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The usual dimension of the plastic houses is 25m × 6.5m. Each house has a semicircular top covered with clear
plastic treated with an ultraviolet (UV) light protectant. In the center of the semicircular top, a 30 cm portion along
the entire length is left free of the plastic cover, but closed with nylon net. This facilitates ventilation and reduces
the buildup of heat inside. The ventilation facility is made rainproof by erecting a transparent plastic shade over
the top. The side walls are covered with nylon netting. At the front side, a 60-mesh netting double door is
installed (AVRDC, 2007).
There are two types of a temporary plastic house, which is used for a single growing season: a single-bed type
with an arched roof and a double-bed type with an A-shaped roof covered with UV-protectant polyethylene film.
The width is 2.4m for the single-bed shelter and 4.8m for the double-bed shelter. The height at the center of both
types is 2.4 m (Palada et al., 2003). The sides are covered with nylon netting to exclude insect pests and prevent
rain from blowing in. The growth and yield of cucumber, sweet pepper, and small-headed cabbage were
significantly improved when grown under rain shelters during the hot-wet season in Vietnam. In addition, these
structures significantly reduced the incidence of fungal and viral diseases (Hanh, 2003).
About the author
Low net tunnels
Growers who cannot afford the high initial construction costs of nethouses or plastic houses can grow vegetables
under temporary net tunnels. The net tunnels are constructed with U-shaped iron or aluminum bars, which are
covered with nylon netting over each bed (Talekar et al., 2003). Leafy vegetables such as Brassica rapa var
chinensis, B. oleracea var. alboglabra, B. rapa var.
parachinensis, and B. juncea grown under tunnels were less
damaged by heavy rain and insect pests. This resulted in a
reduced number of insecticide applications, better produce
quality, and higher marketable yield. Amaranthus yield has
tripled under net tunnels in Vietnam. Insect populations on
cauliflower under net tunnels were greatly reduced, by 80%
in Cambodia; marketable yields were 1.5 to 2.0 times
greater under net tunnels than in the open field (Palada and
Ali, 2007). Growing head cabbage under net tunnels in the
Solomon Islands reduced insect incidence by 38-72%, and
resulted in significantly higher economic returns (Neave et
al., 2011).
Low-cost, temporary net tunnels. – R. Srinivasan
Ramasamy Srinivasan is an
Entomologist and Head of
Entomology Group at AVRDC
– The World Vegetable Center.
He has ten years research and
development experience in
tropical vegetable entomology,
with special interests in insect-
plant interactions, chemical
ecology of insect pests,
biological control, and insect
growth regulators.
This Technical Innovation
Brief is published by:
SP-IPM Secretariat
Vegetable production under protective structures reduces yield losses from insect pests, diseases, and heavy
rains, and results in higher productivity and returns per unit area. Protective structures enable growers to
produce vegetables successfully during the off-season, which enhances the availability of fresh produce at times
when vegetables are usually in short supply. Because vegetable prices are higher during the off-season, growers
also enjoy higher returns per unit area.
Further reading
AVRDC. 2007. Report 2004. Publication Number 07-691. AVRDC –The World Vegetable Center Shanhua, Taiwan. 158 pp.
Hanh, N.T. 2003. Crop diversification under shelter during wet season. In: L.T. Thuy, V.T. Tinh, D.H. Hoa, N.T.Hanh, N.K.
Chien, V.T. Hien, and N.D. Hung (eds.). Off-season and tomato and year-round vegetable production under shelter in
Hanoi. Research Institute for Fruits and Vegetables, Hanoi, Vietnam. pp. 34-38.
Harmanto, T. H. J. 2006. Evaluation of net greenhouses for tomato production in the tropics. Hannover University, PhD
Neave, S.M., Kelly, G., and Furlong, M.J. 2011. Field evaluation of insect exclusion netting for the management of pests on
cabbage (Brassica oleracea var. capitata) in the Solomon Islands. In: Abstracts from the Sixth International Workshop
on Management of the Diamondback Moth and Other Crucifer Insect Pests, 21-25 March 2011, Kasetsart Unversity,
Nakhon Pathom, Thailand. Publication No. 11-746. AVRDC – The World Vegetable Center, Taiwan. 101 pp.
Palada, M.C. and Wu, D.L. 2009. Grafting sweet peppers for production in the hot-wet season. International Cooperator’s
Guide, AVRDC Publication Number: 09-722-e.
Palada, M.C. and Ali, M. 2007. Evaluation of technologies for improving year-round production of safe vegetables in peri-
urban agriculture of Southeast Asia. Acta Horticulturae, 762: 271-281.
Palada, M.C., Roan, Y.C., and Black, L.L. 2003. Rain shelters for tomato production in the hot-wet season. International
Cooperator’s Guide, AVRDC Publication Number: 03-552.
Shahak, Y., Ratner, K., Zur, N., Offir, Y., Matan, E., Yehezkel, H., Messika,Y., Posalski, I., and Ben-Yakir, D. 2008.
Photoselective netting: an emerging approach in protected agriculture. Acta Horticulturae, 807: 79-84.
Talekar, N.S., Su, F.C., and Lin, M.Y. 2003. How to produce safer leafy vegetables in nethouses and net tunnels.
Asian Vegetable Research and Development Center, Shanhua, Tainan, Taiwan. 18 pp.
SP-IPM Steering Committee Members:
Sikora, R (Program Chair); Nwilene, F (AfricaRice); Ramasamy, S (AVRDC); Staver, C (Bioversity); Buruchara, R (CIAT); Nicol, J (CIMMYT); Kroschel, J (CIP); Yahyaoui, A (ICARDA);
Ekesi, S (icipe); Sharma, H (ICRISAT); Narrod, C (IFPRI); Bandyopadhyay, R (IITA); Heong, KL (IRRI); Bramel, P (DDG –R4D convening center, IITA); Hoeschle-Zeledon, I (Program
Coordinator, IITA)