Tomato/potato blight

 

I signed up for that blight-watch site and have had no warnings as
yet.  The site assumes you are a commercial grower.  Perhaps they
didn't think I was eligible for warning!

Today one chap on our allotment site pulled up all his tomato plants;
at least 2 dozen.  They looked a bit brown 2 days ago but today they
were much worse.

I pulled all the tops off my potatoes, leaving the spuds in the
ground, well covered until I have time to dig them.  

Pam in Bristol

 



There were no Full Smith Periods today, so no warnings.

 

On Thu, 17 Jul 2008 20:49:00 +0100, "Russel Sprout"


You can also use that site to see previous months and years.

They will email a warning if the temperature and humidity are above or
close to (near miss) those that allow late blight to spore and spread.
Two sucessive days, and that's a Full Smith Period. The info is then
for farmers to start spraying fungicide. I use Dithane 945 as it's
slowed the blight's advance long enough to usually get a crop.  I've
had mostly healthy plants while my next door neighbours have a brown
dying mess.  It doesn't kill the fungus, it protects other  leaves
from infection if they haven't been already. One Smith Period isn't a
reason to panic. It's when they come about a week or so apart eg
typical wet weekends. That suits the blight's reproductive cycle.
Otherwise it stays dormant. Bides it's time : (

Btw there are plans to ban mancozeb (vital part of dithane) in the EU
from 2009.  With our weather we wouldn't stand a chance with toms and
spuds. Please consider writing to MP's, Defra, etc. I don't like
chemicals and  this is the only one I use, for a reason.

 Removing infected leaves helps early on, as does covering the soil
with black plastic (other benefits). Above all, don't water the
leaves.!  Some varities seem more susceptable, Roma and Krim in my
experience, with Gardener's Delight (sob) not far behind. This year
I'm growing a few Fastico, supposed to have some resistance. Also try
some early varieties like Stupice, 4th July, Glacier etc. They'll
start producing tomatos before late blight can get a real hold (Sept)
I'm over here in the usually drier Bedfordshire though. Late May-early
June were Smith Periods, as was a week ago, no blight yet seen. Though
I'm going to spray asap.

This site's photos are useful for deciding what's attacking the plant
now ; )   Early blight isn't a reason to pull plants, as only leaves
are affected. Late blight looks different, it looks like the Black
Death....in a brown sort of way!
http://aggie-horticulture.tamu.edu/tomatoproblemsolver/index.html

Good luck!

 

On Fri, 18 Jul 2008  tony newton wrote:

Dithane is the only chemical that seems to prevent powdery mildew on
vines!

David

--
David Rance        writing from Caversham, Reading, UK
david.rance@rance.org.uk http://www.mesnil.demon.co.uk