Grass treatment

Details Grass treatment Grass treatment

2000-09-11

2001-08-07

Clardy, S. Mark (Department: 1616)

Plant protecting and regulating compositions

Plant growth regulating compositions

Micro-organisms or from micro-organisms

Reexamination Certificate

active

06271175

ABSTRACT:

This invention relates to methods and compositions for improving the quality of turf grass. More particularly, the invention is concerned with the control, reduction, or elimination of undesirable grass components of turf, especially of high quality turf consisting mainly of Bentgrass such as
Agrostis stolonifera
or Festuca species.
Poa annua
or Annual Meadow grass (AMG) (also called Annual Bluegrass) is the most troublesome weed of bent grass putting greens in countries as diverse as the United Kingdom, the United States of America, and Australia.
P. annua
is generally considered to be undesirable in putting greens because it is susceptible to abiotic stress, particularly water availability, as well as succumbing to a number of fungal diseases. In addition, if a green is composed of patches of AMG and bent grass, the surface is not as uniform as many players would wish it to be.
Some turf managers attempt to control
P. annua
. The most widely used control method is herbicide application, and a number of compounds have been tested against the species with varying success. However, application of pesticides can be costly, and they may present a problem of groundwater pollution if the green is well irrigated. In addition, there may be associated health risks to golfers or greens staff. Therefore, if AMG is to be controlled on putting greens, a more natural, environmental approach is called for.
The present inventor has previously reported that the abundance of AMG in a golf green may be negatively related to the abundance of fungi in the soil (Gange A. C. 1994, Subterranean insects and fungi: hidden costs and benefits to the greenkeeper. In Science & Golf II, Proceedings of the World Scientific Congress of Golf, eds. A. J.Cochran and M. R. Farrally, 461-466, London E. and F. N. Spoon ). The fungi concerned were vesicular-arbuscular mycorrhizas which are generally abundant in natural plant communities. It was found that the fungi were very low in abundance in golf turf, but when they were common in the soil, there was less AMG in the sward, and vice versa. The original explanation for this relation was that as bentgrass is considerably more strongly mycorrhizal than AMG, then in greens where fungal abundance is high, the bentgrass is more vigorous, and therefore is able to out-compete the AMG.
It has now been found that VA mycorrhizae have a direct growth-controlling effect on
Poa annua
and therefore provide an effective means of control of
P. annua
in turf grass consisting of high proportions of Bentgrass, or Festuca species. This is an unexpected finding for two reasons. First,
P. annua
is usually stated in the literature to be non-mycorrhizal or at most weakly mycorrhizal. Secondly, whilst it has now been found that VA mycorrhizae do colonise
Poa annua
roots, the colonisation retards rather than encourages growth. Moreover, this effect has been found to be independent of phosphorus levels in the soil.
The present invention is therefore based on the discovery of a novel technical effect of VA mycorrhizae which leads to a method of treatment of turfgrass which has not been contemplated hitherto. It is to be understood that the application of VA mycorrhizae, either to grassland or soil in preparation for grass sowing, in accordance with this invention is for the specific intention of suppressing
Poa annua
, as distinct from any other purpose e.g. to stimulate growth or for the recovery of damaged turf. Preparations for use according to the invention do not require the presence of any other bacteria or other organisms or biologically active materials, although these are not excluded if desired as incidental to the primary purpose of the invention.
It is especially important that the composition applied to turf contains very little of, and is preferably substantially free of, other biological materials which could promote growth of
P.annua
and therefore compete with the VA mycorrhiza and conflict with the objectives of the present invention. For example, because
P. annua
dominates turf in areas of high phosphate application, it is highly desirable to avoid the presence in the composition of significant amounts of bacteria which release P from phosphate. The deliberate addition of such phosphate-solubilizing bacteria to the composition is strongly contra-indicated. Preferably, therefore, apart from minimal amounts of other organisms which may be present due to the use of conditions of production which are not totally sterile, the VA mycorrhiza fungi used constitute the sole or principal organismic component of the compositions of the present invention.
The present invention comprises the use of a VA mycorrhiza as a growth-retardant for
Poa annua
. The term ‘VA mycorrhiza’ is used herein to cover all soil-borne fungi which form arbuscules in obligate mutualistic associations with terrestrial plants. Typical representatives of the vesicular-arbuscular fungi are found among the genera Glomus, Acaulospora, Entrophosphora, Gigaspora, Scutellospora and Sclerocytis. Exemplary strains are
Glomus fasciculatum, Glomus caledonium, Glomus mosseae, Glomus versiforme, Glomus intraradices,
and
Glomus etunicatum.
One or more strains of VA mycorrhiza may be used depending on the quality of the turfgrass to be treated. Preferred strains are those of
Glomus mosseae, caledonium, fasciculatum,
and
versiforme.
VA mycorrhizae are widely available organisms and may be obtained, for example, from the International Culture Collection of VAM fungi (INVAM), Florida, United States of America.
To produce VA mycorrhizal inoculum for the purposes of the present invention all infective structures of the fungus can be used, including spores and mycelium produced inside or outside the host root. Infected roots and infected substrates can also be used. Inoculum can be used in the form of slurries, gels, pellets, infected soil, or spore formulations. Especially effective formulations are the clay carrier-based formulations containing the four preferred strains indicated above e.g. those available commercially under the Registered Trade Mark ‘VAMINOC’ (The MicroBio Group Ltd, Whittlesford, Cambridge. UK), such as VAMINOC 8/16, VAMINOC 30/60, AND VAMINOC-T. Inoculant particle sizes can be up to 2 mm or 4-8 mm. Alternative carriers can be selected from, for example, silica gel, bleaching earths, pumice, bauxite, attapulgite, vermiculite, calcined montmorillinite, soil, peat, sand or any other substantially chemically inert material with a suitable porous structure.
The grass which may be treated according to the present invention may be a sport or amenity turf which is already established and which contains unacceptable proportions of
P. annua
. Turf which is mown regularly is particularly suitable for treatment. Alternatively the treatment may be applied to ground on which turf is to be laid or sown e.g. a sand/peat based green sown with bentgrass or a bentgrass/Festuca mixture.
Desirably, the inoculum infectivity, as measured by the “most probable number” (MPN) technique, corresponds to MPN values of from at least 200 or 500 up to 1000 propagules or more per gram. Application of inoculum at a rate of at least 5 or 10 g/m
2
is effective but higher dosages may be used if preferred, e.g. up to about 100 to 250 g/m
2
. Even higher doses, for example up to and in excess of 1 Kg/m
2
, are envisaged in certain applications. The inoculum can be watered into an established green or introduced into the root zone. Application in weather which is either very warm or very cold is inadvisable. The turfgrass may be a golf green, a bowling green, a lawn, or any other kind of grassy area requiring treatment according to the invention. The invention is of particular importance in improving or maintaining the quality of turf consisting mainly of Agrostis Spp or Festuca Spp.


REFERENCES:
patent: 5559079 (1996-09-01), Imaizumi et al.
patent: 0 661 001 (1995-07-01), None
patent: 1 437 877 (1976-06-01), None
patent: 95/12980 (1995-05-01), None
JPOABS Abstract of JP 04-166018, Jun. 1992.*
Gemma et al. “Mycorrhiz

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