Facial Eczema – Prevention better than Cure?
By Ian Wickham
Don’t take it for granted….. that just because you have not been caught out with animals showing clinical symptoms (peeling skin etc) in the most recent few seasons, that this year will be the same.
The fungus Pithomyces chartarum occurs and thrives in locations of warm ground temperatures coinciding with high humidity and moisture.
When the fungus grows rapidly it produces spores containing a toxin called sporidesmin which is susceptible to ultra violet light breakdown, therefore freshly produced spores contain more toxin than do the older spores.
When grazing animals ingest spores of the fungus, it is the sporidesmin toxin that leaches out of the spore and enters the blood stream to cause damage to various organs of the animal.
Some form of dosing the animal with zinc is proven to help control the effects of the toxin and help in the animals recovery.
The use of Zinc Time Capsules has been a preferred system chosen by many of our Graziers for some years now, and these have proven to be effective when applied at the right time.
Dosing with zinc in what ever form has its drawbacks. In itself (as with many medications) zinc carries its own level of toxicity and we have observed lowered growth rates and depletion of copper levels in some animals subsequent to dosing.
A Managed Approach
1. Know your problem.
Each Friday we receive a report by email of the spore counts in all areas of NZ. Please contact our office if you would like to be included on this list.
Get spore counts from your own property. Your Vet can help you with this, or you may do your own.
Decide at what stage and what action you are going to take when the spore count increases to your “Action point”
This should be before spore levels reach 25,000 per gram of pasture.
The first ACTION you should consider is how to reduce the spore numbers your animals are likely to be exposed to.
Spraying pasture with a fungicide containing the active ingredient CARBENDAZIM will kill active spores in the fungus as they germinate, and thus reduce amount of toxin likely to be eaten by the animal.
Spraying may be done by ground application if the contour is flat enough. Alternately, aerial application should be available by Fixed wing or Helicopter.
4. Application rate of carbendazim
Carbendazim should be applied at the rate of 150 grams per hectare and may be mixed in water at the rate of a minimum of 50 litres per hectare using a fixed wing aircraft. Consider a 2 pass application with half the rate of carbendazim applied on each pass.
5. Application strategy
You should plan on what your approach should be in advance. If you have some flatish paddocks suitable for spraying and you have a good amount of pasture available on them, you may consider ground spraying them first to provide for an amount of “safe” feed while you appraise the developing situation. Treatment of long or short pasture is equally effective.
You may consider aerial spraying say half the farm, or even the whole farm if pasture is short and you need to rotate stock over a larger area. Reduction of spore production should be for a period of 4 to 6 weeks.
It should be less costly to use a fixed wing airplane to spray, but this will depend on the water supply at the airstrip. It is expensive to bring in water in a tanker and this may outweigh the ability of the more expensive helicopter being able to operate from a convenient stream or pond supply.
6. Products containing cardendazim with label claim for Facial Eczema control.
Bell-Booth Ltd distribute a product named X-Spore which is an off white liquid containing 500 grams per litre of carbendazim as a suspension concentrate. The label states it should be applied at 300 mL per hectare mixed in 100 to 200 ltrs of water for ground coverage. This gives 150 grams per ha of active ingredient.
A suitable surfactant such as Contact lo Foam from Nufarm Ltd could be added to enhance coverage.
A 20 litre container of X-Spore will cover 66.6 hectares.
X-Spore has been manufactured locally to a very high standard from imported carbendazim for many years and is a well proven product.
Coast Biologicals Ltd distribute a product named Mycotak which contains 800g/Kg carbendazim in the form of a water dispersible granule. It should be applied at the rate of 190 grams of Mycotak per hectare and it is strongly recommended by the distributor that Mycowet surfactant be mixed with Mycotak at the rate of 100 ml per ha to enhance the spreading and foliage deposition of Mycotak.
This gives 150 grams per ha of active ingredient. A 5 kilogram pack of Mycotak will cover 26 hectares.
Check you prices carefully to en-sure you are not paying more than you need to. The writer found significant differences in price of carbendazim from various outlets.
Do your homework on the amount of active ingredient applied per hectare so you can compare prices accurately. Different pack sizes and application rates may otherwise confuse.
Likewise with application costs.
Some ground spray contracts cost more than helicopter application.
If you have an airstrip handy, does it have a water tank near the loading area? Is a spray fitted aircraft available?
Talk to your neighbours for combined application – it may be cheaper.
1. With short pasture length caused by dry weather, there is an increased risk of greater than normal fungus and spore growth.
2. Spraying with carbendazim should prevent facial eczema spores from increasing to dangerous levels. With reduced spores, there will be reduced toxin.
3. If reduced toxin levels avoids the use of zinc dosing of the animals, increased growth rates can be expected and less need for copper supplementation.
4. Monitor spore count. Plan carefully and choose the systems you are going to use to control a potential Facial Eczema outbreak.
5. Consider the reduction of spores as a first line of defence and the dosing with zinc as a second line of defence.
6. Do NOT relax too soon.
In past seasons it has ALWAYS been the period from Mid MARCH to end of APRIL that have shown the highest spore counts – and Mid MARCH to end of MAY the most elevated cattle serum GGT levels.