Commercial Crop Production Fruit and Nuts - Pears

Transcription

1 Table 1. Symptoms, source of inoculum and management of diseases of pears Disease Fire Blight (Erwinia amylovora) Symptoms: Affects blossoms, leaves, twigs and young fruit. Infected blossoms wilt suddenly and turn dark brown, followed by blighting of leaves and terminals. Infected twigs and leaves turn dark brown to black, and leaves cling to the stem, often remaining attached most of the season. Source of Inoculum: The bacteria overwinter at the base of blighted twigs or in cankers on larger limbs. Bacteria are spread by bees and splashing rain. Management: Spray during bloom with fungicides or streptomycin according to manufacturer s directions. Prune out and burn infected twigs. Cut inches below affected tissue. Dip pruning tools in 10 percent chlorine bleach solution between cuts. resistant varieties such as Orient, Moon Glow and Biscamp. Fungicides Aluminum tris Aliette, Flanker Legion Streptomycin sulfate Agri-mycin Firewall Copper hydroxide Champ Champion Kocide Stretch Copper sulfate Cuprofix Oxytetracycline Mycoshield FlameOut Early Leaf Spot or Fabraea (Fabraea sp.) Late Leaf Spot (Cercospora sp.) Symptoms: The disease begins on the lower leaves in early spring. Spots on the leaves, mostly circular in outline, are dark brown to nearly black, with purplish margins. Spotted leaves turn yellow and shed. Source of Inoculum: The fungus survives mainly in infected leaves on the ground. May also form minute cankers on the bark of twigs and shoots. Management: Rake and burn fallen leaves. Begin sprays in April after leaves have unfolded. Orient has moderate resistance, and Maxine is very resistant. Follow pear spray schedule. Symptoms: This disease is first evident about August. The spots are angular to indefinite in outline and brown to grayish. Infected leaves turn yellow and shed. Source of Inoculum: Spread by wind-borne spores. Fungus may overwinter on diseased leaves or other hosts. Mancozeb Dithane Manzate Topsin T-Methyl Ziram Topsin

2 Table 1. Symptoms, source of inoculum and management of diseases of pears Disease Fungicides Quince Rust (Gymnosporangium clavipes) Pear Scab (Venturia pirina) Management: labeled fungicides. Symptoms: Affects fruit of pear, crabapple, apple, hawthorne and quince. Sometimes affects twigs and buds but seldom leaves. Infected fruit is covered with swellings or pustules that erupt to reveal yellowish to orange powdery spore masses. When each pustule erupts, a white fringe develops around each spore mass. Source of Inoculum: This fungus must have eastern red cedar or dwarf or prostrate junipers as alternate hosts to complete its life cycle. Galls are formed on the alternate host in which the fungus survives and infects pears and other plants mentioned. Management: Remove alternate host plants in vicinity of desired trees; or remove all galls from cedar trees during the winter; or follow a regular spray program beginning at blossom and continuing until fruit is formed. A combination of the above measures may be necessary. Symptoms: Dark brown to black spots form on infected fruit, which often are misshapen. Brown lesions form on leaves, but these may appear to be velvety and olive green when the fungus is actively sporulating. Source of Inoculum: The fungus overwinters mainly in infected leaves on the ground but it may also survive in infected twigs. Management: Rake and burn fallen leaves. Begin sprays in April after leaves have unfolded. Follow pear spray schedule. Mancozeb Dithane Manzate Fontelis Pristine Rubigan Sovran Ziram Adament Mancozeb Dithane Manzate Flint Fontelis Merivon Procure Rubigan Scala Sovran sulfur Topsin T-Methyl Vangard Ziram

3 Table 2. Seasonal fungicide spray schedule for pears Developmental Stage Dormant Tight (or Green) cluster Pink Bloom Petal Fall Cover sprays Disease(s) Fire blight Pear scab, early leaf spot and powdery mildew Pear scab, early leaf spot and powdery mildew Fire blight, pear scab, Early leaf spot and powdery mildew Fire blight, pear scab, Early leaf spot and powdery mildew Pear scab, early leaf spot, powdery mildew, sooty blotch and fly speck aluminum tris Aliette Flanker Ledion WDG lb 14 boscalid + pyraclostrobin Pristine WDG 7, oz 74 oz 0 captan 6 Captan Captec 50 W 80 WDG 4L M4 2.5 lb 1.6 lb 1.25 qt/100 gal 0

4 hydroxide Champ Champion Kocide Stretch 2.16% 15% 24.4% 30% 35% 37.5% 40% 50% M1 2-4 pt 1.33 pt 0.67 pt 0.5 lb 1.75 lb 0.33 lb 1 lb 1 lb 1-2 hydroxide + mancozeb ManKocide Metallic equivalent 30% M1 + M3 1.5 lb 128 lb sulfate Cuprofix Metallic equivalent 20% 40% M lb lb 0.5 cyprodinil Vangard 75 WG oz 22 oz 72 fenarimol Rubigan 1 EC fl oz 84 fl oz 30 fenhexamid Elevate 50 WDG lb 6 lb 0 fluxapyroxad + pyraclostrobin kresoximmethyl Merivon SC 7, fl oz 22 fl oz 0 Sovran 50 WG oz 25.6 oz 30 mancozeb Dithane, Manzate, 4 F 75 DF 80 WP M3 4.8 qt 6.4 lb 6 lb 77 oxytetracycline FlameOut, Mycoshield 17% a.i lb/100 gal (200 ppm) 60 penthiopyrad Fontelis 1.67 SC fl oz 61 fl oz 28

5 phosphite (phosphorous acid salts) Fosphite Fungiphite Helena Prophyt Phostrol Topaz Phosphorous acid equivalent (lb/gal) qt 1-3 qt 2-4 pints pints 0 pyrimethanil Scala SC fl oz 40 fl oz 72 streptomycin sulfate Agri-mycin 17, Firewall 17% a.i oz ( ppm) 30 sulfur IAP Dusting Sulfur Liquid Sulfur Six Microthiol Disperss Super-Six Liquid Sulfur Thiolux Jet 80% Thiosperse Wettable Sulfur 53% L 80% 90% 98% M pt lb lb lb 1 tebuconazole + trifloxystrobin Adament 50 WG oz 22 oz 75 thiabendazole Mertect F 1 16 fl oz/100 gal thiophanatemethyl Thiophanatemethyl Topsin, T-Methyl 70 WP 85 WDG 1 1 lb 0.8 lb 3.21 lb 1 triflumizole Procure 50 W 480 SC oz 8-16 fl oz 64 oz 64 fl oz 14

6 trifloxystrobin Flint 50 WP oz 11 oz 14 ziram Ziram 76 DF M3 6-8 lb 56 lb 14 1 Reference to commercial or trade names is made with the understanding that no discrimination is intended nor endorsement of a particular product by LSU or the LSU AgCenter is implied. 2 action groups are determined by the Fungicide Resistance Committee (FRAC). 3 Rates are the amount of formulation per acre unless otherwise indicated. Usually 100 gallons of water are required to give good coverage with boom sprayers. 4 Post-harvest interval (PHI) is the minimum number of days allowed between the last application and harvest. 5 All rates refer to foliar applications unless otherwise noted. Refer to label for other application rates and directions. 6 Post-harvest application only. 7 Soil application. Information in this section was last updated December 2012.