather fleck as we move into more intense ozone-type weather.
With the exception of Actigard, these fungicides must be applied with drop nozzles, to protect any leaves other than the upper ones.
Quadris, Forum, and Revus have absolutely no downwardly systemic activity in the plant.
If the plants are more than about 18-inches-tall, very little protection will be provided to the lower leaves when a fungicide is applied with a horizontal boom.
For more information, call 423-798-1710.