May 26, 2004

Strong blue mold activity is occurring in central Kentucky.  It is mainly associated with greenhouse float systems but also is present in outdoor floats and field plantings.

Activity has been confirmed in Taylor, Green and Jessamine counties, but is likely active in other counties as well.

“The disease is quickly going systemic in transplants causing some people to suspect root diseases rather then blue mold,” said William Nesmith, Extension plant pathologist with the University of Kentucky College of Agriculture. “Evidence collected at the sites supports the hypothesis that initial infections probably occurred in early May, meaning the disease has been cycling and building before the grower realized it was blue mold.”

Nesmith noted that in one county a greenhouse full of plants was destroyed by the disease before the grower was able to identify the problem. (See photos

No fungicide sprays were used in any of the houses at the center of the worst outbreaks, but light activity also was found in several operations receiving fungicide sprays.  Growers generally reported fungicide applications early in the season, but many recently had reduced fungicides as they held plants during wet weather and became busy with other farm activities.

“It’s important to appreciate that contrary to what was said in our May 14 report, considerable inoculum has been generated and was disseminated during the past two weeks right here in Kentucky, consequently blue mold is ahead of us and could build very rapidly as we experience disease-favorable weather,” Nesmith said.

Blue mold warnings have been issued for Green, Jessamine and Taylor counties where the disease has been confirmed.  Blue mold watches have been issued for the following counties that have likely received spores from the above outbreaks: Allen, Adair, Anderson, Barren, Bourbon, Boyle, Clark, Casey, Cumberland, Fayette, Garrard, Harrison, Lincoln, Madison, Marion, Mercer, Metcalfe, Monroe, Scott, Washington and Woodford.

Nesmith emphasized that priority should be given to transplants. Keep fungicide sprays applied for good coverage and as often as labels will allow.  Labeled fungicides for transplant systems can be found in the March 8 issue of Kentucky Pest News available at the College of Agriculture plant pathology web page .

“Growers from all states, including Kentucky, need to be aware of the risk Kentucky-produced transplants may pose to movement of blue mold to other states, and other counties in Kentucky,” he said.  “It’s logical to expect other states to recommend against use of Kentucky transplants now that we have active blue mold.  Kentucky growers are urged to use locally grown transplants to minimize movement of the disease within the state, especially movements counter to those provided by natural wind movements from known sources.”

For crops already in the field weekly fungicide sprays should be put in place immediately in counties under a watch or warning.  Growers statewide should prepare to spray in short order should a watch or warning be issued for their community.  Guidelines for field spraying can be found in the April 26 issue of Kentucky Pest News online .

Growers also should be incorporating cultural controls with emphasis on selecting varieties, reducing plant populations, managing fertility and reducing disease-conducive environments in the field.  Producers are urged to contact their county Cooperative Extension agent for agriculture and natural resources if they suspect they have blue mold or need additional assistance.


Source: William Nesmith, 859-257-7445