What is in this article?:
• Before the rains, Kentucky tobacco was sufferubg nutrient deficiencies directly related to poor root development.
• Rains and the sudden development of severe spotting after the heavy rains has raised concerns that a new and explosive leaf disease is occurring.
AFTER heavy rains left the crop crippled, Kentuck tobacco specialists are concerned that a new and explosive leaf disease is occurring in the state.
Something can be done
The biggest question of all is what to do in fields where this syndrome is occurring. The difficulty in making a recommendation right now is that we really don’t know the exact cause (or causes) of the problem. Until we get a better handle on the situation, the following are some points to consider:
- Although there’s not a pathogen associated with what we are seeing, we are concerned that extensive damage to the foliage will make it more susceptible to target spot and possibly brown spot. An application of Quadris is recommended for growers who have not applied it already. The standard 8 fl oz./acre rate should be sufficient, and growers who are seeing disease already should consider a rate of 10 to 12 fl oz./acre.
- The nutritional problems that we’re seeing right now are not generally associated with deficiencies in the soil, but instead are a result of the inability of roots to reach nutrients that are already there.
- Side-dressing would be of potential value if nutrients can be placed into the root zone without creating additional damage.
Thoughts on fertility strategies include:
- For tobacco that is waist-high or bigger, do not apply more than 25 pounds of actual N per acre.
- For tobacco that is smaller than waist-high, use no more than 50 pounds of actual N.
- Ammonium nitrate would be the ideal N source, but liquid N (UAN) would be an acceptable alternative.
- For potash, 100 pounds /A of sulfate of potash (0-0-50) should be sufficient.
- Foliar nutrient applications historically have not resulted in yield increases. However, under current conditions a foliar application may be effective to deliver a quick dose of nutrients to the crop.
- The most likely benefit from foliar application of fertilizer would be correction of micronutrient deficiencies.
- It will be less likely to see benefits from N, P, and K with a foliar application.
- Be aware that foliar fertilizers can cause leaf burn; do not apply excessive amounts in any one treatment.