Pre-harvest interval

Residue decline study requirements. All residue studies should provide a decline study that shows the dissipation pattern of the residues for at least three different sampling times and shows the MRL. Typical sampling times are suggested to be a pre-harvest interval (PHI) of 1, 3, 7, 14, 21, 28 (30), 45, 60 days, etc. Especially for daily harvested crops such as tomato, cucumber, eggplant and bell pepper, a PHI of 1 day should be selected. 

However, the metabolism of a pesticide may change with crop and pre-harvest interval, or may be completely different in animals. 

Stable in acidic, neutral and basic aqueous solutions Pale yellowish solid, faint characteristic odor Flash point 119°C (Pensky-Martens closed tester) Pyriproxyfen is an insect growth regulator which acts both as an ovacide and as an inhibitor of development (juvenile hormone mimic) against white flies, scale, and psylla. The specificity of pyriproxyfen, and its low mammalian toxicity, allow for some variation in application timing. For example, the lack of toxicity to bees allows pyriproxyfen to be applied during bloom on apple trees, and its low mammalian toxicity allows for a very short pre-harvest interval on citrus The residue definition is for pyriproxyfen alone... 

The time that must pass from application until it is safe to harvest a food crop expressed as days to harvest or pre-harvest interval PHI), this is the time required for the residue to drop to safe levels it is often listed as a number in parentheses following the crop name... 

Its persistency is low. Its price is relatively high and this, together with the competition of synthetic products has limited its use. However, the low persistency makes possible its application immediately before harvest, without a pre-harvest interval. 

A very advantageous property of carbaryl, compared with other carbamic acid esters, is its low toxicity to warm-blooded organisms. Its oral acute ld,q value for rats is 400-600 mg/kg. The prescribed pre-harvest interval is in general 7 days and permissible residue values are about 3 ppm. 

Application of pesticides in China should follow Guidelines of Safety Application of Pesticides. There are over 50 laboratories that can conduct pesticide held trials certihed by 1C AM A. The good agriculture practices (GAP) for the safe and effective use of the product must be established. Over 1,000 held trials with over 300 active ingredients in more than 30 crops have been conducted in China. On the basis of these held trials, a series of GAP have been drawn up and new revisional MRLs have been proposed. The main contents in this GAP are common name, crops, application rate and method, maximum number of application, PHI (pre-harvest interval), and recommended MRLs. 

Guidelines of Safety Application of Pesticides, Good Agriculture Practices, Pre-Harvest Interval, ICAMA, Residue Data Requirements, Field Trials, Residue Analysis Method... 

The dissipation curve was statistically calculated and plotted accordingly [11]. Corresponding values for LOD, LOQ, and percent recovery from non-treated samples are shown below. In this particular case, to reach, for example, a dtrus fruit tolerance of 0.1 mg/kg for bifenthrin, the Pesticide Agenda would recommend a pre-harvest interval of 28 days to the growers. 

Pre-harvest Interval 7 days, tomato. 14 days potato and 50 days, cottonseed ... 

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