Cercospora leaf spot was diagnosed on Acer x freemanii 'Autumn Blaze' maples in late September. The disease is characterized by small, 2-3 mm, circular spot with white centers. Also present is physiological leaf scorch and spider mite damage. Together they make leaves unappealing for fall sales. While it is too late to spray now, growers of container trees may need to scout early and lower thresholds for spider mites in addition to scouting and controlling leaf spot diseases earlier in the season to preserve the aesthetic appeal of shade trees sold for fall color. Growers can sweep or use a leaf blower on fabric around pot-in-pot trees to remove fallen, infected leaves, in order to remove a source of innoculum for next year.

For control of leaf spots see Woody Plant Disease Control Guide for Kentucky ID-88. For spider mite action thresholds see Developing an Integrated Pest Management Program for Nurseries Purdue Pub. E-213.

What's Wrong with this Ash?
Many Cimmaron® ash liners developed a canker during the 2003 season. The abnormality was noticed when the trees were in cold storage. The earliest symptom was an orangish, discolored bark, barely discernable unless the bark was wet. Cankers developed on trees in container and field production. Suggestions have included: damaged cambium from stepping on the liners, aerial phytophthora, and phlyctema coin canker. No organism has been found. Please send any suggestions to afulcher@uky.edu.

Survival in Cold Storage

Plan now for proper cold storage conditions. Trees in cold storage above 40F often lose an excess of carbohydrates by respiration. This leads to a poor survival percentage the first growing season. Ideal cold storage is between 34-38F.

Also, plan now to minimize the amount of time liners are in cold storage. Moderate storage is generally not harmful but a longer cold storage period can lead to a loss of carbohydrates and a lower root growth potential.

Liners planted in spring 03, weeks after other liners from the same source nursery and in the same storage conditions, were continuing to die when scouted in September. The liners planted earlier have great survival percentages.

This liner likely did not have enough energy reserves to grow roots after a long period in cold storage.

Source: Kozlowski, T. and S. Pallardy. 1997. Growth Control and Woody Plants. Academic Press.

Best Management Practices Workshop - A Focus on Insects

Louisville: Tuesday, February 17, 2004
Contact: Donna Michael at 502/425-4482, dmichael@uky.edu

Princeton: Wednesday, February 18, 2004
Contact: Amy Fulcher at 270/365-7541 ext. 279, afulcher@uky.edu

Dr. Daniel Potter, University of Kentucky
Grubs of Turfgrass: Identification and Control
Leafhoppers and Borers: Flight, Phenology, and Control

Dr. Dave Shetlar, Ohio State University
Foliar Insect Pests of Woody Plants: ID and Control
Insect Pests of Herbaceous Plants: ID and Control
Chemical Label Changes

Joe Collins and Carl Harper, Kentucky Nursery Inspectors
Nursery Certification Program
Japanese Beetle: Meeting Quarantine Regulations
Emerald Ash Borer
Periodic Cicada: Lifecycle and Landscape and Nursery Implications

Dr. Win Dunwell, Donna Michael, Amy Fulcher
Resistant Plant Selections

Pesticide - 3 general CEUs + 1 cat. 3, 10, 12, Certified Arborist - 4 CEUs