and Integrated Pest Management - part - usaid

IMPLEI MENTATION
Cost Objectives
IPM ON ESTATE CROPS IN MALAYSIA 35
IPM should be the cheapest way of controlling pests. However, this
implies cost in the long rather than short term, and includes acceptable losses as
well as direct expenses of control measures. A chosen control measure may not
be the cheapest for the immediate job, but should have minimum risk of side
effects whilst giving the required results. A cultural policy may not be the
cheapest for an agronomic benefit, but if it reduces losses to pests or expenditure
on other control methods, it can add up to the lowest cost strategy overall. For
example, very frequent and complete harvesting of cocoa may give a raised cost
per ton harvested, especially at time of trough crop, but with its value in control
of cocoa pod borer (CPB) (Mumford 1986), it can be the most profitable
procedure.
Census Monitoring and Economic Damage Levels
It is important to know the relationship between pest numbers and crop
loss. This requires two stages - the iclationship of an amount of damage to crop
loss, and of numbers of pests to an amount of damage. Crop loss studies can
either directly compare yields at given numbers of pests, or use simulated
damage related indirectly to pest numbers. This approach is exemplified in oil
palms by Wood (1977). Detailed studies show that there is no limit to losses
due to pests. 50% or more reduction in a crop may be sustained regularly or
sporadically if there is no control, or if it is misdirected. The cost of
inlerventions can be related to the losses that would otherwise occur, but some
degree of prediction is needed about how an incipient buildup is likely to
progress.
Census Monitoring and Control Measures
I
Proven census systems exist for most common pests in plantation crops in
Southeast Asia. For occasional pests they usually are done in stages with first,
a generalized alert system, followed by a detailed count on a grid, where incipient
infestation is noted. The laiter is carried out until the outbreak declines
(naturall,,, or after intervention), and is then continued long enough to cover the
period of likely re-outbreak (see statement 10).
Where key pests are concerned, such systems may be used to ensure that
chemical applications are kept to a minimum, by response only to spots where
outbreaks are beginning (e.g. llelopeltis spp. on cocoa - Youdeowei &
Toxopcus 1983). In such cases, the optimum point for intervention needs to be
determined - in some cases a certain level can be tolerated before treating larger
areas. In others, less total amount of treatment is needed if there is response at
first sign of the pest at individual grid points.
Census is generally used to determine the optimum time of intervention in