Multiformulation dips for controlling storage disorders of apples and pears. II. Assessing scald inhibitors

Superficial scald (scald) was adequately controlled by diphenylamine (DPA), butylated hydroxytoluene (BHT and Topanol), and Ethoxyquin and partly controlled by Topanol O (a BHT emulsion formulated for calcium chloride compatibility). Mixing calcium chloride (calcium) with these scald-inhibitors tended to improve the level of scald control, although this effect was not always significant, and Benlate reduced the effectiveness of Ethoxyquin. The phytotoxic effect of individual dip components caused appreciable wastage from lenticel spotting. Lowest lenticel spotting occurred with Ethoxyquin and DPA miscible oil (MO), while BHT miscible oil formulations Topanol and Topanol O caused excessive spotting. Calcium was also highly co-inductive to lenticel spotting, and this effect was compounded by the inclusion of scald inhibitors with calcium. In using mixed ingredient (multiformulation) dips, DPA as a miscible oil or powder gave effective scald control without greatly increasing lenticel spot when calcium was added. However, this effect was more apparent on ‘Granny Smith’ and since calcium did not improve fruit firmness on ‘Delicious’, its inclusion in post-harvest dips for this cultivar is not warranted.