*2.2.1 Distribution*

Bakanae or foot rot is one of the important emerging diseases of rice, caused by *Fusarium fujikuroi* (Nirenberg) [teleomorph: *Gibberella fujikuroi* (Sawada) Ito]. The disaese has become a major concern in basmati growing tracts of north India during last few years [37, 38]. The northern western states like Punjab, Haryana, eastern UP, Uttarakhand and Delhi are facing serious problem of disease especially in basmati growing regions. But recently the disease is emerging as a major problem in eastern and north eastern states like Odisha, West Bengal and Assam leading to the susceptibility of popular varieties in this region [39]. Bakanae disease induces grain sterility resulting in a considerable loss of grain yield [40]. Reports have shown that the disease can cause even 70% yield loss and quality under field conditions [41]. In eastern and north eastern states of India, popular varieties like Pooja, Swarna and Abhishek became highly susceptible to the disease. Earlier reports indicates that, the disease occurs sporadically in Asia. The term 'Bakanae' is of Japanese origin meaning 'bad', 'naughty' or 'foolish' seedling, indicating the unusual early elongation of seedlings due to the production of gibberellins on infection process. The fungus produces both gibberellins which causes seedling elongation and fusaric acid, attributed to seedling death [42].

#### *2.2.2 Identification symptoms*

Initial symptoms appear as pale green and lanky seedling sporadically in the field. The seedling later shows abnormal elongation which is much taller than normal plant. The intermodal length will be more and production of fibrous roots seen from each nodes. White powdery mass of the pathogen produces in each node later covers entire plant. The entire plant gets killed without producing any grains. Death of the plants is called as foot-rot. The pathogen produces two toxins, (1) Gibberellic acid which is a growth hormone leads to elongation symptoms and (2) Fusaric acid which lead to death of the young seedlings.

The symptoms and disease severity is mainly depends on the quantity of these two metabolites produced in response to pathogen infection and environmental conditions. The pathogen is both seed-borne and soil-borne, so the infection may occur either by sowing the infested seeds in non-infested fields or by sowing the healthy seeds in infested fields. The inoculums of the pathogen may build up in soil if a susceptible variety grown in the same field year after year. Seed-borne inoculum plays a major role in secondary transmission of the disease under favorable environmental conditions by producing numerous conidia and infects fresh plant [43]. The pathogen infects rice grains during field and carried to storage, the contaminated seeds after sowing in field will results in disease incidence by the colonization of pathogen in seedlings [44]. *F. fujikuroi*-infected seedlings show morphological and colure abnormalities (**Figures 5**–**8**). The abnormal symptoms include elongation, stunting, large angle between leaf and stem, production of roots from each node and yellowish-green leaves [45]. Because of the different kinds of symptoms, bakanae disease is a complex and contradictory (e.g., elongation and stunting symptoms), and depends on varietal response also.

#### *2.2.3 Epidemiology and Integrated management*

Management of the disease is very challenging as the pathogen is seed borne. Once the disease establish in field, it is very difficult to manage. Most commonly

**Figure 5.** *Death of the seedling after transplanting.*

**Figure 6.** *Abnormal elongation of seedlings.*

**Figure 7.** *Production of fibrous roots from nodes.*

used management practice was hot water treatment or fungicide seed treatment [45]. But it was found ineffective as the thermal effect is not efficiently transmitted to the pericarp layer of the seeds. Several fungicides also found in effective as seed treatment chemicals due to development of resistance and as a result fungal spores will not destroy [46]. But several researcher shown that, some of the fungicides as seed treatment and seedling dip treatment found effective [47]. There are also reports of management of the disease with Biocontrol agents such as *Bacillus* spp. (), *Pseudomonas* spp. A combination antagonistic yeasts and thermotherapy was

*Emerging Minor Diseases of Rice in India: Losses and Management Strategies DOI: http://dx.doi.org/10.5772/intechopen.99898*

**Figure 8.** *White powdery mass of the pathogen at the base of stem.*

found to be efficient in managing the disease [48]. Presently the disease is emerging as an alarming state in almost all the rice growing areas of India and worldwide [38]. Looking for alternative management practices other than usage of chemical fungicides is the need of the hour. Alternative management measures such as usage of bio-control agents, chemical elicitor compounds which induce resistance are promising. Along with this, identification of rice bakanae resistant cultivars is more promising and to be taken up in priority [49]. Many researchers have screened numerous accessions against rice bakanae disease to identiofy genes/QTLs responsible for resistance [50, 51]. Select suitable resistant varieties for sowing. Varieties like Chandan, Improved Tapaswini, Sarasa, Kshira, CR Dhan-311, Wifa-10, Improved Lalat, Palguni, Saket-4, Maudamani, Kalinga-II, Naveen, Kalinga-I, CR Dhan-305, Khitish, Satabdi, CR Dhan-310, CR-29-83, IR-29, Udaya, Padma. Treat the seeds with carbendazim 50% WP @ 2 g/kg or biological control agents like *Trichoderma* or *Pseudomonas* talc based formulations @ 8–10 g/kg of seeds. Remove and destroy infected plants from main field. Do not used farmer saved seeds for sowing in the next season. Foliar spray with combination fungicide, Trifloxystrobin 25% + Tebuconazole 50% WG (75%WG) @ 1 g/lit will give the protection to some extent.
