NOTES MANUFACTURING
J. E. Irvine
Journal American Society of Sugar Cane Technologists, Vol. 16. 1996
Engineering Sugarcane for Resistance to Sugarcane Mosaic Virus T. E. Mirkov
Dept. of Plant Pathology and Microbiology Texas A&M Agricultural Experiment Station, Weslaco, TX
Journal American Society of Sugar Cane Technologists, Vol. 16, 1996
restricted the upward progression of the row surface, differences in water furrow depth were difficult to interpret due to ruts in the field.
Effects of Soil Amendment with Organic Wastes on Pythium Root Rot of Sugarcane N. Dissanayake, J. W. Hoy and G. A. Breitenbeck
LSU Agricultural Experiment Station Baton Rouge, LA
Stubble decline, a complex of factors causing reduced ratoon yields, is the most important constraint to sugarcane productivity and profitabilty in Louisiana. Pythium root rot has been shown to play a role in stubble decline. The objectives of our research were to evaluate the potential of amending soils with different organic wastes to suppress Pythium root rot and to identify the major biological and chemical properties of organic wastes which may contribute to root rot suppression. Plants of CP 70-321 were grown in the greenhouse in Pythium-infested field soils amended (20%, v/v) with composts derived from municipal solid waste (MSW), municipal yard waste (MYW), cotton gin trash (CGT), or various tree barks. Additional treatments included amendments with dried sewage sludge (SS) and well-rotted sugar mill filtercake (FC) (10%, v/v). The effects of amendments on root rot severity and plant growth were evaluated after 8 to 10 weeks. Measurements included root fresh weight, shoot dry weight, shoot number, and extent of root colonization by Pythium. In addition, the severity of lateral root rot and root system discoloration was ranked on a scale of one to four.
Sewage sludge, CGT and FC amendments consistently suppressed Pythium root rot and enhanced root and shoot growth. Results using MYW and tree bark composts were inconsistent.
MSW compost had no effect or enhanced disease severity and reduced plant growth. All organic wastes enhanced microbial activity and increased organic matter and plant nutrient levels in amended field soils. Sewage sludge, FC and CGT had higher microbial activity levels, contained higher levels of P and total N, and had lower C:N ratios than the other organic wastes. The MSW compost used in this study contained high salt concentrations (1000-2000 mg/kg), which may explain the poor plant growth observed with this treatment. Beneficial effects of SS, FC and CGT on plant growth parameters did not appear to be due to enhanced plant nutrient levels.
Plants grown in soils amended with steam-sterilized SS, FC and CGT contained comparable nutrient levels to those grown in soils amended with the corresponding nonsterile wastes, but plant growth was not increased. This finding and the observed reductions in root colonization by Pythium and root rot severity suggest that the beneficial effects of amending soils with some organic wastes are primarily due to suppression of root rot. Suppression appears to arise from biological factors present in some organic wastes rather than from the nutritional or physicial benefits obtained by adding these materials to soils.
Journal American Society of Sugar Cane Technologists. Vol. 16. 1996
Heritability of Resistance to Sugarcane Red Rot and the Effect of Environmental Stress on Disease Severity
Zhi Yin, J. W. Hoy and S. B. Milligan LSU Agricultural Experiment Station
Baton Rouge, LA
Heritability of resistance to sugarcane red rot, caused by Colletotrichum falcatum, was studied using ten progeny of 40 crosses and their 24 parental clones during 1992 and 1993. An inoculation method was used to evaluate resistance, in which stalks were inoculated in the center internode, held under controlled environmental conditions for six weeks, then assessed for disease development. The number of nodes passed by internode rot symptoms, the number of rotted nodes in each direction from the inoculation point, and the extent of rotting based on percent discoloration in the inoculated internode and four internodes on each side were recorded. An internode rot index was calculated based on the number of nodes passed and the average extent of internode rotting. Narrow-sense heritability estimates determined by mid-parent-offspring regression for the disease variables ranged from 0.18±0.04 to 0.32+0.06. Genetic gain in resistance, assuming a 10% selection intensity, ranged from 14 to 27% of the mean. The internode rot index provided the highest heritability estimate and the most potential genetic gain by selection. Broad-sense heritability estimates for both parents and offspring, determined by variance component analysis, was high with a single-year model, but it was very low with a combined-year model. The results indicate that genetic variation for red rot resistance is significantly affected by environmental conditions, and single year results for evaluation of disease resistance are not reliable. An additional problem that may have affected the heritability study was that high levels of resistance are rare in the current breeding population.
Field experiment results suggest that resistance to red rot is affected by drought stress at planting. Shoot counts in plots planted with stressed, inoculated stalks were reduced for each of seven cultivars in two experiments. Cultivars were variable in their response to drought stress alone. Poor drainage reduced shoot populations for each of three cultivars. Shoot populations were lowest in the stressed, inoculated treatment, but the additional reductions resulting from inoculation were not significant. Deficient oxygen levels did not occur at the soil depth where the stalks were planted. The results suggest that poor drainage affects red rot severity and plant cane stand establishment through an indirect effect on the root system.
Potential Use of Gramoxone Extra in Sugarcane James L. Griffin, Patrick A. Clay, and Donnie K. Miller
LSU Agricultural Experiment Station Baton Rouge, LA
Gramoxone Extra was evaluated in 1994 and 1995 for ryegrass control (Lolium multiflorum Lam.) and sugarcane response. Mid-Febraary applications were made to ryegrass 6 to 20 inches tall prior to sugarcane emergence. In mid-March, ryegrass was approximately 30 inches tall and sugarcane was 2 to 12 inches. Ryegrass control ranged from 79 to 85% with Gramoxone Extra applied in mid-February at 1.5 pints/A, while 2 pints/A provided 80 to 93%
control. Mid-March application of Gramoxone Extra at 2 pints/A controlled ryegrass 80 to 87%.
Sencor, Sinbar, Atrazine, or Karmex applied in mid-March provided no more than 32% ryegrass control. In some cases control of ryegrass was increased when Atrazine or Karmex was tank mixed with Gramoxone Extra. Sugarcane shoot populations in early May following Gramoxone Extra application at 2 pints/A in February were 9 to 31% greater than when Atrazine or Karmex
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was applied in March. Even so, application of Gramoxone Extra did not improve cane or sugar yields, probably due to the favorable early season growing conditions. Tolerance of CP 70-321 to Gramoxone Extra applied at 1 and 2 pints/A in mid-March or early April was evaluated in fields free of ryegrass. Early and late applications were made to sugarcane 12 and 24 inches tall, respectively. Although visual sugarcane injury 26 days following the April application of Gramoxone Extra was as high as 25%, it was not reflected in differences in sugarcane shoot populations and heights measured in late April, or cane and sugar yields. In our studies, removal of ryegrass and other winter weeds from sugarcane with Gramoxone Extra in the spring resulted in faster drying of fields, improved tillage, and earlier cane emergence. Additionally, elimination of weeds promoted better placement of soil applied herbicides and more efficient fertilizer utilization.
Studies are underway to evaluate combinations of Gramoxone Extra with Sencor or Sinbar applied in the spring for bermudagrass control. When Sencor or Sinbar was applied to emerged bermudagrass, control 2 weeks after application was no more than 51%. Addition of Gramoxone Extra increased control of bermudagrass to around 85%, but also increased sugarcane injury. The subsequent effect of these treatments on bermudagrass reinfestation, sugarcane stalk population, and yield will be determined. Additionally, Gramoxone Extra will be evaluated as a postemergence-directed treatment for bermudagrass control in the row middles after layby.
Effective control of bermudagrass at this time may reduce the potential transport of bermudagrass in seed cane to clean fields and in harvested cane delivered to the mill.
Evaluation of Adjuvants with Roundup for Improved Johnsongrass Control and Rainfastness
Donnie K. Miller and James L. Griffin LSU Agricultural Experiment Station
Baton Rouge, LA Edward P. Richard, Jr.
USDA-ARS Houma, LA
Field studies were conducted to evaluate rhizome johnsongrass [Sorghum halepense (L) Pers] control with Roundup and various additives. Treatments containing Roundup D-Pak at 20 oz product/A plus additives were applied in 1993 to johnsongrass 41 to 75 inches tall with 15 to 20% seedhead emergence and in two studies in 1994 to plants in the vegetative stage 20 to 36 inches tall. Addition of Herbex (0.25% v/v), Break-Thru (0.25% v/v), or HM 9207A (0.5% v/v) alone or plus Quest (0.25% v/v) gave 64 to 74% control of johnsongrass 14 days after treatment (DAT). This level of johnsongrass control was greater than the 53% obtained with addition of Induce (1.0% v/v). Johnsongrass regrowth did not occur following topgrowth removal 14 DAT.
In the first study conducted in 1994, all additives controlled johnsongrass 14 DAT at levels comparable to the Induce standard, 78%. In the second study, addition of DyneAmic, HM 9207A, or LI 700 (0.5% v/v), Activator 90 or Herbimax (1.0% v/v), Herbex, Break-Thru, or Silwet L-77 (0.125% v/v), or LI 700 plus AC A (0.5% + 1 oz/A) controlled johnsongrass 61 to 79%. This level of control was greater than the Induce standard that provided 50% control.
Johnsongrass regrowth following application of Roundup plus all additives was equivalent and less than for the nontreated control. Simulated rainfall studies were conducted to evaluate rhizome johnsongrass control with Roundup and spray adjuvants under field conditions. Plots received either no rainfall or rainfall 15 or 60 min after herbicide application using a rainfall
Journal American Society of Sugar Cane Technologists, Vol. 16, 19%
at 30 oz product/A plus Kinetic HV (0.25% v/v), LI 700 or DyneAmic (0.5% v/v), Induce or Activator 90 (1.0% v/v), or LI 700 plus AC A (1.0% v/v + 1 oz/A). In 1994, Roundup D-Pak was evaluated with Kinetic HV (0.25% v/v), Break-Thru (0.15% v/v), and Induce (1.0% v/v).
Growth stage of rhizome johnsongrass both years was the same as described for the additive studies.
In 1993, johnsongrass control 14 DAT was similar regardless of additive used and was no greater than 62% when averaged across simulated rainfall timings. Johnsongrass control averaged across additives was 27 and 54% for the 15 and 60 min rainfall timings, respectively, which was less than for no rainfall (93%). Even though johnsongrass control ranged from 27 to 93%o, regrowth did not occur following topgrowth removal. At the 15 min rainfall timing in 1994, johnsongrass control with Roundup D-Pak was greater with addition of Break-Thru (40%) than with Kinetic HV (31%), with both higher than Induce (19%). At the 60 min rainfall timing and no rainfall, similar johnsongrass control was observed among additives; highest control was observed for the no rainfall treatment (68 to 72%). Johnsongrass regrowth was equal for Roundup D-Pak plus Induce and Kinetic HV, and greater than that for Roundup D-Pak plus Break-Thru.
Runoff Losses of Pesticides as Affected by Management Practices for Sugarcane H. M. Selim, R. L. Bengtson, and R. Ricaud
LSU Agricultural Experiment Station Baton Rouge, LA
In this study, we quantified the movement of atrazine, sencor (metribuzin), and guthion (azinphosmethyl) in surface runoff and subsurface flow from sugarcane plots under different pesticide management practices. These data are necessary to quantify water quality benefits and effectiveness of best management practices (BMPs) on reducing nonpoint source pollutants from herbicide, and insecticide applications. The soil is a commerce silt loam (Aerie Fluvaquent, fine- silty, mixed, nonacid, thermic) which was planted to sugarcane variety CP70-321 in September 1992. Three types of chemical applications were carried out: a full broadcast (high treatment), a 36-inch band application (conventional or standard treatment), and a 24-inch band application (low treatment). The design consisted of a total of six plots (2 replications x three treatments) with each plot having 9 six-foot rows with a surrounding levee. At the lower end of each plot, a sump (6.5 ft in depth) was installed. In each sump, a water pump was connected to a flow meter to measure the volume of runoff outflow An automatic water sampler was connected to each sump with collection triggered when runoff water was detected. Samples were subsequently analyzed for pesticides and nutrients. Cumulative amounts of chemical losses in runoff waters were highest for full broadcast (high treatment) and lowest for the 24-inch band treatment.
Results also indicated that for the high treatment, atrazine concentrations were 600-700 ppb measured 6 days following applications. For the standard (conventional) treatment, these concentrations ranged from 120 to 140 ppb. The amounts of runoff losses represent some 10%
loss of the atrazine applied for each treatment. For sencor, lower concentrations in the runoff were detected (20-60 ppb) along with lower commutative amounts in comparison to that for atrazine. Due to the limited rainfall amounts during 1993, no guthion runoff losses were detected. For 1994, the amounts of guthion losses in runoff waters were extremely small. These amounts represent a maximum of less than 0.1% loss of that applied. Moreover, rainfall distribution patterns and timing of application directly influenced the amount susceptible for runoff. For the low treatment where one guthion application was made, no guthion losses in runoff waters were detected.
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Outfield Variety Tests: More Than Just Yields Charley Richard, Wendall Jackson, and Herman Waguespack, Jr.
American Sugar Cane League Thibodaux, LA Donnie D. Garrison
USDA- Houma, LAARS Kenneth L. Quebedeaux LSU Agricultural Experiment Station
New Iberia, LA
Through the cooperative effort of the American Sugar Cane League, the United States Department of Agriculture-Agricultural Research Service, and Louisiana State University Agricultural Center, the Louisiana Sugarcane Variety Development Program has provided sugarcane growers with superior varieties for nearly 70 years. Breeding strategies have focused on developing erect varieties with early sucrose accumulation, cold and pest resistance, stubbling ability, and general adaptation to the state's subtropical climate. Varieties are selected for their potential as commercial varieties or as breeding material within this recurrent selection program.
The final stage of the program, outfield variety testing, is designed to evaluate candidate varieties across the major geographical areas of the sugarcane belt by comparing them to commercially grown check varieties. Because larger plots over more locations are used in outfield tests, more confident estimates of varietal performance can be made. At this stage, there is increased emphasis on adaptation to mechanical harvesting, resistance to natural populations of diseases and insects, and stubbling ability. Test procedures have been modified over the years to improve efficiency and provide results that ultimately form the basis for releasing candidate varieties to the Louisiana industry. Current test field procedures are presented in this paper. Yield data from the outfield tests compare favorably to industry yields and help in preparing variety recommendations. Test field results and/or observations can also be used to address industry concerns regarding crop rotation, harvesting efficiency, disease occurrence and spread, planting dates, herbicide tolerance and maturity patterns. Harvesting losses in adverse conditions are documented in this paper using outfield results as a standard for industry comparison. The numerous uses of the outfield results dictate that this stage of the Louisiana Sugarcane Variety Development Program be conducted in such a manner as to provide the maximum amount of useful data.
Diagnosis of Ratoon Stunting Disease of Sugarcane by PCR-Based Procedures.
Gustavo Astua-Monge and Robert E. Stall University of Florida
Gainesville, FL Michael J. Davis University of Florida
Homestead, FL
The sequences of the ribosomal RNA genes as well as the spacers regions between them
Journal American Society of Sugar Cane Technologists. Vol. 16, 1996
transcribed spacer region (ITS) located between the 16S and 23 S rRNA genes may provide unique sequences with a potential for detection and identification of closely related bacteria.
After comparing the sequence of the spacer region between Clavibacter xyli subsp. xyli and a closely related species, two regions were found that may be suitable as amplification targets by PCR. Computer programs were used to select two sets of primers to amplify the regions. The specificity of the primers was tested against several plant pathogenic and saprophytic bacteria commonly found in nature. As a result, a 267 bp fragment was found to be common in phytopathogenic coryneform bacteria, but the bacteria were easily distinguished by a unique restriction pattern when the fragment was digested with the endonuclease Ddel. On the other hand, a 234 bp fragment was found to be specific for the four strains of Clavibaoter xyli subsp.
xyli tested. These strains are representative of four different regions throughout the world including Florida.
Development of a PCR Assay for Diagnosis of Leaf Scald Disease of Sugarcane
Michael J. Davis University of Florida
Homestead, FL Philippe Rott CIRAD-CA Montpellier Cedex 1, France
Dean W. Gabriel University of Florida
Gainesville, FL
Xanthomonas albilineans, the causal agent of leaf scald disease, produces the phytotoxin, albicidin, which interferes with DNA replication in chloroplasts resulting in chlorosis of affected plant tissues. Albicidin is produced by all naturally occurring strains of X. albilineans and is unique to the pathogen; thus, the genes involved in albicidin production might provide a suitable target for a PCR-based diagnostic assay for leaf scald disease. We have cloned DNA fragments which complement albicidin production in isolates of the bacterium where albicidin production has been blocked by Tn5 mutagenesis. For development of PCR primers, an 832 bp subclone of one of these cloned DNA fragments was sequenced. Computer programs were then used to select candidate primer pairs from the sequence and evaluate their exclusivity with respect to other known DNA sequences. Two 19 base oligonucleotides were selected for further study as primers and commercially synthesized. In preliminary PCR tests with the oligonucleotides primers, the expected 664 bp DNA product was obtained for all five strains of the pathogen tested. The strains were representative of the two genetic types of X. albilineans presently known to occur in Florida.
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Metadatabase Analysis Method for Identifying Factors Affecting Sugarcane Production
D. L. Anderson