In Australia, sour rot control on citrus fruit usually involves combining chemical fungicides with sanitisers and/or generally regarded as safe compounds (GRAS). Careful evaluation is necessary because the effects of chemical mixtures can be neutral,additive, synergistic or antagonistic. Generally, research strategy has two main aims; sour rot spore control in water suspensions, and sour rot control on fruit. The first approach involves the evaluation of sanitisers, such as calcium hypochlorite, chlorine dioxide, chloro-bromo-dimethyl-hydantoin and peroxyacetic acid, in 'simulated' packing line processes. Sanitisers added to fungicide dips can reduce sour rot spore loads but chemical incompatibility is common: Sanitisers can quickly lose activity rendering them ineffective. The response varies with sanitiser active, fungicide active and fungicide formulation, making evaluation an on-going task as new actives and formulations are commercialised. The second approach aims to enhance sour rot controlon fruit by combining fungicides and GRAS compounds. Currently, citrus packers combine mineral salts, such as sodium carbonate and sodium bicarbonate, to improve sour rot control. Organic salts, such as potassium sorbate, also have demonstrated efficacy.Sanitising these solutions is problematic, with the choice of fungicide, salt and sanitiser influencing compatibility and efficacy.
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