Pests of Specific Crops

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Pest Description AESCULUS - HORSE CHESTNUT Diseases: Leaf Blotch (Guignardia aesculi): Reddish-brown leaf spots and blotches with bright yellow margins appear in summer. Very similar to scorch (see below) but with small black fungal fruiting bodies (pycnidia) in the centre of the spot. Pycnidia develop early in June and release spores that initiate secondary infection cycles throughout the summer in wet weather. Leaf Scorch (environmental): Large, reddish-brown blotches with bright yellow haloes appear during hot weather in summer, often on margins of leaves. No black fungal fruiting bodies are present, unlike Guignardia blotch (see above). AMELANCHIER - SASKATOON Diseases: Black Leaf and Witches’ Broom (Apiosporina collinsii): Typical “Witches’ broom” symptoms are on new growth. Suckers are infected. Infected leaves roll downward and become covered with a black mould on the upper surface and a grey felt-like mat on the lower surface. It has been found occasionally on fruit in the Interior. Leaf and Berry Spot (Entomosporium mespili): Small, angular leaf spots on foliage and fruit. Worse under high moisture and warm temperatures. Petioles, stems and flower stalks may also be infected causing leaf and fruit drop. Monilinia Brown Rot and Mummyberry (Monilinia amelacchieris): Brown spots on leaves and fruit, mummified fruit. Favoured by humid weather and insect damage. Can also cause blossom blight and twig infections. Chemical Control (rate per 100 L water; or per unit area if indicated) Nursery or newly-transplanted trees: DACONIL 2787F: 250 mL DACONIL Ultrex: 150 g Apply at bud break and repeat every 7-14 days as needed. FUNGINEX DC: 300 mL. Apply once between bud break and white tip stage; 60 days to harvest. KUMULUS DF: 7.5 kg/ha. Apply at flower bud break and 10-14 day intervals. TOPAS 250E: 500 mL/ha; apply 3 times a year at white tip, petal drop and green fruit stage. No fungicides are specifically registered for this disease, but application of TOPAS 250E for leaf and berry spot (above) should help to control Monilina rot also. Cultural Management Rake and destroy fallen leaves where the fungus overwinters. Established landscape trees may be infected every year without serious injury or decline. Fungicide applications are not usually necessary or practical on large, landscape trees. May appear on susceptible trees every year, but is rarely damaging in the long term. Good growing conditions and proper watering may reduce the severity of symptoms. Remove and destroy all infected seedlings and transplants. Prune shoots 10- 20 cm below the infected area on mature plants, usually after leaf drop in the fall. Remove and burn all infected leaves and prunings, and any plants with crown infections. Increase air circulation and reduce leaf wetness by spacing nursery plants, controlling weeds, and avoiding overhead irrigation. Remove and burn, bury or compost fallen leaves if severe disease; or disc under in larger orchards. Prune out lower branches in orchards. Remove and burn, bury or compost mummified berries and fallen leaves. Powdery Mildew (Microsphaera podosphaera or Erysiphe spp.): See General Disease Management: Powdery Mildew, Chapter 9. 4 • Pests of Specific Crops Nursery Production Guide
Pest Description Rusts: Fungal fruiting bodies called “aecia” occur in yellow-brown leaf spots. Leaf drop, swelling of infected petioles, and mummification of fruit are common symptoms. The alternate host (juniper) is required for infection to recur each year. Common rusts (Gymnosporangium spp.) that produce “aecia” on Amelanchier in W. Canada: Chemical Control (rate per 100 L water; or per unit area if indicated) See General Disease Management: Rusts, Chapter 9. Clavariform Rust (Gymnosporangium clavariiforme): Yellow-brown leaf spot; fruit mummification. Common in Coastal BC. Aecia also occur on Crataegus (hawthorn) and other Rosaceae. Alternate hosts are in Juniperus Sect. Oxycedrus. Inconspicuous Juniper Rust (G. inconspicuum): Swelling of petioles; mummification of fruit. Occasional in Southern Interior only. Aecial hosts are Amelanchier and hawthorn. Alternate hosts are Juniperus Sect. Sabina. Juniper Broom Rust (G. nidus-avis): Common in Southern Interior. Other aecial hosts are quince and mountain ash. Alternate hosts are in Juniperus Sect. Sabina. Nelson’s Juniper Rust (G. nelsonii): Yellow leaf spot. Common in Southern Interior. Aecia on Amelanchier only. Alternate hosts are in Juniperus Sect. Sabina. Quince Rust (G. clavipes): Swelling of petioles; mummification of fruit. Not common in BC. Aecia also occur on many other Rosaceae species including quince, pear, apple, cotoneaster and hawthorn. Alternate hosts are in Juniperus. ANDROMEDA POLIFOLIA - BOG ROSEMARY Diseases: Red Leaf Spot (Exobasidium vaccinii): Red circular spots appear on upper side of leaves followed by defoliation. Symptoms usually appear in the early spring, although infection probably occurred during the previous fall/winter rains. ARCTOSTAPHYLOS - KINNIKINNICK Diseases: Root Rot (Pythium/Phytophthora spp.): Soft, brown roots on container plants. Basal rot of cuttings and poor rooting. AZALEA and RHODODENDRON Diseases: Cylindrocladium Blight and Root Rot (Cylindrocladium scoparium): The pathogen attacks a broad range of ornamentals, causing leaf spots, stem cankers, root rot and wilt. It is spread in soil and water, and by wind. Disease is favoured by high humidity and high temperature. It overwinters as microsclerotia in soil and infected plant tissue. Damping Off/Basal Rot of Cuttings (Pythium/Phytophthora spp. and other fungi): See also Root Rot, Wilt and Foliar Blight, below. Leaf Burn (Environmental): Leaves become brown then grey to white. Margins and interveinal areas are normally affected first. Leaf burn may be due to summer sunburn, winter desiccation or salt injury. Cultural Management Remove the juniper hosts listed below from within 2 km of Amelanchier plantings. Remove Juniperus communis. Remove J. scopulorum. Remove J. horizontalis and J. scopulorum. Remove J. horizontalis and J. scopulorum. Remove all junipers from within 2 km of Amelanchier plantings. Overwinter container stock in polyhouses to help prevent disease spread; avoid overhead watering and reduce humidity in greenhouses. See General Disease Management: Damping Off and Stem Rot of Cuttings and Root Rots Caused by Phytophthora and Pythium, Chapter 9. PHYTON 27: 125-275 mL See General Disease Management: Damping Off and Stem Rot of Cuttings, Chapter 9. Grow sun-sensitive varieties in partial shade, and wintersensitive varieties in sheltered locations. Avoid salt injury from overfeeding. Nursery Production Guide Pests of Specific Crops • 5
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Page 3: Pest Description Bacterial Blight (
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 and 42: Pest Description Berckmann’s Blig
Page 43 and 44: Pest Description ULMUS - ELM Diseas

Pests of Specific Crops

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