Biology and Management of Invasive Terrestrial Weed Species of Trinidad Dr. Puran Bridgemohan Ph.D Kimberly Singh MSc. Renaldo Lewis MSc. November 2015 Preface Invasive Weed Species possess the potential to devastate and spread rampantly through fields, plantations, agricultural plots and domestic gardens and also pose health problems to both humans and animals. The need to identify and control these species is very evident, influencing the genesis of this publication. “Biology and Management of Invasive Terrestrial Weed Species of Trinidad” is a manual which contains detailed biological descriptions of the major characteristics of the some weed species found in Trinidad. Suggested methods of management are also included in the descriptor to aid in control of the invasive weed. A principle component of the manual is the photographs, both in field and in laboratory, of each weed species. The whole plant, root systems, leaves, flowers and seeds are captured in order to assist in the proper and accurate identification of each weed. The invasiveness of each weed has been ranked according to the “Invasive Species Assessment Protocol: Evaluating Non-Native Plants for their Impact on Biodiversity”, which was developed by L.E. Morse, J.M. Randall, N. Benton, R. Hiebert and S. Lu of Arlington, Virginia. The authors wish to thank all the personnel that assisted in the preparation of this Manual. In particular, special thanks go to Pooran Jaikaran and Lakeraj Balroop, who made great efforts in sourcing weed specimens for observation and photography. This project was funded by CABI / GEF through The University of Trinidad and Tobago and was facilitated by the University’s Waterloo Research Campus, Waterloo Estates, Waterloo Road, Carapichaima. Dr. Puran Bridgemohan Associate Professor [ Weed Scientist ] , The University of Trinidad and Tobago Kimberly Singh Environmental Analyst/Research Technician, The University of Trinidad and Tobago Renaldo Lewis Environmental Analyst/Research Technician, The University of Trinidad and Tobago December 2015 i Table of Contents Preface ..................................................................................................................................................... i Objectives ............................................................................................................................................... 2 Approach ................................................................................................................................................ 3 Chapter 1: Invasiveness ........................................................................................................................... 5 Chapter 2: Weed Biology ........................................................................................................................ 6 Weed Propagation Methods ................................................................................................................. 6 Weed Dispersal Mechanisms ............................................................................................................... 7 Chapter 3: Impacts of Invasive Weed Species .......................................................................................... 8 Chapter 4: Allelopathy........................................................................................................................... 10 Chapter 5: Management of Invasive Weeds ........................................................................................... 11 Biological Survey .................................................................................................................................. 12 Axonopus Compressus - Savannah Grass ........................................................................................... 13 Brachiaria mutica - Paragrass ............................................................................................................ 16 Commelina diffusa - Watergrass ........................................................................................................ 19 Cyperus rotundas - Nut Grass ............................................................................................................ 22 Echinocjloa colonum- Jungle Rice ..................................................................................................... 25 Eleusine indica - Fowl Foot ............................................................................................................... 28 Parthenium hysterophorus - Whitetop ............................................................................................... 31 Paspalum conjugatum - Buffalo Grass ............................................................................................... 34 Paspalum fasciculatum - Bamboo Grass ............................................................................................ 37 Rottboellia cochinchinensis - Corn Grass ........................................................................................... 40 Setaria poiretiana - Gamalot ............................................................................................................. 43 Sporobolus indicus - Tapia Grass ....................................................................................................... 45 Urochloa fusca - Birdseed-grass ........................................................................................................ 48 Urochloa maxima - Guinea Grass ...................................................................................................... 50 Summary Table of I-Rank Invasiveness ................................................................................................. 53 References ............................................................................................................................................. 54 Glossary ................................................................................................................................................ 56 Appendix .............................................................................................................................................. 59 Objectives The objectives of the manual titled “Biology and Management of Invasive Terrestrial Weed Species of Trinidad” are as follows: To provide a biological description of important invasive weeds throughout Trinidad To provide visual aids to assist in the identification of invasive weed species To rank the invasiveness of weed species in Trinidad to allow for prioritization of management efforts To provide information on the management options available to treat with invasive weed species 2 Approach The tool used to assess invasiveness in this manual is referred to as the “Invasive Species Assessment Protocol: Evaluating Non-Native Plants for their Impact on Biodiversity”, which was developed by L.E. Morse, J.M. Randall, N. Benton, R. Hiebert and S. Lu of Arlington, Virginia (see Appendix 1). The invasiveness of the identified weed species was assessed using twenty (20) assessment questions which are grouped into four sections, describing their ecological impact, both trends and current distribution and abundance and management difficulty. In all cases, each question was scored on a scale of “A” to “D” with “A” indicating the greatest negative effect on native species and natural biodiversity followed by B, C and D answers, corresponding respectively to lesser degrees of impact. For each question, an attempt was made to select one precise answer (single-letter answer) that best characterized the species being assessed. Numerical values were pre-assigned to the letter answers for each of the 20 questions. Within each of the four sections, the letter answers chosen were equated to their corresponding numerical values and tallied to determine the “sub-rank” value (see Table 1) of the section. The “sub-rank” value was used to rank each section in terms of its significance as high, medium, low or insignificant. The significance of the sub-rank values were then equated to pre-assigned numerical values (see Table 2) which were used to determine the “I-Rank” of the species being assessed. The “I-Rank” categorizes the species’ negative impact on natural biodiversity within the region as high, medium, low or insignificant. Finally a text comment summarizing the key information underlying the species’ sub-ranks and its I-Rank was used to describe it invasiveness. Table 1: Sub-Rank Intervals Sub-section Sub-rank Interval I. Ecological Impact 78 -102 High 52 – 77 Medium 27 – 51 Low 0 – 26 Insignificant II. Current Distribution and Abundance 28 - 36 High 19 – 27 Medium 3 10 – 18 Low 0 – 9 Insignificant III. Trend in Distribution and Abundance 55 -72 High 37 – 54 Medium 19 – 36 Low 0 – 18 Insignificant IV. Management Difficulty 39 - 51 High 27 – 38 Medium 14 – 26 Low 0 – 13 Insignificant Table 2: I-Rank Significance I – Rank Interval Significance 76 – 100 High 51 – 75 Medium 26 – 50 Low 0 - 25 Insignificant All weeds were sourced in the field and photos were taken in-field and in the laboratory to depict the whole plant, seeds, flowers and root system. All photos were captured by Kimberly Singh and Renaldo Lewis. 4 Chapter 1: Invasiveness Species which are considered to be invasive are usually non-native, abundant and known or suspected to cause significant reductions in native species populations, severe alterations of native ecological communities, or significant changes in ecosystem processes