where Ct is the pesticide concentration in the tomato at the time t,
Charvest is the concentration at the time of harvest and k is the degradation
constant. As there were observations below the limit of detection
(LOD), and zero values cannot be log transformed, the value of ½ LOD
was added to all data before the analyses were done. The estimated
pesticide concentrations at harvest (Charvest) for the untreated tomatoes
are given together with the rate of decay for all pesticides where a significant
time effect was detected in the ANCOVA. All analyses were
done using the software program R (R Development Core Team).