and Integrated Pest Management - part - usaid

356( I'FUsTICII).. MANAGt~I-MENT AND IPM INSct >1'It ..AsI' AS IA
Some advantages and liinitation'; are inherent in these two approaches,
pronpting NMagalh loa ct al. (198 I) to adopt a system in which tile merits of
both approaches are retained at tle sale lile that the limitations are minimized.
The system colsists of (a) selecting a major growing area for tie commodity of
interest, (b) coniducting pesticide managemient surveys in the area to pinpoint the
more commonly used insecticides, (c) arranging for farmer cooperators who will
be monilored closely, (d) getting samples for residue analysis from cooperators
,Ad other farmers, (e) conducting residue trials in experiment stations with
populair pesticides used by farmers but usii:g heavy and larner-level application
regimes, ard (1) conducting 'niarket-basl:et' type .mpling in major urban
markets. Ancillary sitidies on the effect of' washi'l! nd cooking may also be
dolie to give a coinplete picture of the pesticide ii. the crop of interest. Tile
sysem Ias been applied to 'pechay' (Brassica cmpesiris spp. chinensis)
(Nlagal::il et al. 19,'1I) ard string beans (VI'ia sesqtdlwdai.c Fruw.) (Tejada et
al. 1983). The merit of the nodified approacli is its capability to go back to the
farniers with positive advice on what to do in order to reduce pesticide levels
wilhout jeopardizing their cr'p protection practices. This is necessary since the
local inrketing system does not allow for disposal of Irodlce because of high
residue conret1. The recoinieidation ol pesticide iisa(ce and preharvest intervals
(I) Its) would now have greater iiiipact beca use it is stI)ported by actual data.
There were few reports on pesticide residues prior to 1977 (Saplala 1954,
Pablo 1965, Magalhba & Sanchez 1968, Barril et al. 1974). At present, the
residue dalahase includes insecticide residue levels in agricultural produce like
vegetables (cabbage, pechay, string beans, green beans, toiato, and bush sitao);
cotton (:secd, oil, cake); tobacco; banana; grains (rice, corn); dried fish; and the
components of the rice paddy environment (soil, paddy water, rice plant, fish,
and snails). Residue levels are also studiCd in humans (milk, abdominal fat,
urine, and blood).
INSECTICIDE RES!I)UES IN FARM PRODUCE
String Beans
Using the above-mentioned modified approach, Tejada et al. (1983)
conducted i,;ecticide residue trials on string beans. Table I shows the levels of
diazinon and methyl para!hion residues in string becan samples taken from farmer
cooperators in Carmona, Cavite. Only trarcs of diazinon were detected three days
after the last spray application, and no detectable residues of methyl parathion
after five days. Washing reduced the residues of diazinon by 20% to 33% and
methyl parathion by 33% to 49%. In the field residue trials at UPLB, no
mevinphos residue was detected even three hours after spray application (Table
2). For monocrolophos and malathion, no residue was detected two days after
spraying. The most persistent inscticide was triazophos with 0.9 mg/kg residue
even after five days. The use of double the recommended dosage resulted in
hivher initi;l residue level, but loss was also faster. Except for triazophos,
which still had a relatively high residue level by the fifth day (1.9 mg/kg), a 5to
7-day PI may be recommended. On the other hand, of the 96 string bean