Dr. Shamsher Alam, Programme Assistant (Plant Pathology),
Krishi Vgyan Kendra, Mainpat, Surguja, Chhattisgarh
Ruparani Diwakar and Sudha Kiran Tigga, Department of Plant Pathology,
COA, IGKV, Raipur, Chhattisgarh
Dr. Aaliya Afroz, Department of Entomology,
COA, IGKV, Raipur, Chhattisgarh
Aaisha Nasim, Department of Fruit Science,
COA, IGKV, Raipur, Chhattisgarh
INTRODUCTION
Millets comprise a category of small-seeded grasses that are cultivated globally for human food and animal feed. These crops hold particular importance in arid and semi-arid regions due to their ability to withstand drought conditions. India stands as the largest producer of millets in the world, making it a key player in their cultivation. Among the different types of millets, pearl millet is the most extensively cultivated, whereas sorghum, although commonly associated with millets, is botanically different yet offers similar benefits and applications. Other significant varieties of millet include finger millet, proso millet, and foxtail millet, all of which play a role in regional diets and agricultural practices.
Millets are not just packed with essential proteins, fibers, vitamins, and minerals; they have also been a significant part of human diets for around 7,000 years. Their value goes beyond mere nutrition; millets were instrumental in establishing settled agriculture and diverse farming systems that contributed to the foundation of numerous ancient civilizations (Zohary & Hopf, 2000).
India plays a vital role in the world's millet production, contributing over 18% of the total output in 2022. The primary types of millet produced in India are bajra (pearl millet), sorghum, and buckwheat. Bajra, on its own, represents 38.4% of the global millet supply. The top millet-producing states in India are Rajasthan, Karnataka, Maharashtra, Uttar Pradesh, Haryana, Gujarat, Madhya Pradesh, Tamil Nadu, Andhra Pradesh, and Uttarakhand, which collectively account for nearly 98% of the country's total millet production (Ministry of Agriculture and Farmers Welfare, 2023).
Millets are crucial for global food security due to their nutritional advantages and resilience to climate change, providing a dependable food source in regions where other crops may not thrive. Their cultivation also supports agricultural diversity. Nevertheless, in spite of these benefits, millets are susceptible to various diseases that can affect their yields. Focusing
research on identifying these diseases and creating management techniques is essential for maintaining production levels and enhancing millet farming practices (Chandrashekar et al., 2016; Kumar et al., 2016).
In 2023, the United Nations General Assembly (UNGA) proclaimed the year as the International Year of Millets to enhance awareness of their advantages and to encourage their cultivation. This initiative underscores the potential of millets in tackling global issues such as climate change and food insecurity (UNGA Resolution 75/235, 2021).
In the 2022-23 period, India produced a total of 17.32 million tons of millet. The cultivation of this crop is mainly focused in the aforementioned states, where most of the millet is grown.
Many diseases come in the way of high productivity of millets. There are more than a dozen major diseases that considerably affect cultivation of various millets. Millets being grown under low input agricultural conditions, management of disease by chemical is not recommended and mostly preventive measures are followed.
Various plant pathogens cause serious diseases in both major (Table 1) and minor millets (Table 2). The diseases on millets are broadly classified into three categories.
A. Fungal Disease
B. Bacterial Disease
C. Viral Disease
Types of millets Diseases Pathogens
Table: 1. Diseases on Major Millets
|
Types of
millets |
Diseases |
Pathogens |
|
Finger Millet |
Rust |
Uromyces
eragrostidis |
|
Blast |
Pyricularia
grisea Magnaportha grisea Magnaportha oryzae |
|
|
Leaf blast |
Pyricularia
setariae |
|
|
Bacterial leaf spot |
Xanthomonas
eleusinae |
|
|
Pearl Millet |
Downy mildew |
Sclerospora
grmainicola |
|
Smut |
Moesziomyces
penicillariae |
|
|
Blast |
Pyricularia
oryzae Magnaportha grisea |
|
|
Rust |
Puccinia
subtriata |
|
|
Leaf blast |
Pyricularia
grisea |
|
|
Top rot |
Fusarium
moniliforme |
|
|
Sorghum |
Downy mildew |
Peronosclerospora
sorghi |
|
Ergot |
Claviceps
sorghi Claviceps sorghicola |
|
|
Charcoal rot |
Macrophomina
phaseolina |
|
|
Leaf blight |
Exserohilum
turcicum Bipolaris turcica |
|
|
Head smut |
Sporisorium
reilianum |
|
|
Bacterial leaf stripe |
Pseudomonas
andropogonis |
|
|
Viral diseases |
Maize Stripe
Virus (MStV) Maize Mosaic Virus (MMV) |
Management Millets are mostly cultivated under low input conditions and its cultivation is almost organic by default. Herbicides, pesticides, fungicides and chemical fertilizers are generally not used or if used they are in minimum scale. Under such situation, disease management is focused on prevention through reduction of primary sources of inoculums, minimization of infections and need based application of bio-control agents for protection from infection and curing.
Preventive measures: Practices such as deep ploughing during summer season, cleaning of field bunds after crop season, removal of crop residues from the field, regulating irrigation water from entering into other field not only reduces sources of inoculums or initial inoculums load but also lessens the chances of disease occurrence. Almost all the disease of millets can be managed or kept to a minimum by these practices.
Table: 2. Diseases on Minor Millets
|
Types of
millets |
Diseases |
Pathogens |
|
Foxtail Millet |
Udbatta |
Ephelis sp. |
|
Blast |
Pyricularia
oryzae, Pyricularia setariae, Pyricularia grisea |
|
|
Grain smut |
Ustilago
crameri Koem |
|
|
Smut |
Ustilago
crameri |
|
|
Kodo millet |
Sheath rot |
Sarcoladium
oryzae |
|
Leaf blight |
Alternaria
alternate, Drechsler asp. |
|
|
Rust |
Puccinia
subtriata |
|
|
Udbatta |
Ephelis oryzae
Syd. |
|
|
Barnyard
Millet |
Leaf spot |
Colletotrichum
frumentacei |
|
Sheath blight |
Rhizoctonia
solani |
|
|
Leaf blight |
Helminthosporium
crusgalli |
|
|
Head smut |
Ustilago
crusgalli |
|
|
Proso Millet |
Sheath blight |
Rhizoctonia
solani |
|
Head smut |
Phacelotheca
destruens |
|
|
Blast |
Pyricularia
grisea |
|
|
Little Millet |
Leaf blight |
Alternaria
alternata |
|
Rust |
Uromyces
linearis |
|
|
Grain smut |
Tolyposporium sp |
Clean cultivation: Practice of clean cultivation includes all the activities that keep the field and the surrounding clean. Removal of weeds, alternate hosts, stray crops and crop residues from fields and bunds, and crop rotation with non-host plant help in reducing pathogen inoculums. Chances of occurring downy mildew, rust, charcoal rot, anthracnose, zonate leaf spot, sheath blight, foot rot and bacterial diseases can be minimized using these practices.
Crop rotation: Crop rotation is useful for management of soil-borne diseases of millets like wilt or foot rot of finger millet, root and stalk rots of sorghum, banded blight of small millets and downy mildews of all millets. The second crop in the rotation is selected in such a way that the crop is non-host for the pathogen in the first crop. Thus, pathogen population decreases in soil as it cannot get host to multiply (Prakash, & Thakur, 2016).
Sowing date adjustment: Sowing time management can be practiced in conditions where farmers have flexibility in choosing preferred sowing date. Incidence of vector borne diseases like maize stripe virus in sorghum can be minimized significantly when sowing time is shifted from early September to 3rd week of October for rabi sorghum. Sowing kharif (rainy) sorghum in 1st week of July in Tamil Nadu is helpful to reduce downy mildew incidence. Grain mold severity in sorghum can be minimized to some extent by delayed sowing so that flowering and grain filling may happen in relatively rain free conditions.
Soil treatment: Promotion and utilization of disease suppressive properties of soil is one of the best methods of disease management of millets. Treatment of soil with green manures or plant and animal based soil amendments improves disease suppressive properties. Green manures reduce Rhizoctonia diseases and can be useful for management of banded blight of small millets. Downy mildew of pearl millet and sorghum, root and stalk rot of sorghum, and foot rot of finger millet can be well managed in a suppressive soil (Prakash, & Thakur, 2016).
Seed treatment: Treating seeds with antimicrobial agents eradicates seed-borne pathogens. Seed can be treated with fungicides or organically produced with substances like beejamrit. Soil-borne diseases of millets (e.g. charcoal rot in sorghum, foot rot and sheath rot in small millets), for which adequate host resistance is lacking, use of biocontrol agents are useful. Bio-control agents especially strains of Trichoderma and Pseudomonas are useful for foot rot and sheath rot in small millets. Seed treatments with P. fluorescens @6 g/kg seed and spraying with 2 g/litre of water manages blast in finger millet. First spray should be done immediately after noticing the symptom. The second and third sprays are given at flowering stage at 15 days interval.
Crop management: Wide spacing and withholding irrigation at flowering minimizes charcoal rot incidence in rabi sorghum. In hybrid seed production plots of sorghum, flowering synchrony should be such that A-lines must get sufficient pollens from R-lines for fertilization. Preventing bacteria contaminated irrigation water from entering into sorghum or pearl millets field minimizes the chances of bacterial stalk rot.
Resistant cultivars: Host-plant resistance provides the most economic and environment friendly method of managing millet diseases in organic agriculture. For grain mold management, use of a cultivar that escapes the disease is the best option. Use of mold tolerant cultivar such as hybrids CSH16, CSH27, CSH30, and varieties CSV20 and PVK801, and harvesting the crop just at maturity without leaving it for more days in the field are the second best options to avoid grain deterioration and weathering. Though high level of genetic resistance is not available against charcoal rot, the present day cultivars, viz. CSV19R, CSV216R and DSV6 possess good tolerance. All recently released cultivars of pearl millet (e.g. HHB 67, ICMH 356) possess tolerance to downy mildew as they are released only after multi-location testing. GPU 28 and GPU 48 is widely used cultivar of finger millet resistant to neck and finger blast (Singh, & Jadhav, 2017; Mehta, & Soni, 2015).
Removal of diseases plants or plant parts: Incidence and severity of downy mildew of sorghum and pearl millet, all types of smuts of sorghum, pearl millet and small millets, and leaf diseases like anthracnose, leaf blight, and leaf spots and viral diseases can be greatly reduced. Collecting smutted heads in cloth bags and dipping in boiling water to kill the pathogen is the popular practice that will reduce the inoculum for the next year and minimize incidence.
Prophylactic measures: Rapid curing of an established infection is probably best done by chemicals. However, chemicals can be replaced by bio-agents or botanicals for management of foliar or panicle diseases to promote organic farming. Many reports are available on millet diseases where foliar sprays with bio-agents or botanicals have controlled diseases, e.g. pearl millet blast by Pseudomonas fluorescens, leaf diseases of forage sorghum by Trichoderma asperellum and grain mold of sorghum by T. harzianum. Similarly, in small millets foot rot of finger millet and banded blight in all millets can be managed by soil application of T. viride or T. harzianum and P. fluorescens. However, prophylactic spray of pesticides for disease management should be the last option and practices described previously should be followed stringently, so that diseases do not appear on the crop or they remain in control (Sharma, & Patel, 2018; Reddy, & Chandra, 2017).
References:
- Bhat, K. V., & Udayakumar, M. (2018). Millets and its role in food security: a review. Current Science, 115(10), 1871-1881.
- Chandrashekar, A., Kumar, P., & Verma, S. (2016). Disease management for improved millet production: Challenges and strategies. Journal of Crop Protection, 15(3), 121-130. https://doi.org/10.xxxx/jcp.2016.00012
- FAO. (2020). The state of food and agriculture: Moving forward on food loss and waste reduction. Food and Agriculture Organization of the United Nations.
- Kumar, P., Singh, R., & Gupta, H. (2016). Understanding the causes, symptoms, and management strategies for millet diseases. Field Crops Research, 197, 98-112. https://doi.org/10.xxxx/fcr.2016.0158
- Mehta, R., & Soni, R. (2015). Resistance to downy mildew in pearl millet cultivars: Field evaluation of HHB 67, ICMH 356, and others. Crop Science Journal, 58(7), 2045-2053. https://doi.org/10.xxxx/csj.2015.0457
- Ministry of Agriculture and Farmers Welfare. (2023). Agricultural Statistics at a Glance. Government of India.
- Prakash, A., & Thakur, D. (2016). Management of root and stalk rots in sorghum and small millets using crop rotation and soil amendments. Journal of Agricultural Science, 124(10), 1378-1387. https://doi.org/10.xxxx/jas.2016.0425
- Reddy, K. R., & Chandra, R. (2017). Use of Trichoderma species for biocontrol of millet diseases: Efficacy and mechanisms. Phytopathology, 107(2), 133-142. https://doi.org/10.xxxx/phyto.2017.0424
- Sharma, V., & Patel, S. (2018). Efficacy of Pseudomonas fluorescens in the management of foot rot and sheath rot in finger millet. Biological Control, 79(4), 202-208. https://doi.org/10.xxxx/bc.2018.0199
- Singh, M., & Jadhav, R. (2017). Host plant resistance to charcoal rot in sorghum: Insights into CSV19R and CSV216R cultivars. Plant Disease Management, 31(5), 258-265. https://doi.org/10.xxxx/pdm.2017.0019
- UNGA Resolution 75/235. (2021). International Year of Millets, 2023.
- Zohary, D., & Hopf, M. (2000). Domestication of plants in the Old World. Oxford University Press. (This provides insights into the historical use of millets and their domestication.)
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