Wednesday, September 16, 2009

Greenhouse - Anthracnose on Pansy

With the wet growing conditions, watch for anthracnose on fall pansy. The following is more information.

Anthracnose on Pansy

The University of Maryland plant diagnostic clinic received a pansy sample with a severe leaf spot problem. Pansies can have a number of foliage diseases, but this time anthracnose, caused by the fungus Colletotrichum, was the culprit. The black setae (hairlike projections) and orange spore masses of the pathogen are often visible with a hand lens in the center of the lesions. Foliar application of fungicides such as the strobilurins (Heritage and others), chlorothalonil (Daconil), or thiophanate methyl (Cleary’s 3336) can protect foliage from anthracnose infection. There are lots of spores in the lesions, and they can be moved by splashing water, so it’s always a good idea to avoid overhead irrigation to reduce disease spread.

Photos below by Karen Rane

Information from the September 4, 2009 edition of the Greenhouse TPM/IPM Bi-Weekly Report from the University of Maryland Cooperative Extension Central Maryland Research and Education Center

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