Topic: Planting After Blight

[bison1947]

Dug up three rows of Desiree today which had blight
lost about half so at least we got something.

Now the plan was to transplant more Leeks in the same
bed is this ok & if not what do we have to do about the
ground where the blight was??

Tnx in advance

Bill....

[Kepouros]

Bison, I hope that you left the potatoes in the ground for 14 days after you cut the tops down.  This is essential for 2 reasons:
1. To allow the potato skins to set, without which they won`t keep long term.
2. To allow blight spores on the surface of the soil to die.

The blight spores will normally only survive for up to a fortnight if they are not on a living host. and if you leave the soil surface undisturbed for 14 days after you have cleared away the haulm it is considered safe to dig.  However, if you cut the haulm and lift the potatoes immediately afterwards you may well be digging in bits of infected foliage, which will allow the blight to persist in the ground until those infected bits of foliage have rotted away, and this can take quite a time.  If you have done this there is nothing that you can now do to sanitise the soil except to let nature take its course.

However, if you stick to planting leeks there you shouldn`t have any trouble.  Potato blight doesn`t attack leeks.  Don`t plant potatoes there again for another 3 years.

[Jeannine]

I have a question re blight??

I have never had it so am not familiar with it but understand there is a lot about.

My spuds in the ground have had it, they are mush, I presume because they were under water for three weeks,however the ones in the high raised beds that were only under for a day and a bit are OK.

Can I presume I do NOT have blight do you think, the toms in my greenhouse are OK too.

The raised beds are about 10 feet from the mushy lot.

The greenhouse is adjacent to the raised bed.

XX Jeannine

[Kepouros]

Are you sure that the potatoes which turned to mush in the ground did actually have blight?  Maybe they simply rotted through being under water for 3 weeks.  Potato blight has nothing to do with being under water, but is an airborne fungus disease specific to the solanum family.  If the flooded potatoes had got blight, then it is most unlikely that all the potatoes in the other bed as well as the toms would have survived completely unscathed.

The only way to find whether you have blight infected plants is to inspect them carefully for signs of blight.  This usually appears first on the upper surface of the foliage as a small blackish or purplish spot, and the underside of the leaf will have a slightly larger area of greyish "felting" around the spot.
The spot enlarges rapidly, tending to become more brownish as it does so and the leaf begins to look generally sick. The blight then travels back inside the leaf to the stem, and then down the stem to the roots, at which point the plant dies.  It sometimes happens that a blight spore will lodge in a leaf axil on the stem, in which case the stem around that point turns black.

While blight cannot be cured, it can be greatly slowed down if all infected leaves are rigorously removed as soon as the infection shows on them - thus reducing the chance of the blight getting back into the stems - and regular spraying is carried out, which may well keep the plant alive long enough to produce some sort of crop.

[Jeannine]

there is no foliage it has all gone in the floods along with all the caulis etc,this is why I am hoping it is drowning

[Kepouros]

I was referring to your inspecting the foliage on the potatoes in the raised bed, which you say are ok, and the greenhouse tomatoes.  That is the only way that you can be sure that they are not infected

[gerbera]

I've got blight on my hanging basket tomatoes. I've been removing affected foliage....but what can I spray it with?

[Jeannine]

Everything else if fine just as normal

[Kepouros]

Then it`s most unlikely that the spuds which rotted had blight at all, they simply rotted because of the standing water.