Location: Application Technology Research
Project Number: 5082-21000-001-26-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Oct 1, 2019
End Date: Jun 30, 2022
Objective 1. Expand ambrosia-beetle monitoring surveys to additional high density orchards in NC and NY and initiate monitoring surveys in OH to understand the breadth of ambrosia beetle species associated with Rapid Apple Decline (RAD) in the Eastern US. Objective 2. Determine the impact of drought stress on ethanol production, ambrosia beetle attack, and physiological indicators of tree health for an apple variety ‘Honeycrisp’ on three dwarfing rootstocks.
Objective 1. In 2019 and 2020, ambrosia beetles will be monitored using ethanol-baited traps within orchard locations in NC, NY, and OH. In Years 1 and 2, traps will be monitored weekly from March through October, and monthly from November through February. At each monitoring location, trees will also be monitored for attacks and symptoms. Objective 2. The impact of drought stress on ‘Honeycrisp’ will be evaluated in a potted tree study. Tree whips (no branching, 1 to 2 cm tree diameter) previously planted in ~40-liter containers using a standard bark-based potting mixture, will be subjected to drought-stress, flood-stress, and untreated control conditions. No-choice experiments will be conducted using these trees, whereby adult female ambrosia beetles will be caged to the stems of trees. Trees will be placed in a randomized complete block design in a greenhouse. Colonization success will be evaluated for each specimen, including establishment of fungal gardens and offspring production within the galleries. To better understand the relationship between water stress, host ethanol production, and beetle colonization in apple, ethanol emissions from bark tissues will be quantified over time. Ethanol emissions will be evaluated at the initiation of the experiment and repeated on the same dates in which ambrosia beetle colonization is evaluated using solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). In addition to analyzing for ethanol using SPME, commercially available ethanol sensors and a portable gas chromatograph will also be tested for detecting ethanol.