Resource Book on Horticulture Nursery Management

Integrated Weed Management:
Integrated Weed Management (IWM) approach aims at minimizing the problem of
residue of herbisides found in plant, soil, air and water. An Integrated Weed Management
may be defined as the combination of two or more weed-control methods at low input
levels to reduce weed competition in a given cropping system below the economical
threshold level. It has proved to be a valuable concept in a few cases, though much is still
to be done to extend it to the grass root farmer level. An IWM involves the utilization of
a combination of mechanical, chemical and cultural practices of weed management in a
planned sequence, so designed as not to affect the ecosystem.
The nature and intensity of the species to be controlled, the sequence of nursery
plants that are raised in the rotation, the standard of nursery plants to be produced, the
time of availability of the resources used in the method and the economics of different
weed-management techniques are some of the potent considerations that determine the
success for the exploitation of the IWM approach.
4.2.4 Biopesticides Application in Horticulture Nursery
Introduction
Biopesticides are certain natural plant products that belong to the so called
secondary metabolites that include thousands of alkaloids, terpenoids, phenolics and
minor secondary chemicals.
Biopesticides have usually no known function in photosynthesis, growth or other
basic aspects of plant physiology; however, their biological activity against insect pests,
nematodes, fungi and other organisms are well documented. Every plant species has
developed an inbuilt unique chemical complex structure for protection against pests. The
plant kingdom offers us a diverse array of complex chemical structures and almost every
imaginable biological activity. These biodegradable, economical and renewable
alternatives are used especially under organic farming systems.
Crop losses due to insect pests and diseases are estimated to be more than 30 per
cent in terms of agricultural crop produce. Though the crop productivity increases
significantly due to use of mostly chemical pesticides, their continuous use contributed to
increasing environmental threat to natural resources, wildlife, non-target beneficial
species. It also results in development of pest resistance and resurgence of the pest attack.
Mounting concern for environment has, therefore, led to evolve an alternate coherent pest
management programme which is eco-friendly, self sustaining and yet provide effective
management of pests and diseases. In this context the use of biopesticides or pesticides of
microbial origin are becoming increasingly important.
The Characteristics of Biopesticides:
� Eco-friendly,
� Possess higher degree of host specificity,
� Genetically stable and do not pose the risk of resistance development,
� Compatible with biofertilizers and many agrochemicals,
� Can be exploited under the ambit of integrates pest management (IPM).
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