Runner Bean Halo Blight

Crinkmeister

Just had to burn this years runner bean plants as they were infected with halo blight. Never had it before and the standby plants in the greenhouse, from the same seeds, are showing no signs, so it's not carried by the seed. How would I have got it?


I have also burnt the canes just in case.

madjackslam

According to the RHS

Halo spot/blight is a bacterial disease carried on the bean seeds,
which causes the leaves to have brownish, water-soaked
spots that are surrounded by a yellow halo. There are no
remedies, so infected crops should be destroyed, but using
fresh seed from a reputable supplier should avoid the
problem.

https://www.rhs.org.uk/Plants/PDFs/Plant-trials-and-awards/Plant-bulletins/runnerbeans.pdf

Crinkmeister

Thanks Jack - however, if the disease was carried in the seed, why are the plants in the greenhouse not affected? Seed from same packet, sown at the same time, in the same compost in the same (intially) greenhouse?

madjackslam

I don't know. Although this Wikipedia article suggests that the disease tends to develop in cold, rather than hot, conditions, which would fit with what you've found.

Living_proof

It sounds more like a blight-type condition to me. My runner beans were fine but French beans failed on the first sowing, despite being regularly watered. Wilko replaced them and the second lot have come through within days.