Crop-crop diversity as a key component of IPM in Castor

Introduction

The green revolution of the late 1960s, responsible for rapid agricultural growth, was largely confined to irrigated areas bypassing the vast rainfed tracts. Nearly half of the cultivated area in India will remain rain-fed even after realizing the full irrigation potential. Rainfed areas produce the bulk of coarse cereals, pulses, oilseeds and fibre crops. More importantly, rainfed regions provide livelihood to a majority of rural poor and as a result, they are often described as hot spots for civic strife.

The productivity of crops grown in rainfed areas is considerably lower than the potential and much lower than that of irrigated crops. Enhancing this productivity is therefore important for growth, equity and sustainability in the farm sector. Crop production in rainfed regions is by nature dependent on monsoon behaviour and is therefore highly risky. Rainfed regions are also highly heterogeneous in terms of land terrain, soil productivity, climate and socio economic conditions, all of which influence the crop productivity. Another important factor that affects crop production is the incidence of pests and diseases. With the poor capacity of the farmers to invest

Another important factor that affects crop production is the incidence of pests and diseases. With the poor capacity of the farmers to invest in plant protection measures, the incidence of pests and diseases often leads to significant losses of productivity and income to the farmers.

As an insurance against biotic and abiotic stresses, farmers in rainfed regions have diversified their farming systems. Rainfed regions are thus more diversified in cropping systems compared to irrigated areas. Small and marginal farmers in rainfed areas generally grow more crops per unit area as inter and mixed cropping systems (Walker and Ryan, 1990). These systems, meet the diverse family needs and also are less prone to pests and diseases. As the components in the system differ in their growth behaviour and nutrient and water requirements, it helps in risk minimization.

Dependence on chemical pesticides has led to the problems such as insect pest resistance, resurgence and the escalating cost of cultivation. Considering the ill effects of chemical pesticides and the growing preference for chemical-free food products, efforts are under way to develop and popularize Integrated Pest management (IPM) technologies. Such technologies need to be affordable by the farmers and should fit into the existing farming systems. Research revealed that farmers adopt such components of IPM as intercropping and border crops more readily. In other words, cultural components of IPM need to be emphasized more as they require relatively

Research revealed that farmers adopt such components of IPM as intercropping and border crops more readily. In other words, cultural components of IPM need to be emphasized more as they require relatively less external inputs and are more likely to be adopted by the farmers. Crop diversity is a situation wherein different crops are grown simultaneously. Crop-crop, crop borders and crop-weed diversities are different forms of crop diversity (Baliddawa, 1985).

Intercropping and mixed cropping systems are more popular forms of crop-crop diversity practised in rainfed agriculture. These systems provide situations that are less pest-prone compared to the monocultures. The genetic uniformity of monocultures leads to susceptibility to pests (Bhatnagar and Davies, 1979). The factors that contribute to reduced pest populations in intercropping include physical protection from wind, shading (Litsinger and Moody, 1976), prevention of dispersal (Kayumbo, 1975) production of adverse stimuli, olfactory stimuli camouflaged by main crop (Aiyer, 1949), presence of natural enemies (Russell, 1989 and Tonhasca, 1993) and availability of food (Fukai and Trenbath, 1993) Research in diversified agro ecosystems demonstrated that these systems tend to support less herbivore load than the corresponding monocultures (Altieri and Letourneau,1982 and Risch,1981).

Thus, there is considerable scope to develop a system that is diverse and less prone to pests and diseases. When other pest management technologies are superimposed on such systems, it becomes much easier and cheaper for the farmer to manage the pests rather than in monocultures which are more prone to pest incidence and require considerable investments in pest management. Low external input IPM (LEIIPM) seeks to optimize the use of locally available resources by combining different components of the farming system.

 

Methodology

A two-step methodology was followed to achieve the intended objectives. In the first step, experiments were conducted on farmers’ fields to test the impact of intercrops on various insect pests of castor crop. Combinations found effective along with some other systems popular with the farmers or suggested by them were evaluated in farmers’ fields. In the second step, different LEIIPM modules were superimposed on the systems found effective and efficient in the earlier steps..read more

 

Results

In castor based intercropping systems, the incidence of leafhopper, Empoasca flavescens, semi looper, Achaea janata, whitefly, Trialeurodes ricin, tobacco caterpillar Spodoptera litura and shoot and capsule borer Conignethes punctiferalis were predominantly noticed. The impact of castor based intercropping systems on the incidence of these insects is discussed here under..read more

 

 

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  • Central Institute of Dryland Agriculture

 

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