Ergot: A New Disease Threat to Sorghum in the Americas and Australia orghum, Sorghum bicolor (L.) Moench, is the world's fifth most important cereal crop, cultivated on about 45 million hectares for food, feed, beverage, and fodder. The most significant technological change since the 1960s has been the development and use of F 1 hybrid seed ( 14), which has lead to a dramatic improvement in the crop's productivity. Sorghum cultivation in intensive, commercialized systems where yields average 3 to 5 t ha -1 relies almost totally on hybrid seed. In contrast, yields vary widely and average less than 1 t ha -1 in low-input production systems.Ergot is a serious disease that affects the production of F 1 hybrid seed. Ergot is particularly severe in male-sterile lines (Alines) when either nonsynchronous flowering of A-line and restorer lines (R-lines) or adverse environmental conditions result in a lack of viable pollen and delayed seed set. In India, losses of 10 to 80% have been reported in hybrid seed production fields. Similarly, ergot epiphytotics in Zimbabwe result in regular annual losses of 12 to 25% and occasionally in total losses.

Amplified fragment length polymorphism (AFLP) based genetic diversity was analyzed for 232 Colletotrichum sublineolum isolates collected between 2002 and 2004 from three geographically distinct regions of Texas, and from Arkansas, Georgia, and Puerto Rico. Results revealed significant levels of polymorphism (59%) among the isolates. Even so, genetic similarity between isolates was high, ranging from 0.78 to 1.00. Clustering of similar isolates did not correlate with either geographic origin or year of collection. Pathotypes of 20 of the isolates were determined using 14 sorghum lines previously used in Brazil and the United States and 4 from Sudan. Seventeen new pathotypes were established from the 18 isolates that gave uniform and consistent reactions on all host differentials over 2 years of greenhouse testing. Differentials BTx378 and QL3 were resistant to all isolates while BTx623 and TAM428 were universally susceptible both years. Each of these lines had shown differential responses in prior studies indicating that the pathogen population has sufficient diversity to adapt rapidly to changes in resistant host lines deployed. When the 2-step pathotype classification scheme was used, the 18 isolates examined in this study were placed in four Eur J Plant Pathol (2012) 133:671-685

No abstract

Current knowledge of yield potential and best agronomic management practices for perennial bioenergy grasses is primarily derived from small-scale and short-term studies, yet these studies inform policy at the national scale. In an effort to learn more about how bioenergy grasses perform across multiple locations and years, the U.S. Department of Energy (US DOE)/Sun Grant Initiative Regional Feedstock Partnership was initiated in 2008. The objectives of the Feedstock Partnership were to (1) provide a wide range of information for feedstock selection (species choice) and management practice options for a variety of regions and (2) develop national maps of potential feedstock yield for each of the herbaceous species evaluated. The Feedstock Partnership expands our previous understanding of the bioenergy potential of switchgrass, Miscanthus, sorghum, energycane, and prairie mixtures on Conservation Reserve Program land by conducting long-term, replicated trials of each species at diverse environments in the U.S. Trials were initiated between 2008 and 2010 and completed between 2012 and 2015 depending on species. Field-scale plots were utilized for switchgrass and Conservation Reserve Program trials to use traditional agricultural machinery. This is important as we know that the smaller scale studies often overestimated yield potential of some of these species. Insufficient vegetative propagules of energycane and Miscanthus prohibited farm-scale trials of these species. The Feedstock Partnership studies also confirmed that environmental differences across years and across sites had a large impact on biomass production. Nitrogen application had variable effects across feedstocks, but some nitrogen fertilizer generally had a positive effect. National yield potential maps were developed using PRISM-ELM for each species in the Feedstock Partnership. This manuscript, with the accompanying supplemental data, will be useful in making decisions about feedstock selection as well as agronomic practices across a wide region of the country.

that with more than 300 ng g Ϫ1 cannot be used as livestock feed. Preharvest aflatoxin (AF) contamination is one of the main limita-Aflatoxin contamination has been associated with tions for corn (Zea mays L.) production in the southern USA causing abiotic stresses such as drought and high temperature enormous economic losses and posing a risk to animal and human (Payne, 1992) and biotic stress such as insect damage health. The objectives of this study were (i) to evaluate and compare hybrids of new and selected potential sources of AF resistance for (McMillian et al., 1985;Windham et al., 1999). There AF accumulation under field conditions, (ii) to identify the inbreds are different complementary approaches to prevent or with the most consistent expression of resistance under different hyreduce aflatoxin: cultural practices to optimize crop probrid combinations and growing conditions; and (iii) to estimate comduction, natural host plant resistance and beneficial secbining abilities of white and yellow inbreds for aflatoxin accumulation ondary traits, biotechnology approaches, and the use of and secondary traits. Two diallels among six local and exotic white nontoxigenic strains of the A. flavus as biocompetitive and six yellow maize inbreds were evaluated at three locations in agents (Brown et al., 1998; Widstrom, 1987). Biotechnol-Texas. Inoculation with Aspergillus flavus Link:Fr. isolate NRRL ogy approaches aim to incorporate resistance through 3357, either directly through the silk channel or as infested kernels the addition or enhancement of genes that regulate comon the soil surface, was effective in promoting AF accumulation in pounds that inhibit aflatoxin production or fungal develhybrids. White hybrids with low aflatoxin were CML269 ϫ TxX24 opment and the reduction of aflatoxin production by and CML269 ϫ CML176. CML269, CML176, and CML322 were the targeting the gene cluster regulating aflatoxin biosynwhite inbreds with the lowest most consistent AF in hybrids and had the best GCA for aflatoxin resistance. Yellow hybrids with low AF thesis. Beneficial secondary traits such as husk covering were FR2128 ϫ Mp715, Tx772 ϫ Mp715, and Tx772 ϫ CML326.and tightness, physical properties of the pericarp (thick-Tx772 and FR2128 had the best GCA for reduced AF across locations ness, wax), and drought or heat stress tolerance are or at specific locations. Inbreds CML326 and Tx772 had consistently contributing factors to aflatoxin resistance. Hybrids low aflatoxin accumulation in hybrids across environments. AF conmore adapted to the growing area with good husk covertent was correlated with husk cover, ear rot ratings, and insect damage. age and insect resistance generally accumulate less afla- Exotic inbreds have genetic factors that can contribute to the reductiontoxin (Lillehoj et al., 1975). Resistance to aflatoxin conof aflatoxin contamination.tamination is under genetic control and genetic variation for response to AF has been found in corn (Widstrom et al.* Indicates significance at P ϭ 0.05. ** Indicates a si...