TIMELY INFORMATION. February 15, 2012 OCTOBER-DECEMBER PLANT DISEASES FROM THE AUBURN PLANT DIAGNOSTIC LAB

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1 PLANT PATHOLOGY SERIES TIMELY INFORMATION Agriculture & Natural Resources February 15, 2012 PP-711 OCTOBER-DECEMBER PLANT DISEASES FROM THE AUBURN PLANT DIAGNOSTIC LAB OCTOBER-DECEMBER PLANT DISEASES FROM THE BIRMINGHAM PLANT DIAGNOSTIC LAB DISEASE POSSIBILITIES FOR FEBRUARY Charles Ray Research Fellow IV Jim Jacobi Extension Plant Pathology Specialist Kassie Conner Interim Diagnostician Debra Johnson Lab Technician IV ALABAMA A&M AND AUBURN UNIVERSITIES, AND TUSKEGEE UNIVERSITY, COUNTY GOVERNING BODIES AND USDA COOPERATING The Alabama Cooperative Extension System offers educational programs, materials, and equal opportunity employment to all people without regard to race, color, national origin, religion, sex, age, veteran status, or disability.

2 Auburn Plant Disease Report, October-December (D. Johnson) The Auburn Plant Diagnostic Lab received 241 plant samples during October, November, and December. Twelve of those were for identification, 87 were for plant problem/disease diagnosis, and 142 were Phytophthora ramorum survey samples. There were also 48 soil samples submitted for the P. ramorum survey. Although 33 of the survey samples tested positive for Phytophthora sp. and DNA extractions were submitted to the USDA lab in Beltsville, Maryland for speciation, none proved positive for P. ramorum. We also received 484 soil samples for nematode analysis. Table 1. October-December Plant Diseases Received at the Auburn Plant Diagnostic Lab Plant Disease/Problem County Arborvitae Botryosphaeria Canker * Bermudagrass Phytophthora Root Rot Madison (2) Bermudagrass Scales, Brown Patch, Thatch Montgomery Nematodes Blueberry Abiotic Lee Boxwood Phytophthora Crown Rot Lee Boxwood, American Volutella Blight Morgan Camellia Anthracnose Calhoun Centipede Anthracnose, Nutrient Mobile Cleyera Fusarium Root Rot Mobile Crape Myrtle Sooty Mold Escambia Cryptomeria Botryosphaeria Canker, Maskell Scale Dale Phytophthora Root Rot Lee Monroe Cypress, Italian Spider Mites Dale Cypress, Leyland Botryosphaeria Canker, Cercospora Baldwin Needle Blight Cercospora Needle Blight Botryosphaeria and Seiridium Cankers * Dracaena Over-Fertilization * Houston Euonymus Euonymus Scale Muscogee, GA Frangipani Stalk Rot Mobile Gardenia, Dwarf Phytophthora Root Rot Forrest, MS 2

3 Grape Anthracnose * (2) Mites * Grapefruit Sun Scorch * Holly Alternaria Leaf Spot, Edema * Pythium Root Rot Montgomery Hydrangea Cercospora Leaf Spot Madison Fusarium Crown Rot Planted Too Deep, Pythium Root Rot Powdery Mildew Mobile Muscogee, GA Baldwin Indian Hawthorn Entomosporium Leaf Spot Madison Jasmine, Asiatic Rhizoctonia Root Rot Montgomery Juniper Cercospora Needle Blight Lee Kale Alternaria Leaf Spot Lee Lettuce Bacterial Leaf Spot Mobile Maple, Sugar Anthracnose Lee Oak Bacterial Scorch, Obscure Scale Madison Passion Flower Barnacle Scale Lee Peach Gummosis Lee Rose Black Spot Madison Spider Mite Damage Satsuma Graft Incompatibility, Melanose * Soft Rush Spider Mite Damage Lee Blount Soybean Cercospora Blight Dallas Spruce, CO Blue Charcoal Rot * Botryosphaeria Canker, Rhizosphaera Needle Cast * Spruce, Serbian Rhizosphaera Needle Cast * St. Augustinegrass Brown Patch, Gray Leaf Spot, Take-All Mobile Chinch Bugs, Gray Leaf Spot, Take-All Take-All Patch Sugarcane Termites * Calhoun Covington; Mobile; Escambia, FL Tomato Bacterial Wilt Autauga 3

4 Turnip Aphids Clarke Cercospora Leaf Spot Elmore Wirestem Montgomery Willow, Weeping Black Leaf Spot Lee Zoysia Brown Patch Forrest, MS Brown Patch, Low ph Montgomery Brown Patch, Low ph, Thatch Brown Patch, Take-All Patch, Thatch Montgomery Brown Patch, Thatch Lee Curvularia Blight Montgomery Take-All Autauga * Counties are not reported for commercial samples. Birmingham Plant Disease Report, October-December (J. Jacobi) Table 2. October-December Problems Seen in the Birmingham Plant Diagnostic Lab Plant Disease/Problem County Aucuba Phytophthora Root Rot Southern Blight (Sclerotium) Azalea Armillaria Root Rot Azalea Mite Damage Phomopsis Dieback Begonia, Dragon Wing Cladosporium Leaf Spot Bentgrass Dollar Spot * Bermudagrass Bermudagrass Decline Boxwood Boxwood Mite (2) Macrophoma Stem Canker (2) Chaste Tree Cercospora Leaf Spot Shelby Cryptomeria Botryosphaeria Canker Cypress, Leyland Botryosphaeria Canker Eggplant Phomopsis Blight Hackberry Hackberry Gall Psyllid Hibiscus Mealybugs St. Clair Holly, Possomhaw Fruit Rot (Colletotrichum) 4

5 Hydrangea, Oakleaf Armillaria Root Rot Phytophthora Root Rot Impatiens Root Knot Nematode Indian Hawthorn Armillaria Root Rot Juniper Passalora Needle Blight Shelby Pestalotia Blight Spruce Spider Mite Loropetalum False Spider Mite Maple Tar Spot (Rhytisma) Pecan Pecan Scab Blount Pecan Phylloxera Blount Plum, Purple leaf Black Knot Rose Armillaria Root Rot Spider Mites Strawberry Phytophthora Root Rot * Sweet Potato Scurf Winston Sycamore Sycamore Lacebug Powdery Mildew Disease Possibilities for February (D. Johnson) Expect Phytophthora Root Rot to be a continued problem on trees, shrubs, and bedding plants. Affected roots become brown and rotted and are often watersoaked. The outer cortex may easily slip from the inner root tissue. The lower foliage may yellow and dieback. This fungus is often associated with wet soils. Control may mean removing the plant and associated soil or protective drenches. Fungicides will not cure affected plants but may protect healthy plants from infection. Botryosphaeria Cankers are often found on the limbs of woody plants and can often be removed unless the infection is on the main stem. Cut 3 inches beyond the canker edge cleaning the shears with 10 percent bleach or 70 percent rubbing alcohol between cuts. Cankers caused by other pathogens might also be successfully removed in this manner. The list below includes some of the disease problems and their symptoms that might be encountered in February. Refer to the pertinent fact sheets, timely information sheets, spray guides, and the Alabama Pest Management Handbook for detailed control measures. 5

6 Arborvitae Phytophthora Root Rot: Dieback; brown, wet-rotted roots; root may dry and be easily pulled apart. CONTROL: Sanitation, control excess soil moisture; protective fungicide drenches; see Alabama Pest Management Handbook. Azalea Phytophthora Root and Crown Rots: Roots and stem near soil line appear water-soaked, brown; dieback. CONTROL: Sanitation, improve soil drainage. See Alabama Pest Management Handbook and ANR-571. Bermudagrass Nematode Damage: Various patches of yellowed turf; poor root development, stunted growth. A soil analysis is required for definitive diagnosis. CONTROL: See ANR-523. Bermudagrass Take-All: Areas of turf yellow and thin; roots decay in spots. CONTROL: See Alabama Pest Management Handbook and ANR-823. Blackberry Botryosphaeria Canker: Elongate, sunken, cracked, lesions on branches or trunk. CONTROL: Prune affected stems at least 3 inches beyond cankers. Blackberry Phomopsis Canker: Small sunken lesions, usually on small branches. CONTROL: Prune affected branches at least 3 inches beyond canker edges. Blueberry Botryosphaeria Canker: Elongate, sunken, cracked, lesions. CONTROL: Prune affected stems. Boxwood Phytophthora Crown and Root Rots: Dieback, wilt, yellowed foliage; rotting of lower trunk; roots become light brown, rotted, water-soaked; the outer cortex of the root is easily separated from its core. CONTROL: Sanitation; maintain proper water and fertility. See Alabama Pest Management Handbook. Camellia Algal Leaf Spot (Cephaleuros): Velvety green, reddish, or brown slightly raised spots develop on upper leaves under wet conditions. Older spots may have white centers and or become grayish green, looking almost lichen-like. CONTROL: See Alabama Pest Management Handbook. Camellia Colletotrichum Leaf Spot (Anthracnose): Light brown circular spots; under close inspection orange-pink-white-brown sporulation may be seen on the lesions. CONTROL: Sanitation; Cleary s 3336 protective sprays. Camellia Sudden Oak Death: Bleeding cankers on trunk, limbs; brown leaf spots, often starting at tip and growing toward petiole. So far, this disease appears to be limited to nursery container plants. CONTROL: Contact Alabama Department of Agriculture or this lab for instructions. Cedar, Red (Juniper) Pestalotia Tip Blight: Tips of twigs turn brown to gray. CONTROL: Maintain proper fertility and watering schedules; selective pruning. 6

7 Cedar, Red (Juniper) Phomopsis Dieback: Browned twig tips. Dieback extends further down twig with time; cankers. CONTROL: Sanitation. See Alabama Pest Management Handbook or ANR Cedar, Red (Juniper) Phytophthora Root Rot: Dieback. Roots become brown, wet, and rotted, later drying out. CONTROL: Sanitation. Reduce irrigation and improve soil drainage. See Alabama Pest Management Handbook for control in nursery settings. Centipede Take-all Patch: Small circular light or reddish brown patches which may coalesce into large areas of dead or declining turf. CONTROL: Using appropriate management practices are more effective than chemical controls; see ANR-823. Bayleton; turf replacement may be necessary. Cypress, Leyland or Mexican Phomopsis Twig Canker: Sunken round or elliptical brown twig lesions. CONTROL: Sanitation; Cleary s 3336 can be used as protective spray. Cypress, Leyland Botryosphaeria Canker: Cracked, elongate, sunken lesions or cankers on branches or trunk. CONTROL: Sanitation; prune affected branches 3 inches beyond canker edge. Cypress, Leyland Cercospora Needle Blight: Needles near stem in lower crown turn brown; browning spreads up and out; may also stunt tree growth. CONTROL: See Alabama Pest Management Handbook under Christmas Tree. Cypress, Leyland Seiridium Canker: Elongate, sunken stem lesions; sticky sap oozes from lesions. CONTROL: Remove affected branches and dead trees. Promote plant vigor. Euonymus Cercospora Leaf Spot: Round or irregular brown leaf spots. CONTROL: Sanitation; Cleary s 3336 or Heritage. Gardenia Bacterial Leaf Spot: Small, angular, wet, dark leaf spots. CONTROL: Remove damaged plants; avoid over-head watering. Gardenia Pestalotia Leaf Spot: Gray or brown leaf spots, often secondary after cold damage. CONTROL: Remove damaged leaves and debris. Gardenia Phytophthora Root Rot: Roots become brown, brittle; plants show general decline. The disease may spread to adjacent plants. CONTROL: Remove diseased shrubs and replace with Phytophthora-resistant plants. See ANR-571. Geranium Botrytis Blight: Brown leaf spots, blight of blossoms and leaves. Stem blight. CONTROL: See Alabama Pest Management Handbook. 7

8 Greenhouse Crops Botrytis blight: Blossoms with large, brown, irregular areas, these being covered with a delicate gray webbing during humid weather. CONTROL: See Alabama Pest Management Handbook. Decrease humidity. Holly Anthracnose (Colletotrichum Leaf Spot): Small brown circular leaf spots. CONTROL: Cleary s 3336 may be used as protectant. Holly Phomopsis Canker: Cankers on small branches; dieback. CONTROL: Sanitation. Holly Phytophthora Root and Crown Rots: Roots dark and decayed, outer cortex easily separates from inner core; lower trunk decayed. CONTROL: Sanitation, reduce excess soil moisture. See Alabama Pest Management Handbook. Hydrangea Armillaria Root Rot: Black threadlike structure may be present around root or crown areas; thin white fungal mats may appear under bark. CONTROL: Remove affected plants and surrounding soil; replant away from hydrangea. Hydrangea Phytophthora Root Rot: Primarily a problem in container-grown plants. Initially, a sudden wilting of foliage, also yellowing, stunting, or leaf fall. Feeder roots brittle and brown. CONTROL: Remove all plants with damaged foliage, reduce excess water from area and improve drainage; Subdue, Banrot, or Banol may be applied to adjacent plants as a protectant and may be effective on roots with low level of infection. Hydrangea Powdery Mildew: Leaves have patches with white, dusty coating. CONTROL: See Alabama Pest Management Handbook; see ANR Indian Hawthorn Anthracnose: Round to irregular, brown leaf spots. CONTROL: Sanitation; Cleary s 3336 or Halt protective sprays. Ivy Anthracnose: Irregular brown spots often occurring along veins. CONTROL: Sanitation; Cleary s 3336 or Domain. See Alabama Pest Management Handbook. Ivy Phytophthora Root Rot: Roots initially brown and water-soaked, then dry. Foliage wilts, dieback. CONTROL: Sanitation, reduce irrigation. See Alabama Pest Management Handbook and ANR Jasmine Phytophthora Root Rot: Dieback; roots brown and soft rotted. CONTROL: Sanitation, improve soil drainage; may require replacing with Phytophthora-resistant ground cover. See ANR-571. Juniper: See Cedar, Red. Kudzu Asian Soybean Rust: Small yellow spots may become white or brown. CONTROL: Sanitation. 8

9 Lavender Bacterial Leaf Spot: Small, dark leaf spots. CONTROL: Remove damaged plants; avoid over-head watering. Lavender Phytophthora Root Rot: Roots brown, decayed, water-soaked; the outer cortex of the root is easily separated from its core. CONTROL: Sanitation. Check soil water and fertilizer. Protective drenches of Subdue or Aliette in nursery settings. Ligustrum: Cercospora Leaf Spot: Large, round to angular, dark brown leaf spots. CONTROL: Sanitation; Cleary s 3336, Halt, or Domain protective sprays. Liriope Anthracnose: Cream-colored blotches and leaf tips which may have tiny black specks on surface. CONTROL: See Alabama Pest Management Handbook. Liriope Fusarium Crown Rot: Dry rot of lower stem. CONTROL: Avoid plant stress. Cleary s 3336 as protective spray. Liriope Phytophthora Crown Rot: Crowns brown, wet-rotted; plants wilt, yellow, die. CONTROL: Remove plants and associated soil; improve drainage. Fungicides not recommended in landscapes. Liriope Rhizoctonia Crown Rot: Lower stems brown and dry. CONTROL: Sanitation. See Alabama Pest Management Handbook. Magnolia Algal Leaf Spot: Circular, greenish or reddish brown, slightly raised leaf spots. CONTROL: Sanitation. See Alabama Pest Management Handbook. Maple Phytophthora Root Rot: Roots brown to reddish-brown and brittle. Leaf yellowing and drop. The fungus may girdle stem near soil line. Symptoms often show on one plant then spread to nearby plants. CONTROL: See ANR-571. Mondograss Anthracnose (Colletotrichum): Brown to reddish-brown blotches, often along leaf edge or tip. CONTROL: See Alabama Pest Management Handbook. Oats Crown Rust: Orange pustules, mainly on leaves; severe infections cause yellowing, poor growth. CONTROL: Contact Austin Hagan. Pansy Fusarium Stem Canker: Dry decay, shriveled stem; wilt, poor growth. CONTROL: Rotate to plants not related to pansy. Pansy Phytophthora or Pythium Crown and Root Rots: Crown and roots become brown and water-soaked. CONTROL: Sanitation; see Alabama Pest Management Handbook and ANR Peach Botryosphaeria Canker, Gummosis: Oval sunken lesions on bark with cracked edges and resin exudate. CONTROL: Sanitation. 9

10 Peach Phomopsis Twig Blight: Oval, sunken cankers; branch cankers may result in dieback and wilting; discoloration evident when out bark is removed. CONTROL: Sanitation. Contact Ed Sikora. Pear Fireblight (Erwinia): Black dieback, blossom blight; twigs may have a shepherd s crook appearance. CONTROL: See Alabama Pest Management Handbook. Peony Botrytis Blight: Brown blotches on leaves, stems, blossoms. CONTROL: Sanitation. See Alabama Pest Management Handbook. Petunia Phytophthora Foliage Blight/Root and Crown Rots: Leaf spots, dieback, blight; roots and crown brown, wet rotted. CONTROL: Remove damaged plants. See Alabama Pest Management Handbook. Photinia Armillaria Root Rot: Plant decline. A thin, white mycelial layer may be found under the bark or on roots, as well as black thread-like rhizomorphs on roots. Honey-colored mushrooms may be present. CONTROL: Sanitation of plants and roots. Crop rotation. See ANR-907. Plum Black Knot: Green, swollen, elongated galls in spring become black in summer. CONTROL: Pruning; see ANR Apply Captan at green tip stage. Potato Scab: Circular, raised or sunken. scabby lesions up to 8 mm on tubers. CONTROL: Maintain a slightly acid soil; crop rotation; resistant varieties. Rhododendron Phytophthora Root Rot: Dieback; roots become brown, watersoaked, rotted. CONTROL: Remove damaged plants; reduce excess soil moisture. See Alabama Pest Management Handbook. Rose Armillaria Root Rot: Dieback, reduced shoot growth, leaf dwarfing; white, fan-shaped mats under bark; black fungal strands on collar and root system; golden mushrooms in surrounding area. CONTROL: Remove affected plants; replant with less susceptible species and avoid plant stress, particularly drought. See ANR-907. Rose Black Spot (Diplocarpon rosa): Round black spots with feathery edges. CONTROL: See ANR-505 and Alabama Pest Management Handbook. Rose Brand Canker: Brown oval sunken lesion on stems. A microscopic exam may be required to distinguish this from other canker diseases. CONTROL: Sanitation; avoid continually wet conditions in winter. Protective fungicides labeled for black spot. Rose Brown Canker: Elongate brown cankers. CONTROL: Remove cankered limbs, cutting 3 inches beyond canker edge; plant removal if trunk is affected. Protective sprays on nearby roses using fungicides labeled for black spot. Rose Cercospora Leaf Spot: Circular brown leaf spots. CONTROL: See Alabama Pest Management Handbook for Black Spot. 10

11 Rose Common Canker: Red to yellow spots in the bark become light brown cankers with a dark brown margin, becomes shrunken and cracked. CONTROL: Avoid injury to canes; prune the affected canes with sharp tools immediately above the node and at an angle. Rose Downy Mildew: Irregular yellow spots that blacken with age. CONTROL: Sanitation; see Alabama Pest Management Handbook. Rose Phytophthora Root Rot: Dieback; roots brown and wet-rotted, later dried out. CONTROL: Remove and destroy all plants with dieback; improve soil drainage, water levels. Protective drenches may prevent spread to nearby healthy plants. See Alabama Pest Management Handbook. Rose Powdery Mildew: White powdery coating on leaves and stems. CONTROL: See Alabama Pest Management Handbook and ANR-407. Rosemary Botryosphaeria Canker: Cracked, elongate, sunken lesions or cankers on branches or trunk; oozing of sap may occur. CONTROL: Sanitation; prune affected branches 3 inches beyond canker edge. St. Augustinegrass Brown Patch: Brown blotches on individual blades; whole blade may become brown. CONTROL: See Alabama Pest Management Handbook. St. Augustinegrass Take-All Patch (Gaeumannomyces): Circular light to reddish-brown patches of turf. CONTROL: Maintain soil ph between ; use ammonium forms of nitrogen. Strawberry Phytophthora Root and Crown Rot: Dieback, wilting, stunting, yellowing of lower foliage; crown and roots brown and soft rotted. CONTROL: See Alabama Pest Management Handbook and ANR-906. Strawberry Pythium Root Rot: Roots brown and water-soaked. CONTROL: Contact Ed Sikora. Strawberry Rhizoctonia Root and Crown Rots: Browning of internal crown tissue; dark brown lesions on young roots. CONTROL: Contact Ed Sikora. Sweet Potato Black Rot (Ceratocystic fimbriata): Initially small dark spots appear on roots. The rot tends to remain firm and shallow. CONTROL: Plant in new area next season; sanitation. See Alabama Pest Management Handbook for a commercial crop and ANR-948. Tomato Bacterial Wilt: Plants wilt and die without yellowing or spotting. An affected stem will produce a milky ooze if cut and placed in water. CONTROL: Rotate away from Solanaceous plants at least 4 years; fumigation, solarization. See ANR

12 Tomato Early Blight: Dark, irregular zonate lesions form and encircle stems of young plants which wither and die. Small, dark spots on older leaves may enlarge to 1 cm zonate spots; leaves yellow and fall off. CONTROL: Sanitation, good fertility, weed control. See ANR Tomato Fusarium Wilt: Yellow, wilting of lower leaves which progress upward; browning of vascular tissue. CONTROL: Remove affected plants; use a new planting site; resistance to Fusarium is limited. Tomato Target Spot: Initially, small light brown lesions with dark edges become larger leaf spots, blotches; sunken specks on fruit may develop into pitted, dark round spots with concentric rings. CONTROL: Rotate from Solanaceous crops; control weeds; remove plant debris. Wheat Bipolaris Leaf Spot: Small brown elongate leaf spots. CONTROL: None. Wheat Leaf Rust(Puccinia): Orange to dark red pustules on leaf blades and sheaths. See Alabama Spray Guide. Wheat Powdery Mildew (Erysiphe): White to gray fluffy mycelium on upper surface of leaf blades. See Alabama Spray Guide. Zoysia Brown Patch (Rhizoctonia): Rapidly developing large circular or irregular patches; individual blades show brown lesions, crowns show lesions and rot. CONTROL: See ANR