Pests of Specific Crops

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Pest Description CYDONIA - QUINCE Diseases: Chemical Control (rate per 100 L water; or per unit area if indicated) Fire Blight (Erwinia amylovora): See General Disease Management: Fire Blight, Chapter 9. Rust (Gymnosporangium clavipes): This rust fungus infects quince, apple, hawthorn, cotoneaster and saskatoon. Yellow-orange pustules (aecia) appear on lower side of leaves in summer. Juniper is the alternate host. See under AMELANCHIER and MALUS. Insects: Cherry Ermine Moth: See MALUS: Apple Ermine Moth. ERICA - HEATHER (see CALLUNA) EUONYMUS Diseases: Anthracnose (Colletotrichum gloeosporioides): This warm-weather fungus (optimum 25-30 o C) causes small leaf lesions with white, grey or tan centres and dark or reddish borders. Stem cankers are small, oval and may be raised and scabby. Larger cankers may girdle the stem causing dieback. Most common on E. japonica and E. fortunei (‘Canadale Gold’ is more susceptible than ‘Emerald ’n Gold’, which is more susceptible than ‘Emerald Gaiety’). No fungicides are registered for use on quince. DACONIL 2787F: 250 mL DACONIL Ultrex: 150 g Apply when new growth emerges and at 7-14 day intervals. Not a common disease in BC. Fungicides may be needed for control in Interior nurseries or in unusually hot weather at the Coast. Cultural Management Pick off infected leaves. Rake up and burn, bury or compost. New infections occur each year from infected junipers. Remove nearby junipers. Collect and burn, bury or compost crop debris. Space plants for good air circulation and time watering so plants dry quickly. Plants grown under shade have a lower incidence of the disease. Prune out infected branches if possible. E. japonica does not thrive with repeated pruning. Powdery Mildew (Oidium euonymus japonica): Green cultivar ‘Patens’ is very susceptible. Variegated cultivars are not usually affected. Water forcibly sprayed on foliage under fast drying conditions may reduce disease. See General Disease Management: Powdery Mildew, Chapter 9. FORSYTHIA Diseases: Bacterial Blight (Pseudomonas syringae pv. syringae): This bacterial disease causes dark black streaks on young shoots, often on one side of the shoot. Flowers wilt and turn brown. Buds are blackened. Infection occurs in cool, rainy weather in spring and fall. Stem Gall (Phomopsis sp.): This fungus causes nodular growths along stem and twigs. Multiple galls may cause reduction in vigour, or dieback of small twigs. FRAXINUS - ASH Diseases: Anthracnose (Discula sp. (Apiognomonia)): This fungus causes leaf blotches and marginal scorch in rainy springs. Premature leaf fall can occur. ‘Modesto’ ash is very susceptible and should not be grown in Coastal areas of BC. When buds start to open in spring apply: COPPER SPRAY 50: 200 g At fall leaf drop and in January apply: COPPER SPRAY 50: 600 g DITHANE DG, M-45 or WSP 80WP: 275-350 g PENNCOZEB 80WP: 275-350 g Begin at bud break and repeat every 7-14 days during wet weather. Improve air circulation. Prune out and destroy wilted shoots. See General Disease Management: Bacterial Blight/Canker, Chapter 9. Cut off and destroy branches and canes that bare galls. Galls resemble those caused by crown gall bacteria, but are usually higher up in the bush. Control measures are warranted only when the disease occurs annually. Rake up and burn, bury or compost fallen leaves. 14 • Pests of Specific Crops Nursery Production Guide
Pest Description Leaf Spot (Cercospora sp. and other fungi): Discrete leaf spots, generally smaller than anthracnose lesions and not on margins of leaves. Severe infections may cause premature leaf fall. Rust (Puccinia sparganoides): This fungus forms aecia on leaves of ash in Central and Eastern North America only. Not known to occur in BC. Insects: Ash and Lilac Borer (Podosesia syringae): It was first reported in BC in 2006, but is well established in the US. The adult is a clearwing moth that is similar in appearance to a paper wasp. It usually has a single generation per year. The female moth deposits her eggs in bark crevices within 10 to 14 days of emergence. Upon hatching, the larvae tunnel into the trunk and feed beneath the bark. The larvae do excavate galleries in the wood. The mature, 3 cm larvae overwinter inside the tree. Adult moths emerge the following spring. Infestations lead to unsightly scars and swollen areas on the trunk and, can weaken branches. Severe infestations can kill a tree. Hosts include European ash, privet, lilac and mountain ash. Fall Webworm (Hyphantria cunea): Branches may be defoliated by hairy caterpillars with black heads and pale yellow bodies with dark stripes along back. Webs are usually on tips of branches in late summer and fall. Moths are pale and 1.2 cm long. GLEDITSIA - HONEY LOCUST Insects: Honey Locust Plant Bug (Blepharidopterus chlorionis): The pest was detected in Oregon in 2008. It has one generation per year. Eggs hatch in early spring and the nymphs feed on new growth, causing stippling and leaf distortion. Adults also feed on leaves that can lead to defoliation. Honey Locust Pod Gall Midge (Dasineura gleditchiae): Pupae overwinter in the soil and adults emerge in the spring when new growth begins. The adult is a small fly (3 mm long). Eggs are laid in expanding leaflets and hatch in a few days. Larval feeding cause leaves to become globular or pod-like. The pods contain one or more whitish larvae. After 3-4 weeks of feeding, the larva pupates and an adult fly emerges. Galled leaflets may drop prematurely. Continued galling and defoliation may cause the death of small branches, but new growth often develops at the base of dead twigs. There may be three or more generations per year. Chemical Control (rate per 100 L water; or per unit area if indicated) DACONIL 2787F: 250 mL DACONIL Ultrex: 150 g Apply at spring bud break and repeat every 7-14 days as necessary. NOVA 40W: 25-34 g Apply every 10-14 days. See General Insect and Mite Management: Bark Beetles and Woods Borers, Chapter 11. Pesticide sprays should be applied before eggs hatch. Use pheromone traps (isomate-P) to monitor for moth emergence. Spray 10 to 14 days following emergence. AMBUSH 500EC: 7 mL DIPEL WP: 62.5 g DIPEL 2X DF: 31 g ORTHENE 75% SP: Mist blower = 1,312 g/1,000 L; Hydraulic sprayer = 637 g/1,000 L POUNCE 384 EC: 9 mL SEVIN T&O: 230-350 mL HORTICULTURAL OIL (97%): 1 L Use to control the eggs. Since the eggs hatch within a couple of days, application timing is critical. Monitor expanding leaflets for red eggs in the spring (late March to early April) and spray when eggs are found. Cultural Management Rake up and burn, bury or compost fallen leaves. Fungicide treatment is rarely necessary. Water and mulch trees to reduce stress. Do not wound the trunk or main branches. Remove webs as soon as seen in mid-summer. See General Insect and Mite Management: Caterpillars and Moths, Chapter 11. Nursery Production Guide Pests of Specific Crops • 15
Page 1 and 2: Pests of Specific Crops 14 (updated
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: Pest Description Insects: Cotoneast
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 and 42: Pest Description Berckmann’s Blig
Page 43 and 44: Pest Description ULMUS - ELM Diseas

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