Arthropod Pest Management in Organic Vegetable Greenhouses

This chapter comprehensively covers arthropods (mainly insects and mites), nematodes, fungi, and plasmodiophorids in the context of being prime agents for spreading plant viruses. Insects are the largest class of plant-virus–transmitting vectors wherein acquisition and transmission of pathogens by an insect vector is essential to start the infection cycle of disease. Some viruses can infect plants when insects tap into the phloem to feed; other viruses infect plant cells through a wound site created by a leaf-feeding insects The epidemiology of plant diseases caused by insect-carried plant viruses involves four main components—pathogen, insect, plant, and environment. Thus, interactions among insect vectors, viruses, and host plants mediate transmission by integrating all organizational levels, from molecules to populations. The latest research in the field of managing plant viruses through vectors management have been deliberated with special reference to the use of crop protection, plant resistance, modification of farming practices, biotechnology, and typical integrated pest-management strategies.

Integrated management of vectored viral diseases of plants

Greenhouse horticultural crops grown all over the world are vulnerable to various pest attacks as the protected crops provide stable and favourable microclimates for development of pest populations. The losses caused due to insect, mite and nematode pests in greenhouses crops like tomato, okra, capsicum, gerbera, carnation, cucumber, lettuce, beans and strawberry are tremendous. Crop losses are mainly due to pests like, whiteflies, thrips, leaf-miners, aphids, mites and nematodes. The most important components of pest management in greenhouse horticultural crops include preventive measures, scouting and early detection and curative measures. Exclusion techniques include the use of physical barriers, use of insect-proof nets, provision of double door, use of reflective or metalized mulches and ultraviolet (UV) radiation absorbing sheets. Preventive strategies also include humidity and temperature control, pre-season clean-up and inspection of personnel and planting materials entering into the net house. Curative measures involves with the Cultural control, Collection and destruction alternate host plants including weeds, Hand-picking of pest stages, Balanced use of fertilizer, Pinching and pruning the plants, Trap cropping and Crop rotation. By adopting suitable pest management technology, the growers can look forward to a better and additional remuneration for high-quality produce of horticultural crops raised under protected cultivation. Protected cultivation of crops can be defined as controlled environment agriculture that is highly productive, conservative of water and land and protective. Protected cultivation of high value vegetables and cut-flowers has shown tremendous potential during the last decade or so. The technology involves the cultivation of horticultural crops chiefly vegetables and flower crops in a controlled environment wherein the factors like the temperature, humidity, light, soil, water and fertilizers are manipulated to attain maximum produce as well as allow a regular supply of them even during off-season. Greenhouse horticultural crops grown all over the world are vulnerable to various pest attacks as the protected crops provide stable and favourable microclimates for the development of pest populations. Generally, the natural enemies that keep pests under control outside are not present under protected condition. For these reasons, pest situations often develop in the indoor environment more rapidly and with greater severity than outdoors. The losses caused due to insect, mite and nematode pests in greenhouse vegetable and flower crops are tremendous. These pests are of much importance and need to be managed properly so as to prevent the crop losses and increase yields in protected vegetable and flower cultivation. By adopting suitable pest management technology, the growers can look forward to a better and additional remuneration for high-quality produce of horticultural crops raised under protected cultivation. 

Pest Management in Horticultural Crops Under Protected Cultivation

We report here on the development of a system for producing cruciferous vegetables without using chemical pesticides. This system enables small-scale farmers in hilly and mountainous areas in the western region of Japan to grow products of equivalent volume and quality to those produced by standard practices. The first steps in developing the system involved modifying and creating methods to protect cruciferous vegetables against insect pests. Crops were protected from flying pests, such as the white cabbage butterfly, cabbage armyworm, diamondback moth, cabbage sawfly, leafminer fly, cabbage bug, striped flea beetle, and brassica leaf beetle using a 0.6 mm mesh screen. Bacillus thuringiensis preparations, the use of which is permitted by Japanese Agricultural Standards for organic plants and organic processed foods of plant origin, were used to prevent damage caused by butterfly larvae, (white cabbage butterfly, cabbage armyworm, and diamondback moth) that hatch from eggs deposited on the outer surface of the screen through which they can invade. Invasion by crawling pests, such as the striped flea and brassica leaf beetles, was suppressed by covering the ground around the greenhouse with a mulching sheet to control weeds that form the habitat for these pests. Aphids passing through the 0.6 mm mesh screen were eliminated by a banker plant system employing the aphid parasite Diaeretiella rapae (McIntosh), a natural predator. Solarizing the soil before cultivation destroyed the pests' larvae, pupae, or eggs residing underground, such as those of the striped flea beetle and cutworm, while pest damage by vegetable weevils was prevented by inserting our newly invented traps just underground. The second step in developing the system involved dealing with higher greenhouse temperatures during summer that would result from the 0.6 mm mesh screen cover. To keep the wet bulb globe temperature (WBGT) around the worker within acceptable limits, a battery-powered ventilator consisting of a cart, fan, solar battery, and ordinary battery was used as well as installing simple roof windows, all of which effectively lowered the WBGTs. By combining these methods, we were able to demonstrate that the system was highly effective for producing quality cruciferous vegetables in greenhouses and in open fields.

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Development and Implementation of an Environmentally Conscious System for Producing Cruciferous Vegetables by Small Farms in a Hilly and Mountainous Area of Western Japan

蛍光灯を用いたトマトの群落内補光について, 早朝2時間, 午前中2時間, 日中9～10時間の補光時間帯が収量におよぼす影響の比較を行った. 午前中と日中の補光を日射200μmol m-2s-1 PPF以下の時に限り行う処理も検討した. 補光は早朝よりも, さらに温度の上がる午前中の時間帯の方が増収効果が高くなった. 日中通して補光する処理はさらに増収効果が高かった. しかし, 午前中と日中日射の弱いときのみ補光する処理は, 同じ時間帯を通して補光するより減収となった. 補光時間の短縮には, 収量を落とさない制御アルゴリズムなど, まだ検討の余地があると考えられた. 続いて, 栽培試験の結果をもとに本研究の補光方式の経済性について検討し, 補光時間は2時間の方が9時間よりも費用対効果が高いが, 2時間照射でも, 実用性向上のためには電力や照明器具のコスト低減が必要であることを示した.

Kazushi Ojima

Papers

Development and Implementation of an Environmentally Conscious System for Producing Cruciferous Vegetables by Small Farms in a Hilly and Mountainous Area of Western Japan

Yield-increasing effect and economical efficiency of supplemental lighting inside tomato canopy in some lighting schedules.