Dieback of Yew, Cryptomeria, Arborvitae and assorted conifers

This has been a trying year so far for the Tenn Green Industry. Winter months were drier than normal in most locations. The dry weather continued into Spring as evidenced by NOAA, and coincided with the Easter freeze which was unprecedented in recent history. This combination of a drought, warm weather, a freeze that was followed by severe drought, is causing widespread damage in nurseries and landscapes.

While damage to evergreen conifer trees and shrubs was not visible at first, it is currently quite visible in many landscape locations throughout the state. In Middle Tennessee, dieback on yew is quite common. On a three-mile drive along Old Hickory Blvd. in South Nashville on Friday afternoon, almost every subdivision entrance had yew showing moderate to severe dieback.

Several of the plantings that I stopped by to photograph had several things in common. First, there was no irrigation at most of the plantings showing severe damage. Second, there was no bark splitting on branches or main stems as I have observed in other plant species.

Third, the damage was randomly scattered throughout the canopy of most plants. Fourth, I could see no correlation between sheared or pruned and unpruned plants. Fifth, some of the plants were mulched, others were not. Sixth, no fungal fruiting bodies or wood boring insects were observed on any of the damaged plants.

Dieback on other plant genera has been observed. Home owners, grounds managers and nursery producers have noted dieback on arborvitae, cryptomeria and other species. I have noticed dieback on cryptomeria before, but have never associated a fungal pathogen with this problem. Dirr in his ‘Manual of Woody Landscape Plants’ notes this dieback as a problem of cryptomeria in the Southeast.

So what is to be done at this point? In some cases I have seen, landscape plants are totaled and should be removed and replaced when conditions are more favorable for planting. In other cases, dead shoots can be removed and with a year or two of corrective pruning, things could be back to normal. Nursery producers will prune out damaged parts, cutting into live tissue; if the damage does not go to the ground.

If possible, plants need to be irrigated when dry conditions occur. Here’s hoping that the rest of 2007 and 2008 is more normal on the climatological front. ‘ Dr. Alan Windham, UT Ext. Plant Pathologist

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The Emerald Ash Borer (EAB) has the potential to decimate ash in North America. It has been found as close as southwestern Ohio (Cincinnati area) and it is only a matter of time before it reaches Ky and Tenn. There is an EAB web page at http://pest.ca.uky.edu/EXT/EAB/welcome.html ‘ Dr. Frank Hale, UT Ext. Entomologist

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Workshops on the new QuickBooks Premier that offers the ability to track nursery inventory for the first time will be held at the Nursery Research Center in McMinnville July 24-26 and at the Grundy Extension Office in Coalmont on Aug. 6-8. The cost of the workshop will be $175 per company (for one representative) and an additional $90 for a second company participant. Call 931-473-8484 to make reservations in Warren County and 931-592-3971 for Grundy County.

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There will be a Fire Ant meeting at the TSU Nursery Research Center in McMinnville on Thursday, August 2, from 7 to 9 p.m. to explain the required treatments for nurseries in the Viola and Irving College areas going under regulation for Fire Ants.

Hopeful research is being conducted locally to develop more practical and economical treatments for certifying shipment of nursery stock from regulated areas.