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 #29
March 24, 2005

Insects
Asian Ambrosia Beetle (AAB)
If present, Asian Ambrosia beetles should be flying or have already flown, depending on your location. Traps can be used to monitor beetle flight. Ethanol is used as the lure; stressed trees release ethanol. The ethanol can be diluted to 70% without a reduction in efficacy. A study showed that bifenthrin, chlorpyrifos, esfenvalerate, or permethrin were the most effective against AAB. Another study found that permethrin could induce AAB to leave the host tree up to 4 weeks after attack and that many of the trees survived for an unspecified period before being destroyed. Therefore, permethrin-based insecticides may have repellent properties to AAB and might have the potential to save attacked trees, if applied shortly after AAB attack.

Entomologists at UK are trying to monitor the distribution and movement of AAB across the state, so please submit a sample through your county Extension office if 2-3mm, reddish beetles are caught in traps or if the characteristic toothpick-shaped extrusions protrude from the trunk.

 

Source: Excerpts from an article written by Mark Halcomb, U.T. Nursery Extension Specialist.

Photo from the University of Missouri Integrated Pest Management Pest Updates website.

 

Economics

A PNP budget that can be customized with your nursery's expenses is at http://www.uky.edu/Ag/HortBiz/pubs.html#budgets
(You will need Microsoft Excel to run this program.)

Cultural
Fertilizing
Nitrogen is found in fertilizers as nitrate (ex. calcium nitrate), from ammonium or nitrate (ex. ammonium nitrate), or just ammonium (ex. urea, diammonium phosphate). Soil and nitrogen are both charged and this influences how well the soil retains the nitrogen. Nitrate is a anion; it has a negative charge. Ammonium, a cation, has a positive charge. Field soils generally are negatively charged and thus positively charged elements are more tightly bound than those with negative charges. Therefore, nitrate is leached more easily from irrigation or rainfall than ammonium. Regardless of the form applied, nitrogen is converted into nitrate when absorbed by the plant. Nitrate tests are available for some horticultural crops to assess nutrient status.

 

Controlled release fertilizers are available for field production. Considering that urea must be applied approximately every 3-6 weeks, a CRF of some type would save labor and enhance growth by providing plants with a more constant supply of nitrogen. Recent prices of CRF for field production are $18 to $50 per bag depending on type of nitrogen and whether or not micronutrients are included. The application technique and rate of fertilization will influence the number of trees fertilized per bag.

Handling and Planting
Thanks to the many nursery growers who attended the Nursery Winter Workshops and shared ideas during or after the program. A few of the great ideas related to liner handling and care are:

1. Use a digital camera to document the condition of liners when delivered.
2. Paint a line on the trunk representing to what depth the liner should be planted so that workers can easily see when they are planted too deep.
3. Paint different colored stripes on the transplanter to represent different spacings so that as the most recently set plant reaches the color representing the desired spacing, the next plant is placed in the trench.
4. Apply Wilt-Pruf® to the root system. The product literature states "For drought, windburn, transplanting, and bulb storage protection - dip or spray to run-off at a dilution rate of 1:10."
5. Budget time for labor to straighten trees after heavy, 2-3" spring rains.

     

 

Try to keep roots moist while transporting and transplanting liners. Moist burlap wrapped around roots or dipping in mud slurries are options. Some growers prefer commercial dips such as Terrasorb. Researchers at Auburn University dipped bareroot Ulmus americana 'Liberty' in water, Terrasorb, or Terrasorb plus citric acid before an 8 week cold storage period. After storage they lined out the trees. They found no advantage to the Terrasorb treatments.

Source: Tilt, et al. Bareroot Shade Tree Liner Production in Containers. Proceedings of the Southern Nursery Association Research Conference. 45:41-43. Photo at right provided by Dr. Robert McNiel.

 


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