Sugarcane-growing Regions Research Articles

Identification of resistance to Sugarcane mosaic virus, Sugarcane streak mosaic virus, and Sugarcane bacilliform virus in new elite sugarcane accessions in India.

Sugarcane mosaic and leaf fleck diseases are significant viral diseases affecting sugarcane crops in India. The use of resistant sugarcane varieties is considered the most economical and effective approach to manage viral diseases, especially in vegetatively propagated crops such as sugarcane. Sugarcane mosaic virus (SCMV) and Sugarcane streak mosaic virus (SCSMV) are the primary pathogens responsible for mosaic disease in sugarcane-growing regions of India. Sugarcane bacilliform virus (SCBV), causing leaf fleck disease, is also often found in mixed infections with mosaic symptoms. The study aimed to identify new sources of resistance by screening sugarcane germplasm for resistance to SCMV, SCSMV, and SCBV. The screening was carried out under high inoculum using the infector row method in both plant and ratoon crops. Out of 129 genotypes tested, only 8 were found to be free of mosaic viruses, indicating a rare occurrence of resistant sources. The study revealed that mosaic disease is widespread, with nearly 95% of tested varieties/genotypes being infected with mosaic viruses. SCMV, SCSMV, and SCBV were detected in 121 out of 129 genotypes using the RT-PCR and PCR assays. Based on their response to the viruses, the tested genotypes were categorized into different resistance grades: highly resistant (grade 1), resistant (grade 2), moderately resistant (grade 3), susceptible (grade 4), and highly susceptible (grade 5). The results of the study provide valuable information about elite resistance resources that can be used for the prevention and control of mosaic disease. These resistant genotypes could also serve as potential donors for mosaic and leaf fleck disease resistance in breeding programs.

Genetic Diversity and Pathogenicity of Fusarium fujikuroi Species Complex (FFSC) Causing Sugarcane Pokkah Boeng Disease (PBD) in China.

Pokkah boeng disease (PBD), a sugarcane foliar disease, is caused by various Fusarium spp. within the Fusarium fujikuroi species complex (FFSC). In the current study, we investigated the diversity of Fusarium spp. associated with PBD in China. In total, 320 leaf samples displaying PBD symptoms were collected over 10 consecutive years (2012 to 2021), during winter and summer, from six various sugarcane-growing regions (Guangxi, Yunnan, Guangdong, Zhejiang, Hainan, and Fujian) in China. Phylogenetic analysis of Fusarium spp. was reconstructed using translation elongation factor 1-α, and DNA-directed RNA polymerase II largest subunit and second-largest subunit multigene sequences. Evolutionary studies of these regions categorized the isolates into four FFSC species (F. sacchari, F. proliferatum, F. verticillioides, and F. andiyazi). The identified isolates, which developed irregular necrotic patches and rotting symptoms on the sugarcane plant after approximately 30 days were tested for their pathogenicity. Symptoms that appeared during pathogenicity testing were consistent with those observed under field conditions. Each strain of the pathogenic Fusarium spp. belonged to different vegetative compatibility groups (VCGs), and there was no affinity between VCGs. Our results contribute to understanding FFSC and accurately identifying Fusarium spp. associated with the sugarcane crop.

Genetic and morphological variants of Acidovorax avenae subsp. avenae cause red stripe of sugarcane in China.

Sugarcane (Saccharum spp.) is an important cash crop for production of sugar and bioethanol. Red stripe caused by Acidovorax avenae subsp. avenae (Aaa) is a disease that occurs in numerous sugarcane-growing regions worldwide. In this study, 17 strains of Aaa were isolated from 13 symptomatic leaf samples in China. Nine of these strains produced white-cream colonies on nutrient agar medium while the other eight produced yellow colonies. In pairwise sequence comparisons of the 16S-23S rRNA internally transcribed spacer (ITS), the 17 strains had 98.4-100% nucleotide identity among each other and 98.2-99.5% identity with the reference strain of Aaa (ATCC 19860). Three RFLP patterns based on this ITS sequence were also found among the strains of Aaa obtained in this study. Multilocus sequence typing (MLST) based on five housekeeping genes (ugpB, pilT, lepA, trpB, and gltA) revealed that the strains of Aaa from sugarcane in China and a strain of Aaa (30179) isolated from sorghum in Brazil formed a unique evolutionary subclade. Twenty-four additional strains of Aaa from sugarcane in Argentina and from other crops worldwide were distributed in two other and separate subclades, suggesting that strains of A. avenae from sugarcane are clonal populations with local specificities. Two strains of Aaa from China (CNGX08 forming white-cream colored colonies and CNGD05 forming yellow colonies) induced severe symptoms of red stripe in sugarcane varieties LC07-150 and ZZ8 but differed based on disease incidence in two separate inoculation experiments. Infected plants also exhibited increased salicylic acid (SA) content and transcript expression of gene PR-1, indicating that the SA-mediated signal pathway is involved in the response to infection by Aaa. Consequently, red stripe of sugarcane in China is caused by genetically different strains of Aaa and at least two morphological variants. The impact of these independent variations on epidemics of red stripe remains to be investigated.

Biology of the Most Widely Distributed Sugarcane Stem Borers, Diatraea spp. (Lepidoptera: Crambidae), in Colombia.

Most studies on insect biology and ecology of sugarcane borers have focused on Diatraea saccharalis (Fabricius),the most widely distributed species in the Americas. Little information is available on the biology of other borer species present in Colombia, such as D. indigenellaDyar & Heinrich, D. busckella Dyar & heinrich,and D. tabernellaDyar, that present greater expansion and damage in sugarcane-growing regions. The biology of all four species was accordingly studied under laboratory conditions. Diatraea saccharalis presented the shortest development time (39.4days) and D. busckella the longest (58.2days). Immature survival was higher for D. saccharalis (83%) and D. tabernella (77%), with the latter also presenting the highest pupal weight (256.6mg). Observations on reproduction indicate that D. tabernella develops a larger number of egg masses per female (67.3) as compared with D. saccharalis (28.7). All three species spent more time in the pupal stage and resulted in greater pupal size than D. saccharalis; in particular, D. indigenella showed longer female longevity than D. saccharalis. High immature survival rate and greater reproductive success in D. tabernella could potentially generate a larger population in the field, whereas D. busckella takes longer to complete its development, thus increasing the chances of causing greater injury to sugarcane plants. Discussion on biology, ecology, and pest management of these little-known species is done using as model the better-known D. saccharalis.

Impacts of Sugarcane Fires on Air Quality and Public Health in South Florida.

Background:Preharvest burning of sugarcane is a common agricultural practice in Florida, which produces fine particulate matter [particulate matter (PM) with aerodynamic diameter ()] that is associated with higher mortality.Objectives:We estimated premature mortality associated with exposure to from sugarcane burning in people age 25 y and above for 20 counties in South Florida.Methods:We combined information from an atmospheric dispersion model, satellites, and surface measurements to quantify concentrations in South Florida and the fraction of from sugarcane fires. From these concentrations, estimated mortalities attributable to from sugarcane fires were calculated by census tract using health impact functions derived from literature for six causes of death linked to . Confidence intervals (CI) are provided based on Monte Carlo simulations that propagate uncertainty in the emissions, dispersion model, health impact functions, and demographic data.Results:Sugarcane fires emitted an amount of primary similar to that of motor vehicles in Florida. from sugarcane fires is estimated to contribute to mortality rates within the Florida Sugarcane Growing Region (SGR) by 0.4 death per 100,000 people per year (95% CI: 0.3, 1.6 per 100,000). These estimates imply 2.5 deaths per year across South Florida were associated with from sugarcane fires (95% CI: 1.2, 6.1), with 0.16 in the SGR (95% CI: 0.09, 0.6) and 0.72 in Palm Beach County (95% CI: 0.17, 2.2).Discussion: from sugarcane fires was estimated to contribute to mortality risk across South Florida, particularly in the SGR. This is consistent with prior studies that documented impacts of sugarcane fire on air quality but did not quantify mortality. Additional health impacts of sugarcane fires, which were not quantified here, include exacerbating nonfatal health conditions such as asthma and cardiovascular problems. Harvesting sugarcane without field burning would likely reduce and health burdens in this region. https://doi.org/10.1289/EHP9957

Watershed restoration in the Florida Everglades: Agricultural water management and long-term trends in nutrient outcomes in the Everglades Agricultural Area

Water quality degradation from agricultural runoff remains a pressing problem worldwide. A major challenge for restoring water quality is the need for long-term evaluation of governance and management interventions. In agricultural contexts, the primary interventions are best management practices designed to minimize nutrient losses by reducing fertilizer application, soil erosion, and drainage. Most studies are undertaken over short time scales or a few farms, which makes it difficult to connect management to water quality outcomes at larger scales. This paper addresses these gaps by examining 22 years of water quality trends at monthly time scales across the entirety of the 166 small, artificial drainage basins in the Everglades Agricultural Area, the sugarcane-growing region of Florida, USA. The Everglades Forever Act mandated the adoption of best management practices to reduce phosphorus loads but devolved implementation to farms collectively rather than requiring individual compliance. We examined the effect of biophysical and management drivers on long-term trends for two outcomes: a ratio of pumping-to-rainfall, which measures drainage decisions, and total phosphorus load per acre. We analyzed the magnitude and consistency of observed trends using Theil-Sen and Mann-Kendall analysis respectively across wet and dry seasons. Statistically significant downward trends were more common for decreases in magnitude than in consistency for both variables, indicating important management shifts have occurred but that some have not been continually improved over time. However, we also found statistically significant upward trends in a small number of basins for both variables. These results suggest that devolving management to farms has led to a widespread shift in management but that incentives for ongoing improvement would be valuable. Findings on biophysical and management drivers were limited, indicating that more fine-grain data may be needed to better detect their effects.

Optimizing Soil and Fertilizer Phosphorus Management According to the Yield Response and Phosphorus Use Efficiency of Sugarcane in Southern China

The objective of this study was to determine the suitable range of available phosphorus (P) and fertilizer application rate in a sugarcane-growing region with red soil in southern China. Thirty-five monitoring sites were selected to investigate the soil available P in relation to crop yield, P-use efficiency (PUE) and soil total P under four different P rates. Compared with the no-P treatment, all three treatments involving fertilizer P presented sugarcane yields increased to varying extents, with an average increase of 17.6–25.8%. The yield-increasing effects and PUE in each P treatment decreased with increasing soil available P. The agronomic critical values of available P for sugarcane according to the linear-linear, linear-plateau and Mitscherlich models were 27.7, 41.5 and 17.0 mg kg−1, respectively. When the response of the yield-increasing effects of P fertilizer to soil available P and the agronomic critical values of the three models were combined, the linear-linear model exhibited the best fit. An observable change occurred in the available P response to total P. After the change point, the available P increased dramatically with increasing total P, possibly leading to decreased PUE or even triggering water pollution. Therefore, 28–50 mg kg−1 is the suggested range of suitable soil available P for the sugarcane-growing region. In addition, when the soil P budget and current relatively high level of available P are considered, applications of P fertilizer at 120 kg P2O5 ha−1 (1/2 the conventional P fertilizer rate) are recommended in this region.

The impact of climate change on the Australian sugarcane industry

Abstract This study assesses the impact of climate change on changes in sugarcane output for Australia’s main sugarcane-growing regions, using a dataset for the years 1964–2012. We test for accelerated effects of climate change post-1995 (the midpoint in our testing period), as well as for possible non-linear impacts of climate change that are related to the geographical location of sugarcane plantations. Our findings show that increases in atmospheric carbon concentration have had a significant negative impact on sugarcane output after 1995, which contrasts with an earlier positive effect before 1995. Peak temperatures also had a larger impact on sugarcane output after 1995. For areas south of the tropical line and from 1995 onwards, an extra kilometer of distance from the tropical line corresponds to an increase of 1 million tons in sugarcane output growth. Our study tests for additional variables (irrigation, sugarcane diseases, fertilizer use, and dominant sugarcane variety planted) with results remaining similar. We conclude by discussing implications for policymakers and future research, in particular, the importance of factoring in regional differences and non-linear effects into adaptation planning across agricultural regions.

Comparison of IC-RT-PCR, Dot-ELISA and Indirect-ELISA for the Detection of Sorghum Mosaic Virus in Field-Grown Sugarcane Plants

Sorghum mosaic virus (SrMV) is a virus that causes mosaic symptom on sugarcane worldwide. In recent years, SrMV is becoming the most predominant pathogen for sugarcane mosaic disease (SMD) in Guangxi province, the major sugarcane-growing region in China. To facilitate the detection of SrMV, high throughput and sensitive serology-based detection techniques were developed and compared with RT-PCR assay. A high titer polyclonal antibody against bacterial-expressed recombinant coat protein of SrMV was first generated. The specificity and sensitivity of the resultant antibodies were evaluated by Western blotting, indirect-ELISA and Dot-ELISA. SrMV could be detected in crude sap at dilution 1:100 by Dot-ELISA, 1:1000 by indirect-ELISA, and at 1:100,000 by IC-RT-PCR. Meanwhile, a non-reactive result was found in SrMV-free extracts. In a randomly collected field sample pool, 60% of the samples showed SrMV-positive by IC-RT-PCR, similar to that of RT-PCR assay, compared with 46% by indirect-ELISA or 48% by Dot-ELISA. Besides, IC-RT-PCR, Dot-ELISA and indirect-ELISA methods achieved an agreement with RT-PCR procedure of 90, 86 and 78% for the detection of SrMV, respectively. Taken altogether, our findings indicate that IC-RT-PCR is a simple, sensitive and reliable method for SrMV detection, which holds a great potential for SMD control, quarantine programs and the diagnosis of SrMV in asymptomatic infected plant samples.

Sugarcane Workers in Search of Justice: Rural Labour through the Lens of the State

AbstractDrawing from case file records generated in rural labour courts in Brazil’s north-eastern state of Pernambuco between 1965 and 1982, this paper demonstrates how these forums reified class-based exploitation, even as they purportedly protected workers’ rights. The paper focuses on two districts in the state’s sugarcane-growing region, both of which reveal a clear pattern of inferior treatment for rural as opposed to non-rural workers. Interpreting the evidence as a function of long-term patterns of social and economic relations in the region, the paper also sets this case in a larger context of rural labour history around the world.

Optimizing urease inhibitor usage to reduce ammonia emission following urea application over crop residues

Abstract Nitrogen loss as ammonia (NH3) is a major problem when urea is topdressed over crop residues. The treatment of urea with N-(n-butyl) thiophosphoric triamide (NBPT) temporarily inhibits urease activity and reduces NH3 volatilization loss under many agro­ecological conditions. However, the amount of straw on the soil in green sugarcane trash blanketing (GCTB) systems affects the success of NBPT in reducing NH3 loss. We hypothesized that an increase in the NBPT concentration in urea above the current level (530 mg NBPT kg−1 urea) in Brazil is necessary to reduce the NH3 volatilization and to improve the efficiency of urea in GCTB systems. We evaluated the NH3 loss from urea treated with NBPT under field conditions in GCTB systems. Six field trials were conducted across the State of Sao Paulo, the main sugarcane-growing region in Brazil. The treatments were urea, ammonium nitrate, urea treated with NBPT at concentrations of 530, 850, 1500, and 2000 mg kg−1, and a control plot without N fertilizer. The amount of volatized NH3 was assessed through a closed semi-static collector containing two acid-trap foam disks, and analyzed by colorimetry using flow injection analysis. NBPT concentrations above 530 mg kg−1 delayed the time of maximum rate of loss and also reduced cumulative NH3 loss. Ammonia emissions were linearly reduced with increasing NBPT concentrations until 1000 mg kg−1. Any further increase in the NBPT concentration did not result in a substantial reduction of NH3 volatilization. Increasing the NBPT concentration in urea is an effective approach to optimize the adoption of urea-based fertilizers in tropical GCTB systems.

Evaluating Sugarcane Productivity in China over Different Periods Using Data Envelopment Analysis and the Malmquist Index

Nonparametric methods of data envelopment analysis and the Malmquist Index (MI), both based on a time-series analysis, were applied to examine the production efficiency performance and trend of China’s sugar industry from 2004 to 2013 in the four main sugarcane-growing regions of Guangxi, Yunnan, Guangdong and Hainan provinces, which produce more than 90 % of the total sugarcane production in China. The data used in the analysis were from ‘All China Data Compilation of Costs and Returns of Main Agricultural Products (2005–2014)’ of the Price Department of the National Development and Reform Commission. Our analysis revealed that the comprehensive efficiency of sugarcane production in China was relatively low. The average scores of technical efficiency, pure technical efficiency and scale efficiency were 0.760, 0.954 and 0.792, respectively. These scores decreased yearly from 1.000, 1.000 and 1.000 in 2004 to 0.507, 0.978 and 0.518 in 2013, respectively, resulting in a negative impact on the development of the Chinese sugar industry. Additionally, the analysis based on the MI also demonstrated a decline in the trend of sugarcane productivity during 2004–2013 with the total factor productivity index score of 0.894, a slight increase in the technical generalization level with the technical efficiency change index score of 1.002 and a decrease in technological innovation with the technical change index score of 0.880. Our study clearly indicates that Chinese sugarcane productivity needs significant improvement.

A global sensitivity analysis of cultivar trait parameters in a sugarcane growth model for contrasting production environments in Queensland, Australia

Abstract New sugarcane cultivars are continuously developed to improve sugar industry productivity. Despite this sugarcane crop models such as the ‘Sugar’ module in the A gricultural P roductions S ystem s IM ulator (APSIM-Sugar) have not been updated to reflect the most recent cultivars. The implications of misrepresenting cultivar parameters in APSIM-Sugar is difficult to judge as little research has been published on the likely values of these parameters and how uncertainty in parameter values may affect model outputs. A global sensitivity analysis can be used to better understand how cultivar parameters influence simulated yields. A Gaussian emulator was used to perform a global sensitivity analysis on simulated biomass and sucrose yield at harvest for two contrasting sugarcane-growing regions in Queensland, Australia. Biomass and sucrose yields were simulated for 42 years to identify inter-annual variability in output sensitivities to 10 parameters that represent physiological traits and can be used to simulated differences between sugarcane cultivars. Parameter main effect (S i ) and total effect (ST i ) sensitivity indices and emulator accuracy were calculated for all year-region-output combinations. When both regions were considered together parameters representing radiation use efficiency ( rue ), number of green leaves ( green_leaf_no ) and a conductance surrogate parameter ( k L ) were the most influential parameters for simulated biomass in APSIM-Sugar. Simulated sucrose yield was most sensitive to rue , sucrose_fraction (representing the fraction of biomass partitioned as sucrose in the stem) and green_leaf_no . However, climate and soil differences between regions changed the level of influence cultivar parameters had on simulation outputs. Specifically, model outputs were more sensitive to changes in the transp_eff_cf and k L parameters in the Burdekin region due to lower rainfall and poor simulated soil conditions. Collecting data on influential traits that are relatively simple to measure (e.g. number of green leaves) during cultivar development would greatly contribute to the simulation of new cultivars in crop models. Influential parameters that are difficult to measure directly such as transp_eff_cf and sucrose_fraction are ideal candidates for statistical calibration. Calibrating crop models either through direct observation or statistical calibration would allow crop modellers to better test how new cultivars will perform in a range of production environments.

Biology and management of sugarcane yellow leaf virus: an historical overview.

Sugarcane yellow leaf virus (SCYLV) is one of the most widespread viruses causing disease in sugarcane worldwide. The virus has been responsible for drastic economic losses in most sugarcane-growing regions and remains a major concern for sugarcane breeders. Infection with SCYLV results in intense yellowing of the midrib, which extends to the leaf blade, followed by tissue necrosis from the leaf tip towards the leaf base. Such symptomatic leaves are usually characterized by increased respiration, reduced photosynthesis, a change in the ratio of hexose to sucrose, and an increase in starch content. SCYLV infection affects carbon assimilation and metabolism in sugarcane, resulting in stunted plants in severe cases. SCYLV is mainly propagated by planting cuttings from infected stalks. Phylogenetic analysis has confirmed the worldwide distribution of at least eight SCYLV genotypes (BRA, CHN1, CHN3, CUB, HAW, IND, PER, and REU). Evidence of recombination has been found in the SCYLV genome, which contains potential recombination signals in ORF1/2 and ORF5. This shows that recombination plays an important role in the evolution of SCYLV.

Harvest disruption projections for the Australian sugar industry

Purpose– This study aims to investigate the effects of climate change on harvestability for sugarcane-growing regions situated between mountain ranges and the narrow east Australian coastline.Design/methodology/approach– Daily rainfall simulations from 11 general circulation models (GCMs) were downscaled for seven Australian sugarcane regions (1961:2000). Unharvestable days were calculated from these 11 GCMs and compared to interpolated observed data. The historical downscaled GCM simulations were then compared to simulations under low (B1) and high (A2) emissions scenarios for the period of 2046-2065. The 25th, 50th and 75th percentiles of paired model differences were assessed using 95 per cent bootstrapped confidence intervals.Findings– A decrease in the number of unharvestable days for the Burdekin (winter/spring) and Bundaberg (winter) regions and an increase for the Herbert region (spring) were plausible under the A2 scenario. Spatial plots identified variability within regions. Northern and southern regions were more variable than central regions.Practical implications– Changes to the frequency of unharvestable days may require a range of management adaptations such as modifying the harvest period and upgrading harvesting technologies.Originality/value– The application of a targeted industry rainfall parameter (unharvestable days) obtained from downscaled climate models provided a novel approach to investigate the impacts of climate change. This research forms a baseline for industry discussion and adaptation planning towards an environmentally and economically sustainable future. The methodology outlined can easily be extended to other primary industries impacted by wet weather.

A Dual Ensemble Agroclimate Modelling Procedure to Assess Climate Change Impacts on Sugarcane Production in Australia

Climate is a key driver of sugarcane production and all its by-products. Consequently, it is important to understand how climate change will influence sugarcane crop productivity. Ensembles from a crop model and climate projections form part of the dual ensemble methodology to assess climate change impacts on sugarcane productivity for three major sugarcane-growing regions in Australia—Burdekin, Mackay and New South Wales (NSW). Different parameterisations of a crop model injected with climate outputs from eleven statistically downscaled general circulation models (GCM) were used to estimate regionally averaged sugarcane yields for the base period 1971 to 2000. The forward stagewise algorithm selected crop model parameterisations that best explained the observed yields. Leave-one-out cross validation assessed the predictive capability of the equally weighted crop ensemble members characterised by the selected crop model parameterizations. A Monte Carlo permutation testing procedure was employed to measure the significance of the predictive correlations. The predictive correlations between historical yields and simulated historical yields for the Burdekin, Mackay and NSW were 0.69 (p = 0.030), 0.83 (p < 0.001) and 0.70 (p = 0.034), respectively. Simulations were run based on GCM projections for 2046 to 2065 for a low (B1) and a high (A2) emission scenario, with and without elevated CO2 levels. We found it was plausible for industry to consider an increase in yields to all three regions under the B1 scenario and highly plausible for NSW under the A2 scenario. Higher CO2 levels resulted in lower demand of water for the crop, particularly in the Burdekin region and suggested that industry could expand into regions currently considered as marginal owing to the benefits of increased transpiration efficiency that are associated with increased CO2. Although this study favoured neutral or positive impacts on sugarcane production, industry should not overlook negative impacts when developing a risk management framework in response to a changing climate.

Ethanol from Sorghum

Ceres Sementes do Brasil, Ltda is an affiliate of Ceres, Inc, founded in 1996 with headquarters in Thousand Oaks, California, USA, focused on development and marketing of non-food grasses for advanced biofuels and biopower with the aim of providing new opportunities for growers and a cleaner environment for us all. In 2009, Ceres Inc. founded its first Brazilian affiliate in Sao Paulo and initiated research in Brazil aiming to prepare the Brazilian market form commercialization of sweet sorghum and high biomass sorghum hybrids developed for production of biofuel and bioenergy. Ceres works directly with leading mills and suppliers of biofuel technologies to facilitate the introduction of sweet sorghum into existing operations and infrastructure and also carry out tests with leader institutions and innovative producers. Ceres current products are commercialized under the brand Blade® and plans to introduce a number of high-yielding sorghum hybrids with high biomass and high sugar content to complement or expand feedstock supplies in sugarcane-growing regions. In addition to a conventional breeding program, Ceres is developing genetically modified seeds, improved for productivity and agronomic characteristics. We hold a wide collection of plant genes that we plan to introduce in our sorghum breeding program in Brazil. The presentation will cover some considerations about the opportunities for sweet sorghum as a complementary alternative to sugarcane for production of ethanol, electric energy and, in the future, sugar production. It will also discuss some perspectives related to high biomass sorghum as a current alternative to complement biomass production before the sugarcane crop and potential markets in pellet production, heat/vapor and second generation ethanol. The challenges to the adoption of these alternative crops and to the development of new conventional as well as genetically modified hybrids will be addressed.

Pathological and Molecular Variation in Colletotrichum Falcatum Went Isolates Causing Red Rot of Sugarcane in the Northwest Zone of India

Abstract Red rot is one of the most wide spread sugarcane diseases in the country and has been a constraint on sugarcane productivity. Pathological as well as molecular studies were used to characterize the 11 isolates of Colletotrichum falcatum Went collected from sugarcane cultivars of different sugarcane-growing regions in northwestern states of India, to assess pathogen diversity. Seven reference pathotypes of C. falcatum from the northwestern zone of India were compared with four newly collected isolates of the same pathogen. All the newly collected isolates and existing pathotypes were inoculated on a set of 14 differentials in August 2011 by the plug method. After 60 days of inoculation, the observations were recorded and the pathotypes/isolates were categorized as resistant, intermediate, and susceptible according to the virulency behavior. On the basis of pathological categorization and comparison with reference pathotypes, it was concluded that the three isolates R1001 (CoJ 64), R1002 (CoS 88230), and R1004 (CoSe 92423) are similar to the existing isolate Cf 08, except for isolate R0401 from CoS 8436 (Shahjahanpur, Uttar Pradesh). This isolate differs from all the reference pathotypes of the northwestern zone of India indicating the existence of a new pathotype. Pathological results revealed that variety CoJ 64 is the ancestor/source of prevailing new races in nature because these three new isolates showed similarity with Cf 08, of CoJ 64. In this area, Cf 08 was widespread. The isolates were further tested for their variability with random amplification of polymorphic DNA (RAPD) primers. Twenty RAPD primers were screened, out of which seven gave amplification. Out of seven amplified primers, only two primers showed the polymorphism among 11 isolates (seven reference pathotypes and four new isolates) of C. falcatum. Analysis of the genetic coefficient matrix derived from the scores of RAPD profiles showed that minimum and maximum per cent similarities among the tested C. falcatum isolates existed in the range of 11.11 to 87.5, respectively. The dendogram analysis by the unweighted pair group method with arithmetic mean (UPGMA), separated two main clusters. The first cluster comprises only two isolates (Cf 07 &amp; Cf 08), however the second cluster comprises all the other isolates (Cf 01, Cf 02, Cf 03, Cf 09, Cf 11, R1001, R1002, R1004 and R0401), confirming high genetic diversity among the isolates. The study also indicates the possibilities of a new isolate (R0401) in Shahjahanpur, which needs further investigation at the sequence level. The investigation is in progress.

Mexican Rice Borer (Lepidoptera: Crambidae) Injury to Corn Greater Than to Sorghum and Sugarcane Under Field Conditions

The Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), is the key pest of sugarcane (Saccharum spp.) in Texas; it can attack several grassy crop and noncrop host plants and has spread into Louisiana. Through small-plot, commercial field, and pheromone trap experiments, this study demonstrates that the pest uses corn, Zea mays L., more than sugarcane and sorghum, Sorghum bicolor (L.) Moench, but when corn is harvested in late summer, injury to nearby sugarcane strongly increases during the next approximately equal to 2 mo to harvest. Corn was more infested than sugarcane and sorghum in commercial fields regardless of whether sampling occurred on field edges or farther into field interiors. Differences in numbers of infested stalks and in numbers of larval entry holes between field edges and interiors were not detected. We found that Mexican rice borer infestation of corn can cause loss of ears, and lodging, shattering, and complete destruction of maturing stalks. The larger quantities of adult Mexican rice borers captured in pheromone-based traps placed at corn field edges compared with sorghum and sugarcane field edges further indicates that corn is preferred to sugarcane and sorghum. The basis for the pest's attraction to corn and implications to potential range expansion to other U.S. sugarcane-growing regions are discussed.

Evaluation of Mehlich 3 as a Universal Nutrient Extractant for Australian Sugarcane Soils

This study evaluated the suitability of the Mehlic h3 universal extractant as a part of a multielement test to assess the nutrient status of Australian sugarcane soils. Soil samples from BSES Soil Exchange Programs, representing all major soil types and geographic sugarcane-growing regions, were analyzed using existing BSES, acid-based extraction methods for calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), copper (Cu), zinc (Zn), iron (Fe), manganese (Mn), and phosphorus (P) and the ASPAC 10B3 method for sulfur (S). These were compared with the Mehlich 3 procedure. Mehlich 3 results for Ca, Mg, Na, S, and Mn correlated highly with the BSES procedures (R2 = 0.95, 0.98, 0.99, 0.91, and 0.91, respectively). Satisfactory correlations were also obtained with 0.1 M HCl–extracted Zn, Cu, and Fe (R2 = 0.89, 0.85, and 0.85, respectively) and with the BSES sulfuric acid (H2SO4)–extracted P (R2 = 0.81). The poorest correlation (R2 = 0.79) was observed for K. In conclusion, the Mehlich 3 procedure is suitable as a diagnostic tool to assess the basic nutrient status of Australian sugarcane soils.