Field Fertilization of Douglas-fir and Its Effect on Adelges cooleyi1 Populations
- 1 June 1974
- journal article
- Published by Oxford University Press (OUP) in Environmental Entomology
- Vol. 3 (3) , 501-504
- https://doi.org/10.1093/ee/3.3.501
Abstract
Population levels of Adelges cooleyi (Gillette) were evaluated for 2 yr on 7-yr-old Douglas-fir trees after fertilization with 3 forms of nitrogen. Aphid fecundity on trees individually treated with equivalents of 50 and 200 Ib N/acre (56 and 224 kg N/ha) was 11–42% higher than on untreated trees in the first year of study and dropped to normal in the 2nd year. Winter survival of the aphid was 10–20% higher than normal on fertilized trees in both years. In the same period, aphid establishment appeared to be reduced on fertilized trees. Two years after fertilization, the population levels were essentially the same on treated and untreated trees.Keywords
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