Changes in surface microflora of apple and pear fruits by application of pesticides and their relation with biocontrol of post-harvest diseases.
Calvente, V.; Benuzzi, D.; Obuchowicz, N.; Hough, G.; Tosetti, M. I. S. de;
Agro Food Industry Hi-Tech Year: 1999 Vol: 10 Issue: 1 Pages: 30-33 Ref: 17 ref.
1999
บทคัดย่อ
The evolution of natural microflora of apple (cv. Red Delicious) and pear (cv. William) fruits during ripening was studied in relation to the application of pesticides used to combat preharvest pests with the aim of studying how the pesticide application might be manipulated to enhance the beneficial effect of the natural microflora against post-harvest diseases. Yeasts dominated the fruit epiphytic microflora prior to the application of pesticides (deltamethrin + dicofol or esfenvalerate + dicofol), whereas after the treatments, moulds dominated. Twenty days after the last application, the dominating flora was still moulds, but 30 days after the treatment (final harvest), yeasts predominated again. In vitro assays of pesticide toxicity for yeasts showed that deltamethrin was more toxic than esfenvalerate and dicofol was the least toxic. None of the 3 pesticides was toxic for the pathogen Penicillium expansum. Fruit wound colonization assays revealed that wounds were colonized by moulds or yeast
s depending on the harvest time (20 d or 30 d after the pesticide application). Rhodotorula glutinis and Cryptococcus laurentii from epiphytic microflora were effective for reducing the incidence of blue mould on apples. It is suggested that a yeast dominated microflora could be a natural agent of rot control. The appropriate timing of preharvest pesticide application in relation to beneficial microflora of fruits and the need to include the fruit microflora among the ecological selectivity tests of preharvest pesticides are discussed.