Disease Management for Transplant Systems

There are two other areas of tobacco production that we need to be concerned with as far as controlling diseases. Plant diseases that are spread by wind or diseases spread by insects.

Wind

Blue Mold is our biggest concern here, at one time we could just use Ridomil at setting time and all of our worries would be taken care off. But that was before Blue Mold developed a strain that was resistant to Ridomil.

 Cultural practices such as location of field plays a part in Blue Mold. Tobacco set where you can get good air movement want have as much problems with Blue Mold. Tobacco set next to woods or close to streams will have more Blue Mold. Tobacco fields that has tobacco set closer together in the rows and with narrower rows can have more of a problem. Also tobacco that has leaves that hang down instead of growing up the stalk can have more of a problem. So select a location with good air movement and don't set too high a population of transplants. I would select a variety based on yield and resistance to Black Shank first if Black Shank is a problem and not worry too much about the growth habit of the tobacco.

Syngenta developed a product called Actigard that works well for Blue Mold. The tobacco plant needs to be at least 18 inches tall, application before the plant reaches this height can result in crop injury. Usually Blue Mold doesn't blow into Kentucky early enough to infect tobacco earlier than this. Make an application of Actigard at 18 inches using 0.5 oz/ac, wait 10 days and make another application at the same rate. That should take care of Blue Mold. There has been another fungicide called Quadris that has had a Section 18 label for use on tobacco. The company is trying for a full federal label this year, but so far haven't received it. Quadris has been labeled for Frog Eye Leaf Spot, but this fungicide could help protect our tobacco that is under 18 inches tall for Blue Mold, other folar diseases and also on Black Shank, but I don't know if it will carry that on the label

Insects

There also is a class of diseases caused by viruses. Now we know that you can't cure a virus disease once the plant has got it. These viruses are carried by insects, such as aphids, flea beetles and thrips. There is even a situation when two or three of the viruses together infect a plant called a virus complex. Some varieties carry resistance to this virus complex, check the disease traits for the variety that you select. Some of the viruses diseases that you will see are; Alfalfa Mosaic virus, Tomato Spotted Wilt virus, Tobacco Mosaic virus and Tobacco Ring Spot virus. The best way to control these diseases is to control the insects that carry them. Use Admire or Platinum as a drench on your trays or in your setter water. Check the label for rates, recommendations and restrictions.

Now there is one exception, Tomato Spotted Wilt virus is spread by a small insect called a thrip. This small insect is carried in from the Gulf states on the wind. It is blown in and feeds on the bottoms of the leaf. By the time you notice the damage, the thrip is long gone. You will see scattered plants throughout the field start to wilt down on one side, then parts of the leaf will turn down. When this first starts to happen you may even think that it is black shank damage. This is a disease that once it starts to become noticed there is nothing that you can do. Usually it just happens once and does not continue to happen throughout the growing season. So control the aphids and flea beetles and you want see much of these diseases.

Major Problems

Black Shank: resistant varieties, use Ridomil

Transplants: Terramaster, control pythium, set a good health transplant

In the Field: use Admire or Platinum to control aphids or flea beetles, Actigard for Blue Mold and take a look at Quadris. This will be a very important fungicide if it can get a federal label. A healthy leaf with no diseases taking a portion of that leaf gets us more pounds to the acre and it takes just as much labor cost to harvest a 2400 pound to the acre crop as a 2800 pound to the acre crop.