Incidence of Major Pest and Diseases under Natural Field Condition in Pole Type French Bean (Phaseolus vulgaris L.) Genotypes

French bean (Phaseolus vulgaris L.) is one of the most common and widely grown vegetable crops in India with a chromosome number of 2n=22. According to Vavilov (1950), the origin of French bean is Southern Mexico and Central America, while the Peruvian-Ecuadorian-Bolivian area is considered to be a secondary centre of origin. It originated from the wild species Phaseolus aborigineus (L.) and was domesticated in Mexico, Peru, and Colombia about 8000 years ago. This crop has extensive geographical distribution in the world.

It is an important legume vegetable belonging to the family Leguminosae or Fabaceae and has worldwide significance as a source of food and feed. The genus Phaseolus contains about 70-80 species, among which Phaseolus vulgaris (L.) accounts for 90 per cent of cultivated species around the world (Evans, 1979). There are four cultivated species of Phaseolus viz., Phaseolus vulgaris, P. coccineus, P. lunatus, and P. acutifolius var. latifolius, wherein all the species are self-pollinated except P. coccineus, which is cross-pollinated.

French bean is known by several names related to its purpose of usage as a vegetable viz., string bean, snap bean, salad bean, haricot bean, and green bean. However, the terms bean, dry bean, kidney bean, and navy bean are designated to pulses (George, 1985). Furthermore, string bean, dwarf bean, and pole bean pertain to distinct growth patterns. In different languages, it has diverse identities viz., rajmash in Hindi and tingala avare in Kannada. French bean varieties are categorized based on their growth habits i.e., bush type with compact segments, semi-pole type with more extended segment, and pole type with viny growth longer than semi-pole type (Prabhakar et al., 2016).

French bean has a wide range of genetic variations in terms of growth habit (determinate vs. indeterminate), days to maturity, seed size, colour and quality (cooking ability and palatability), vegetative and reproductive growth, pigmentation, leaf size, shape and orientation, and resistance to pests (Leakey, 1970). The choice of promising genotypes from a diverse genetic base and their subsequent utilization for hybridization is one of the strategies for improving the productivity of any crop including beans.

It is cultivated all over the world and has a wide geographical distribution. French bean is mainly used for immature green pods. Rajmash or dried pods are utilized as a pulse and provide a good source of protein for humans (Abate, 2006). Immature pods are eaten fresh and can be easily preserved by freezing, canning, or dehydrating. Dried beans are eaten boiled, baked, fried, or ground into flour. It is highly nutritious as 100 g of green pods contain 1.7 g protein, 4.5 g carbohydrates, 221 IU vitamin A, 11 mg vitamin C, and 50 mg calcium (Gopalakrishnan, 2007). French bean can be used to some extent against diabetes and cardiac problems and is a wonderful natural cure for bladder burn. It has both carminative and reparative qualities in the treatment of constipation and diarrhea (Duke, 1981).

French bean is a short-duration crop; hence, it can be grown in various cropping systems across the hills and plains of India. This vegetable is predominantly cultivated in the states of Himachal Pradesh, Punjab, Haryana, Uttar Pradesh, Bihar, Gujarat, Madhya Pradesh, Maharashtra, Karnataka, Andhra Pradesh, and Tamil Nadu. The total cultivation area for French bean in India is around 2.9 lakh hectares with an annual production of 27.25 lakh tonnes and an average productivity of 9.09 tonnes per hectare. In Karnataka, this crop is grown in an area of 0.17 lakh hectares with 1.94 lakh tonnes of production and productivity of 11.07 tonnes per hectare.

The use of resistant varieties offers a practical and cost-effective approach to managing pests and diseases in green beans. The development and assessment of high-yielding legume varieties with resistance to pests and diseases are crucial for maximizing the crop's production potential (Neritu, 2008). An integrated pest management (IPM) strategy is considered the most effective method for controlling pest problems in beans, as it combines multiple proven techniques to keep pest populations at manageable levels. These methods include cultivating resistant varieties, encouraging natural predators, applying organic and bio-pesticides, practicing crop rotation, and adopting cultural measures such as removing field debris.

This study was undertaken to identify high-yielding bean varieties with strong tolerance to pests and diseases. Accordingly, the present investigation was designed to evaluate insect and disease incidence in pole-type French bean genotypes grown under open conditions.