PEST STATUS OF FILBERT (HAZELNUT) INSECTS: A 10-YEAR STUDY

Abstract

AbstractTwo blocks (one .36, other .48 ha) of filbert (hazelnut), Corylus avellana L., trees were left unsprayed for 10 years and the pest status of different species determined by periodic field examination and damage counts. The omission of all pesticides resulted in excessive build-up of the filbertworm, Melissopus latiferreanus (Wals.) (Lepidoptera: Olethreutidae) populations resulting in an average of over 20% nut damage. Filbert leafroller, Archips rosanus (L.) (Lepidoptera: Tortricidae), and filbert aphid, Myzocallis coryli (Goeze) (Hemiptera: Aphididae), populations declined and no apparent economic damage was caused by these two pests. No damage was observed from other recorded arthropod pests.An economic analysis of standard filbert pest control programs in the Willamette Valley of Oregon indicated that during the study years, the total insecticide spray expenditures in commercial orchards ranged from 6.5% to 18.3% of the yearly returns in U.S. dollars/ha. Damage in unsprayed study orchards during this 10-year period suggests that the sprays applied for the control of aphid and leafroller yielded no return, while the sprays applied for control of the filbertworm returned an average of $3.80 for every dollar spent.