Fungi live on infected bean seed and in debris on top of garden soil. Moderate, frequent rainfalls, especially if accompanied by winds, provide perfect conditions for spread of anthracnose.
Plant beans in a different location each year and purchase disease-free seed each year. Anthracnose is spread quickly and easily when plants are wet, so avoid handling or working around plants when the leaves are moist. Apply a copper soap fungicide when beans first begin to flower and continue at 7- to 10-day intervals for as long as needed. If possible, apply when rain or other moisture won't dampen plants for at least 12 hours after application. We recommend Soap-Shield Flowable Liquid Copper Fungicide.