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Send horticultural questions to ktilt@acesag.auburn.edu.
| PLANT | DISEASE | DESCRIPTION | CONTROL | |
| AZALEA | Powdery Mildew (Microsphaera) (Greenhouse location) | White, buff-colored dusty coating on leaves. | Apply a protective fungicide (See APMH); sanitation. | |
| AZALEA | Cercospora Leaf Spot (Stress Related) | Brown, circular-irregular spots (1/4 to 1/2 inch, 0.6-1.2 cm diam.) on yellowed or otherwise weakened/stressed plants. | Remove stress factors; sanitation. | |
| 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 APMH. | |
| BEDDING PLANTS | Pythium Root Rot (Greenhouse location) | Roots become brown and water-soaked. | Sanitation; see handbook; reduce irrigation schedule. | |
| BOXWOOD | Macrophoma Blight | Foliage turns reddish, yellow or brown with small black dots (about 1 mm diam.) scattered across leaf surfaces. | Remove stress situation; sanitation. | |
| DIANTHUS | Anthracnose (Colletotrichum) | Reddish brown irregular spots on foliage. | Sanitation; Cleary's 3336 may help. | |
| DIANTHUS | Rhizoctonia Shoot Blight | Brown elongated lesions. | Sanitation; see APMH. | |
| DIANTHUS | 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, BOSTON | Rhizoctonia Aerial Blight | Blight areas on fronds. | See 1998 recommendation. | |
| 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. | |
| GERANIUM | Phytophthora Stem Rot | Lower stem areas become black and water-soaked. | Sanitation; see APMH. | |
| HOLLY | Phytopthora Root Rot | Roots, especially feeder roots, show a wet, water-soaked, rotted condition where the outer layer easily slips off the central cylinder. | Sanitation; see the APMH. | |
| JUNIPER | Phytophthora Root Rot | Roots, especially feeder roots, show a wet, water-soaked, rotted condition where the outer layer slips off the central cylinder. | Sanitation. See the APMH. | |
| 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. | |
| 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 | |
| PANSY | Botrytis Bud Rot | Buds become brown, sometimes with gray over-tones. | Sanitation. See 1998 recommendations. | |
| PANSY | Myrothecium Crown Rot | Plants wilt and yellow and dieback. Crowns become brown and limp; sometimes tiny white and black cushions are visible on crowns. | Sanitation. Daconil treatments may give some protective control. | |
| PANSY | Pythium Crown Root Rot | Dark brown, water-soaked decay at crown area. | Sanitation. See handbook. | |
| PANSY | Thielaviopsis Root Rot | Black lesions on stunted roots. Plants stunted. | Sanitation. See handbook. | |
| 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 APMH. | |
| POINSETTIA | Pythium Root Rot (Greenhouse location) | Roots are brown and water-soaked; outer root tissues slide easily away from inner root core. | Sanitation; See APMH. | |
| 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. | |
| SNAPDRAGON | Rhizoctonia Stem Canker | Brown sunken cankers on lower stems. | Sanitation; Cleary's 3336 or Domain. | |
| TULIP | Penicillium Bulb Rot | Brown blotches on bulb, sometimes with green/gray spore masses. | See APMH for dip recommendations. | |
| VINCA | Phytophthora Root Rot | 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 APMH. | |
| VINCA | Phythium Root Rot | 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 APMH. | |
| VINCA | Thielaviopsis Root Rot | Roots show black lesions and blotches. Tops grow poorly. | Keep potting mix or soil pH on the low side of normal, about 5.5-6.0. Cleary's or Domain drenches may help. |
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Send horticultural questions to ktilt@acesag.auburn.edu.