411!! GERANUIMS... - Knowledgebase Question

Baltimore, Ma
Question by LawWilliams
June 17, 2010
I HAVE A POTTED RED GERNUIM ON MY PORCH.. IT IS NOW TURNING BROWN WITH YELLOWING SURROUNDING THE BROWN PARTS..
THE PLANT IS NOW ONLY HALF BLOOM ALSO.. I COULD SEND A PHOTO IF YOU SEND ME AN EMAIL ADDRESS..
THANKS MS WILLIAMS FROM MARYLAND


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Answer from NGA
June 17, 2010

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Like all plants, geraniums have their share of disease and insect problems. One disease common to geraniums is bacterial leaf spot, caused by the bacterium Xanthomonas pelargonii. It is especially prevalent in warm, wet weather where plants are grown in crowded conditions. Disease symptoms include small (pinhead size), circular or irregular, brown, sunken spots on older or lower leaves. Large numbers of spots will occur on a single leaf, these will coalesce killing a large portion of the leaf which will then drop off. As the disease moves through the plant, the lower leaves wilt and yellow. In severe cases, the stem will possess black stem cankers killing the upper portion of the stem. Leaves infected with bacterial leaf spot should be removed as soon as it is noticed. Severly infected plants should be removed. There is no chemical cure for bacterial leaf spot. Make sure and destroy infected plants and plant parts this fall.

Another common disease of geranium is a fungal disease known as botrytis leaf spot or botrytis blossom blight (Botrytis cinerea). Botrytis is favored under cool, moist conditions or where plants are watered frequently. Leaves develop zonate, brown leaf lesions which develop a grayish brown mass of fungal spores. The lower leaves will yellow and rot. Flowers may also become infected. They show discolored petals which wilt and fall. Remove affected leaves and flowers. Fungicide sprays, when environmental conditions are favorable, will help reduce levels of this disease. Chlorothalonil (Daconil 2787) is widely available and will help to control botrytis.

Be sure to apply according to label directions.

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