Plant protecting and regulating compositions – Plant growth regulating compositions – Micro-organisms or from micro-organisms
Reexamination Certificate
2002-05-06
2003-05-27
Clardy, S. Mark (Department: 1616)
Plant protecting and regulating compositions
Plant growth regulating compositions
Micro-organisms or from micro-organisms
C504S150000
Reexamination Certificate
active
06569807
ABSTRACT:
STATEMENT OF GOVERNMENT INTEREST
The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
FIELD OF THE INVENTION
The present invention relates generally to bioherbicides suitable for controlling a population of target aquatic weeds, and more particularly to mycoherbicidal compositions, methods of preparing the same, and methods for controlling the population of target aquatic weeds.
BACKGROUND
Many of the world's waterways and water systems have become infested with aquatic weeds to the detriment of local wildlife and water traffic. Typically, the aquatic weeds are of non-indigenous origin unintentionally introduced into an area with little or no natural enemies. In other instances, excess nitrates from runoffs have enabled the aquatic weeds to thrive and spread. These infestations can effectively choke local ecosystems comprising native fauna and flora, and disrupt water traffic and drainage. Their ability to survive under less than desirable conditions and their high growth rate has enabled aquatic weeds to circumvent many of the currently available population control measures.
The more common population control measures are chemical herbicides and mechanical harvesters. Chemical herbicides pose health hazards to both humans and other non-targeted plants and animals. In many places, aquatic weeds have developed resistance to certain chemical herbicides further complicating the control of their population. Mechanical harvesters have also been used with limited success, and provide marginal population control. Most mechanical harvesters are expensive, and require frequent usage to achieve even modest population control.
A more environmentally safe population control measure that is also cost-efficient, relies on biological agents in the form of mycoherbicides. Mycoherbicides are typically formulated with one or more fungal pathogens or metabolites, or both thereof with herbicidal activity. The fungal pathogens are typically specific to infecting a certain spectrum of plant types, thus providing useful targeted delivery. One fungal pathogen,
Mycoleptodiscus terrestris
(Gerd.) Ostazeski, has been studied for its potential in controlling populations of target aquatic weeds.
M. terrestris
is a fungus classified in the family Dematiaceae of the Hyphomycetes class within the subdivision Deuteromycotina. There are about ten known species of Mycoleptodiscus and each are classified according to the presence of appendages on the spores, orientation of the appendages (e.g., polar, polar and lateral) on the spores, location of the appendages (e.g., apex or apex and base) on the spores, and spore septation and size.
Current processes and compositions for the preparation of a mycoherbicide have been limited to the preparation and use of
M terrestris
mycelium. However, the mycelium of
M. terrestris
exhibits limited viability, poor stability, and a short shelf life. The ability of
M. terrestris
mycelium to control weed populations can diminish rapidly under certain conditions typically associated with normal storage and handling. These shortcomings have required high application rates and immediate use to obtain adequate population control efficacy against aquatic weeds.
It would be an advance in the art of bioherbicides to develop a mycoherbicidal composition, which can be applied either in wet or dry form, comprising an effective population control agent efficacious against a broad range of aquatic weeds including hydrilla. It would be a further advance in the art to develop a mycoherbicidal composition with enhanced biological viability and stability, specifically comprising a fungal pathogen as the population control agent that is extremely desiccant-tolerant, is capable of germinating both sporogenically and vegetatively, and is highly efficacious against hydrilla and other aquatic weeds, while being easy and relatively inexpensive to prepare and to use. It would also be desirable to provide a method of preparing such fungal pathogens in the form of a microsclerotium that can efficiently and effectively maximize the biomass production thereof.
SUMMARY
The present invention is directed generally to mycoherbicidal compositions, and methods of preparing and using the same for aquatic weed population and growth control. The mycoherbicidal composition is comprised of a fungal pathogen in the form of a stable melanized hyphal aggregate or microsclerotium, that is extremely desiccant-tolerant and highly viable, is capable of germinating both sporogenically and vegetatively, and is efficacious against hydrilla and other aquatic weeds. The fungal microsclerotium avoids many of the problems typically associated with mycelium-based pathogens including poor stability, limited viability, and short shelf life. The desiccant-tolerant microsclerotium maintains enhanced viability for providing improved germination rate, ease of storage and handling and better shelf life.
The present composition may be applied in wet or dry form suitable for effective dissemination over an area infested by target aquatic weeds including, but not limited to, those selected from
Hydrilla verticillata
(L.f.) Royle (“hydrilla”),
Myriophyllum spicatum L
. (“Eurasian watermilfoil”),
Egeria densa L
. (“Brazilian Elodea”), and combinations thereof.
In one particular aspect of the present invention, there is provided a mycoherbicidal composition suitable for controlling the growth and population of target aquatic weeds, which comprises an aquatic weed population control effective amount of a microsclerotium of a fungal pathogen. Optionally, the composition may further include a suitable carrier. The present invention may include fungal pathogens selected from strains of the genera Fusarium, Cercospora, Alternaria, Mycoleptodiscus, and the like. In a preferred form of the present invention, the fungal pathogen is
Mycoleptodiscus terrestris
(
M. terrestris
).
In another particular aspect of the present invention, there is provided a method for controlling the growth and population of target aquatic weeds, where the method comprises applying an aquatic weed population control effective amount of the mycoherbicidal composition of the present invention to a treatment site in which the fungal pathogen can contact and infect the target aquatic weeds.
In a further aspect of the present invention, there is provided a method for preparing a microsclerotium of a fungal pathogen having aquatic weed population control activity, where the method comprises growing the fungal pathogen under suitable growth conditions sufficient to compel the fungal pathogen to form a microsclerotium.
DETAILED DESCRIPTION
In accordance with the present invention, a mycoherbicidal composition is provided for controlling the growth and population of aquatic weeds. The mycoherbicidal composition generally comprises a target aquatic weed population control effective amount of a microsclerotium or melanized hyphal aggregate of a fungal pathogen having aquatic weed population control activity and, optionally, may further include a suitable carrier. The microsclerotium of the fungal pathogen present in the mycoherbicidal composition of the present invention is capable of tolerating conditions associated with low moisture and exhibits improved viability even after drying and storage.
In addition, the microsclerotium of the fungal pathogen is capable of germinating both vegetatively to yield mycelium as a primary inoculum for attacking the target aquatic weed, and sporogenically to yield spores for employment as a secondary inoculum. The ability of the microsclerotium to germinate sporogenically advantageously extends the efficacy and duration of the present compositions containing the same against the aquatic weed. The ability to sporulate enables the fungal microsclerotium to be used as a preventative against impending re-infestations of the aquatic weed.
As used herein the term “microsclerotium” refers to t
Jackson Mark A.
Shearer Judy F.
Baugher Jr. Earl H.
Kipnes Allen
The United States of America as represented by the Secretary of
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