Pesticide selection criteria
The recommendations suggested by Tene-Ag encompass cultural, mechanical, biological and, wherever necessary, chemical strategies for managing crop health problems. These recommendations are developed, and regularly updated, by specialists in Agricultural Entomology, Plant Pathology and Plant Physiology.
The decision to include a chemical pesticide (or, conventional pesticides) in a recommendation against a specific pest depends on the phenological stage of the crop, nature of the target pest, seriousness of the damage, nature of the pesticide, safety level of the pesticide, effectiveness of the pesticide, pre-harvest interval and phytotoxicity. The steps for identifying pesticides against a pest are as follows.
The currently registered pesticides, as per the list given by CIB, are considered.
According to Step 2, the HHPs given to cause harm to human beings are called High Risk HHPs (HR-HHPs), and those that are given to cause harm to either bees, or aquatic life, or both, but not to human beings, are called Low Risk HHPs (LR-HHPs).
Non-HHPs and LR-HHPs are further classified based on their Oral LD50 values given by the government of India into Ia (< 50 ppm); Ib (51 to 500 ppm); II (501 to 1000 ppm); III (1001 to 5000 ppm); and U (> 5000 ppm) categories. [As Dermal LD50 values are not available for several pesticides, it could not be used as a criterion.]
Pesticides in each of the acceptable categories (as per Step 5) are further classified based on their solubility and persistence. Pesticides that have low values for both solubility and persistence are called LowSP, while those that have moderate/high values for either solubility or persistence are called HighSP.
For every pest in Sativus, the list of Label Claim pesticides, published online by the CIB, is noted. These pesticides are compared with the Safety Table and the most safe pesticides with Label Claim are shortlisted. Peer-reviewed publications are consulted to compare the effectiveness of the shortlisted pesticides. Pesticides are considered for recommendation based on effectiveness and safety.
When Step 10 also does not shortlist any satisfactory pesticide, then the basket of Safe Pesticides is consulted before making a recommendation. A basket of Safe Pesticides is created for different problem groups viz., chewing insects, sucking insects, thrips, mites, leaf miners, ascomycetes fungi, basidiomycetes fungi, oomycetes fungi and deuteromycetes fungi. All pesticides that are claimed by the manufacturers to be effective against a problem group are given a Safety Rank (the criteria for ranking are listed in the Safety Table). Peer-reviewed literature is consulted to compare the effectiveness of these pesticides. The decision to recommend a pesticide depends on its Safety Rank and effectiveness.
These registered pesticides are classified as Highly Hazardous Pesticides (HHPs) or non-HHPs according to the global standards mentioned here.
All HR-HHPs are rejected; they are not considered for recommendations under any circumstance.
From Step 5, all Ia and Ib pesticides are rejected; they are not considered for recommendations under any circumstances.
A Safety Table is prepared based on the above Steps (1 to 7). Here, HHP Status is given the highest priority followed by Hazard category and Solubility/Persistence.
When there is no Label Claim pesticide against a specific pest, or when all the Label Claim pesticides are either HR-HHPs, or belong to Ia/Ib categories, then all the pesticides with Label Claim for the target crop are listed. These pesticides are compared with the Safety Table and the most safe pesticides with Label Claim are shortlisted. Further, the effectiveness of the shortlisted pesticides against the target pest is considered before making the decision.
The mode of action, whether contact/systemic/translaminar, phytotoxicity and Pre-Harvest Interval (PHI) are noted for each pesticide. These characteristics are considered while positioning a pesticide in a recommendation. If a pest occurs at different phenological stages of a crop, then pesticides with varying modes of action are positioned at different phenological stages to tackle the problem of resistance development in the target pest. Contact/translaminar pesticides are given higher priority over systemic pesticides as pest organisms have a higher rate of resistance development against the latter. Pesticides with systemic action are given a lower priority during the reproductive phase of a crop. LR-HHPs toxic to bees are avoided during the flowering period.