Pests of Specific Crops

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Pest Description Redwood Bark Beetle (Phloeosinus sequoiae): The beetle commonly attacks weakened, dying or dead trees. The female beetle will bore into the inner bark and lay about 50 eggs. The emerged larvae feed in the sapwood and phloem. It overwinters as an adult or larva. Adults emerge in the summer and feed on small branches of cedar and cypress, which can lead to flagging. Root Weevils: Adults may girdle twigs a few centimeters from tips. Tips turn brown making the tree unmarketable. Serious damage may occur on landscape plantings also. TILIA – LINDEN Diseases: Sooty Mould: Black mould grows on aphid secretions on leaves. Mites: Gall Mite (Phytoptus tiliae): Mites form red to greenish, pocket-like galls on the upper surface of leaves. Galls are about 5 mm long. This is a pest of T. cordata. TSUGA - HEMLOCK Diseases: Botrytis Blight (Botrytis cinerea): Botrytis causes a foliar blight of seedlings and container-grown plants in humid conditions. Tip Blight (Sirococcus conigenus): Death of young shoots, often forming a “hook” at the tip. Also causes seed decay and seedling blight. See under PICEA. Insects: Hemlock Woolly Adelgid (Adelges tsugae): This sucking insect appears as white, cottony puffs on the bark and base of needles. Infestation often leads to the production of abundant black, sooty mould. Premature needle drop may occur. See Comment 30 in Federal Plant Quarantine Regulations in Chapter 2. Hemlock Looper (Lambdina fiscellaria): Pale yellow caterpillars, up to 25 mm long, with a double row of small black dots along body, cause severe defoliation of outer shoots and twigs. Chemical Control (rate per 100 L water; or per Cultural Management unit area if indicated) See General Insect and Mite Management: Bark Beetles and Wood Borers, Chapter 11. See General Insect and Mite Management: Root Weevils, Chapter 11. Control aphids to reduce sooty mould. See General Insect and Mite Management: Aphids and Adelgids, Chapter 11. Dormant season only: DORMANT OIL: 2 L See General Disease Management: Botrytis Blight and Storage Moulds, Chapter 9. See General Disease Management: Sirococcus Blight, Chapter 9. INSECTICIDAL SOAP 47% or 50.5%: 2 L; spray after May 1 LANDSCAPE OIL: 1-2 L to control eggs, nymphs and adults See General Insect and Mite Management: Woolly Adelgids, Chapter 11. FORAY 48BA: 2.4-3.2 L/ha THURICIDE 48LV: 160-240 mL Nitrogen fertilization has been shown to enhance adelgid survival and negate pest control measures. If this insect is a problem, reduce nitrogen fertilization as much as possible. See General Insect and Mite Management: Caterpillars and Moths, Chapter 11. 42 • Pests of Specific Crops Nursery Production Guide
Pest Description ULMUS - ELM Diseases: Dutch Elm Disease (Ceratocystis ulmi ): BC is free of Dutch Elm Disease, which is spread by bark beetles, such as the Native and European Elm Bark Beetles. The vectors do occur in BC. Beetles acquire the fungus in the fall when they tunnel under the bark of infected branches to breed. They spread the pathogen when they emerge and feed on new, young twigs. The first symptoms of disease are wilt and dieback of branches in mid-summer, often on only one side of the tree. Dark streaks can be found in the sapwood of infected branches. American elm is highly susceptible; Siberian and Chinese elm may become infected but do not wilt and die, so these resistant species rarely transmit the fungus. Other fungal diseases may cause branch dieback on elm with similar symptoms. Wet Wood or Slime Flux (Erwinia nimmipressuralis, and other bacteria): This bacterium is an invader of old, weakened or damaged trees and is a sign of other injury. It causes slimy, smelly cankers on trunks and branches and/or discolouration of interior wood. Exudate runs down the trunk causing further discolouration of the bark and attracts insects. It commonly affects old poplars, horse chestnuts and maples. Insects: Elm Leaf Beetle (Xanthogaleruca luteola): Attacks all elm species. The black, grub-like, larvae skeletonize the lower side of the leaf. Can lead to premature leaf drop. In the spring, the adult beetles lay yellow eggs in clusters on the underside of leaves. Larvae pupate on the ground at the base of the tree or in bark crevices. Adult beetles leave the tree to find a suitable overwintering site in the fall. European Elm Bark Beetle (Scolytus multistriatus): See Dutch Elm Disease (above). Woolly Apple Aphid (Eriosoma larigerum): This aphid causes clusters of rolled, twisted, and dwarfed leaves at the growing tip of elm shoots. Eggs overwinter on elm. After hatching in the spring, the insect then moves to apple, where it feeds on leaves and roots. It is present all summer. Chemical Control (rate per 100 L water; or per unit area if indicated) Tree Injection: Cultural Management ARBOTECT 20-S: See product label for application rate, etc. To control the disease-vectoring beetle, see European Elm Bark Beetle (below). Management: BC and Alberta remain free of Dutch Elm Disease. Rapid identification and removal of infected trees before beetles can breed in dead branches is essential to prevent its spread. Contact the Pacific Forestry Centre, Victoria, the Canadian Food Inspection Agency, or your local BCMA office immediately, if you observe wilt disease symptoms on an Ulmus tree. Do not bring Ulmus or Zelkova into BC. See British Columbia Plant Protection Regulations, Chapter 2 for information on the voluntary nursery certification program for the disease. Nurseries, parks and landscapers are advised to monitor American elm for dieback and prune out any dead or dying elm branches in the dormant season to prevent beetle breeding. Affected trees may die quickly, or limb by limb, and are a risk to fall down. Trees may be cleaned up to some extent by drilling holes just below the affected area and inserting plastic pipe to drain exudate from the trunk. An infected tree will eventually have to be cut down. ACECAP 97: for rate, see label or Aphids and Adelgids, Chapter 11. CONSERVE or SUCCESS 480 SC: 2.5 mL ENTRUST 80 W: 1.5 g ORTHENE 75% SP: Mist blower = 1,312 g/1,000 L; Hydraulic sprayer = 637 g/1,000 L (do not apply to American elms) THIONEX EC: 125-175 mL THIONEX 50 W: 100 g SEVIN T&O: 230-350 mL Nursery: Apply insecticides to prevent beetle feeding. Follow a regular spraying and monitoring program. ACECAP 97: for rate, see label or Aphids and Adelgids, Chapter 11. INSECTICIDAL SOAP 47% or 50.5%: 2 L POUNCE 384 EC: 9 mL Greenhouse only: IMPOWER 60WP: See label. See General Insect and Mite Management: Aphids and Adelgids, Chapter 11. Nursery Production Guide Pests of Specific Crops • 43
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Page 3 and 4: Pest Description Bacterial Blight (
Page 5 and 6: Pest Description Rusts: Fungal frui
Page 7 and 8: Pest Description Mealybugs: These s
Page 9 and 10: Pest Description Insects: Mealybugs
Page 11 and 12: Pest Description CORNUS - DOGWOOD D
Page 13 and 14: Pest Description Insects: Cotoneast
Page 15 and 16: Pest Description Leaf Spot (Cercosp
Page 17 and 18: Pest Description Web Blight (Rhizoc
Page 19 and 20: Pest Description Juniper Webworm (D
Page 21 and 22: Pest Description Blister Spot (Pseu
Page 23 and 24: Pest Description Insects and Mites:
Page 25 and 26: Pest Description Sydowia Blight/Tip
Page 27 and 28: Pest Description Needle Cast (Cycla
Page 29 and 30: Pest Description Sooty Mould: Black
Page 31 and 32: Pest Description Coryneum Blight, S
Page 33 and 34: Pest Description PSEUDOTSUGA - DOUG
Page 35 and 36: Pest Description Pear Trellis Rust
Page 37 and 38: Pest Description ROBINIA Diseases:
Page 39 and 40: Pest Description SALIX - WILLOW Dis
Page 41: Pest Description Berckmann’s Blig

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