Topic: Tomato blight and potatoes

[Robert_Brenchley]

What I got was in June so I assume it was EB. Whatever, I got a few (I mean a few) first earlies, but nothing else. Never mind, these things happen.

[philcooper]

.....in June so I assume it was EB. ......

What trusting faith you have - if the spots were brown it was probably good old English foliage blight - bad news. If the spots were black it was probably the new fangled US Early Blight - not really a problem

[Robert_Brenchley]

It was six years ago and I haven't had problems that early since, so I assume that whatever it was, it's gone!

[cliff_the_gardener]

Phil,
With potatoes early blight isn't a problem - as you say, because the spuds are harvested and eaten rather than stored.  The issue for me is if it affects the toms - which are in active growth then the effect is more of a problem.
The RHS advise for my spuds, I recall, was that it wouldn't affect early crops cropping.  I seem to recall the improtance of having well fed crops.  Could be treated with standard chemicals for blight.

[philcooper]

..... Could be treated with standard chemicals for blight.

Could be but Bordeaux mixture doen't get into the plant like chemical fungicides

Phil

[cliff_the_gardener]

agreed hence if using Bordeaux mixture the need for repeat applications every 3 weeks or after it rains

[mat]

Bordeaux mixture doen't get into the plant like chemical fungicides

I am intregued as to how copper doesn't get absorbed by plants?  Any ideas?  ???

mat

[cliff_the_gardener]

Bordeaux mixture is copper sulphate CuSO4.
As I understand it, it is the copper sulphate itself that is toxic to fungi.
A copper nail would kill a tree, which is what I think is underlying your question.  Having said that copper is a trace element needed by plants.  So everything in moderation.

[plot51A]

Lost all my tomatoes to blight last year too. This year am trying some blight resistant  varieties as well as others which are supposed to be good outdoors and some of the same as I grew last year to see what happens! Also plan to use wind breaks and protect from rain. Have the bordeaux mixture at the ready. One variety allegedly blight resistant and NOT an F1 is Legend - but it is from T & M! You can't win them all.

[Robert_Brenchley]

Let us know how you get on. If everyone who grows outdoor toms pools whtever they learn, we should be able to make some progress.

[philcooper]

I am intregued as to how copper doesn't get absorbed by plants?  Any ideas?  ???

mat

Bordeaux mixture is a finely ground mixture of copper sulphate and slaked lime which is disolved in water to make a very thin paste which coats the leaves and stems of the potatoes but is too coarse to be absorbed. The thin layer prevents the spores' root things (for which there is a posh name) getting into the flesh and hence into the plant.

Unfortunately the coating is not long lasting and easily washed off by rain hence the need to respray every 2 - 3 weeks or after rain to ensure the efficacy (that's a posh word I do know) of the treatment

Phil