Progress 10/01/06 to 10/01/10
Outputs
OUTPUTS: Quinoclamine is used in Europe, and was under evaluation in the United States for liverwort (Marchantia polymorpha)control in nursery crops. Liverwort is a non vascular, chlorophyll-containing plants that produce a mat that can completely cover the media surface and thereby reducing water and nutrient entry into the media. POST-applied quinoclamine control liverwort. However liverwort structures and tissues differ in their sensitivity to POST-applied quinoclamine. Specifically archegonial receptacles (female) are much more tolerant of quinoclamine than either antheridial receptacles (male) or thalli (foliage). A series of studies were conducted to first, document the degree of differential sensitivity between tissues to quinoclamine. And secondly, attempt to determine the basis of this differential sensitivity. From a dose response the LD50 of antheridial receptacles was estimated to be 1.6 kg/ha. Similarly, the LD50 for thalli (the foliage) was estimated to be between 1.3 and 3.4 kg/ha, depending on age. The LD50 of archegonial recepticales could not be estimated, but exceeded 8 kg/ha. Chlorophyll content varied between liverwort tissues. But the content did not parallel with quinoclamine sensitivity. Absorption as determined with 14C quinoclamine was less in archegonial receptacles than in either antheridial receptacles or thalli. Scanning electron microscropy of the surface of the liverwort tissues/structures revealed that archegonial receptacles had smaller and fewer pores (equivalent to stomates in higher plants) than either antheridial receptacles or thalli. We conclude that the tolerance of archegonial receptacles to quinoclamine can be partially, but not exclusively, attributed to reduced absorption. And this reduced absorption can be attributed to the limited porosity of the archegonial receptacles. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
across nearly all herbicide - plant interactions, the flowering and fruiting structures are more sensitive than the foliage. But quinoclamine and liverwort apparently stands as the sole exception to this rule, in that archegonial receptacles were less absorptive to quinoclamine than either antheridial receptacles or thalli. And this differential sorption can likely be attributed to differential pore characteristics. However, in the opinion of the authors the differential sorption resulting from differential pore characteristics provides only a partial explanation for the differential quinoclamine sensitivity. While this will likely not play a major role in finding effective control methods for liverwort, it does stand a a very unique botanical abnormality.
Publications
- Altland, James E., G. Wehtje, Jeff Sibley, Michael E. Miller, and Charles H. Gilliam. 2011. Differential response of liverwort (Marchantia polymorpha) structures to POST-applied quinoclamine. Weed Sci. 59: In press.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: A frequent observation made by the authors is that liverwort tissues varied in their sensitivity to POST-applied quinoclamine. Specifically archegonial receptacles (female)are much more tolerant of quinoclamine than either antheridial receptacles (male)or thalli (asexual foliage). This is unusual in that generally in herbicide-plant interactions, flowering and fruiting structures are more sensitive to POST-applied herbicides than foliage. A dose-response study revealed that the LD50 of thalli ranged from 1.1 to 3.0 lb/a, depending on plant age. The LD50 for antheridal receptacles was comparable, i.e. 1.4 lb/a. But the LD50 for archegonial receptacles could not be measured, they were immune to the rate evaluated. Studies were undertaken in the hope of determining the basis of this very pronounced differential susceptiblility. Sorption studies using 14C-quinoclamine revealed that archegonial receptacles absorbed less quinoclamine than either thalli or antheridial receptacles. While this difference was significant, it is insufficient to explain the near immunity of archegonial receptacles. Another possible explanation is differential chlorophyll content. Chlorophyll content varied between the liverwort structures. Specifically, chlorophyll content in declining order was as follows: thalli, archegonial receptacles and antheridial receptacles. Other possible explantion may lie in anatomy of these structures. This will be evaluated with electron microscopy. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
At this time there is no herbicide that is both registered for use, and truly effective in controlling liverwort. And also at this time, it appears unlikely that quinoclamine will be registered in the United States. However, several of the PROTOX-inhibiting herbicides that are used in agronomic and horticultural crops appear to have adequate efficacy on liverwort. And prehaps they will find utility for use in nursery crop production. And when (and if) this occurs, we hope that will be be better able to explain their efficacy.
Publications
- Altland, J. E., G. Wehtje, M. L. Mckee and C. H. Gilliam. 2008. Liverwort response to quinoclamine in a pine bark substrate. Weed Sci. 56:762-766.
- Wehtje, G., J. E. Altland and C. H. Gilliam. 2009. Interaction of glyphosate and pelargonic acid in ready-to-use weed control products. Weed Technol 23:544-549.
- Wehtje, G., J. E. Altland, C. H. Gilliam, S. C. Marble, A. J. Van Hoogmoed, and G. B. Fain. 2009. Weed Growth and efficacy of PRE-applied herbicides in alternative rooting substrates used in container-grown nursery crops. Weed Technol 23:455-459.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Liverwort (Marchantia polymorpha) is increasingly problematic in nursery crop production. This species thrives in the low light, high humidity, and high fertility conditions associated with plant nurseries. Liverwort has been primarily a weed problem in cooler regions of the United states such as the Northeast and the Pacific Northwest. However, liverwort has been increasing prevalent in the southeastern U.S. during the cooler months. The herbicide quinoclamine is being evaluated for POST, over-the-top application on nursery crops for liverwort control. It is used for this purpose in Europe. Excellent liverwort control combined with minimal phytotoxicity to numerous ornamental species has been reported by several researchers. A frequent observation made by the authors during these aforementioned studies was that liverwort tissues varied in their sensitivity to POST-applied quinoclamine. Specifically archegonial receptacles (female)are much more tolerant of quinoclamine than either antheridial receptacles (male)or thalli (vegatation. Generally in herbicide-plant interactions, flowering and fruiting structures are more sensitive to POST-applied herbicides than foliage. Studies were conducted to determine the relative tolerance of archegonial to quinoclamine. Absorption of 14C-quinoclamine was less in archegonials compared to other tissues. But not to the degree that would explain the field observations. Simialry, clorophyll content was less in archegonials, but not the the degree that would explain the field observations. Stomates were smaller and less numerous on the archegonials. All the above factors, in combination with less spray retention is the most likely explanation. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The registiation of this herbicide is uncertain at this time. But if it is registered, we beleive that we can offer reccomendatins that will render it very effective for the target weed.
Publications
- Altland, J. E., G. Wehtje, M. L. Mckee and C. H. Gilliam. 2008. Liverwort response to quinoclamine in a pine bark substrate. Weed Sci. 56:762-766.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: The herbicide quinoclamine is under development for liverwort control in nursery crops. However it is not registered for this use at this time. In out previous work we established that control of liverwort with quinoclamine is independent of both application volume and pressure; Control is influenced almost exclusively by the rate (active ingredient) of the application. And while liverwort is a non vascular plant, absorbed quinoclamine does translocate within treated thalli. Thus it is not strictly contact in nature. Quinoclamine has been viewed as predominately postemergence active. However, some preemergence activity as been suspected. Growth media sorption studies with 14C quinoclamine indicates that only 0.64% of the amount that enters the media remains unabsorbed and thus available for uptake by either established plants or propagules. Computer modeling revealed that a large portion of the surface of the quin molecule is positively charged, which likely attributes to
the high absorptivity. In a simulation of preemergence activity, hydroponically grown liverwort and germinating gemmae were exposed to increasing quinoclamine concentrations. Phytotoxicity to both plants and gemmae was obtained with a minimal concentration of 4 to 6 ppm. Results in toto indicate that the projected use rate will result in sufficient quinoclamine on the aqueous phase of the pine bark substrate to provide preemergence activity and thus contributed to the overall efficacy of postemergence-applied applications.
PARTICIPANTS: Dr. Charles Gilliam, Dr. James Altland, Dr. Michael Miller and Adam Newby
TARGET AUDIENCES: Nursey managment personnel, and prehaps herbicide physiology researchers
PROJECT MODIFICATIONS: I plan to do some electron microscopy examination of the liverwort tissues. Specifically, I would like to determine why female angiospores are so very tolerant of quinoclamine as well as most other herbicides.
Impacts
We hope that the studies described above will aide in getting this much needed product registered.
Publications
- 1. Altland, J. E. G. Wehtje, C. H. Gilliam and M. E. Miller. 2007. Liverwort (Marchantia polymorpha) control with quinoclamine. Weed Technol. 21:483-487.
- 2. Newby, A, J. E. Altland, C. H. Gilliam and G Wehtje. 2007. Pre-emergence liverwort control in nursery containers. Hort. Technol. 17(4) 496-500.
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Progress 01/01/06 to 12/31/06
Outputs
Nearly all previous research focusing upon the use of quinoclamine to control liverwort utilized very high spray volumes (. i.e. > 100 g/acre). This high volume requirement was based upon the asumption that since liverwort is a non vascular plant, translocation of a herbicide within its tissues would be minimal. Therefore high spray volume was seen as a requirement to maximize foliar coverage. This assumption was deemed to be weak and not based upon established facts. To test this assumption, quinoclamine was applied to liverwort in a factorial arrangement of three rates (1.28, 1.7 and 3.4 lbs a/Acre) three spray volumes (40, 120, 200 GPA and three spray pressures (20, 40, and 60 PSI). Control was influenced only by rate. Absorption and translocation studies using 14C-Quinoclamine, established that absorption into liverwort thalli approached 70% of the amount applied within 9 h after application. And although liverwort lacks vascular tissue, absorbed quinoclamine was
readily translocated away from the site of entry, and tended to be translocated toward the margins of the thalli. We speculate that the preceived requirement for high spray volume may be a misdirected assumption based upon the high proportion of inert ingredients within the current formulation (i.e. only 26% active). Quinoclamine is strictly a foliar-active, non residual herbicide. In other studies, preemergence active heribicides such as oxiadiazon, oxyflurofen and diuron appear to have limited, but prehaps worthwhile activity against liverwort.
Impacts
I believe that Information generated todate will enhance the preformance of this product upon its netry into the market.
Publications
- Newby, A. F., C. G. Gilliam, and G. R. Wehtje. 2006. Evaluation of quinoclamine and diuron for postemergence control of liverwort. Combined Preoceeding of Interantion plant progagators societ. 55:556-566.
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