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Date last updated: 
01 August 2008

White Rust 
reproduced with kind permission from Peter Fraser 

White Rust is here to stay like it or not even growers with the super chemicals are having trouble some have even cut their plants down while some growers have decided to call it a day a bit drastic i think.
How do you spot white rust the picture on the left shows the upper surface of the leaf indicating yellow type spots turn the leaf over picture on the right you will see yellow/brown pustules its when these burst that the disease spreads. I have put a list of chemicals that will help you they may work or not prevention is better than
having to cure the problem its no good jumping in the sea and then sitting on the beach all night then going to the doctors and complaining of a cold. it should be pointed out that there are over 20 strains of white rust

Prevention
At the end of the season if you have the equipment you can heat treat your stools but i should point out that this is not foolproof some growers have done this and have still ended up covered with White Rust the following notes are for people that do not have the equipment to heat their stools

1 At the end of the season when you dig up your stools remove all the green foliage and also remove the soil ( This can be risky i have done this and next year the stools have throwing no cuttings ) Then dip the stools in SYSTHANE available at most garden centres and let them drain off before boxing them up in fresh clean compost

2 Now to your plot all old plant debris should be removed better still go to your Plant Hire Shop and hire a FLAME GUN and go over your plot killing all debris sterilise your plot also if you feel better

3 Hot water treatment of stools
You can hot water treat your stools, there is chapter in the CHRYSANTHEMUM GUIDE - a 'must have' publication for all growers. If you do not have one I have them for sale at 13.95 to non members of the N.C.S, or 11.95 to N.C.S. members. 

CHEMICALS AVAILABLE TO THE AMATEUR GARDENER

Systhane (Myclobutanil )

Fungus Clear ( Penconazole )

Dithane 945 ( Mancozeb )

Rose Clear 3 Combined insecticide fungicide ( Bifenthrin & Myclobutanil )

Images of white rust on chrysanthemum leaves:


Upper Surface of Leaf

Under Side Of Leaf

Spraying Programme
Every 10 days Ring the changes don't use the same chemical each week alternate
Also use soft soap 1, 5mil spoonful to a 4.5 litres( 1 Gallon ) dissolve this in a can with boiling hot water stir till dissolved and pour into the gallon of water don't use to much hot water just enough to dissolve the soap this will act as a wetting agent and will leave greasy surface on the leaf which may prevent spoors from attacking the leaf

I should point out that none of the chemicals will kill white rust but will act as a preventative
All the chemicals are available in most garden centres and the soft soap is available from CHEMPAK PRODUCTS
If you are not sure about anything in this article give me a ring at a reasonable time or drop me a E-Mail

A question I have been asked several times is will HOT WATER TREATMENT stop me catching white rust next year the simple answer is NO! What it will do is eradicate any white rust virus you have on YOUR stools so you will have a clean start next year. However if you obtain plants from other sources they may carry the spores and it will start over again if you are not vigilant and keep spraying also when you plant out if 'old dolly' up the road has a garden full of pot mums and they are covered with it you could be in trouble if you are not vigilant and keep spraying.

Link to Peter's website:  Peter Fraser's website

Peter Fraser 
NCS 
Membership & Sales 
Manager

 

Copyright 2006 Paul Barlow.