Evaluation of post-harvest disease control with regards to the new maximum residue level of five ppm for prochloraz on mangoes in the European Union.
Swart S. H., Broekhuizen W. van
Author Affiliation: QMS Agri Science, P O Box 416, Letsitele 0885, South Africa.
Research Journal - South African Mango Growers' Association 24 : 73-77
Abstract : The effects of increased prochloraz concentration and heating of the fungicide solution on postharvest diseases of mangoes were evaluated. Prochloraz at 90 ml/100 l of water, applied as a heated dip treatment, was very effective to reduce anthracnose (caused by Colletotrichum gloeosporioides [Glomerella cingulata]) on naturally infected mangoes, and better than the registered 180 ml/100 l treatment at ambient temperature. Indications are that increased prochloraz concentration did not induce better postharvest anthracnose control. Therefore, regarding anthracnose control, prochloraz should be used at 90-180 ml/100 l as a dip treatment in a heated (50°C) solution. Results indicate that there is no need to increase prochloraz concentration when anthracnose is the major problem. Results showed that an increase in prochloraz concentrations and heating of the prochloraz solution did enhance control of stem-end rot (caused by Botryosphaeria spp., formerly known as Nattrassia mangiferae) on mangoes. Prochloraz concentrations higher than the registered 180 ml/100 l can be used, without exceeding the allowed European Union MRL of 5 ppm, to enhance control of stem-end rot and possibly soft brown rot (also caused by Botryosphaeria spp.). These diseases are currently the major cause of postharvest decay on mangoes exported from South Africa. Therefore, results of this trial suggest that prochloraz should be registered at a higher dosage, possibly 720 ml/100 l at 50°C, but these results should be tested for at least another season and on different mango cultivars.