Black gram (Vigna mungo) is native to the Indian Subcontinent (Royal Botanic Gardens, Kew, 2025), from the seasonally dry (Ustic soils) areas. Black gram is an erect, bushy, hairy, herbaceous legume reaching 30 to 100 cm in height with trifoliate leaves (Figure 17). It has small yellow flowers (Figure 17) and short flat pods reaching 4 to 6 cm (FAO, 2022) with 4 to 10 black or mottled colored seeds (Figure 18).

Once established, it is drought resistant because of its taproot that explores deeper soil for water and allows it to survive on residual soil moisture after the rainy season. Black gram is used as a pulse, cover crop/green manure, and fodder in many cropping systems.

Cultivation

A wide temperature range of 8 to 40°C reflects its elevation range of up to 2000 m (FAO, 2022). Black gram thrives in heavier to moderately textured pH-neutral soils that are at least 50 cm deep and well-drained.  

Working with multiple varieties, Veeramani (2019) found that a 20 x 10 cm spacing resulted in higher yields than a recommended spacing of 30 x 10 cm. To reduce disease incidence, farmers space plants further apart in the wetter season (for increased air circulation under humid conditions), and closer when it is drier.

Sow seeds 5 to 6 cm deep and ensure enough water for germination, flowering, and pod development (Nargund et al., 2024). Vermicompost-treated soil has been shown to facilitate good germination and early growth parameters of seedlings (Bhattacharya et al., 2019).

Common rotations with black gram include maize (Zea mays), potato (Solanum tuberosum), rice (Oryza sativa), wheat (Triticum aestivum), mustard (Brassica juncea), toria (Brassica rapa), and include intercropping with pigeon pea (Cajanus cajan), sugarcane (Saccharum officinarum), sunflower (Helianthus annuus), groundnut (Arachis hypogaea), sorghum (Sorghum bicolor), and pearl millet (Pennisetum thypoides) (DPD, 2016; Soundararajan and Chitra, 2012). Farmers also plant black gram as a catch crop9 (Nargund et al., 2024).

Control weeds early to avoid competition for space and nutrients. Choudhary et al. (2012), found two weeding events, one at 15 and another at 25 to 30 days after seeding, controlled weeds sufficiently.

Harvest green pods in 60 to 80 days, and mature beans in 75 to 130 days (FAO, 2022). Harvest grain when 70 to 80% of the pods turn black and are mature to avoid pod shattering in the field (Nargund et al., 2024). Dry the pods for a few days before threshing. Dry the seeds in the sun for 3 to 4 days, reducing seed moisture content to 8 to 10% before storage.

Pests and diseases

Fungal diseases that commonly affect black gram include powdery mildew (fungal order Erysiphales), leaf blight (Cercospora canescens), and anthracnose (Colletotrichum spp.). Wider spacing helps reduce fungal disease severity. To reduce transmission, remove and destroy affected plant residues or rogue (remove) affected plants. To control, apply sulfur or Bordeaux mixtures (CuSO₄) according to local recommendations. Some botanicals have also shown promise for controlling certain diseases. Leaf extract of neem (Azadirachta indica) at 100% concentration retarded germination of pathogen (leaf blight) spores; and soil disinfestation with crucifer (Brassicaceae) residue and solarization helped release substances which inhibited Fusaruim oxysporum, an indicator of soil-borne pathogen control (Iqbal et al., 2019; Uddin et al., 2013).

Yellow mosaic virus also affects black gram. Control its insect vector, whitefly (Bemisia spp.), and rogue infected plants to help control the spread of the virus.

Table 2 summarizes a review by Nargund et al., 2024 of major insect pests and proposed IPM practices.

Stored Grain

Pulse beetle (Callosobruchus chinensis) is a pest of stored grain. Black pepper (Piper nigrum), neem oil, and mustard oil effectively protected harvested black gram for 5 months (Thakur and Pathania, 2013). Farmers can use these products for safe seed storage as they are available in the local markets and non-toxic.

References