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IInnnnoovvaattiioonn BBrriieeff
No. 12, May 2011
Vegetable Production under Protective Structures
Ramasamy Srinivasan
Urban and peri-urban vegetable production (UPVP) systems offer farmers enhanced market opportunities with
better economic returns. UPVP systems significantly contribute to urban food supplies, especially of vegetables.
The impact of UPVP systems is limited by a number of factors including insect pests and disease problems.
Insects are developing resistance to many of the most widely used pesticides in UPVP, prompting many farmers
to grow vegetables under protective structures which block the entry of pest and prevent crop infestations.
CGIAR Systemwide Program
on Integrated Pest
Management (SP-IPM) is a
global partnership that draws
together the diverse IPM
research, knowledge and
expertise of the international
agricultural research centers
and their partners to build
synergies in research outcomes
and impacts, and to respond
more effectively to the needs
of farmers in developing
Protective structures
There are two types of protective structures: permanent and temporary. AVRDC – The World Vegetable Center
has designed suitable nethouse and plastic house structures and appropriate maintenance procedures that
emphasize preventing entry of all damaging insects, thereby reducing the need to use pesticides.
Permanent nethouses
Permanent nethouses, if carefully constructed and properly maintained, can last for at least five years. The most
widely used structure is 2 m high made of galvanized iron tubing covered with nylon net (Talekar et al., 2003).
Coarser net (16- to 32-mesh size) is used for larger sized insects, such as lepidopteran moths, whereas finer net
(50- or 60-mesh size) is used to exclude smaller insects, such as thrips, whiteflies, and aphids (Talekar et al.,
2003; Harmanto, 2006; Shahak et al., 2008; Palada and Wu, 2009). Coarser nets allow a free airflow with
minimum build-up of temperature inside. The nethouse is usually constructed to cover an area of 500 m2. It has
been demonstrated that 15 cycles of various leafy vegetables could be produced free of any pesticide use
without losing yield or quality over a two-year period. In
addition to leafy vegetables, tomato, eggplant, cabbage,
cauliflower, broccoli, yard-long bean, and bitter gourd can
also be grown successfully in nethouses (Talekar et al.,
2003). In northern parts of India, such as Punjab, AVRDC
introduced adaptations to the original design, especially in
the shape of the nethouse. A net-room with a double door
entry point was provided at the front side, using poly-grip
assembly to fix the net, and with the net stitching parallel
to the hoops, which makes the nethouses more durable
under the climatic conditions of the region.
Improved nethouse as designed for the climatic conditions
in Punjab. – S. Sain
SP-IPM Technical Innovation
Briefs present, in short, IPM
research findings and
innovations for the
management of pests, diseases,
and weeds in agricultural
This and other IPM Briefs are
available from
Long-lasting, sturdy plastic house. – R. Srinivasan
Plastic houses
These are permanent structures lasting for about
four to five years, which utilize transparent but
sturdy rainproof plastics used mainly for longer
duration fruit vegetables such as tomato, sweet
pepper, and cucumber. These plastic houses not
only protect the crop from rain, but also keep the
insect pests away, thus allowing profitable tomato
production during the hot-wet season.