Lexington, Kentucky 40546
Nursery Update - A Kentucky Cooperative Extension Service Update for the Kentucky Nursery Industry
By Amy Fulcher, Extension Associate - Nursery Crops
University of Kentucky Department of Horticulture
Update #32
June 15, 2005

Asian Ambrosia Beetle (AAB)
We are continuing to get reports and samples of suspected Asian ambrosia beetle. During a discussion with Ohio State University entomologists and horticulturists, it was determined that an acceptable field test for Asian ambrosia beetle is the presence of toothpick-like frass extrusions from the trunks and the presence of a fungus when a section of the trunk with entrance holes is sealed in a plastic bag with a moist paper towel. Please be aware that rain and wind will knock off the frass extrusions. Nursery Update #31 mentions more details on identification. We have several incidences of suspected Asian Ambrosia beetle on redbuds so be sure to scout redbuds and any stressed plants thoroughly. Rogue affected plants and burn immediately! Asian ambrosia beetles have been found exiting trees on the burn pile the day after being rogued.

Redbud infestation
Redbud infestation
Typical AAB appearance, photo courtesy of UF.
New Introduction
Bill Holleran is the new greenhouse and nursery crops marketing specialist with the Kentucky Department of Agriculture, Division of Value Added Plant Production. Bill is eager to meet those in the ornamental horticulture industry. Bill can be contacted by email at Bill.Holleran@ky.gov or by phone 502-564-4983 x 253.

Managing pH

Here are some brief tips on managing substrate pH:

Test each shipment of bark as it arrives for chemical properties, such as pH and CEC, and physical properties, such as total porosity, air space, and container capacity.

There are real differences between fresh and aged bark:

Total Porosity
Air Space
Container Capacity
Available Water (% Volume)
Fresh Pine Bark

Aged Pine Bark


NCSU researchers found that cotoneasters grown in fresh pine bark were smaller than those grown in aged pine bark. Addition of nitrogen did not correct the problem, which would indicate that competition with microorganisms for nitrogen was not the cause. Physical properties tests show that aged pine bark substrate has a greater container capacity and available water than fresh pine bark. Growers using fresh pine bark inventories may benefit from irrigating more frequently, using less water at each irrigation event.

Test your water pH at least once, at the beginning of the season.

Use the pH and alkalinity of the water and the pH of the substrate to fine tune your fertilization plan.

Ammoniacal nitrogen lowers the pH of the substrate through nitrification, a process driven by bacteria, not the plant. Cool weather (below 60F) significantly inhibits nitrification.

Nitrate nitrogen raises the pH, but only by being taken up by the roots of the plant. When applied to unhealthy roots or plants, small plants, or stressed plants the change in pH may be minimal.

Urea is converted into ammoniacal nitrogen and can be treated as another source of ammoniacal nitrogen.

The sulfur coating on sulfur-coated urea will lower the pH for two reasons: the sulfur itself and the urea it covers are both acidfying.

Nitrogen source may affect plant color: For years greenhouse growers have used the fact that plants fertilized with ammoniacal nitrogen tend to be greener than those fertilized with nitrate nitrogen.

Nitrogen source may affect plant growth: Greenhouse growers have also used the tendency of ammoniacal nitrogen fertilized plants to have greater petiole and stem elongation and greater leaf expansion. Those plants fertilized with nitrate nitrogen have shorter petioles and stems and smaller leaves.

Sources: "How do you manage aged versus fresh pine bark?", Proceedings of the Southern Nursery Association, 2004 and Understanding pH Management for Container-Grown Crops, Meister Publishing. Table from NCSU web publication Managing Container Substrates


Nursery Summer Pruning

June 16, 2005

Wearren and Son Nursery, Inc.
406 Cotton Lane
Taylorsville, KY 40071


9:00am - 12:00pm
Pruning Deciduous Ornamental and Shade Trees
Brent Wearren and Greg Goodpaster

Getting Started: planning, training employees, selection and care of equipment, proper liner selection

Pruning Basics: making proper cuts

Training the Central Leader: taping, flexing, using directional cuts

Developing a Quality Plant: Year 1, Year 2, Year 3

Special Techniques: whipping, notching, weeping plants

Brent Wearren is a 3rd generation nursery producer who was grafting at age 8! Already a seasoned nurseryman, Brent went on to study horticulture at Michigan State University. Now in his 25th year of growing trees, Brent has grown the nursery to 740 acres with shipments going from Colorado to the New England states and as far south as the Carolinas. With Brent's eye for detail and a penchant for planning it is no surpise that Wearren and Son Nursery, Inc. is a leader in quality, not only in Kentucky, but across the US.

Isopropyl alcohol provided to sterilize pruners. Please bring your pruners and drinking water. Be sure to dress for the weather.

Contact Amy Fulcher, UK Extension Associate for Nursery Crops at 859.257.1273 to sign up and for driving instructions.

Sponsored by: KY Integrated Pest Management and by the Kentucky Horticulture Council
Hosted by: Wearren and Son Nursery, Inc.

Educational programs of the Kentucky Cooperative Extension Service serve all people regardless of race, color, age, sex, religion, disability, or national origin.

Scouting Report
It is time for the second insecticide application for flatheaded appletree borer and the first application of peachtree borer. Maple mites are active. Bagworms are present. Leafhoppers are low in number (below the Purdue threshold for spraying) but damage is already evident. Powdery mildew is visible on Cornus florida, flowering dogwood. Honeyloust mite numbers are low. Please consult the IPM Calendar for Deciduous Tree Production for specific spray recommendations.

Source: Scouting report provided in part by Derrick Hammons, courtesy of KY IPM.

Educational programs of the Kentucky Cooperative Extension Service serve all people regardless of race, color, age, sex, religion, disability, or national origin.
Note: Trade names are used to simplify the information presented. No endorsement by the Kentucky Cooperative Extension Service is intended, nor is criticism implied of similar products that are not named. Always read product label before use.