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Blast, caused by Pyricularia grisea (teleomorph: Magnaporthe grisea), is the most devastating disease of finger millet affecting production, utilization, and trade in Africa and Southeast Asia. An attempt was made to select a set of putative host differentials that can be used to determine virulence diversity in finger-millet-infecting populations of M. grisea. Thus, a differential set comprising eight germplasm accessions selected from finger millet core collection (IE 2911, IE 2957, IE 3392, IE 4497, IE 5091, IE 6240, IE 6337, and IE 7079) and a resistant ('GPU 28') and a susceptible ('VR 708') variety was developed. This differential set was used to study pathogenic variation in 25 isolates of M. grisea collected from Karnataka, Telangana, and Andhra Pradesh states in India. Based on the reaction (virulent = score ≥4 and avirulent = score ≤3 on a 1-to-9 scale) on host differentials, nine pathotypes were identified among 25 M. grisea isolates. Pathotype 9, represented by isolate Pg23 from Vizianagaram, was the most virulent because it could infect all of the host differentials except GPU 28. This study will be helpful in devising strategies for monitoring virulence change in M. grisea populations, and for identification of blast resistance in finger millet for use in disease resistance breeding programs.

Blast, also known as leaf spot, caused by Pyricularia grisea (teleomorph: Magnaporthe grisea), is a serious disease affecting both forage and grain production in foxtail millet in India. For the identification of new and diverse sources of blast resistance, a foxtail millet core collection comprising 155 accessions was evaluated against the Patancheru isolate (Fx 57) of M. grisea. In a field screen during 2009 and 2010, 21 accessions were identified with neck and head blast resistance against Fx 57. In a greenhouse screen, 11 of the 155 accessions exhibited seedling leaf blast resistance to the same isolate. Further evaluation of the selected 28 accessions (found resistant to neck and head blast under field conditions during 2009 and 2010 or leaf blast in the greenhouse screen) against four M. grisea isolates (Fx 57, Fx 58, Fx 60, and Fx 62 from Patancheru, Nandyal, Vizianagaram, and Mandya, respectively) led to the identification of 16 accessions with leaf, sheath, neck, and head blast resistance to at least one isolate. Two accessions (ISe 1181 and ISe 1547) were free from head blast infection and showed resistance to leaf (score ≤3.0 on a 1-to-9 scale), neck, and sheath blast (score ≤2.0 on a 1-to-5 scale) against all four isolates. In addition, ISe 1067 and ISe 1575 also exhibited high levels of blast resistance. Blast-resistant accessions with superior agronomic and nutritional quality traits can be evaluated in multilocation yield trials before releasing them for cultivation to farmers.

Blast, also known as leaf spot, caused by Pyricularia grisea (teleomorph: Magnaporthe grisea), has emerged as a serious disease affecting both forage and grain production in pearl millet in India. Pathogenic variation was studied in a greenhouse using 25 M. grisea isolates collected from four major pearl-millet-growing states in India (Rajasthan, Haryana, Maharashtra, and Uttar Pradesh) on 10 pearl millet genotypes (ICMB 02444, ICMB 02777, ICMB 06444, ICMB 93333, ICMB 96666, ICMB 97222, ICMB 99444, 863B, ICMR 06222, and ICMB 95444). Differential reactions to the test isolates were recorded on ICMB 02444, ICMB 93333, ICMB 97222, 863B, and ICMR 06222. The 25 isolates were grouped into five different pathotypes based on their reaction types (virulent = score ≥ 4 and avirulent = score ≤ 3 on a 1-to-9 scale). For the identification of resistance sources, a pearl millet mini-core comprising 238 accessions was evaluated under greenhouse conditions against five M. grisea isolates (Pg118, Pg119, Pg56, Pg53, and Pg45) representing the five pathotypes. Of 238 accessions, 32 were found to be resistant to at least one pathotype. Resistance to multiple pathotypes (two or more) was recorded in several accessions, while three accessions (IP 7846, IP 11036, and IP 21187) exhibited resistance to four of the five pathotypes. Four early-flowering (≤50 days) blast-resistant mini-core accessions (IP 7846, IP 4291, IP 15256, and IP 22449) and four accessions (IP 5964, IP 11010, IP 13636, and IP 20577) having high scores (≥7) for grain and green fodder yield potential and overall plant aspect were found to be promising for utilization in pearl millet improvement programs. Identification of five pathotypes of M. grisea and sources of resistance to these pathotypes will provide a foundation for breeding for blast resistance in pearl millet in India.

Anthracnose, leaf blight, and rust are important biotic constraints to grain and forage sorghum production worldwide and are best managed through host plant resistance. A sorghum mini-core collection, consisting of 242 germplasm accessions developed from a core collection of 2,246 landrace accessions originating from 58 countries, was evaluated to identify sources of resistance to foliar diseases. The mini-core accessions were evaluated in anthracnose- and leaf-blight-screening nurseries under artificial inoculation in the rainy and late rainy seasons, respectively, during 2009 and 2010. For rust resistance, screening was done under artificial inoculation in the greenhouse as well as in the field under natural infection. In all, 13 accessions were found resistant (score ≤3.0 on a 1-to-9 scale) to anthracnose and 27 to leaf blight in both 2009 and 2010. Six accessions exhibited resistance to rust in both the greenhouse and the field. In the resistant accessions, a wide range of diversity was observed for agronomic traits such as days to 50% flowering, plant height, and grain yield/plant, and morphological characteristics such as grain or glume color, glume coverage, endosperm texture, and panicle type (ear head compactness). Three mini-core accessions (IS 473, IS 23684, and IS 23521) exhibited resistance to all three diseases. These accessions with multiple disease resistance will be useful in sorghum disease resistance breeding programs.

Grain mold and downy mildew are important biotic constraints to grain sorghum (Sorghum bicolor) production worldwide and are best managed through host plant resistance. A sorghum mini-core collection composed of 242 germplasm accessions developed from a core collection of 2,246 landrace accessions from 58 countries was evaluated to identify sources of grain mold and downy mildew resistance. Of the 242 accessions, 140 that flowered during the rainy season (the other 102 accessions were photoperiod sensitive) were screened for grain mold resistance in a grain mold nursery under field epiphytotic conditions during 2007 and 2008. All 242 accessions were screened for downy mildew in the greenhouse using a sandwich inoculation technique. Fifty accessions were resistant to grain mold (≤10% mean severity). These resistant accessions represented four basic and six intermediate races of sorghum that originated from 21 countries and exhibited considerable diversity for agronomic and morphological traits. Downy mildew resistance (mean incidence ≤10%) was observed only in six (IS 28747, IS 31714, IS 23992, IS 27697, IS 28449, and IS 30400) of the 242 accessions. One accession, IS 23992, exhibited resistance to both the diseases. The morphologically and agronomically diverse accessions that are resistant to grain mold or downy mildew should be useful to sorghum disease resistance breeding programs.

Host plant resistance is the major component in the management of fungal diseases in chickpea (Cicer arietinum). We screened a chickpea mini-core collection composed of 211 germ plasm accessions representing the diversity of the global chickpea germ plasm collection of 16,991, maintained at the International Crops Research Institute for the Semi-Arid Tropics to identify sources of multiple disease resistance. The accessions were screened for resistance against As-cochyta blight (Ascochyta rabiei), Botrytis gray mold (Botrytis cinerea), Fusarium wilt (Fusarium oxysporum f. sp. ciceris), and dry root rot (Rhizoctonia bataticola) under a controlled environment. High levels of resistance were observed to Fusarium wilt (FW), where 21 accessions were asymptomatic and 25 resistant. In all, 3, 55, and 6 accessions were moderately resistant to Ascochyta blight (AB), Botrytis gray mold (BGM), and dry root rot (DRR) respectively. ICC 11284 was the only accession moderately resistant to both AB and BGM. Combined resistance also was identified for DRR and FW in 4 accessions, and for BGM and FW in 11 accessions. Through this study, chickpea germ plasm accessions were identified that possess high levels of resistance to more than one fungal disease and would be useful in chickpea multiple disease resistance breeding programs.