FOLIAR APPLICATION OF CALCIUM CHLORIDE FOR IMPROVING APPLE QUALITY AND REDUCING RESIDUAL PESTICIDES

To evaluate the effectiveness of the continuous foliar application of 6 biweekly sprays of an 0.5% solution of calcium chloride (from the early stage of apple formation, until 2 weeks prior to harvest) to reduce Diazinon and Phosalon residues in apples, an investigation was carried out in one of the orchards of Damavand, Tehran, in the 1999 growing season.
Eight treatments with seven replications (one tree per replication) were tested: T1) the grower’s conventional fertilization (control); T2) T1 + foliar application of 0.5% CaCl2; T3) deep placement of all recommended chemical fertilizers according to the soil test analysis without manure; T4) T3 + foliar application of 0.5% CaCl2; T5) T3 + manure; T6) T5 + foliar application of 0.5% CaCl2; T7) T5 + balanced irrigation; and T8) T6 + balanced irrigation.
The hypothesis of this study was to reduce the residual effects of pesticides with balanced fertilization, controlled irrigation and foliar application of 0.5% CaCl2 during the growing period of the fruit.
The concentrations of some nutrients plus residual pesticides revealed that:

– Concentrations of N, K, Fe, Zn, and Cu from deep placement plus manure treatments (T5, T6, T7, and T8) were significantly greater in relative to other treatments and the concentrations of these elements in T3 and T4 were higher than those of the control plot.
However, last differences were not significant.

– Concentration of Ca in all foliar application treatments, i.e.
T2, T3, T6, and T8 was significantly increased.
While Ca concentration in the control plot was 80 mg/kg on a fresh weight basis, it was increased to 140 mg/kg in T6.

– While the percentage of water in apple fruit in the control plot was 84.7, it was decreased to 83.8% in treatments seven and eight (balanced irrigation), but this difference was not significant at 5% level.

– The residue of both pesticides (Diazinon and Phosalon) was significantly reduced after foliar Ca applications.
The difference of Diazinon concentration between treatments was significant (P=0.01) and reduced from 4.0 microgram per kilogram (ppb) to 3.0 ppb, and the difference of Phosalon concentration among treatments was significant (P=0.05), and decreased from 1.24 ppb to 1.10 ppb due to calcium application.
These results show the importance of calcium chloride application in improving the quality of apples as well as reducing pesticides residues, which is very important for human safety.

IV International Symposium on Mineral Nutrition of Deciduous Fruit Crops

M.J. Malakouti, M. Afkhami

diazinon, phosalon, apple fruit firmness, and pesticide residues

https://doi.org/10.17660/ActaHortic.2001.564.42