page_title: Eriosoma lanigerum
section_title: Impact on apple trees
hierarchical_section_title: Eriosoma lanigerum / Impact on apple trees
caption_attribution_description: English: Title: Apple growing in California Identifier: applegrowinginca178alle (find matches) Year: 1951 (1950s) Authors: Allen, F. W. (Frank Wisdom), 1887-1982 Subjects: Fruit-culture; Apples Publisher: [Berkeley&#160;: College of Agriculture, University of California] Contributing Library: University of California, Davis Libraries Digitizing Sponsor: University of California, Davis Libraries View Book Page: Book Viewer About This Book: Catalog Entry View All Images: All Images From Book Click here to view book online to see this illustration in context in a browseable online version of this book. Text Appearing Before Image: . Text Appearing After Image: Woolly apple aphid infestation on apple twig. Photo courtesy of E. O. Essig. What to look for. As the names im- ply, aphids are small insects either green, reddish, or whitish (in the case of woolly types) insects. They are usually present in groups (see photo). Control of aphids is best obtained by a dormant spray of 2.5 gallons of dor- mant oil emulsion plus 1 pound of dinitro phenol (or 1 quart of 30 per cent dinitro cresol) per 100 gallons of water. This spray destroys the rosy and green apple aphid in the egg stage, and reduces the overwintering colonies of woolly aphid. To control woolly aphids that attack the roots a different method is used. In the fall, when the soil is dry and warm, level the soil around the base of the tree. Apply from&#160;% to 1 ounce of paradichloroben- zene (PDB) around the tree in a circle about 2 inches wide, with the inside of the circle 2 to 4 inches from the trunk. Cover the PDB with soil to a depth of 2 to 4 inches, and pack it down with a few pats of the shovel. The PDB crystals will give off a vapor that will penetrate the soil and kill the aphids. FRUIT TREE LEAF ROLLER, Archips argyrospila (Walker), attacks the foliage and young fruit soon after the buds open in the spring. What to look for. These insects may be identified by their characteristic method of tying leaf clusters together and feeding on immature fruit and foliage. In the winter their presence may be noted by A close view of San Jose scale. Photo courtesy of E. O. Essig. the smooth, flat, grayish egg masses found on the bark and limbs. Control is obtained with DDT spray. The first codling moth spray (see page 1) will also control leaf rollers. TUSSOCK MOTH, Hemerocampa ve- tusta Bdv., is more commonly known as the horned caterpillar. It is in the cater- pillar stage that it does damage to both foliage and fruit. What to look for. This pest is bril- liantly colored, clothed with tufts of black and white hair. White, felty egg masses may be found during the winter on the trunk and limbs of the trees. Control is obtained with the DDT spray used against codling moth. ORANGE TORTRIX (skin worm), Ar- gyrotaenia citrana, is seasonally serious in the coastal areas where it feeds on the surface of the fruit and at the stem and blossom ends. What to look for. The adults deposit flat, yellowish egg masses on the trunks, limbs, and foliage. The larvae tie clusters of leaves together with silk and feed on the fruit and foliage under the protection of this covering. NOTE: The DDT spray recommended for codling moth, as described on page 1, will also give good control of fruit tree leaf rollers, tussock moth and leafhop- pers. Substitute DDD in the spray to control orange tortrix. SECTION Vl-Page 3 Note About Images Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.
context_page_description: Eriosoma lanigerum, the woolly apple aphid, woolly aphid or American blight, is an aphid in the superfamily Aphidoidea in the order Hemiptera. It is a true bug and sucks sap from plants.
context_section_description: Where colonies of E. lanigerum feed on twigs and roots the tree forms galls, which are small initially but increase in size over time and are most damaging when they are formed among the roots. Continued feeding in the roots can destroy the roots and consequently reduce the growth of the tree or kill it. The aphids are attracted to the sunken sites caused by the perennial canker fungus Cryptosporiopsis perennans and the galls are then the most frequent places on the tree for the fungus to re-infect it. The galls can also allow infection by Gloeosporium sp. The galls are more sensitive to cold weather than the surrounding tissue and burst at -18 °C(0 °F), the resulting damage providing the fungus with an entry site for reinfection. As the aphids feed they produce a honeydew which drips onto the fruit allowing the growth of sooty mould which has an impact on the saleability of the fruit. The honeydew can also create unpleasant conditions for orchard workers to work in due to high levels of sticky honeydew excreted. The honeydew can also cover the leaves allowing the mould to grow there too. The aphids can also infest the apples, especially on varieties with an open calyx when the aphis can feed on the apple core.
caption: Infestation of E. lanigerum on apple in California
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