THE AUBURN AND BIRMINGHAM PLANT DIAGNOSTIC LABS AND AN OVERVIEW OF ALABAMA PLANT DISEASES IN 2000

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EXTENSION PLANT PATHOLOGY, EXTENSION HALL, AUBURN UNIVERSITY, AL 36849-5624 April 20, 2001 PP-479 THE AUBURN AND BIRMINGHAM PLANT DIAGNOSTIC LABS AND AN OVERVIEW OF ALABAMA PLANT DISEASES IN 2000 The

1 EXTENSION PLANT PATHOLOGY, EXTENSION HALL, AUBURN UNIVERSITY, AL April 20, 2001 PP-479 THE AUBURN AND BIRMINGHAM PLANT DIAGNOSTIC LABS AND AN OVERVIEW OF ALABAMA PLANT DISEASES IN 2000 The Plant Diagnostic Lab at Auburn routinely receives plant problem samples for diagnosis and soil samples for nematode analysis from numerous clients from all sections of the state. In 2000, total samples received were Many (approximately 59%) of the plant samples are referred from county Extension agents who diagnose many of the state s common diseases. Agent-referred samples are typically the new/unusual or difficult to diagnose problems. Sometimes plant samples are sent directly to the diagnostic facility from growers, homeowners and others. Soil nematode analysis samples are sent directly from the grower. The Plant Diagnostic Lab at Birmingham was designed to primarily serve the five counties (Blount, Jefferson, St. Clair, Shelby, and Walker) that comprise the Birmingham Metro area. The lab is located in the center of Jefferson County within the new C. Beaty Hanna Horticulture and Environmental Center at the Birmingham Botanical Gardens. The new diagnostic lab began operation in early February of 2000, and received a total of 652 samples for the year. Most of the samples were from homeowners, with the remaining samples coming from commercial clientele (lawn and landscape maintenance companies, golf course superintendents, and other plant care professionals). The majority of samples (95%+) were submitted directly to the lab by clientele. In addition to diagnostic services, the Plant Diagnostic Labs are in positions to document the locations of new and destructive disease outbreaks statewide. Plant samples received in the lab for problem diagnosis are handled by plant pathologists, entomologists, agronomists, and horticulturists, depending upon the nature of the problem. Insect and plant samples sent to the lab at Auburn for identification are generally referred to the appropriate entomology, agronomy or horticulture specialists. Responses to plant and soil sample inquiries consist of (1) the diagnosis or analysis results and (2) control recommendations. Responses are made by phone, electronic mail, fax or letter, depending upon the situation. The Plant Diagnostic Lab at Auburn is part of the Entomology and Plant Pathology Department and the Alabama Cooperative Extension System. The Plant Diagnostic Lab at Birmingham is part of the Alabama Cooperative Extension System and the Jefferson County Extension Program.

2 More information on the Auburn Plant Diagnostic Lab is available at your local county Extension office, and at the lab itself at 101 Extension Hall, Auburn University. For information on the Birmingham Plant Diagnostic Lab, contact the Jefferson County Extension Office or the Birmingham Lab which is located at the C. Beaty Hanna Horticulture and Environmental Center at the Birmingham Botanical Gardens in Birmingham. Information access through the WWW is available at for the Auburn lab. The Birmingham lab information is under construction and will soon be available also at this same web site. This web site can also be accessed by going to the WWW ACES homepage at The Auburn lab information can also be obtained through the WWW homepage of the Department of Entomology and Plant Pathology at Copies of the 2000 Annual Reports of the Auburn and Birmingham labs are available upon request. You may request reports by phone, , or mail. (Contact information for the Auburn Lab: phone ; mailing address - Auburn Plant Diagnostic Lab, 101 Extension Hall, Auburn University, Auburn, AL Contact information for the Birmingham Lab: phone ; jjacobi@acesag.auburn.edu; mailing address - C. Beaty Hanna Horticulture and Environmental Center, 2612 Lane Park Road, Birmingham, AL ****************************** The following summaries are from the 2000 records of the Auburn and Birmingham Plant Diagnostic Labs with supplement field and survey information predominantly from Extension Plant Pathologists (Austin Hagan, Ed Sikora and emeritus Bill Gazaway). The year of 2000 will be remembered for its hot and predominantly dry summer and its very dry fall. Over-all, disease incidence and severities in 2000 were reduced as compared to years with more moderate temperatures and less severe droughty periods. Field Crops. Most all of the field crops in the state were severely damaged by drought and heat. Early in the season (April), Helminthsporium leaf spot and wheat spindle streak mosaic virus were diagnosed on wheat in Madison County. Wheat spindle streak virus is not a common disease in the Southeast. Also early in the season, Pythium, Fusarium, and Rhizoctonia were diagnosed as root rot diseases of cotton. Fusarium crown rot of cotton was especially common this past year. In June, charcoal stem rot on field pea and soybean were observed. This is a dry condition disease, and it is recognized by the tiny black sclerotia scattered through the stem cortex. The abundance of these sclerotia cause the lower stem to appear gray. Infected plants wilt and dieback. Tomato spotted wilt virus (TSWV) was confirmed on peanut early in the growing season. TSWV depends upon thrips for disease spread. Insecticides are not totally effective, but their application is helpful in some situations. Pseudomonas bacterial leaf spot was diagnosed on soybean in July. There were no field crops sent for diagnosis after July. 2

3 Fruits, Nuts, and Vegetables. Diseases on fruits, nuts, and vegetables were not as common as usual due to the drought. In April, pepper bacterial leaf spot, sweet potato Rhizoctonia crown rot and tomato spotted wilt virus on tomato were seen. Tomato spotted wilt virus was most damaging in the tomato commercial production area in southeast Alabama and also in home gardens throughout the state. In April-May, bacterial speck and spot were detected on many backyard tomato samples. Fireblight was a common occurrence on Bradford pear in May. In the Mobile area, powdery mildew was noted on blueberry. In June cucumber mosaic virus was identified on tomatoes from Blount and Winston Counties. Infected tomatoes were stunted and showed mild leaf mottle and distortion. This is an aphid transmitted virus. Rapid removal of infected plants will help prevent virus spread. Insecticide application may help, but, in many situations, disease will spread rapidly despite sanitation and insecticide efforts. In July apple blotch, caused by Alternaria mali, was noted as a new report for Alabama. Other diseases seen on vegetables included Rhizoctonia crown rot on sweet potato; bacterial leaf spot on pepper; Fusarium wilt on tomato; Fusarium crown/root rot and Rhizoctonia & Pythium crown & root rot on garden beans; powdery mildew on cucumber; charcoal stem rot and Rhizoctonia crown rot on field pea; bacterial wilt, cucumber mosaic virus, early blight, Fusarium crown rot on tomato; Alternaria leaf spot and Fusarium melon rot; Fusarium ear rot and rust on corn; mosaic virus on summer squash; Pythium and Fusarium crown rot, mosaic virus, root knot nematode on watermelon; corn smut on corn; Fusarium fruit rot, Prunus necrotic ringspot virus, and watermelon virus II were seen on pumpkin fruit last October. Fruit and nut diseases noted were anthracnose and Botryosphaeria canker on blueberry; black rot (Guignardia) on muscadine; bacterial spot on peach; common leaf spot (Mycosphaerella) and bacterial leaf spot on strawberry; cedar-apple rust on apple; pecan scab. Garden tomatoes were the most common vegetable brought to the Birmingham lab. As with other sections of the state, bacterial spot, Fusarium wilt, and tomato spotted wilt were the most common diseases. Two-spotted spider mite was a common mite problem on garden tomato and snap bean last summer. Despite the drought of last summer numerous ornamental diseases were seen with 140 different plant types submitted and 259 different biotic diseases diagnosed. The following are some of the diseases identified: algal leaf spot on camellia; Hypoxylon atropunctatum canker on red oak; fusiform rust on pine; black spot, powdery mildew, crown gall, mosaic virus on rose; Cercospora leaf spot, Exobasidium gall, Phytophthora root rot on azalea; bacterial blight on geranium, Phytophthora root rot on Indian hawthorn; bacterial leaf spot on oak leaf hydrangea; bacterial leaf spot on English ivy; Alternaria leaf spot on marigold; fireblight on Bradford pear; Cercospora leaf spot, Phytophthora crown & root rot, Pythium crown & root rot, Rhizoctonia crown rot on pansy; Cercospora leaf spot on rhododendron; spot anthracnose on dogwood; tar spot on silver maple; anthracnose, Fusarium wilt, & Pythium root rot on marigold; Colletotrichum leaf spot, Phytophthora aerial blight, Botrytis blight, and Rhizoctonia blight on annual periwinkle; Volutella blight on boxwood; tomato spotted wilt virus on peony; Phytophthora and Pythium crown/root rot and Phytophthora aerial blight on petunia; Botryosphaeria canker on aucuba; root knot nematode on popcorn tree; Colletotrichum blossom 3

4 blight on hydrangea; Fabraea leaf spot on Bradford pear; Cercosporella (Asperisporium, Cercospora) blight on juniper; Phytophthora root rot on Shore juniper; Phytophthora crown rot, Seiridium canker on Leyland cypress; Cercosporella blight on arbor-vitae; rust on morning glory; Phomopsis cane canker on rose; Pythium root rot on snapdragons; Phomopsis canker on tulip poplar. Phytophthora parasitica blossom blight was diagnosed as a new disease of chrysanthemum. In the Birmingham area, the severe drought last summer and fall had a big impact on the short and long-term plant health of landscape ornamentals. However, even with the hot, dry conditions, we received several samples with Pythium and Phytophthora root rot due to overwatering. A total of 102 ornamental plants (51% of total samples) were submitted for insect and disease identification. On woody ornamentals, fire blight was very common on ornamental and backyard fruiting pears and apples last spring. Some of the other diseases observed on woody ornamentals included: Botrytosphaeria dieback on aucuba, Phomopsis dieback on azalea; Macrophoma leaf spot, Phytophthora root rot, and Volutella blight on American boxwood; Volutella blight on English Boxwood; Botryosphaeria dieback, bacterial shot hole, and Phytophthora root rot on cherry laurel; Pythium root rot on clematis; Botryosphaeria and Seridium Canker on Leyland cypress; Dutch elm disease on slippery and winged elm; powdery mildew on Japanese holly; Cylindrocladium leaf spot on yaupon holly; Armillaria root rot and Phytophthora root rot on oakleaf hydrangea; black rot on Boston ivy; Kabatinia tip blight on juniper; Phytophthora root rot on shore juniper; algal leaf spot on southern magnolia; anthracnose on Japanese maple; anthracnose and Botryosphaeria canker on red maple; cucumber mosaic virus and Pythium rot on nandina; Fusiform rust on live and Shumard oak; Volutella blight on pachysandra; Dothistroma needle blight on Japanese black pine; Lophodermium needle cast and needle rust on loblolly pine; Cercospora leaf spot on ligustrum; Cercospora leaf spot on rhododendron; Botrytis blight on rose; and Botryosphaeria dieback on wax myrtle. On herbaceous ornamentals the following diseases were observed: Pythium root and crown rot of dianthus; anthracnose on foxglove; powdery mildew on garlicvine; anthracnose on Hosta; Rhizoctonia stem and root rot on impatiens; bacterial soft rot and Heterosporium leaf spot on iris; southern blight on Liatrus; anthracnose on mondograss; black root rot and Pythium root and crown rot on pansy; Phytophthora blight on petunia; Pythium root rot on poinsettia; and Phytophthora blight on annual vinca. Turf. After tomatoes, turf grasses were the most numerous samples submitted. The number of centipede samples submitted was 86. Numbers of bermuda grass samples were 65; St. Augustine grass, 52; and zoysia grass, 43. With bermuda, the most common problem was low soil ph (16). Helminthosporium leaf spots & crown rots (10), leaf rust (5), and ring nematode (6) were also seen. On centipede, many samples were diagnosed with low ph (12), or other suspect environment problems. With St. Augustine grass, 36 samples were diagnosed with takeall patch. A few samples were observed with brown patch (6) and gray leaf spot (6). On zoysia, low ph (9) and rust (6) were the most commonly seen problems. Also dollar spot samples (4) were noted. 4

5 A total of 131 turf samples (36% of total samples) were received at the Birmingham lab. Pythium blight and/or root rot (7) was the most common disease on bentgrass (16 samples); anthracnose was a unusual find on one sample. On St. Augustinegrass (49 samples), take-all root rot (19) and chinch bugs (7) were the most common problems. Abiotic problems (drought, localized dry spots, winter injury, etc.) were the most common problems on zoysiagrass (52 samples), followed by take-all root rot, dollar spot, and rust. Damage from billbug (Sphenophorus spp.) was also seen on zoysiagrass. Early damage from billbugs resembles dollar spot with small spots of dead and dying grass. On bermudagrass (12 samples), dollar spot (3), and Helminthosporium blight (2) were the most common disease problems. Fungal diseases on centipedegrass samples (12) consisted primarily of brown patch, fairy ring and take-all root rot. Fairy ring (Agaricus spp.) was identified on an athletic field overseeded with perennial ryegrass. Prepared by Jackie Mullen & Jim Jacobi, both Extension Plant Pathology Specialists at the Plant Diagnostic Labs, Auburn & Birmingham locations, respectively. 5

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