Pat Lynch

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Anthracnose control on edible beans

It may not eradicate the disease but spraying now will make a difference

Anthracnose on edible beans is not new to Ontario. In the ’70s there was a strain introduced that was so bad one or two growers were ordered to plough their field under.

A breeding program in the early ’80s delivered resistant varieties. Over the years the organism changed so that current varieties do not have resistance to the prevalent strains of anthracnose.

Anthracnose on edible beans first shows up as plants slightly stressed with reddish coloured veins on the under surface of the leaf. Most growers cannot diagnose anthracnose on their edible beans until the circular lesions are present. These distinctive lesions will appear in August. By the time they appear the disease is too far advanced to control. Typically the lesions continue to grow until the beans are scarred. I have seen anthracnose in a field where bin run seed was used and the disease was so bad that the field could not be harvested.

Anthracnose is spread by seed, equipment, wind and people. It can last in the ground on plant debris. Generally a one-year rotation gets rid of disease that is on plant debris in the soil.

Seed treatment with DCT or Dynasty is the first line of defense. But seed treatment does not give 100 per cent control. Seed fields treated last year still may have had low levels of anthracnose on the seed. The wet weather conditions last year were favourable to the spread of anthracnose.

You can spray for anthracnose now. A fungicide sprayed for anthracnose control will not eradicate anthracnose but will make a difference. BF
 

Posted on: 
July 12, 2010

Pat Lynch CCA (ON) is an independent crop consultant with over 35 years experience in Ontario agriculture. If you wish to ask specific crop production questions or respond directly to Pat, email him at patrick.lynch@ sympatico.ca

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