Application horticultural crops

Recommended methods of application for vegetables and ornamentals

Contans^®WG is a water dispersible granule which is mixed with water and applied by spraying onto the soil using conventional spraying equipment.  The treated soil surface must be well mixed into the upper soil layer by using a rotary hoe or similar machinery.
Under good conditions (soil temperature: 12 to 25 °C (54 to 77 °F), sufficient moisture in the soil) C. minitans needs two to three months to destroy the surviving pathogenic structures in the soil.  For this reason Contans^®WG has to be applied two to three months before an anticipated outbreak of Sclerotinia.

Contans^®WG may be also applied and/or drenched via an overhead (sprinkler or pivot) irrigation system, where registered accordingly (France, USA).  Water can easily distribute the spores of C. minitans in the topsoil layer; however, the texture of most soils allows spores not to go further down than a depth of 2 – 3 cm (about 1 inch).

Conditions

The effectiveness of Contans^®WG depends on the soil temperature (optimally 12 – 25 °C/54 – 77 °F) and on sufficient moisture in the soil.
Even at a soil temperature of 5 °C (41 °F), the sclerotia of the pathogen are fully infected by C. minitans within 110 days after a treatment with Contans^®WG.  If the soil temperature decreases below 0 °C (32 °F) or rises above 27 °C (81 °F), C. minitans ceases activity and rests in the soil; even so the fungus will not be destroyed during this period.  Once the temperature returns to between 1 and 27 °C (34 and 81 °F), C. minitans will continue to parasitize the sclerotia.
This permits Contans^®WG to be applied during cold seasons or before the hot seasons in zones with a warmer climate.

Nevertheless, an application should be avoided, if soil temperatures during the subsequent 10 days are likely to exceed 27 °C (81 °F), as the weakest phase of the antagonistic fungus C. minitans is the germination phase after application.  The fungus C. minitans establishes on the pathogen within 10 days and then is quite resistant.
The strategy for the countries with a warmer climate is to solve the disease problem and apply Contans^®WG well before the hot phase of the year, possibly repeatedly, if susceptible crops are grown consecutively.  The sustainable effect of Contans^®WG is due to the reduction of the pathogen Sclerotinia spp., which will have its impact even in the hot season, when an application might be skipped.

Rate of application

The rate of application of Contans^®WG depends on the depth of incorporation (dilution effect), the disease pressure, but also on the time available between application and the anticipated outbreak of the disease.  The maximum rates at any depth provide relatively fast destruction of the pathogen (see above).  As local conditions and farm practises differ worldwide, the best use recommendations are adapted regionally.  Labels may therefore differ slightly.  You are advised to download the label and/or to contact the technical adviser of the local responsible distributor.

A rate of application of 1 to 2 kg / ha (1 to 2 lb/acre) is recommended for the treatment of harvest residues.

Registration

Contans^®WG is registered as a pesticide in various countries.

In the European Union the use of Contans^®WG in organic farming is licensed in accordance with regulation (EEC) No.  2092/91, Annex II B (II).

Time of application

1. At least two to three months prior to planting crops susceptible to Sclerotinia rot
   Crops which normally get infected by the mycelium growing in the soil must be treated at least two to three months prior to planting/sowing.
   After application, the soil must not be tilled to a greater depth than that at which Contans^®WG has already been incorporated.  Otherwise untreated soil will be transferred from the lower to the upper soil layer and induce infection. New trial results showed that even an application onto the crop (spray application followed by irrigation) can effectively prevent the disease by creating a barrier in the soil which stops the mycelium growing through the soil.
2. Immediately before sowing/planting a susceptible plant, but at least two to three months before an anticipated Sclerotinia-outbreak.
3. For crops which normally get infected through spores, the product can be applied immediately before planting, if infection is not anticipated earlier than two to three months after the application.
4. After harvesting, before incorporating onto the harvest residues
   After harvesting a crop which has been infected by Sclerotinia spp., the residues are treated with Contans^®WG before they are incorporated into the soil.  This directly contaminates and eradicates the surviving structures (sclerotia).  Recontamination of the soil with the disease causing fungus is thus effectively prevented.  Treatment of the harvest residues is generally recommended.  It is especially important on farms with short rotations of crops, susceptible to Sclerotinia spp.! Post-harvest treatment is the precondition for a sustainable reduction of the pathogens in the soil.
5. Before a non-susceptible crop; before the soil lies fallow (e.g.  in the autumn)
   Contans^®WG can be applied before the soil lies fallow or directly before planting a crop that is not susceptible to Sclerotinia.  The antagonistic fungus C. minitans then has sufficient time to destroy the pathogenic sclerotia. Treated soils should not however be ploughed before planting the susceptible crop so as to prevent untreated sclerotia coming from deeper soil layers infesting the top soil.