THE ROLE OF SHEARING IN THE TRANSMISSION OF DIPLODIA PINEA IN SCOTS PINE CHRISTMAS TREES IN KENTUCKY

• Main Author: Bateman, Amy
• Format: Others
• Published: UKnowledge 2007
• Subjects: Sphaeropsis sapinea|Pinus sylvestris|Shearing|Fungal Transmission|Disinfestant
• Online Access: http://uknowledge.uky.edu/gradschool_theses/486; http://uknowledge.uky.edu/cgi/viewcontent.cgi?article=1489&context=gradschool_theses

Diplodia tip blight is an important disease of pines, especially Scots pine Christmas trees in Kentucky. The hypothesis for my thesis work was that D. pinea could be acquired and transmitted on the tools during annual shearing of the Christmas trees. Samples taken from tools after shearing on two different Christmas tree farms in Kentucky in 2005 and 2006 yielded D. pinea colony forming units, but in very low quantities; typically less than 10 CFUs per collection. Diplodia-associated dieback from the sheared tips was never found in the field, suggesting that transmission and subsequent infections were not occurring via these sheared tips. Controlled infections indicated that a minimum of 100 spores was necessary to create symptomatic infections on sheared tips. Lysolandamp;reg; Disinfectant Spray did not remove D. pinea from tools when sprayed on them after shearing, but it did effectively prevent spore germination in vitro. Observations of Diplodia lesion development on one Scots pine Christmas tree farm in Kentucky during the springs of 2006 and 2007 suggested that D. pinea infections occurred primarily via the bases of needle bundles on elongating shoots. The most likely source of inoculum was dead infested pine tissues within and beneath the canopy. The use of a protectant fungicide may have resulted in an observed dramatic decrease of disease on this farm.