2005 Blue Mold Epidemic in North America
Annual Report from the North American Plant Disease Forecast Center
December 2, 2005
Dr. C. E. Main, T. Keever, M. Miller
North American Plant Disease Forecast Center
Department of Plant Pathology
North Carolina State University
Raleigh , NC
The end of the 2005 tobacco growing season marks the end of the 10 th year of blue mold forecasts provided by the North American Plant Disease Forecast Center (NAPDFC). Forecasts were issued via the internet three times a week on Monday, Wednesday, and Friday through the bulk of the growing season. Additional forecasts were issued when warranted by threatening weather patterns or special events. Forecasts were also made available via a toll-free telephone “hotline” for growers without ready access to the internet. Visitors to the NAPDFC website were given up-to-date information about the current status of the blue mold epidemic and impending transport events across the North American continent. Users could find maps and detailed information about individual disease reports and locations. Such information is important in assisting growers in managing their crop and assessing their risk for developing blue mold. For the 2005 growing season, the NAPDFC issued more than 430 unique forecasts from March 18 th through September 19 th.
Blue mold occurred in most of the tobacco growing regions during 2005. Unusually, blue mold infection was sparse with sources more isolated than in previous years. Also unusual was that the southern Georgia and South Carolina growing areas remained uninfected. 2005 is the second year in a row in which there was no blue mold activity reported in Florida or Georgia. In total, 29 counties reported blue mold across 9 different states.
The NAPDFC does not know the impact of blue mold on this year’s harvest at the time of writing, but indications from the field suggest a lesser impact than in years past. The area hardest hit by blue mold was the Ohio Valley region. This area had the largest scattering of infected locations with 15 counties reporting disease. Six counties reported blue mold in the normally susceptible southern Appalachian area. The large growing areas on the southeastern Coastal Plains had only three counties report infection.
As in 2004, the 2005 blue mold epidemics began in an unusual fashion. The first report of blue mold in the US came from northern Kentucky. Normally, blue mold finds its way into the US from Cuba and first takes hold in the southeastern US in March or April. Also strange, was the timing of the first case of blue mold in the US. The first case was reported at the end of June; very late in the season. Blue Mold has most often appeared in the US in the early spring. Currently, the NAPDFC believes that the first case of blue mold in Kentucky was related to a long distance transport event beginning in east Texas. We believe that wild tobacco, infected with blue mold, may have been the source on the Kentucky infection. However, this cannot be confirmed, and the NAPDFC has received no reports of blue mold on wild tobacco in east Texas. Additionally, our analysis of meteorological data from the suspected period of infection has not shown a specific transport event that can support this scenario. As a result, overwintering or transport from another location remains a possibility.
Once blue mold took hold in northern Kentucky, it spread to northern Tennessee, southwestern Virginia and southeastern Pennsylvania quickly. Most transport events for the season were short-range cases, where blue mold would jump no more than several counties. Only three long-range events were successful in transporting blue mold a significant distance. Eastern Maryland, southeastern Pennsylvania, and the Connecticut River valley were all infected due to long-range transport events.
The summer weather patterns had a direct bearing on the spread of blue mold this season. The 2005 summer was one of the hottest and driest on record for much of the south and east. The strong sunlight and absence of moisture inhibited both sporulation and subsequent spore survival. Furthermore, very few strong frontal systems were able to penetrate into the tropical air that occupied the southern and eastern US and thus could not act as a consistent mechanism for facilitating long-range transport events. High pressure, frequently in control of the weather over the South, kept transport events originating from traditional overwintering locations in Cuba and Texas away from US growing areas, delaying the onset of blue mold until much later in the season than is usual.
We at the NAPDFC would like to express out pleasure in announcing the fact that our forecast services for blue mold were more popular than in any previous year. The NAPDFC website underwent extensive redesign in an effort to create a better forecast product for our users. At the peak of the forecast season, the NAPDFC blue mold forecast site received 800-1000 visitors a day and average around 1,000,000 hits per month. We have never before received this kind of traffic and interest and we would like to thank our users for helping to make this forecast season a success.
This represents a short report describing the 2005 blue mold epidemic. A more complete report will be available at a later date following detailed analysis of all disease reports, meteorological records, and state impact data. The complete set of day-by-day forecasts can be reviewed on the NAPDFC’s website: http://www.ces.ncsu.edu/depts/pp/bluemold/
The NAPDFC thanks all the reporting coordinators for each state and adjoining countries for their participation during 2005. If you wish to become part of the forecast system, or need further information, contact C. E. Main or the NAPDFC directly. For a complete description of the NAPDFC, refer to the APSNet feature article, “Forecasting Long-Range Transport of Downy Mildew Spores and Plant Disease Epidemics” at http://www.aspnet.org/online/feature/forecast/
Dr. Charles Main
NAPDFC Leader
ce_main@ncsu.edu
Thomas Keever
Lead Forecaster
thomas_keever@ncsu.edu
First Reports of Blue Mold to the NAPDFC in 2005 (a)
| County/State | Date Reported | Probable Source (b) | Impact (c) |
| Hardin/KY | 6/30/2005 | East Texas? | Not Yet Known |
| Lancaster/PA | 7/7/2005 | Western VA | Not Yet Known |
| Overton/TN | 7/9/2005 | East Texas? | Not Yet Known |
| Washington/VA | 7/11/2005 | KY/TN | Not Yet Known |
| Hampden/MA | 7/15/2005 | PA | Not Yet Known |
| Rockingham/NC | 7/15/2005 | KY/TN/VA | Not Yet Known |
| Buncombe/NC | 7/17/2005 | KY/TN/VA | Not Yet Known |
| Dane/WI | 7/24/2005 | Ohio Valley | Not Yet Known |
| St, Mary’s/MD | 8/3/2005 | Several Candidates Possible | Not Yet Known |
| Jefferson/IN | 8/5/2005 | KY | Not Yet Known |
- (a) Occurrence confirmed by a state coordinator or other expert
- (b) Some first occurrences could be the result of multiple sources
- (c) Information will be updated as it is made available to the NAPDFC
[Return to Blue Mold Homepage]