About the Book

Wheat (Triticum spp.) is one of the oldest and the most important food crops. It is the second most important cereal following rice in the world. It constitutes an important part of human diet globally. It is called “king of cereals” being widely cultivated, produced and used throughout the world. It is a staple food crop of about two billion people providing 55% of carbohydrates and 20% of food calories globally. Besides being an important source of carbohydrates, globally, it is the leading source of vegetable protein in human food, having a protein content of about 10-13%, which is relatively high compared to other major cereals. Its protein is rich in niacin and thiamine content. When eaten as the whole grain, wheat is a source of multiple nutrients and dietary fibre. Whole grain wheat flour (100 g) provides 340 calories of energy, 11 g dietary fibre, 2.5 g fat, 61 g carbohydrates, 0.4 g sugar, 363 mg potassium, 357 mg phosphorus, 137 mg magnesium, 34 mg calcium, 3.6 mg iron, and 2.6 mg zinc. Currently, 95% of all the wheat produced at the global level is bread wheat. The bread wheat flour is used to make chapati, bread, biscuits, pastry products, and the commercial production of starch and gluten. In contrast, durum wheat is specifically grown for semolina production for use in pasta and macaroni products. Wheat is an annual self-pollinated crop which belongs to the tribe Triticeae (= Hordeae) in the grass family Poaceae (Gramineae). The archaeological record suggests that wheat was first cultivated in the regions of the Fertile Crescent around 9600 BCE. The Fertile Crescent is a crescent shaped region in the Middle East spanning modern-day Iraq, Syria, Lebanon, Palestine, Israel, Jordan, and northern Egypt together with the northern region of Kuwait, southern region of Turkey and the western portion of Iran. Einkorn wheat (Triticum monococcum), originated in the Fertile Crescent, was the first domesticated wheat. Subsequently, spelt wheat (T. spelta), emmer wheat (T. turgidum ssp. dicoccum), durum wheat (T. turgidum ssp. durum) and hexaploid bread wheat (T. aestivum) were cultivated in the regions covering Mediterranean Basin, Eastern Europe, Western Europe, Asia and others. Wheat is one of the most widely adapted crops because of its ability to grow under diverse environmental conditions ranging from sea level to regions as high as 4570 m above msl in Tibet. No wonder that wheat is grown on more land area than any other food crop. Throughout the world, wheat is cultivated over an area of around 219 million hectares with a total production of nearly 772 million tonnes (FAO Stat., 2019). Maximum area under wheat is in India (14%) followed by Russia (12.43%), China (11.14%) and the USA (6.90%) which altogether account for about 45 per cent of global area. World trade in wheat is greater than for all the other crops combined. Globally, India is ranked next to China in wheat production. In India, wheat is the second most important cereal crop after paddy both in terms of area and production. During 2020- 21, India harvested a record ~110 million tonnes of wheat from an area of ~33 million hectares with productivity ~3500 kg ha-1. Wheat accounts for more than one third of India’s total food grain production and constitutes the major component of country’s food security. India is fortunate in enjoying diversity in wheat cultivation as it grows three kinds of wheat, namely, the hexaploid bread wheat or common wheat Triticum aestivum L. (2n = 6x = 42, AABBDD genomes), the tetraploid durum wheat T. turgidum ssp. durum (Desf.) Husn, and emmer wheat T. turgidum ssp. dicoccum (Schrank ex Schubl) Thell (2n = 4x = 28, AABB genomes). Durum and bread wheats exhibit differential response to the pathotypes of leaf and stem rusts pathogens. Although not clearly demonstrated, emmer wheat too can have a distinct rust resistance spectrum. Bread wheat contributes to around 95% of all the wheat produced, durum wheat’s share is ~5% whereas emmer wheat is grown in only ~50,000 hectares. Hence, durum and emmer wheats’ cultivation needs to be encouraged for enriching the diversity in our wheat cultivation thereby reducing the chances of buildup of rust epidemics. Wheat crop is host to several biotic stresses, particularly fungal pathogens causing considerable grain quality and yield losses. The changing climate is leading to shifting of disease infections from their traditional areas of occurrence to new areas of the world with increased vulnerabilities, causing serious concern to global wheat production. On an average, around 30% of the global wheat production is lost to diseases and insect pests every year. As per some estimates, wheat losses due to rusts alone can be up to the extent of US$ 4–5 billion annually on global scale. Reducing the extent of this loss can help in achieving the estimated demand of wheat, which is expected to increase up to 60% by the year 2050. Hence, bringing out a compendium of wheat diseases highlighting their management strategies by the Indian Phytopathological Society to mark the Society’s Platinum Jubilee celebrations is a very timely effort in this direction. Chapters on the three rusts, spot blotch, loose smut, flag smut, Karnal bunt, hill bunt, head scab, powdery mildew, foot rot, blast, and chlorotic streak and stunting (Phytoplasma) diseases of wheat are included in this compendium. Most of these diseases are of global economic importance and occur regularly in different parts of India. Wheat blast though not yet detected in India, is a potential threat to our wheat cultivation as it has been known to occur in the neighbouring country Bangladesh since 2016. Chlorotic streak and stunting (Phytoplasma) disease has been observed attacking the wheat crop in central India since 2015 only. We wish to express my sincere thanks to all the learned contributors for their excellent contributions. We are grateful to the Indian Phytopathological Society for giving us this opportunity of becoming a part of this compendium.

Contents

          Introduction (1-2)

1. Leaf Rust of Wheat - S.C. Bhardwaj and Subodh Kumar (3-7)
2. Stripe Rust of Wheat - Om P. Gangwar (8-11)
3. Stem Rust of Wheat - Pramod Prasad (12-16)
4. Spot Blotch of Wheat - Rashmi Aggarwal, Malkhan Singh Gurjar and Mahender Singh Saharan (17-20)
5. Loose Smut of Wheat - Ritu Bala, Divya Bhandari and Jaspal Kaur (21-24)
6. Karnal Bunt of Wheat - Malkhan Singh Gurjar, Mahender Singh Saharan, Rashmi Aggarwal and Ritu Bala (25-29)
7. Fusarium Head Blight or Head Scab of Wheat - Mahender Singh Saharan, Rashmi Aggarwal, Malkhan Singh Gurjar and Jaspal Kaur (30-33)
8. Powdery Mildew of Wheat - P. Nallathambi, C. Umamaheswari, Santosh Watpade and B. Aarthy (34-37)
9. Flag Smut of Wheat - Sudheer Kumar and Prem Lal Kashyap (38-41)
10. Hill Bunt of Wheat - Sudheer Kumar and Prem Lal Kashyap (42-44)
11. Foot Rot of Wheat - Gurudatt M. Hegde, Priyanka Jadhav, Uday R., Kumar Lamani, Suma Biradar, Sudhakar Kulkarni and Suresh Ghatanatti (45-49)
12. Wheat Blast - T.L. Prakasha, R.M. Phuke, J.B. Singh. A.Divya and A.N. Mishra (50-53)
13. Chlorotic Streak and Stunting Disease of Wheat - G.P. Rao (54-56)