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UK - Commercial Production of Ornamental Plants


Enhancing Control of Calico Scale with Limited and No Pesticide Applications


Issue:  Two Kentucky nursery growers have struggled with a large outbreak of calico scale the last few years.  Calico scale is a debilitating insect on many shade trees.  A single female may lay 4500 eggs.  Of particular concern, is the unfortunate easy with which this pest can be shipped to customers.  During the fall and spring shipping seasons, the second instar stage is present on the bark of twigs and branches but is difficult to detect because of its extremely small size and similar coloration as the bark.  Therefore, assessing the population presence/absence in order to determine if a tree is pest free and, in a condition to be shipped, is difficult.  Additionally, because of its large host range and apparent ease of distribution, growers with this pest must spray a large percentage or all of their acreage. 


What Has Been Done: Through the efforts of our Nursery Scouting program, we were able to assist the nursery growers referred to below (and others) scout for calico scale, determine pest distribution within each nursery, and disseminate calico scale information generated by the UK Entomology Department and through the Nursery IPM program.  This information included hand-stripping trees of adult females prior to oviposition to eliminate the opportunity for egg hatch and spraying based on degree day predictions of egg hatch.  Field tests conducted by the Nursery Scout and the first author demonstrated that the adult female couldn’t survive off of the tree and did not release eggs after being removed from the tree. 


Impact:  The IPM for Nursery Crops program saved a 500 acre nursery the costs of spraying and greatly reduced pesticide impact on the environment and nursery workers.  The grower chose to hand strip the gravid female scales after the Nursery Scout demonstrated that that procedure had a 100% success rate of controlling the gravid females and eliminated crawler hatch.  Nursery workers performed this task while already in the field removing suckers and straightening trees.  Had the nursery sprayed the entire 500 acres, it would have cost approximately $4100 per application.


The IPM for Nursery Crops program saved a 350 acre nursery from the cost of multiple spray applications and from applications being made at the incorrect time.  This was accomplished by assisting the grower in utilizing a degree day calculation developed in the UK Entomology Department to identify the optimum time to spray and the most effective insecticide.  Each spray application of the entire 350 acres costs a total of $2900 and uses 20 tanks of insecticide in 10,000 gallons of water, according to the nursery owner. Therefore, each ineffectively scheduled insecticide would cost the nursery owner an additional $2900.  The impact is the greater control that this nursery is experiencing due to informed nature of their management plan and the elimination of the economic loss and environmental costs of ineffective spray applications. 


Both nurseries have gained an appreciation for the enhanced control and reduced costs that precision applications can offer and the effectiveness of alternative techniques.


For more information on this project contact:
Ms. A. Fulcher

Extension Associate for Nursery Crops

 N318 Agriculture Science North

 University of Kentucky

 Lexington, KY 40546-0312


Kentucky IPM

Original document: 1 October 2005

Last updated: 29 March 2006

Scoutcat logo courtesy of C. Ware, copyright 2000

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