Kaolin sprays and individual fruit bagging effects on quince fruit quality

Abstract

Mediterranean fruit fly damage to quince fruit is wide spread in central Greece. The use of alternatives to chemical insecticides, including kaolin sprays (Surround WP) and individually bagging of each fruit with a paper bag were studied. During the summer 2009, quince tree branches were sprayed with 5% kaolin periodically from July and at the same time individual fruit were bagged in gray paper bags. Two farms, a conventional (University of Thessaly Experimental Farm in Velestino) and an organic farm (Lechonia Magnesias), both located in central Greece were used. Kaolin-treated leaves had higher chlorophyll content and were macroscopically greener than control leaves, but did not have higher productivity based on specific leaf weight measurements. The greener leaf color could be due to less stressful conditions experienced. At harvest, fruit from kaolin-treated branches were greener than fruit from control branches and the latter were greener than the bagged fruit. In kaolin-treated quince fruit, the soluble solids content, percent dry matter content and starch index were similar to control fruit. Bagged fruit seemed to have inferior quality based on lower starch and dry matter content. In conclusion, kaolin treatment to branches did not significantly affect leaf productivity (although leaf chlorophyll content increased) and fruit quality although it seemed to slightly delay skin color yellowing. Unfortunately under these conditions, kaolin was not able to protect the quince fruit from fruit fly damage. On the contrary, fruit bagging resulted in more yellow fruit and less starch that could be perceived as more advanced maturity, but with lower percent dry matter and organoleptic quality than the fruit from the other two treatments. Nevertheless, bagged fruit were free of fruit fly damage.