NOVEMBER PLANT DISEASES FROM THE AUBURN PLANT DIAGNOSTIC LAB NOVEMBER PLANT DISEASES FROM THE BIRMINGHAM PLANT DIAGNOSTIC LAB

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EXTENSION PLANT PATHOLOGY, EXTENSION HALL, AUBURN UNIVERSITY, AL 36849-5624 December 16, 2004 PP-579 NOVEMBER PLANT DISEASES FROM THE AUBURN PLANT DIAGNOSTIC LAB NOVEMBER PLANT DISEASES FROM THE

1 EXTENSION PLANT PATHOLOGY, EXTENSION HALL, AUBURN UNIVERSITY, AL December 16, 2004 PP-579 NOVEMBER PLANT DISEASES FROM THE AUBURN PLANT DIAGNOSTIC LAB NOVEMBER PLANT DISEASES FROM THE BIRMINGHAM PLANT DIAGNOSTIC LAB NOVEMBER INSECT REPORT FROM THE AUBURN PLANT DIAGNOSTIC LAB DISEASE POSSIBILITIES FOR DECEMBER Jackie Mullen Extension Plant Pathology Specialist-Auburn Jim Jacobi Extension Plant Pathology Specialist-Birmingham Charles Ray Research Fellow IV-Auburn Auburn Plant Disease Report-November (J. Mullen) Most of November was unusually warm and wet in all sections of the state. (See further comments by Jim Jacobi, p. 5. Our plant sample load for November was unusually high with 168 plant samples received. Many of these samples (111) were ornamentals and soybeans submitted by Alabama Department of Agriculture Inspectors. Our usual client samples in November came to a total of 57. Many of our client samples were landscape ornamentals, greenhouse plants, and turf. Since most of the state had not experienced a freeze in November, landscape plants and turf continued to be in an actively developing condition. The following diseases were seen in landscapes & greenhouses: Colletotrichum leaf spot and Phytophthora root rot on azalea; Macrophomina, Volutella blights and Pythium root decay on boxwood; Phytophthora root rot

2 on camellia; brown patch on centipede; Botrytis blight & Pythium root rot on columbine; downy mildew on cucumber; Phytophthora and Pythium crown and root rot on gardenia; Phytophthora root rot on heather; secondary bacterial decay after fungus knat larvae damage on iris; Cercospora leaf spot on Kudzu; Phytophthora blight on Leucothoe; Cercosporidium blight on Leyland cypress; algal leaf spot on southern magnolia; Fusarium crown & root rot and Pythium crown rot on pansy; Heterosporium canker on Platycodon; Piricularia blight (blast) on ryegrass; anthracnose and Asian soybean rust on soybean; charcoal rot on soybeans; zuchinni yellow mosaic virus on summer squash; brown patch and take-all patch, on St. Augustine; Phomopsis blight on strawberry; Pythium root rot on turnip seedlings. John Olive at the Springhill Ornamental Horticulture Research Center noted seeing downy mildew on turnip and mustard greens in the Mobile area. Downy mildews typically cause an angular leaf spot/blight when cool (55-75 F) and wet/humid conditions exist. See the Handbook for fungicide recommendations. Asian soybean rust, caused by the fungus Phakopsora pachyrhizi, was confirmed on a soybean sample collected by a Alabama Agriculture Department Inspector in Mobile on November 19. Confirmation was made by microscopic study and PCR testing. Subsequently to this first detection of this disease in Alabama, the disease was similarly confirmed to be present in Baldwin and Cullman counties. At the same time as the AL confirmations were being made, this disease was being confirmed in GA, FL, MS, and LA. After USDA confirmed the initial state finds of this disease, the subsequent county confirmations were turned back to the individual state (triage) diagnostic labs. In AL, we received 66 soybean samples and seven weed samples for soybean rust determination. Of the 66 soybean samples received (in Nov.-Dec.), 34 were found to be positive for rust. The positive samples were collected from the following counties: Baldwin, Blount, Cherokee, Cullman, DeKalb, Elmore, Escambia, Etowah, Henry, Houston, Lauderdale, Limestone, Madison, Marshall, Mobile, Monroe, Morgan & Tuscaloosa. Many of the soybean samples were volunteer plants. None of the weed samples were found to have Phakopsora rust, although five of the seven did have a rust disease. Kudzu and legume weeds are reported to be susceptible to Asian soybean rust. Check with Ed Sikora for more information on this rust disease. Also see and We are continuing to check ornamentals submitted by State Department of Agriculture Inspectors for Phytophthora ramorum blight (SOD). This fall another nursery in Oregon (Hines Nursery) was found to contain Phytophthora ramorum infected plants and records showed that plants from the nursery had been shipped to retail stores in many states. Alabama received some of these plants so these Hines Nursery plants have been placed on a hold status until symptomatic plants submitted by inspectors can be tested at the Auburn lab using Phytophthora ELISA tests. Any positive reacting plants must be further processed to determine the exact species of Phytophthora present. Final determination will be made at a USDA Beltsville lab. 2

3 Table November Plant Diseases Seen In The Plant Diagnostic Lab at Auburn. Plant Disease County Azalea Colletotrichum Leaf Spot Tuscaloosa Phytophthora Root Bullock Boxwood Macrophoma Blight Lee, Tuscaloosa Pythium Root Decay Volutella Blight Tuscaloosa Lee Camellia Phytophthora Root Bullock Centipede Brown Patch (Rhizoctonia) Calhoun, Lee Columbine Botrytis Blight * Pythium Root * Cucumber Downy Mildew (Pseudoperonospora) * Gardenia Phytophthora & Pythium Crown & Root Decay * Iris Fungus Knat Larvae * Secondary Bacterial Crown Decay * Kudzu Cercospora Leaf Spot Baldwin, Mobile Leucothoe Phytophthora Blight * Leyland Cypress Cercosporidium Blight *, Colbert Magnolia, Southern Algal Leaf Spot Montgomery Pansy Fusarium Crown & Root * 3

4 Pythium Crown Montgomery, * Plant Disease County Platycodon Heterosporium Canker Disease * Ryegrass Piricularia Gray Leaf Spot Pike Soybean Anthracnose (Colletotrichum) Lawrence Mobile Asian Soybean Rust (Phakopsora pachyrhizi) Charcoal (Macrophomina) Baldwin, Cullman, Elmore, Houston, Lawrence Squash, Summer Zuchinni Yellow Mosaic Virus Hale St. Augustine Brown Patch (Rhizoctonia) Autauga, Lee Take-All Patch (Gaeumannomyces) Autauga, Calhoun Strawberry Phomopsis Blight Lee Turnip Pythium Root Pickens *Counties are not reported for greenhouse and nursery samples. Birmingham Plant Disease Report-November (J. Jacobi) We received thirty-eight samples during November. The big story for the month was the heavy rainfall over most of the state (11.13 inches at the Birmingham Airport, which was 6.5 inches above normal). In addition to the heavy rains, the lack of significant freezing temperatures allowed several pests and pathogens to remain active. Some of the problems seen last month included Bipolaris (formerly Helminthosporium) leaf spot on hybrid bermudagrass, large patch on centipedegrass and St. Augustinegrass, and zonate leaf spot on red maple. 4

5 Heavy rains like we had last month can result in the appearance of mushrooms in home lawns. Most mushrooms do not damage the lawn and are more of eye sore than a turfgrass problem. One exception involves mushrooms associated with arc-like or circular patterns in turfgrass called fairy rings. Mushrooms, also called toadstools or puffballs, live on organic matter in the soil. The source of organic matter could be dead tree roots, stumps, or a thick thatch layer in the lawn. When buried wood is completely decomposed, the mushrooms will stop being produced. If excess thatch (> 0.5 inches thick) is the cause of the problem, dethatching or core aeration will help reduce the fungi s food source. Often there is no practical or permanent way to stop the mushrooms unless the source of food can be eliminated. For more information on methods to manage fairy rings, see the following on-line extension publication ( The multicolored Asian lady beetles are once again creating a headache for homeowners as they seek shelter for the winter. The first few cold nights last month caused a large increase in the number of phone calls to the C. Beaty Hanna Horticulture and Environmental Center about this insect. For more information on how to reduce problems associated with the multicolored Asian lady beetle, click on the following links to on-line publications: ( ( 1079/ANR-1079.pdf). Table November Diseases Seen in the Birmingham Plant Diagnostic Lab. Plant Problem County Bermudagrass Bipolaris Leaf Spot & Crown Jefferson Birch, River Anthracnose (Cryptocline) Jefferson Boxwood, American Leafminers Jefferson Centipedegrass Brown Patch (Rhizoctonia) Jefferson Cotoneaster Phytophthora Root Jefferson Fig Common Rust (Cerotelium) Chilton Holly, Japanese Black Root (Thielaviopsis) Shelby Planted Too Deep Jefferson Iris Bacterial Soft Jefferson Magnolia, Grandiflora Algal Leaf Spot Tuscaloosa 5

6 Maple, Red Zonate Leaf Spot (Cristulariella) Jefferson Pansy Black Root (Thielaviopsis) Jefferson Crown (Rhizoctonia & Pythium) Jefferson Plant Problem County Rose of Sharon Scentless Plant Bugs (Niesthrea) Jefferson St. Augustinegrass Brown Patch (Rhizoctonia) Jefferson (2) Snowball, Japanese Planted Too Deep Jefferson Willow, Weeping Cercospora Leaf Spot Jefferson November Insect Report (C. Ray) County Crop Category Specimen Name Shelby Miscellaneous Black Soldier Fly Puparia Tuscaloosa Burford Holly Ornamental Camellia Scale, Tea Scale Pike Rye Small Grain Green June Beetle Larvae Barbour Cattails Miscellaneous Cattail Caterpillar Montgomery Water Hyacinth Miscellaneous Aphids, water hyacinth weevils, a pyralid moth larva Cherokee Iris Ornamental Fungus Gnats Russell Turnip Row Crops Yellowmargined Leaf Beetle Cullman Home Household- Miscellaneous Lacewing Larva Disease Possibilities for December 6

7 December has been a busy month as we were continuing to work with soybean survey samples and Phytophthora ramorum survey samples. Our usual December diseases include black rot (Xanthomonas campestris) and Cercospora or Cercosporella leaf spots on crucifers in the southern sections of the state. Also, Drechslera and/or Bipolaris leaf spots are seen on small grains and forages including oats, wheat, fescue, rye and also ryegrass. Of course, greenhouse plant diseases develop every month of the year. Pansy diseases are also commonly seen, especially anthracnose and Phytophthora crown and root rot. We have recently been seeing Piricularia blight (blast) on annual ryegrass in several areas of Central and South Alabama. With forage situations, grazing is the only recommendation. Check with Austin Hagan if you have questions. The list below includes some common disease problems received in the lab during December of the past few years. Comments on control practices are brief. Refer to the Alabama Handbook for details. Also, remember that sanitation is important in most control situations. Table 3. Disease Descriptions and Brief Control Comments on Some Common Diseases Often Seen in December. Apple Botryosphaeria Canker Sunken, elongated lesions develop on branches and/or trunks. The lesion edges may be cracked at lesions margins. Lesion tissues are brown beneath the branch/trunk bark. Cankered areas should be pruned out, making cuts 3-5 inches beyond the lesion edge. Disinfest shears between cuts. Azalea Cercospora Leaf Spot (Stress Related) Brown, circularirregular spots (¼-½ inch, cm diam.) on yellowed or otherwise weakened/ stressed plants. Remove stress factors; sanitation. Phomopsis Canker Sunken, necrotic lesions on branches; dieback. Pruning. Protective sprays of Cleary s See the AL 7

8 Powdery Mildew (Microsphaera) (Greenhouse location) White, buff-colored dusty coating on leaves. Apply a protective fungicide (See the AL ); Sanitation. Basil Rhizoctonia Stem Stems become brown and dry rotted. Sanitation. Pruning is recommended to lower humidity; water in morning. Plant Disease Description Control Bedding Plants Bacterial Leaf Spot (Greenhouse location) Wet, water-soaked/ black spots become dried and cracked in the centers with water-soaked margins. Sanitation; reduce humidity; increase spacing between plants; See AL Pest Management Pythium Root (Greenhouse location) Roots become brown and water-soaked. Sanitation; See handbook; reduce irrigation schedule. Bentgrass Brown Patch (Rhizoctonia) Brown blotches on foliage; blight. See AL Pest Management Pythium Blight/Root Plants yellow and die from root rot phase of the disease. See AL Bermuda, Coastal Bipolaris Leaf Spot Small, brown, elliptical spots become irregularlyshaped brown blotches. --- Bermuda, Tifgreen Bipolaris sorokiniana Blight Seedling disease & seed rot. See A. Hagan. Boxwood Macrophoma Blight Foliage turns reddish, yellow or brown with small black dots (about 1 mm diam.) scattered across leaf surfaces. 8

9 Remove stress situation; sanitation. Broccoli Black (Xanthomonas) Yellow, V-shaped lesions on leaf edges become darkened and slowly spread down the leaf causing veins to darken. Eventually, tissue rot and decay spreads into the vascular system with the lower center stalk becoming rotted. Crop rotation; seed treatment; see AL Centipede Brown Patch (Rhizoctonia) Foliage develops gray-brown spots, blotches; patches of turn die. Sanitation; apply protective fungicide treatment if grass is not dormant. See AL Pest Manage- ment Collards Black (Xanthomonas) See Broccoli. See Broccoli. Citrus Sooty Blotch Small or large spots appear as a black sooty fungi print. Check with Ed Sikora. Cucumber Anthracnose (Colletotrichum) Light brown angular leaf spots. Sanitation and protective fungicide sprays. See 9

10 Dianthus Alternaria Leaf Spot Typically gray, irregular leaf spots. Sanitation. Cleary s 3336 or Halt may help. Anthracnose (Colletotrichum) Reddish brown irregular spots on foliage. Sanitation. Cleary' s 3336 may help. Rhizoctonia Shoot Blight Brown elongated lesions. Sanitation. See AL Oedema Small, corky, slightly raised spots on lower leaf surfaces sometimes accompanied by yellowish spots on corresponding upper leaf surfaces. Reduce watering on cloudy days. Fern Colletotrichum Leaf Spot/Blight Circular to irregular brown, water-soaked spots on foliage. Sanitation; Cleary s 3336 or Halt will provide protective disease control. Fusarium Leaf Spot Circular to irregular brown, dried spots on foliage. Sanitation. Protective sprays of Cleary s 3336 may be used. Phytophthora Root & Crown Plants develop brown-yellow foliage near the crown area. Roots become brown and water-soaked. Sanitation. See the AL Phomopsis Leaf Spot Circular to irregular brown, dried spots on foliage. Sanitation. Protective sprays of Cleary s 3336 could be used. 10

11 Fern, Boston Rhizoctonia Aerial Blight Blight areas on fronds. See AL Fescue (Lawn) Helminthosporium Crown Leaf blades were yellowed and shrivelled. Tissues at the soil-line were brown and decayed. See ANR-621. Fescue, Red Cool-Season Pythium Blight (Root ) Turf areas become thinned, yellowish, and slow-growing. See the AL Management Fescue, Tall (Forage Crop) Drechslera Leaf Spot (Net Blotch) Small, brown, elliptical spots become irregularlyshaped brown blotches with uneven internal pigmentation that appears to be in a transverse and longitudinal net-like pattern. --- Geranium Botrytis Blight Spots and blight may develop on leaves, flowers, stems. When humidity is high, a gray mold will develop. Sanitation; increase temperatures; increase air circulation to decrease humidity; protective fungicides. Phytophthora Stem Lower stem areas become black and water-soaked. Sanitation; See Alabama Pest Management Holly Phytophthora Root Roots, especially feeder roots, show a wet, water-soaked, rotted condition where the outer layer easily slips off the central cylinder. 11

12 Sanitation; See the AL Holly, Chinese Armillaria Root Lower trunk may show a thin, white mycelial mat beneath the bark; black thread-like fungal structures may be present on the surface of the bark or beneath; honeybrown-colored mushrooms may develop around the holly. Removal of the plant is necessary. Jerusalem Artichoke Fusarium Root Roots become decayed with a brown, dry rot. Juniper Pestalotia Blight Inner foliage turns brown. Remove infected plants from the area and do not replant artichokes for years. Investigate stress conditions. Phytophthora Root Roots, especially feeder roots, show a wet, water-soaked, rotted condition where the outer layer slips off the central cylinder. Sanitation; See the AL Kiwi Phytophthora Crown Dark brown decay. Sanitation. Crop rotation. Avoid wet locations. Lavender Anthracnose Leaf & Stem Spots Circular-irregular brown spots and stem lesions. Sanitation. Protective sprays of 12

13 Cleary s 3336 or Halt. Leyland Cypress Botryosphaeria Canker Sunken, cracked lesions on branches. Pruning. Seiridium Canker Slightly sunken, elongated lesions develop on branches and/or trunk. Resin often oozes out onto bark at points along lesion edge. Tissues beneath bark are brown. Cankered areas should be pruned out, making cuts 3-5 inches beyond the lesion edge. Disinfest shears. Ligustrum Cercospora Leaf Spot Large, brown circular, oval or sometimes angular leaf spots. Sometimes spots have dark brown borders. Sanitation; protective sprays of Cleary' s 3336 or Domain. Lily, Easter Pythium Root Roots become light brown and watersoaked, decayed. Lower foliage turns yellow. Plants wilt & dieback follows. Sanitation. Reduce irrigation. Mondograss Anthracnose (Colletotrichum) Brown blotches on leaf blades; blotches may begin at leaf tips or they may be centrally located on the leaf blade. Cleary' s 3336 or Domain; Protective sprays; Sanitation. Mustard Cercospora Leaf Spot Brown, irregular leaf spots. Small gray patchy areas (spores) may develop on spots. Sanitation. Kocide or Cuprofix Disperss may be used. Oak Botryosphaeria Canker Sunken, elongated 13

14 lesions develop on branches and/or trunks. The lesion edges may be cracked at lesions margins. Lesion tissues are brown beneath the branch/trunk bark. Cankered areas should be pruned out, making cuts 3-5 inches beyond the lesion edge. Disinfest shears between cuts. Oats Bipolaris Spot Blotch Brown-black, elongated spots (1 cm) on leaf blades. See AL Pest Management Drechslera Leaf Spot (Net Blotch) Small brown flecks become longitudinal strips of dead tissue. Often the uneven blotchy discoloration of the dead tissue gives spots a net-like appearance. Outer edges of the brown strips have diffuse areas of yellow or red which may involve the entire leaf blade. Diseased leaves often die. ation; deep plowing; resistant cultivars. See Ala. Possible Barley Yellow Dwarf Virus Plants develop yellowing or reddish discoloration that begins at leaf tips and progresses downward. Plants are stunted. Diagnosis is often difficult when plants are small due to low virus concentrations in plants. Insecticides practical in a few situations. Rust (Puccinia coronata) Foliage develops yellow spots and rusty-orange powdery spore masses; foliage dies. See Austin Hagan. 14

15 Oleander Cercospora Leaf Spot Brown, circular or oval leaf spots. Sanitation. Onion Sclerotinia Blight Water-soaked lesions at soil line/crown area. --- Pansy Botrytis Bud Buds become brown, sometimes with gray over-tones. Sanitation. See 1998 recommendations. Myrothecium Crown Pythium Crown Root Thielaviopsis Root Plants wilt and yellow and dieback. Crowns become brown and limp; sometimes tiny white & black cushions are visible on crowns. Dark brown, watersoaked decay at crown area. Black lesions on stunted roots. Plants stunted. Sanitation. Daconil treatments may give some protective control. Sanitation. See Sanitation. See Pine, Loblolly Sooty Mold Black, sooty layer develops on needles. Black layer may be powdery or as thin dry sheets on needle surfaces. Physically remove superficial coatings. Identify and control insects (may be aphids, scales, or other sucking-mouth parts insects). Poinsettia Botrytis Blight (Greenhouse location) Gray-brown blotches on foliage; during humid conditions a delicate fungal wet may be present over blotch areas. Increase temperatures; decrease humidity; sanitation; see AL 15

16 Pythium Root (Greenhouse location) Roots are brown and water-soaked; outer root tissues slide easily away from inner root core. Sanitation; See AL Pothos Bacterial Leaf Spot (Erwinia) Angular, dark, water-soaked spots on foliage. Sanitation; Do not irrigate over-head. Rose Crown Gall (Agrobacterium) Hard, rough-surfaced galls on the lower cane near the soil-line and on the roots. Remove infected plants. Keep area free of susceptible plants for 2-3 years. Avoid wounds. Rye Bipolaris Spot Blotch Brown, elongated spots on leaf blades. Ryegrass Bipolaris Leaf Spot Small, brown elliptical leaf spots. --- See AL Pythium Blight Rhizoctonia Crown Leaf blades yellow and die; roots become discolored brown with a soft, wet rot. Crown areas develop a brown, dry rot. Plants yellow and dieback. See AL Sanitation. Protective fungicides. See the AL Pest Management Algal Leaf Spot (Cephaleuros) Slightly raised greenreddish brown leaf spots. Sanitation. See the AL Southern Magnolia Snapdragon Rhizoctonia Stem Canker Brown Sunken Cankers on lower stems. Sanitation; Cleary' s 3336 or Domain. St. Augustine Brown Patch (Rhizoctonia) See Centipede. See Centipede. 16

17 Strawberry Anthracnose Crown (Colletotrichum) Plants wilt. Crowns develop red-brown firm rot. Sanitation. Use resistant cultivars. Use healthy transplants. See Ed Sikora. Bacterial Leaf Spot (Xanthomonas) Black, water-soaked (when in early stages), angularshaped leaf spots. Strict sanitation. Avoid overhead irrigation. See ANR- 500A for protective bactericide recommen-dations. Phytophthora Crown/Root Stunted, wilted plants. Roots with reddened core or center. Roots and crowns decay with brown rot. Avoid wet areas. Use disease free and resistant cultivars. Use protective fungicides when disease has been diagnosed in the area. Sweet Potato Fusarium Surface Root Light to dark brown surface decay that is firm and dry. Infected roots eventually become hard & mummified. Avoid wounds. Remove infected plants. Fusarium Root Similar symptoms to Fusarium surface rot except rot extends below vascular ring. Avoid wounds. Remove infected plants. Tomato Anthracnose Fruit Round, colorless, sunken fruit spot areas become large and wet, watery, rotted. Sanitation. See AL Tulip Penicillium Bulb Brown blotches on bulb, sometimes with green/gray spore masses. 17

18 See AL Handbook for dip recommendations. Turnips Cercospora Leaf Spot Small to large, circular-irregular, off-white to pale brown leaf spots. See AL Colletotrichum Leaf Spot Cream-colored, round or oval spots. Sanitation. See AL Vinca Phytophthora Root Roots are brown, water-soaked and the surface tissues will slip easily off the central root cylinder with a small amount of pressure. Sanitation. See AL Pythium Root Roots are brown, water-soaked and the surface tissues will slip easily off the central root cylinder with a small amount of pressure. Sanitation. See AL Thielaviopsis Root Roots show black lesions and blotches. Tops grow poorly. Keep potting mix or soil ph on the low side of normal, about Cleary' s or Domain drenches may help. Wax Myrtle Botryosphaeria Canker Sunken, cracked lesions on branches. Sanitation. Pruning. Wheat Bipolaris Leaf Spot Brown-black, elongated spots (1 18

19 cm) on leaf blades. See AL WE ' EXTENSION PLANT PATHOLOGY & ALFA BUILDING DIAGNOSTIC FOLKS' WISH YOU ALL A HAPPY AND RESTFUL HOLIDAY SEASON! 19

DECEMBER PLANT DISEASES FROM THE AUBURN PLANT DIAGNOSTIC LAB DECEMBER PLANT DISEASES FROM THE BIRMINGHAM PLANT DIAGNOSTIC LAB

January 15, 2004 PP-560 DECEMBER PLANT DISEASES FROM THE AUBURN PLANT DIAGNOSTIC LAB DECEMBER PLANT DISEASES FROM THE BIRMINGHAM PLANT DIAGNOSTIC LAB DISEASE POSSIBILITIES FOR JANUARY PLANT DIAGNOSTIC