Integrated foliar diseases management of legumes

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Integrated foliar diseases management of legumes

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Grain Legumes : Genetic Improvement, Management and Trade International Conference on Grain Legumes: Quality Improvement, Value Addition and Trade, February 14-16, 2009, Indian Society of Pulses Research and Development, Indian Institute of Pulses Research, Kanpur, India
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Integrated foliar diseases management of legumes
S. Pande1, M. Sharma1, S. Kumari2, P.M. Gaur1, W. Chen3, L. Kaur4, W. MacLeod5, A. Basandrai6, D. Basandrai6, A. Bakr7, J. S. Sandhu4, H.S. Tripathi8 and C.L.L. Gowda1 1International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Andhra Pradesh, India; 2International Centre for Agricultural Research in the Dry Areas, P.O. Box 5466, Aleppo, Syria; 3USDA-ARS, 303 Johnson Hall, Washington State University, Pullman, WA, USA 99164; 4Punjab Agricultural University, Ludhiana, Punjab, India; 5Department of Agriculture and Food, Western Australia, 3 Baron-Hay Crt, South Perth, Australia; 6Regional Research Station, CSKHPKV, Dhaulakuan, India; 7Pulse Research Centre, Bangladesh Agricultural research Institute, Joydebpur, Gazipur-1701, Bangladesh; 8College of Agriculture, GBPUA&T, Pantnagar, 263145, Uttaranchal, India. ABSTRACT
Of the most important food legumes grown world over, chickpea (Cicer arietinum L.), lentil (Lens culinaris Medik.), faba bean (Vicia faba L.), grasspea (Lathyrus sativus L.) and field pea (Pisum sativum L.) are grown in cool season, while pigeonpea (Cajanus cajan (L.) Millsp.), blackgram (Vigna mungo (L.) Hepper), mungbean (V. radiata (L.) Wilczek), horsegram (Macrotyloma uniflorum (Lam.) Verdc.), cowpea (V. unguiculata (L.) Walp) and soybean (Glycine max (L.) Merr) are known as warm season legumes. Biotic stresses such as diseases, insect-pests, nematodes and weeds substantially reduce the yield of these legumes in farmers’ fields. Among these, fungi and viruses are the largest and most important groups affecting all parts of the plant at all stages of growth of both cool season and warm season food legumes. According to estimates made in India nearly 10-15% of food legumes production is lost due to diseases alone. Among
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fungi, diseases caused by species of Botrytis and Ascochyta are of great importance to faba bean, lentil, chickpea and field pea. The genus Stemphylium causes foliar disease in lentil and chickpea and Septoria species causes leaf spots in cowpea. The viruses of major economic importance on cool season legumes belong to the Luteoviruses, Nanoviruses, Potyviruses, Carlaviruses, Furoviruses. Perusal of the literature on diseases of food legumes and their management reveals new records of diseases, loss estimations, biology of causal agents, identification of host plant resistance and fungicide use. The purpose of this paper is to review the etiology and biology of major foliar diseases of food legumes and outline current and suggested future research on issues related to disease management strategies globally. Integrated disease management (IDM) modules for important foliar and viral diseases of chickpea (ascochyta blight and botrytis gray mold), pigeonpea (sterility mosaic and Phytophthora blight), lentil (rust, ascochyta blight and stemphylium blight), faba bean (ascochyta blight, chocolate leaf spot and rust), field pea (powdery mildew and Ascochyta complex), mungbean and urdbean (viral diseases and chocolate leaf spot) and cowpea (viral diseases and chocolate leaf spot) are discussed. The IDM involves the individual component of disease management such as host plant resistance (HPR), agronomic practices, judicious use of fungicides, pesticides for vector control, biopesticides for pathogen control, risk forecasting that operate on different aspects of the disease etiology, such that they complement each other and can be applied together in farmers’ fields collectively to provide farmers with maximum economic return. Introduction
Grain legumes play an important role in improving livelihood, nutritional security of farmers and populations in less developed countries as well as sustainability of agriculture in dry areas worldwide. Chickpea (Cicer arietinum L.), lentil (Lens culinaris Medik.), faba bean (Vicia faba L.), grasspea (Lathyrus sativus L.) and field pea (Pisum sativum L.) are grown in cool season, while pigeonpea (Cajanus cajan (L.) Millsp.), blackgram (Vigna mungo (L.) Hepper), mungbean (V. radiata (L.) Wilczek), horsegram (Macrotyloma uniflorum (Lam.) Verdc.), cowpea (V. unguiculata (L.) Walp) and soybean (Glycine max (L.) Merr.) are the warm season legumes. Grain legumes (chickpea, lentil and pea) are important rotational crops in the Pacific Northwest and Northern Great Plains of the United States and central California. The introduction of pulse crops into the agricultural systems in Western Australia (WA) is relatively recent and has been supported by considerable research to adapt and develop varieties and production systems to suit this Mediterranean environment. These grain legumes grown worldwide are prone to attack by a large number of plant pathogens, from fungi, bacteria, phytoplasmas, and viruses to nematodes and parasitic angiosperms, which result in severe economic losses globally. Among these, fungi and viruses are the largest and perhaps the most important groups affecting all parts of the plant at all stages of growth (Table 1). Foliar diseases such as gray mold, chocolate spot, Ascochyta blight caused by species of Botrytis and Ascochyta are of
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Table 1: Important foliar diseases of food legumes and their distribution

Food legume

Disease

Cool season legumes

Chickpea (Cicer

Ascochyta blight

arietinum L.)

Botrytis gray mold

Lentil (Lens culinaris Medik.)

Stunt Rust
Ascochyta blight

Stemphylium blight

Faba bean (Viciae faba L.)

Ascochyta blight Chocolate leaf spot

Rust Necrotic yellows

Field pea

Powdery mildew

(Pisum sativum L.)

Downy mildew

Warm season legumes

Pigeonpea

Sterility mosaic

(Cajanus cajan [L.]

Millsp.)

Causal organism

Distribution

Losses

Ascochyta rabiei

West Asia, northern Africa,

Mediterranean region

Botrytis cinerea

India, Nepal, Bangladesh,

Pakistan, North Africa, Australia,

America

Bean leaf roll luteovirus (BLRV)North Africa, Middle East, India,

Spain, Turkey and the USA.

Uromyces viciae-fabae

Bangladesh, Chile, Ecuador,

Ethiopia, India, Morocco, Nepal

and Pakistan

Ascochyta lentis

Argentina, Australia, Brazil,

Canada, Chile, Cyprus, Ethiopia,

Greece, Iran, Jordan, New

Zealand, Pakistan, Russia, Spain,

Syria, and USA.

Stemphylium botryosum Bangladesh, Egypt, Syria, and

USA

Ascochyta fabae

Mediterranean countries

> 50% 50-100%
50-100% Up to 70%
Up to 70% 5-50%

Botrytis cinerea / Botrytis fabae Uromyces viciae-fabae Faba bean necrotic yellows virus Erysiphe polygoni

Mediterranean countries Mediterranean countries West Asia and North Africa India, Nepal

Up to 50% Up to 50% Up to 80% 10%

Peronospora viciae

30%

Pigeonpea sterility mosaic virus Bangladesh, India, Myanmar, Nepal, Sri Lanka and Thialand

Annual loss of 205, 000 tonnes in India (Kannaiyan et al. 1984)

Mungbean (Vigna radiata [L.] Wilczek and black gram (Vigna mungo [L.] Hepper) Cowpea (Vigna ungiculata [L.] Walp.)

Yellow vein mosaic

Mungbean yellow mosaic virus

Cercospora leaf spot Powdery mildew Cercospora leaf spot

Cercospora cruenta, C. canescens Erysiphe polygoni Cercospora canescens and Pseudocercospora cruenta

Cowpea golden mosaic Cowpea golden mosaic virus

Cowpea aphid-borne mosaic

Cowpea aphid-borne mosaic virus

Bangladesh, India

10-100%

Bangladesh, India, Indonesia, Taiwan, Thailand, Philippines, Malaysia India, southeast Asian countries Fiji, Brajil, Kenya, Nigeria, Zimbabwe, India, Bangladesh, Egypt, Iran, Japan, Malaysia, Thailand Kenya, Nigeria, Tanzania, Cuba, Surinam, USA Europe, Africa, Mediterranean basin, Turkey, Iran, India, Indonesia, China, Japan, Australia, Brazil, USA.

Upto 50% 9-50% 18-42%
60-100% 13 - 87%

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great importance to faba bean, lentil, and chickpea. The genus Stemphylium causes foliar disease in lentil and Septoria species causes leaf spots in cowpea. Around 45 viruses are reported to infect legumes (Bos et al., 1988; Makkouk et al., 2003) worldwide. However, only few are of major economic concern with respect to specific regions. Among the more important groups are the Luteoviruses, Nanoviruses, Carlaviruses, Furoviruses and Potyviruses. The Potyviruses are the most important overall causing economically important diseases in grain legumes. Many of the viruses are seed borne in their legume hosts; some are sufficient to have enabled worldwide distribution.
There are reviews dealing with the individual foliar diseases of cool season and warm season legumes (Kaiser et al., 2000; Pande et al., 2007; Tikoo et al., 2005). In this chapter, attempts have been made to address the management of major foliar diseases of both cool season (chickpea, lentil, faba bean, and field pea) and warm season [pigeonpea, mungbean (greengram), urdbean (blackgram) and cowpea] food legumes and outline current and suggested future research on issues related to importance and disease management strategies for these diseases globally. Integrated disease management strategies for economically important foliar diseases of chickpea (ascochyta blight, botrytis grey mold), pigeonpea (sterility mosaic and phytophthora blight), lentil (rust and stemphylium blight, ascochyta blight), faba beans (chocolate leaf spot), field pea (powdery mildew) and green gram and black gram (viral diseases) have been discussed in details with reference to the available research results on the biology of the pathogen and etiology of the disease to device successful disease management strategies. A successful integrated disease management (IDM) strategy is one under which grain legumes have been protected from the yield-reducing effects of the pathogen rendering the later to economic insignificance. The IDM involves a total system approach to the suppression of pathogen populations to a level where higher yields can be obtained and enables the farmers to achieve maximum economic return. In the IDM system, the individual component of disease management such as host plant resistance (HPR), agronomic practices, judicious use of fungicides, pesticides for vector control, biopesticides for pathogen control etc., need to be compatible or complimentary. Management of foliar diseases of food legumes
The main emphasis in research and development to combat food legume diseases is on host resistance and chemical control where ever applicable, and quite often these components of disease management were practiced in isolation to each other. Recently a shift in scientific thinking and practice in the management of grain legume diseases has been seen and greater emphasis was on identifying, evaluating, and integrating location specific components of integrated disease management (IDM). In general IDM has followed the principles of IPM (Jeger, 2000). The location specific IDM of food legumes is primarily based on host plant resistance (HPR) or genetic resistance; additionally other
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components of diseases management. In some environments, IDM may require a single component used alone (usually HPR) or in combination with one other component (such as fungicide seed treatment) to adequately combat diseases of food legumes. The components of IDM employed in the production of food legumes are listed as follows: l Host plant resistance (HPR), l Disease modeling (prediction) for avoidance of high risk or disease pressure, l Chemical sprays (fungicides, pesticides), l Biological control, and l Cultural (agronomic) practices (sowing dates, plant population etc.).
In this review, disease management practices to control economically important foliar diseases of food legumes have been discussed (Table 2). Management of viral diseases has been discussed separately under the virus disease control section.
3. Cool season legumes 3.1 Chickpea (Cicer arietinum L.)
Major foliar diseases of potential economic importance in chickpea are ascochyta blight (AB) and botrytis grey mold (BGM). These diseases have been comprehensively reviewed by several workers in the past (Nene and Reddy, 1987; Nene et al., 1991; Haware, 1998; Singh and Sharma, 1998; Pande et al., 2005). Recently Pande et al. (2007) have discussed advances in etiology, biology and management of diseases of food legumes and Singh et al. (2007) have discussed chickpea diseases and their management in detail.
Ascochyta blight infection and disease progression occur from 50 to 25 0C with an optimum temperature of 16-20 0C, and a minimum of 6 h leaf wetness. Disease severity increases with the increase in relative humidity (Trapero-Casas and Kaiser, 1992). Cloudiness and prolonged wet weather favour rapid development and spread of both the diseases. The pathogen survives on infected or contaminated seeds, infected chickpea debris which causes AB, produces both rain splashed conidia and wind blown ascospores. The existence of 2-12 races of A. rabiei has been proposed by several researchers (Chongo et al., 2004; Phan et al., 2003). Basandrai et al. (2005) grouped 14 isolates of A. rabiei into eight pathotypes at >0.5 similarity coefficient.
Infection of BGM occurs from 15-25 0C with an optimum temperature of 20-25 0C. High moisture and high relative humidity are congenial for BGM development. Under such conditions there is abundant sporulation of the fungus B. cinerea on dead plant parts, particularly on flowers and pods (Pande et al., 2006). The pathogen B. cinerea is reported to have extreme diversity and adaptability to a wide range of environmental conditions. Existence of 4 - 5 pathotypes of B. cinerea has been reported
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from northern India (Rewal and Grewal, 1989; Pande et al., 2006). Adoption of IDM practices is essential for economical and effective control of AB
and BGM. In several studies conducted in different chickpea growing areas of the world, several sources of resistance to AB were identified (Pande et al. 2005). Furthermore, development of AB resistant genotypes has made it possible to sow the crop during winter in the Mediterranean region thereby doubling the chickpea production potential. On the other hand, an adequate level of genetic resistance to BGM is not available in the cultivated genotypes and fungicides become ineffective under the high disease pressure. Hence, IDM using the available management options is essential to successfully manage the disease and mitigate yield losses. Moderate level of HPR can be combined with other cultural practices and/or application of minimum dosage of fungicides for control of AB and BGM.
A combination of a moderately resistant variety and 2 sprays of chlorothalonil, one during the seedling stage and another at the early podding stage, provided the most economical field control of AB in Syria and Australia (Reddy and Singh 1990, Bretag et al. 2008). In collaboration with the Syrian national program, ICARDA has developed an IDM package for AB management (Akem et al., 2000). The components of this package include use of tolerant cultivars adapted to early sowing, seed dressing with fungicides, and single foliar application of chlorothalonil at seedling or early vegetative growth stages. This package resulted in higher chickpea yields compared with the traditional spring plantings using a local variety without seed dressing or fungicide spray (ICARDA 2003).
Agronomic and cultural management of BGM has been demonstrated in India, Bangladesh and Nepal (Pande et al., 2002). In Bangladesh, an IDM package, comprising cultivation of the BGM tolerant genotype “Avarodhi”, soil application of diammonium phosphate, wider row spacing , seed treatment with carbendazim + thiram (2g/kg seed), and need based foliar application of carbendazim, has been devised (Bakr et al., 2005; Pande et al., 2005, 2006).
The location-specific recommended IDM practices for AB include: (a) use of pathogen-free seed, (b) seed treatment with fungicides, (c) practice of crop rotation, (d) deep ploughing of chickpea fields to bury infested debris, (e) use of disease-resistant genotypes, and (f) strategic application of foliar fungicides. 3.2 Lentil (Lens culinaris Medik.)
Ascochyta blight, rust and powdery mildew are economically important foliar diseases of lentil. Ascochyta blight is caused by A. lentis produces conidia, in a flask-shaped fruiting body (pycnidium), which are spread by rain splash. The teleomorph, Didymella lentis, produces ascospores which can be wind dispersed large distances. The pathogen is both stubble and seed borne. Progress of foliar blight is rapid and epidemic levels can
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be reached under cool and wet weather conditions as a consequent of spores being disseminated by rain splashes. It survives for more than 3 years in infected pods and seeds at 4-5 0C or under shelter outdoors, and 1-5 years at the soil surface. IDM of Ascochyta blight of lentil includes use of resistant cultivars, use of disease free seed, crop rotation, seed treatment and foliar spray. Application of the fungicides benomyl, carbendazim, thiabendazole, chlorothalonil, prothioconazole and strobilurin, are useful for managing Ascochyta blight epidemics.
Lentil rust is caused by Uromyces vicia- fabae (Pers.) de Bary. It is an autoecious fungus; completing its life cycle on lentil. The disease occurs during the flowering/early podding stage as aecia, which may develop into secondary aecia or uredia. The resulting aeciospores and uredospores lead to a further disease spread in the crop season. Uredia rapidly appear a little late in the crop season followed by development of telia. The fungus survives in summer as teliospores. High humidity and cloudy weather with temperatures of 20-22 0C favor disease development. The plants give dark brown or blackish appearance visible as patches in the field.
Integrated management of rust includes control of volunteer plants over the summer and removal of infected lentil debris. It is advisable to use clean seeds without rust contaminations, and to treat the seed with a suitable fungicide such as diclobutrazole. Preventive fungicide sprays of mancozeb at early disease development stage have been recommended. The use of host plant resistance is the best means of rust management. Several rust resistant cultivars have been released in different countries, with resistance originally identified at ICARDA, Syria and in India (Basandrai et al., 2000, Tikoo et al., 2005). There is no clear evidence for the existence of races. Both complete and partial resistance exists and monogenic resistance has been reported (Sinha and Yadav, 1989). Field resistance of lentil to rust is governed either by a single dominant gene, by two independently inherited dominant genes, by two complementary genes or by three independently inherited genes (Basandrai et al., 2005).
Powdery mildew another important disease of lentil has been reported from many countries such as Cyprus, Ethiopia, India, Siberia, Sudan, Syria, Tanzania and the former USSR. In North America, powdery mildew is often observed after lentil started flowering. The disease poses a serious problem on breeding material in plastic or glass houses in both India and Syria, and in India it is also recorded in off-season nurseries in Trans Himalayan regions, like Lahaul Spiti and Sangla etc., but it is rarely seen in the field during the cropping season. A fine powdery, white growth of conidia and mycelium initiates as small spots and rapidly spreads to cover the entire surface of leaves, stems and pods. Later, the leaflets become dry and curled, and are shed prematurely, causing considerable reduction in yield and seed quality. The seeds from infected plants remain small and shrivelled.
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Powdery mildew of lentil is caused by the ectoparasites Erysiphe pisi DC., and E. polygoni DC. and the endoparasite Leveillula taurica (Lév.) Arnaud. Recent evidence showed that E. trifolii also infects lentil (Attanayake et al., 2008). The anamorph stage is responsible for spread of the disease. The teleomorph stage has been reported to occur in India and Sudan (Chitale et al., 1971). Moderately high temperatures and moderate relative humidity favour the disease development. Many lentil genotypes are reported resistant to powdery mildew (Tikoo et al., 2005), and should be planted whenever possible. Foliar sprays with fungicides benomyl, tridemorph, aqueous sulfur, karathane (dinocap), calixin or sulfex (ferrous bisulfide) as well as certain insecticides (Quinalphos, Tnazophos, Phoxim) applied at 10-15 days interval are effective in suppressing mildew growth (Beniwal et al., 1993). 3.3 Faba bean (Vicia faba L.)
Ascochyta blight, chocolate leaf spot and rust are the major diseases of faba bean (van Emden et al., 1988). Ascochyta blight also known as leaf, stem, and pod spot is caused by Ascochyta fabae (teleomorph Didymella fabae Jellis & Punnith). Both stages are described by Jellis and Punithalingam (1991). The fungus is highly specialized to faba bean and is highly variable in culture. Rashid et al. (1991) identified seven genes of resistance and resistance was either monogenic or oligogenic. Limited information is available about the biology of A. fabae (Jellis et al., 1998). More work needs to be done to standardize methods and differential cultivars to establish the A. fabae races.
Chocolate leaf spot is caused by both Botrytis cinerea Pers. ex Pers. and Botrytis fabae Sard. A teleomorph of B. fabae, Botryotinia fabae, was described by Wu and Lu (1991). B. cinerea is a parasite and saprophyte on a wide range of host plants, whereas B. fabae is specialized for the invasion and colonization of Vicia spp. especially V. faba. The existence of races of B. faba has been proposed on the basis of reaction to differentials in Mediterranean countries. More work needs to be done to understand variability in B. fabae. Etiology and biology of the fungus is discussed in detail by Jellis et al. (1998).
Another disease of faba bean, brown rust is caused by the fungus Uromyces viciae fabae (Pra.) Schroter. The pathogen predominantly produces aeciospores and uredospores on leaves, and teliospores are formed in large black sori on stems and petioles (Jellis et al., 1998). While earlier studies mostly focused on cytological aspects, later studies were concerned with biochemical and molecular characteristics. Despite the fact that there is still no stable transformation system available for any obligate biotroph, recent molecular analyses have provided new insights into this highly sophisticated interaction of a fungus with its host (Ralf T Voegele, 2006).
IDM strategy for controlling foliar diseases of faba bean includes the use of disease free seed, avoid sowing too early to minimise disease, follow 3 - 4 year crop rotation and
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select the tolerant variety to the main disease risk in particular region. Thorough and regular crop monitoring is essential if the strategic spray program is to be successful. The timing of fungicide applications depends on the disease level observed, the time since the previous application, and the likelihood of rainfall and other conditions conducive to infection and spread of chocolate spot. Carbendazim is best used when high chocolate spot pressure occurs or when rapid plant growth produces large amounts of unprotected foliage, particularly from mid-flowering onwards. Cholorothalonil and mancozeb are best to be used earlier if rust or Ascochyta is a problem. 3.4 Field pea (Pisum sativum L.)
Peas are adversely affected by serious fungal, bacterial and viral diseases such as: powdery mildew (Erysiphe pisi Syd. (syn. E. polygoni DC), Ascochyta blight or black spot (Ascochyta pisi/A. pinodes), downy mildew (Peronospora pisi), bacterial blight (Pseudomonas pisi), Pea early browning virus (PEBV), Pea enation mosaic virus (PEMV) and Pea mosaic virus (PMV) (Davies et al., 1985; Muehlbauer et al., 1995; van Emden et al., 1988). Kraft et al. (1998) has comprehensively described pea diseases. Etiology and biology of these diseases is reviewed in detail by Saxena and Khare (1998) and Baaya and Erskine (1998).
Powdery mildew occurs all over the world and can cause severe damage in areas where pea is cultivated (Kraft and Pfleger, 2001). Powdery mildew of pea caused by Erysiphe pisi, is a serious disease both in the field and in the greenhouse. All aboveground parts of plants are susceptible to powdery mildew. Pod infection may discolor seeds to a gray brown color. The powdery look of the disease is caused by the profuse production of conidia on the upper leaf surface. Management of powdery mildews of grain legumes is through use of resistant cultivars, especially in late sown crops, which are likely to experience high disease pressure. Resistance in pea is conditioned by two recessive genes (er-1 and er-2) along with two or more modifying genes. Resistance in cultivars homozygous for er-2 is expressed mostly in leaves and this resistance can be rendered ineffective under high disease pressure. The disease is often less severe in areas where overhead irrigation is applied regularly because long periods of free water on host leaves reduce conidium viability and wash conidia from host tissue. Other control measures include fungicide sprays of sulfur and/or demethylation inhibitors such as cyproconazole, fenarimol and triadimenol. Fungicide spray should be applied at least two weeks before harvest to avoid residue on peas.
Ascochyta blight or black spot is the most common and most damaging disease of field pea in southern Australia. Worldwide, the disease is recognized as being caused by any one, or combinations, of three fungi; Mycosphaerella pinodes, Phoma medicaginis var. pinodella and Ascochyta pisi. All three frequently occur together hence the disease is generally referred to as the ascochyta complex of peas. Mycosphaerella pinodes
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causes the most damage to pea crops in Western Australia, Washington, USA and is the principal pathogen involved in nearly all occurrences of blackspot. Mycosphaerella pinodes survives on pea stubble for more than 3 years producing viable ascospores during each growing season. Ascospores are released from pseudothecia on the stubble following rain events of as little as 0.2 mm. The airborne ascospores can infect crops several kilometres away.
IDM includes use of moderately resistant varieties, disease free seed, crop rotation, delay in the sowing, disease forecast model that predicts the time of onset, and progression of ascospores maturity and spread of spores from the source of infection and need based foliar and in-furrow applications of fungicides in conjunction with other agronomic practices (Kraft et al., 1998). 4. Warm season legumes 4.1 Pigeonpea (Cajanus cajan (L.) Millsp.
Sterility mosaic disease (SMD) is the most important foliar disease of pigeonpea in India and Nepal (Reddy and Vishwa Dhar, 2000). Etiology of sterility mosaic is unknown despite of numerous attempts during the past 20 years. Lava Kumar et al. (2000) reported a tenui virus of asymmetric morphology as the cause of SM disease and retained the name of virus as Pigeonpea sterility mosaic virus (PPSMV). PPSMV is flexous, branched filaments measuring 3-8nm in diameter. The SM causal agent is not transmitted through sap or seed. It is transmitted by the eriophyid mite vector. Biology of the mite vector is discussed in detail by Reddy et al., (1990). Information on physiological specialization of SM is limited and is based on symptoms observed on the inoculated plants using the mite vector (Reddy et al., 1990). Recently PCR based techniques are being developed for distinction of different species of eriophyid mites (Vishwa Dhar et al., 2005).
HPR is the most reliable and sustainable method for the management of SMD. Considerable progress has been made in identifying resistance sources and developing resistant cultivars to the disease. Some attention has also been paid to cultural and chemical control of sterility mosaic. Cultural practices include: Destroy ratooned pigeonpea, uproot and destroy infected plants at the initial stage of disease development, crop rotation to reduce inoculum levels and vector populations, chemical control as seed treatment with 25% carbofuran or 10% aldicarb (3g kg-1 seed) and spraying acaricides or insecticides like karathane, metasystox to control the mite vector in the early stages of plant growth (Reddy et al, 1990).
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IndiaDiseasesDiseaseManagementLentil