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Greenhouse experiments were conducted to determine effects of spirea aphid, Aphis spiraecola Patch, feeding and nitrogen fertilization on net photosynthesis (Pn), total chlorophyll content (Tchl), and greenness (Gn) of apple leaves. One-year-old apple trees grown in pots were infested with spirea aphid. Spirea aphid reduced Pn at various levels of infestation, and the reduction perSisted after aphid removal. Pn rates decreased with increasing accumulation of sooty mold. Gn and Tchl were reduced by spirea aphid feeding. Chlorophyll concentrations obtained by methanol extraction technique were linearly related to Gn values obtained with a SP AD leaf greenness meter for both infested and control leaves and for sooty mold and control leaves. Four nitrogen (N) rates were applied to trees in the second year. Pn and Gn were correlated with aphid-day accumulations at each N rate. Pn increased linearly with increasing Gn. Pn and Gn were positively related to N rates. Decrease in Tchl helps to explain the reduction in Pn. Pn may be related to Tchl, but leaf age, nutritional status, and other parameters may influence the results. Callose accumulation at the phloem sieve plates in response to aphid feeding was observed but to a lesser degree than for other aphids reported on apple and pecan leaves.
Document Type: Research Article
Publication date: June 1, 1992
More about this publication?
Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.