Progress 09/01/06 to 08/31/09
Outputs
OUTPUTS: Purple and yellow nutsedges are among the most serious weeds in Florida, the Caribbean, and other parts of the world. Production systems based on plastic mulch and methyl bromide soil fumigation are used for nutsedge suppression in conventional vegetable cropping systems. When methyl bromide is phased out, crop losses due to nutsedges are expected to increase. As an alternative weed management strategy, we evaluated 10 organic hays [shoot straw of bahiagrass, cogongrass, cowpea, millet, nutsedge (Cyperus spp.), sorghum x Sudangrass, sunnhemp, rye, and corn, and sugarcane, four green mulches (cowpea, millet, sorghum x Sudangrass, and sunnhemp), and two plastic mulches (black and IRT) for their efficacy in suppressing nutsedge growth in a raised bed tomato, cv. Tygress crop. The black plastic mulch consistently reduced nutsedge (purple and yellow) emergence and growth more than the organic mulches and the IRT plastic mulch. The green organic mulches, except green sunnhemp, were more suppressive to nutsedge emergence and growth than hay mulches. The greatest suppressive effect on nutsedge was found with green sorghum, green millet, and cogongrass hay. Cogongrass hay did not enhance total yield, but it influenced the proportion of larger fruits. The highest yield of extra large tomatoes per plant was obtained with cogongrass hay mulch. Total yield and proportion of larger fruits were increased with black plastic. ///Fourteen solid substrates including several hays from above were tested as substrates to mass produce Dactylaria higginsii, a potential bioherbicide. These were tested alone or amended with 0.01% indole butyric acid (IBA), potato dextrose broth (PDB), or PDB + 0.01% IBA. Conidial yield from these substrates was measured 4 and 12 weeks after inoculation. Those that were harvested after 4 weeks had a second spore harvest 4 weeks after the first harvest. Conidia were tested for virulence on purple and yellow nutsedges in the greenhouse. Conidial yields were highest when the fungus was grown on purple nutsedge hay without any amendments for 4 weeks. Conidia produced on sorghum and cogongrass hays were slightly larger and thicker walled than those produced on other hay media. Conidia produced on sorghum were the most virulent on nutsedge seedlings. ///In Puerto Rico, watermelon was grown with or without organic soil bed mulches [hays of millet, purple nutsedge, sunnhemp, sorghum, cowpea, cogongrass, bahiagrass, and rye]. Natural populations of purple nutsedge consisted of approximately 100 viable tubers per meter square. Purple nutsedge plants able to grow through the mulches were left unchecked until the end of the crop. Non-mulched, weed-free checks were kept. Plots infested season-long with purple nutsedge were used as weedy checks. Purple nutsedge shoot and tuber production was significantly reduced when watermelon was mulched with bahiagrass (68% lower), nutsedge (45% lower), cogongrass (36% lower), millet (36% lower), and sorghum (34% lower), as compared to purple nutsedge-infested checks. When mulching with cogongrass and nutsedge, watermelon yield was significantly higher than with other mulches. PARTICIPANTS: Raghavan Charudattan, Ph.D., Adjunct Professor and Interim Chair, Plant Pathology Department, University of Florida/IFAS, PO Box 110680, Gainesville, FL 32611-0680 - Principal Investigator and Project Director. Yasser Shabana, Ph.D., Program Manager-Postdoctoral Associate,Plant Pathology Department, University of Florida/IFAS, PO Box 110680, Gainesville, FL 32611-0680 - University-funded postdoctoral associate and project manager; salary and benefits from UF; other research support from this project. Waldemar Klassen, Ph.D., Professor, Tropical Research and Education Center, University of Florida/IFAS, 18905, SW 280 Street, PO Box 111569, Homestead, FL 33031-3314 - Co-PI. Jose Pablo Morales-Payen, Ph.D., Associate Professor, Associate Professor Department of Horticulture, University of Puerto Rico - Mayaguez Campus, P.O. Box 9030, Mayaguez, PR 00681-9030 - Co-PI. Partner Organization - USDA-ARS: Erin N. Rosskopf, Ph.D., Research Microbiologist, USDA, ARS, USHRL, 2001 South Rock Road, Ft. Pierce, FL 34945 - Collaborator. Training and Professional Development: Dr. Ayman Hassan Ali Abou Tabl, Assistant Professor, Mansoura University, Egypt - Trainee and research assistant, partly paid on this project. TARGET AUDIENCES: Target Audience: 1. Growers of conventional horticultural crops. 2. Organic horticultural crop producers. 3. Weed Scientists. 4. Biological control scientists. 5. The general public. 6. Graduate students in weed science and plant pathology. Efforts: 1. Laboratory and classroom application of the results from this project. 2. Dissemination of scientific information through publications in scientific journals. 3. Presentations before scientific peers at national and international meetings. 4. Popular articles and other publications. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Dactylaria higginsii is a potentially useful biological control agent for purple nutsedge and yellow nutsedge. The results obtained from this project will help us develop this fungal pathogen as a bioherbicide. Use of natural, hay-based application of the fungus is likely to be adopted by organic growers of horticultural crops. This project has helped to set the stage for further development of D. higgnisii.
Publications
- 2. Shabana, Y., Rosskopf, E., Morales-Payan J.P., Abou Tabl, A.H., Klassen, W, and Charudattan, R. 2008. Use of hay, green, and plastic mulches to suppress nutsedge in horticultural crops. Caribbean Food Crops Society Meeting, Miami, FL, July 13-17, 2008 (Abstract).
- 3. Morales-Payan, J.P., Marquez-Mendez, P.E., Charudattan, R., Rosskopf, E. Shabana, Y., Klassen, W. 2008. Organic and plastic mulches for suppression of purple nutsedge in watermelon. Amer. Soc. Hort. Sci. Annu. Conf., July 21-24, 2008, Orlando, FL.
- 4. Charudattan, R., Hiebert, E., Elliott, M.S., DeValerio, J.T., and Maia, G.S. 2008. SolviNix, A bioherbicide for tropical soda apple (Solanum viarum). Abstract, 5th Int. Weed Sci. Congress, Vancouver, BC, Canada, June 23-27, 2008.
- 1. Shabana, Y., Charudattan, R., Abou Tabl, A.H., Klassen, W., Rosskopf, E., and Morales-Payan, J.P. 2008. Evaluation of hay, green, and plastic mulches for the suppression of purple and yellow nutsedges in tomato production. Florida Weed Sci. Soc. Abstracts, Feb. 25-26, 2008, Maitland, FL. Abstract.
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Progress 09/01/06 to 08/31/07
Outputs
OUTPUTS: Two field studies were established, one each in Florida and Puerto Rico to determine the nutsedge-suppressive ability dry organic mulches, a green mulch, and plastic mulches using tomato (cv Solar Fire; FL) and watermelon (cv: Crimson Sweet; PR) production systems. The mulches were laid individually by covering the top of the soil beds the same day as the watermelon was transplanted. Natural populations of purple nutsedge (approx. 100 viable tubers per meter square) were used in PR. Pre-germinated purple and yellow nutsedge tubers were transplanted in FL. Controls consisted of unweeded (natural or transplanted) nutsedge plots and nutsedge-free (in FL only) plots. In PR, both plastic mulches reduced nutsedge emergence and growth more than the organic mulches. Among the organic mulches, cogongrass, nutsedge, or sorghum straws provided the best nutsedge suppression, while sunnhemp, cowpea and rye provided the least suppression. In FL, black plastic and sunnhemp hay were the
most effective, with the best suppression provided by infrared transmissible. These results indicate that some of the organic mulches may be valuable tools in reducing purple nutsedge populations in crops./// The feasibility of using solid organic substrates to grow Dactylaria higginsii, a bioherbicide agent for purple nutsedge (Cyperus rotundus) and yellow nutsedge (C. esculentus) was studied. Fourteen solid substrates in the form of dried, cut shoots/foliage, or various whole plants were tested alone or amended with nutrient amendments to raise conidia (spores) of D. higginsii. Spore yields were quantified after 4 and 12 weeks and spore quality determined from virulence estimation on purple and yellow nutsedge seedlings in a greenhouse in FL. Spore yields were highest when the fungus was grown on purple nutsedge hay without amendments for 4 weeks. Spores produced on sorghum and cogongrass hays were slightly larger and thicker walled than those produced on other hay media. Conidia
produced on sorghum were the most virulent on nutsedge seedlings./// These studies are currently being repeated in FL; the PR field study will be repeated in February 2008.
PARTICIPANTS: Dr. Raghavan Charudattan, Professor and Chair, Plant Pathology Department, University of Florida, Gainesville - PI and PD Dr. Waldemar Klassen, Professor, Tropical Research and Education Center, University of Florida, Homestead - Co-PI Dr. Yasser Shabana, Research Associate and Project Manager, Plant Pathology Department, University of Florida, Gainesville Dr. Jose Pablo Morales-Payan, Associate Professor, Department of Horticulture, University of Puerto Rico, Mayaguez - Co-PI Dr. Erin Rosskopf, USDA-ARS-USHRL, Ft. Pierce, FL - Cooperator The project provides for professional development of Dr. Yasser Shabana, Professor and Chair, University of Mansoura, El-Mansoura, Egypt, who has taken an extended sabbatical leave from his university in order to serve as the research manager of this project.
TARGET AUDIENCES: Researchers in weed science, plant pathology, horticultural sciences, and other plant science disciplines. Conventional and organic growers. Agrochemical and biotech companies involved in herbicide development. County extension agents. R. Charudattan (RC), Pablo Morales-Payan (PMP), and Yasser Shabana (YS) have used information from this project in formal classroom instructions at the University of Florida and the University of Puerto Rico-Mayaguez; workshops (RC); scientific meetings (RC, PMP, and YS); extension and outreach presentations to county extension agents (RC).
PROJECT MODIFICATIONS: No changes
Impacts
Purple nutsedge (Cyperus rotundus) and yellow nutsedge (C. esculentus) are the serious weeds in the cropping systems in Florida, Puerto Rico and the rest of the Caribbean and many other parts of the world. They have been reported to cause yield losses of 20 to 89 percent in various horticultural crops. When methyl bromide is phased out, the losses due to nutsedge competition are expected to increase in fumigation-dependent crops. Yields in organic production systems will continue to suffer due to the lack of effective controls. A promising approach to nutsedge control is biological control with the fungus Dactylaria higginsii. The fungus is a highly virulent pathogen but grows very slowly and is difficult to mass produce by industrial liquid fermentation processes. As an alternative, we are attempting to grow the fungus on solid substrates consisting of commonly found organic substrates. The results reported here indicate the potential feasibility of using dried plant
materials (hays) to grow the fungus as well as use hays to suppress nutsedge emergence. Use of organic substrates to grow and apply D. higginsii as a bioherbicide is likely to be applicable in both conventional and sustainable/organic production systems. The methods and techniques we developing are unique and can be scaled up for industrial production, which is one of the objectives of this study.///The impact of this study is three-fold; it is likely to provide: 1) a non-chemical alternative to nutsedge management; 2) a practical means of nutsedge control in organic production systems; and 3) a means to transfer an FLA-AES-patented technology to the marketplace.
Publications
- Shabana, Y., Charudattan, R., Klassen, W., Rosskopf, E., and Morales-Payan J.P. 2007. Use of plant hay for solid substrate production and application of Dactylaria higginsii, a mycoherbicide for the control of purple and yellow nutsedges. Abstracts, International Bioherbicide Group Meeting, Montpellier, France, April 22, 2007.
- Charudattan, R. 2007. Biological control of invasive plants. Pages 406-408., in: Barbosa, L.M., Santos, Junior, N.A., dos (Org.) B238a. A Botanica no Brasil: Pesquisa, Ensino e Politicas Publicas Ambientais. 58 Congresso Nacional de Botanica. Sociedade Botanica do Brasil, Sao Paulo.
- Morales-Payan, J.P., Mendez, P.M., Shabana, S., Charudattan, R., Rosskopf, E., and Klassen, W. 2007. Evaluation of organic and plastic mulches for purple nutsedge (Cyperus rotundus) suppression in a sustainable watermelon production system in Puerto Rico. Caribbean Food Crops Society, 43rd Annual Meeting, September 16-21, 2007, San Jose, Costa Rica. Abstract, p. 105.
- Shabana, Y., Charudattan, R., Klassen, W., Rosskopf, E., and Morales-Payan, J.P. 2007. Raw plant material for cost-effective mass production of Dactylaria higginsii, a mycoherbicide for the control of purple and yellow nutsedges. Abstracts, Florida Weed Sci. Soc., Feb. 26-27, 2007, Maitland, FL.
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