Efficacy of batch mode rotary drum composter for management of aquatic weed ( Hydrilla verticillata (L.f.) Royle )

2018 ◽  
Vol 221 ◽  
pp. 20-27 ◽  
Author(s):  
Mayur Shirish Jain ◽  
Ajay S. Kalamdhad
Weed Science ◽  
2007 ◽  
Vol 55 (5) ◽  
pp. 412-420 ◽  
Author(s):  
Atul Puri ◽  
Gregory E. MacDonald ◽  
Fredy Altpeter ◽  
William T. Haller

Hydrilla is one of the most serious aquatic weed problems in the United States, and fluridone is the only U.S. Environment Protection Agency (USEPA)–approved herbicide that provides relatively long-term systemic control. Recently, hydrilla biotypes with varying levels of fluridone resistance have been documented in Florida. One susceptible and five fluridone-resistant biotypes of hydrilla varying in resistance levels were maintained in 950-L tanks under ambient sunlight and day-length conditions from September 2004 to September 2005 in absence of fluridone. Because fluridone is an inhibitor of the enzyme phytoene desaturase (PDS), the gene for PDS (pds) was cloned from fluridone-susceptible and -resistant hydrilla biotypes. Somatic mutations in amino acid 304 of hydrilla PDS are known to confer herbicide resistance. We determinedpdssequence from these hydrilla biotypes at planting and 12-mo after planting. Two independent mutations at the arginine 304 codon ofpdswere found in the resistant hydrilla plants. The codon usage for arginine 304 is CGT, and a single point mutation yielding either serine (AGT) or histidine (CAT) was identified in different resistant hydrilla biotypes. There were no differences at codon 304 in the PDS protein of any hydrilla biotype 12-mo after planting. Several other mutations were also found in resistantpdsalleles, though their possible role in herbicide resistance is unclear.


Plant Disease ◽  
1999 ◽  
Vol 83 (1) ◽  
pp. 24-28 ◽  
Author(s):  
M. L. Smither-Kopperl ◽  
R. Charudattan ◽  
R. D. Berger

Plectosporium tabacinum, the anamorph of Plectosphaerella cucumerina, was isolated in 1996 from Hydrilla verticillata (hydrilla), an invasive aquatic weed in Florida. P. tabacinum, applied as a suspension of conidia, was pathogenic to hydrilla shoots maintained in aqueous solutions in test tubes. Koch's postulates were fulfilled in several repeated experiments. Infected shoots became slightly chlorotic within 24 h after inoculation. Infected leaves remained intact and were supported by water pressure but collapsed upon removal from water. Histological studies of leaves stained with malachite green and acid fuchsin revealed fungal hyphae within plant cells. The disease developed over a range of temperatures from 15 to 30°C. At 25°C, symptoms were most severe in 5% Hoagland's solution, followed by river water, deionized water, 0.5% Hoagland's, tap water, and spring water. Disease severity increased as inoculum concentration was increased from 105 to 107 conidia ml-1. This is the first report of P. tabacinum as a pathogen of hydrilla, a fully submerged aquatic plant species.


2019 ◽  
Vol 17 ◽  
pp. 736-742 ◽  
Author(s):  
S. Pandi Prabha ◽  
C. Karthik ◽  
S. Hema Chandrika

2016 ◽  
Vol 7 (2) ◽  
pp. 1
Author(s):  
Manuel Rojas ◽  
Renán Agüero A.

Hydrilla verticillata has become an important aquatic weed of irrigation canals at some rice farms of Guanacaste, Costa Rica. This species slows water flow, often causing flooding in adjacent roads, its control increases overall production costs. To evaluate efficiency of the grass carp in controlling Hydrilla three trials were conducted, with varying densities of the fish. In the preliminary trial, 987 kg/ha of grass carp reduced Hydrilla biomass in nearly 62 m3 in 21 days. During the second trial, treatments with 1264 and 2042 kg/ha of the fish completely eliminated the weed after 30 days. However, during the third trial, 1000 kg/ha of the carp only reduced Hydrilla volume in 19 m3, after 66 days. The ratio kg of carp/initial volume of Hydrilla proved to be more important than just the kg/ha of the carp. It was observed that when such ratio was lower than 0.02, the carp did not provide a satisfactory control of Hydrilla; on the other hand, a ratio higher than 0.05 significantly reduced the weed's biomass. The equilibrium point between weed regrowth and biomass consumed by the carp occurred at a ratio close to 0.03.


2018 ◽  
Vol 13 (2) ◽  
pp. 237-246 ◽  
Author(s):  
Eugene Appiah-Effah ◽  
Kwabena Biritwum Nyarko ◽  
Esi Awuah ◽  
Eric Ofosu Antwi

Abstract The aim of the study was to use of rotary drum composter as a low cost method for the removal of Ascaris lumbricoides and Trichuris Trichiura in faecal sludge compost. Two runs of compost experiment (Run 1 and Run 2) were carried out consecutively. Each Run of composting was done in four different rotary drums at real scale using a mixture of faecal sludge and shredded maize cobs and monitored for 12 weeks. Concentration of Ascaris and Trichuris were measured once a week to understand their behaviour. Temperature, Moisture Content and pH were also measured. High concentrations of Ascaris and Trichuris were present in the initial compost mix of both Runs 1 and 2. The concentration of Ascaris and Trichuris respectively in Run 1 ranged from 65–77 eggs/gTS and 30–41 eggs/gTS. In Run 2, measured concentrations of Ascaris and Trichuris ranged from 77–110 eggs/gTS and 46–52 eggs/gTS. After 84 days of composting faecal sludge, Ascaris was removed by a minimum of 82% and Trichuris by a minimum of 88%. The findings showed that plastic composter with paddles performed better compared with the other experiments. This means that the type of composter have a significant impact on the removal of helminth.


2017 ◽  
Vol 27 (5) ◽  
pp. 599-606
Author(s):  
William T. Haller ◽  
Lyn A. Gettys ◽  
Taizo Uchida

Topramezone and bispyribac-sodium were registered for aquatic weed control in the last decade. A primary target for these products is fluridone-resistant hydrilla (Hydrilla verticillata), which is one of the most invasive submersed weeds in the southeastern United States. Both products have water use restrictions that prohibit irrigation of turfgrasses with treated waters until the herbicides have degraded to very low concentrations. The objective of these studies was to identify the concentrations of topramezone and bispyribac-sodium that are phytotoxic to turfgrasses that are commonly planted in Florida. Three species of turfgrass were irrigated twice weekly with 0.5 inch of treated water for 4 weeks (eight irrigations total). Cumulative EC10 values (the herbicide concentration that caused a 10% reduction in biomass compared with untreated control plants) after eight irrigations with water containing topramezone were 3.5, 4.3, and 17 ppb for ‘Palmetto’ st. augustinegrass (Stenotaphrum secundatum), ‘Pensacola’ bahiagrass (Paspalum notatum), and ‘Tifway 419’ hybrid bermudagrass (Cynodon dactylon × C. transvaalensis), respectively. Bispyribac-sodium was less toxic to all turfgrasses evaluated, with EC10 values of 56, 16, and >800 ppb for ‘Palmetto’ st. augustinegrass, ‘Pensacola’ bahiagrass, and ‘Tifway 419’ hybrid bermudagrass, respectively. These results support label instructions and highlight the need to comply with irrigation restrictions because the typical use concentrations for submersed weed control with topramezone and bispyribac-sodium are in the 20–40-ppb range.


Author(s):  
D. L. Holmberg ◽  
F. J. Ryan

Until recently, it was believed that Hydrilla verticillata, a widespread aquatic weed, did not generally produce seeds. There were reports that the monoecious biotype from the U. S. was sometimes capable of producing viable seeds, although these were not described in any detail. Recent work at the USDA ARS Aquatic Weed Research Laboratory, Ft. Lauderdale, FL, identified a monoecious biotype of H. verticillata from Penang Island (Malaysia) that is self-fertile and reliably produces viable seed. This biotype may also be crossed with other biotypes including the female dioecious plant from Florida. This work was undertaken to describe the anatomical characteristics of seeds and developing seedlings, using light and electron microscopy.Seeds and seedlings of the Penang Island biotype and Florida X Penang Island cross were processed for light and scanning electron microscopy (SEM). Fixed and fresh material was used. Seeds and seedlings were fixed in 2% paraformaldehyde and 0.1% gluteraldehyde in 0.1M phosphate buffer, pH 7.0. and dehydrated to 100% ethanol.


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