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Crop to kale affected by the aphid have been reviewed

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crop to kale affected by the aphid have been reviewed and presented below:- Aiyer (1949) formulated a three part hypothesis (1) host plants are more widely spread in intercrops, meaning they are harder to find by the pest, (2) the species serves as a trap crop to detour the pest from finding the other crop, and (3) one species may serves as a repellent to the pest. Saxena (1972) stated that a proper combination of crops is important for the success of inter cropping systems, when two crops are to be grown together. It is imperative that the peak period of growth of the two crop species should not coincide. Crops of varying maturity during need to be chosen so that quick maturing crops complete its life cycle before the grand period of growth of the other crop starts. However, yields of both the crops are reduced when grown as mixed or intercropped, compared with the crops when grown alone but in most cases combined yield per unit area from intercropping are higher. 2.2. Insect pests in intercropping. Intercropping of garlic (Halepyatic et al., l987), onion (Johnson and Mau, 1986), ginger (Chowdhury, 1988), and tomato (Roltsch and Gage, 1990) with different crops have been reported to reduce the population of different target pests. Hussain and Samad (1993) reported that intercropping chilli with Brinjal reduces the population of Aphis gossypii in brinjal. Simmonds el al. (1992) reported plants with antifeedant activities. Among them, Allium spp. is reportedly very effective. Kirtikar and Basu (1975) reported that onion, garlic, coriander (Coriandrum sativum L.) have also strong pungent repellent action.
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Sankar et al . (2007) stated that intercropping cabbage with garlic and onion significantly reduced the population of aphids on cabbage. Similarly, Said and Itulya (2003) indicated that the odour from onion is able to repel P. xylostella from settling on cabbage when in an intercrop. 2.3. Biology of aphids ( 2.3.1. Introduction. The cabbage aphid belongs to the genus Brevicoryne. The name is derived from the Latin words “brevi” and “coryne” and which loosely translates as “small pipes”. In aphids, there are two small pipes called cornicles or siphunculi (tailpipe-like appendages) at the posterior end that can be seen if you look with a hand lens. The cornicles of the cabbage aphid are relatively shorter than those of other aphids with the exception of the turnip aphid Lipaphiserysimi (Kaltenbach). These short cornicles and the waxy coating found on cabbage aphids help differentiate cabbage aphids from other aphids that may attack the same host plant (Carter and Sorensen 2013, Opfer and McGrath 2013). Cabbage aphids cause significant yield losses to many crops of the family Brassicaceae, which includes the mustards and crucifers. It is important to have a comprehensive understanding of this pest and its associated control measures so that its spread and damage can be prevented.
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