CA2345503A1 - Pre-emergent biological control agents - Google Patents
Pre-emergent biological control agents Download PDFInfo
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- CA2345503A1 CA2345503A1 CA002345503A CA2345503A CA2345503A1 CA 2345503 A1 CA2345503 A1 CA 2345503A1 CA 002345503 A CA002345503 A CA 002345503A CA 2345503 A CA2345503 A CA 2345503A CA 2345503 A1 CA2345503 A1 CA 2345503A1
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- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
- A01N63/00—Biocides, pest repellants or attractants, or plant growth regulators containing microorganisms, viruses, microbial fungi, animals or substances produced by, or obtained from, microorganisms, viruses, microbial fungi or animals, e.g. enzymes or fermentates
- A01N63/30—Microbial fungi; Substances produced thereby or obtained therefrom
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Abstract
The present invention provides an isolated biocontrol agent, or a biocontr ol composition, comprising fungal biocontrol agent 94-904A that exhibits weed suppressive activity. Preferably, the biocontrol composition comprises an acceptable medium such as a liquid culture medium or a solid culture medium. The biocontrol agent o r biocontrol composition may be used to suppress the growth of a weeds such as green foxtail (Setaria viridis [L.] Beauv.).
Description
PRE-EMERGENT BIOLOGICAL CONTROL AGENTS
The invention relates to biocontrol agents for suppressing weed growth. More specifically the present invention relates to fungal biocontrol agents for suppression of weed growth.
BACKGROUND OF THE INVENTION
Control of weeds is an important aspect of crop management. Due to several undesirable properties associated with the use of chemical herbicides, alternative weed control practices, including the use of biological herbicides, are desired.
For example, rising economic, environmental and social costs associated with agricultural inputs, spray drift, pesticide residues, gove~~nment legislation for reduced pesticide use, along with the development of herbicide resistance in weeds, make biocontrol agents attractive strategies for weed control.
Biological control of weeds with microorganisms (bioherbicides), preferably involves the production and application of a weed -specific pathogen to a target weed.
The weed specific pathogen is typically a fungus or bacterial pathogen that inhibits or suppresses root, shoot or both root and shoot growth, development, or both growth and development, thereby reducing weed competition. The development of biological crop protection products (bioherbicides) for economically important weed problems in agricultural field crops may help to facilitate harvests, secure yields, and protect the environment. Biological control provides an additional tool to complement an integrated weed management system and helps sustainable agricultural systems by maintaining the ecosystem balance through the preservation of plant and microbial diversity in the field.
There are several documents disclosing the use of fungi as biocontrol agents.
For example, U.S. 5,993,802 teaches methods for suppressing the growth of Calamagrostis canadensis using an isolate of a low temperature basidiomycete fungus, Coprinus psychromorbidus. U.S. 5,472,690 teaches of a mycoherbicide (including at least one or both of Fc~sarium nivalis and Colletotrichum calamagrostidis) effective in the control _ 7 _ of Calamagrostis canadensis and/or related grasses. The control of crabgrass using fungi is disclosed in U.S. 5,92,264, using the fungus Cochliobolees internzedizcs, and U.S.
5,635,444 using a fungus selected from the genus Curvularicc. U.S. 5,747,029, teaches the control of sicklepod weeds using the fungus MyrotlzeciuzYZ verrzecaria.
The control of nutsedge weeds using the fungus Dactylaria lziggimsii is disclosed in WO
98/08389.
U.S. 4,606,751 teaches the biocontrol of Johnson grass using Bipolaris sorghicola spores that are suspended in a solution of water and surfactant, and sprayed onto a field in which the weed is growing.
Annual grassy weeds such as Setaria viridis (L.) Beauv. (commonly known as green foxtail, pigeongrass, wild millet, green bristlegrass, and bottlegrass) develop dense competitive stands and have heavy seed production in spring sown crops. Green foxtail is a principal weed of corn, soybean, cereals, flax, canola, sugar beets, and pastures. The amount of damage to the crop depends on the density of the stand, time of emergence, and length of time the weed and crop are competing. Weed surveys for herbicide-resistant green foxtail have revealed that many of these plants exhibit some degree of herbicide resistance (Beckie, H.J., A. L.egere, A.G. Thomas, L.T. Juras, and M.D.
Devine. 1996 Survey of Herbicide-Resistant Wild Oat and Green Foxtail in Saskatchewan:
Interim Report. AAFC Report, 22 pp.). Therefore, biocontrol of these plants is highly desirable.
However, at present for most of these weeds there are no known satisfactory biocontrol agents for control of green foxtail.( need more types of weeds) An important aspect in the development of a successful biological control agent is an effective delivery system. For biocontrol agents delivered onto target weeds by spraying, it is common for the erect top leaf to survive the attack due to the poor retention of the biocontrol agent on this portion of the plant. Thus, new methods of applying biocontrol agents are desired in the art. Further, traditional application methods such as run-off spraying are generally not suitable for treatment of large areas and thus there is a need in the art for methods to reduce the application volumes of biocontrol agents without reducing the efficacy of the biocontrol agent on the target weeds. To date, variable efficacy has been observed with boipesticide agents at reduced application volumes (Jones 1994, Smith and Bouse, 1981) Previous attempts to control green Foxtail weeds with biocontrol compositions have been relatively poor. In particular, it was noted in other studies that the top leaf of green foxtail consistently exhibited the least amount of disease development following biocontrol application, and reduced spray retention is speculated as a cause because of the erect leaf architecture of green foxtail weeds. Further, the surviving leaf often contributes to regrowth from the apical meristem, reducing the effectivity of the biocontrol agent. Other factors, such as but not limited to age (Green and Bailey 2000) and mineral nutrient content (Filippi and Prabhu 1998) of the leaves, may affect the susceptibility of green foxtail weeds to fungal pathogens.
In field crops, application volumes over 600 L/ha are considered high (Matthews, 1992), and the trend is generally toward volume reduction. In previous experiments, when applied at volumes between 100 to 800 L/ha, the agent 94-409A showed significantly lower efficacy in comparison to the runoff airbrush spray using the same spore concentration. Commonly the erect top leaf developed little disease and survived the attack. It is believed that the poorer eFFicacy is related to a lower amount of fungal propagules received and retained on the plant.
_4_ It is an object of the present invention to overcome drawbacks of the prior art.
The above object is met by a combination of the features of the main claims.
The sub claims disclose further advantageous embodiments of the invention.
SUIVINIARY OF THE INVENTION
The invention relates to biocontrol agents for suppressing weed growth. More specifically the present invention relates to fungal biocontrol agents for suppression of weed growth.
The present invention provides an isolated fungal biocontrol agent Pyricularia IS setariae isolate 94-904A that exhibits weed suppressive activity. Also provided by the present invention is the use of biocontrol agent for controlling green foxtail (Setaria viridis [L.] Beauv.) weeds.
Also provided by the present invention is a biocontrol composition comprising fungal biocontrol agent 94-904A in an acceptable medium and the use of the biocontrol composition for controlling green foxtail weeds. The acceptable medium may comprise a liquid culture medium, a solid culture medium or a combination thereof.
Preferably the acceptable medium is a liquid culture medium.
Also according to the present invention there is provided a method for suppressing weed growth by applying a fungal biocontrol agent 94-904A to a weed.
Preferably the weed is green foxtail (Setaria viridis [L.] Beauv.). Also according to the present invention there is provided a method for suppressing weed growth by applying a biocontrol composition comprising biocontrol agent 94-904A to a weed.
Preferably the weed is green foxtail (Setaria viridis [L.] Beauv.).
_ j _ Further, according to an embodiment of the present invention, there is provided a method of suppressing weeds during crop growth comprising;
a) adding an effective amount of a biocontrol composition comprising fungal biocontrol agent 94-904A formulated in an acceptable medium, to soil to produce a treated soil;
b) planting crops in the treated soil and;
c) growing the crops.
Also according to the present invention, there is provided a method of suppressing weeds during crop growth comprising;
a) spraying an effective amount of a biocontrol composition comprising biocontrol agent 94-904A formulated in an acceptable medium, to an area of plants comprising green foxtail weeds, and;
b) growing said plants.
The biocontrol agent or biocontrol composition may be applied to weeds by any method known in the art, but is preferably applied by spraying, for example, but not limited to airbrush spraying or broadcast spraying. Broadcast application may be effected using a nozzle which enhances the reduction of the size of the droplets which are emitted during application of the biocontrol agent or composition as defined above.
Preferably the nozzles are selected from the group consisting of X8001, X8002 and X8004.
However, other nozzles may also be employed to deliver the biocontrol agent or composition of the present invention.
Also, according to the present invention as defined above, there is provided a biocontrol composition and the use of a biocontrol composition comprising fungal biocontrol agent 94-409A wherein fungal biocontrol agent 94-409A is present in the composition in an amount of about 106 to about 10' spores per ml.
Also, according to the present invention as defined above there is provided a method of inhibiting green foxtail weeds in a desired area, said method comprising, spraying the desired area with between about 250 L/Ha to about 2000 LJHa of a biocontrol composition comprising between about 106 to about 10' spores of fungal biocontrol agent 94-904A.
This summary does not necessarily describe all necessary features of the invention but that the invention may also reside in a sub-combination of the described features.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the invention will become more apparent from the following description in which reference is made to the appended drawings wherein:
FI(TURE 1 shows retention volumes on different parts of green foxtail with airbrush sprayer (runoft~ and broadcast sprayers (1,960 L./ha). The measurements were taken from different plant parts and expressed as ftl/mg dry matter.
FIGURE 2 shows the effect of spray droplet size and travel speed on the retention efficiency of spray on treated plants.
FIGURE 3 shows the effect of application method, spore concentration, and droplet size on the efficacy of 94-409A as a biocontrol agent on green foxtail weeds.
FIGURE 4 shows the effect of increased concentration doses of biocontrol agent 409A on the efficacy of green foxtail weed control with reduced application volumes.
_g_ The invention relates to biocontrol agents for suppressing weed growth. More specifically the present invention relates to fungal biocontrol agents for suppression of weed growth.
The following description is of a preferred embodiment by way of example only and without limitation to the combination of features necessary for carrying the invention into effect.
According to an aspect of the present invention, there is provided fungal biocontrol agent Pyriculria s~~tariae isolate 94-904A. In a preferred embodiment fungal biocontrol agent 94-904A is used to control green foxtail (Setaria viridis) weeds.
By the term "biocontrol agent" it is meant a microorganism which suppresses the growth of, or kills, a target pest, for example, but not limited to a plant or a weed. More specifically, the biocontrol agents of the present invention may be used to suppress the growth of one or more target pests. Without wishing to be bound by theory, the biocontrol agent suppresses the growth of a target pest, for example, a plant or weed (i.e.
exhibits weed suppressive activity), by interfering with the normal growth and development of the target plant or weed. For example, but not wishing to be limiting, the biocontrol agent may inhibit root growth, shoot growth, reduce biomass, inhibit seed production, reduce competitiveness of the target plant or weed for a crop's water and nutrients, or a combination thereof.
As someone of skill in the art will understand, in order for the biocontrol agent of the present invention to be grown, cultured or used in accordance with the embodiments of the present invention, it is preferable that the biocontrol agent be grown in a suitable medium to produce a biocontrol composition or formulation. By the term "suitable medium" or "acceptable medium" it is meant any liquid, semi-liquid or solid substrate which allows biocontrol agent 94-904A to grow, or to remain viable, or both grow and remain viable. Thus, the present invention contemplates a biocontrol composition comprising fungal biocontrol agent 94-904. Preferably, the composition permits an effective amount of fungal biocontrol agent 94-409A to remain viable prior to, and after, being applied to a crop. More preferably, the composition permits fungal biocontrol agent 94-409A to remain viable for a period between about 1 day to about 1 month following application of the biocontrol composition of the present invention onto a plant, or soil.
The biocontrol agent or biocontrol composition of the present invention may be applied to plants, soil or both plants and soil. Preferably, the biocontrol agent or composition is applied to plant foliage, for example the foliage of the target weed.
Alternatively, the biocontrol agent or composition may be applied directly to soil, either before, during or after seeding a crop. The biocontrol agent may be applied by any method known in the art, for example, but not limited to spraying, pouring, dipping or the like. Preferably, the biocontrol composition of the present invention is applied by spraying.
Therefore, the present invention provides for the use of fungal biocontrol agent 94-904A grown and formulated in a suitable composition for the suppression of green foxtail weeds. However, as someone of skill in the art will understand, the amount of the biocontrol composition required for suppression of green foxtail weeds may be dependent on the medium in which fungal biocontrol agent 94-904A is formulated and the method in which it is formulated. For example, but not wishing to be limiting, a formulation and medium which permits a greater percentage of the fungal agent to remain viable may require less biocontrol composition to suppress weed growth than does another formulation and medium in which biocontrol agent 94-904A is less viable.
Further, the amount of a biocontrol composition required for suppression of weeds may be influenced by environmental factors such as but not limited to temperature, humidity, soil pH, and soil type.
Refernng now to Table l, there is shown spray retention on plants by airbrush and broadcast application. The results shown in Table 1 suggest that the retention of spray on whole green foxtail plants generally increases with broadcast application volume. Also suggested by Table 1 is that spray retention on plants following broadcast application at a volume of about 1,960 L/ha produces a similar level to that of airbrush spraying. Thus, the present invention contemplates airbrush and broadcast application of fungal biocontrol agent 94-904A or a biocontrol composition comprising biocontrol agent 94-904A. However, application of biocontrol agent 94-904A or a biocontrol composition comprising 94-904A is not limited to airbrush and broadcast application.
Table 1. Spray retention achieved by airbrush and broadcast applications at different volumes on green (oxtail.
Volumes AirbrushBroadcast Application Volume (IJha)3 ml/pot171 474 477 885 1187 1960 *
Retention Volume (~l/plant) 25.8 3.2 9.8 7.4 11.2 18.3 26.4 * Application volume resulting in runoff on 8 plants at the 3-leaf stage.
Refernng now to Figure l, there is shown the results of spray retention on different plant parts following airbrush or broadcast application using nozzles that vary the droplet size of the spray. As shown by Figure 1, spray retention is slightly higher on leaves than on the stems of plants when spray retention is measured on a dry matter basis.
The results shown in Figure 1 also suggest that broadcast application of the biocontrol composition of the present invention with the XR 8002 nozzle results in greater retention of spray on whole plants and leaves compared to broadcast application using a XR 8004 nozzle or by airbrush spraying. Without wishing to be bound by theory, smaller spray droplets may be better retained on plant leaves than are larger droplets.
Thus modulation of the spray droplet size during application of the fungal biocontrol agent or composition of the present invention may enhance retention of the biocontrol control agent on target weeds.
Effects of droplet size and travel speed on retention efficiency of biocontrol agent Retention efficiency is a term comparing the amount of a biocontrol agent on a plant following application relative to total application volume delivered.
Referring now to Figure 2, there is graphically depicted the retention efficiency of spray following broadcast application using nozzles XR 8001, XR 8002 and XR 8004 and using spray application speeds of 0.5 and 1.1 km per hour. Nozzles XR 8001, XR 8002 and XR
produce progressively greater size droplets. The results shown suggest that application of smaller droplets result in a relatively higher proportion of spray being retained on the target weed. For example, but not wishing to be limiting, broadcast application of a biocontrol composition using a small droplet size nozzle (XR8001) results in greater retention efficiency of the biocontrol composition on plants than do larger droplet size nozzles XR8002 and XR8004 under the specific conditions under which the three nozzles were tested. Also suggested by the results shown in Figure 2 is that the travel speed of the droplets has little effect on the retention efficiency of the biocontrol composition and thus the fungal biocontrol compositions of the present invention may be applied in a wide range of droplet sizes and travel speeds. Preferably, the droplet sizes are small, for example in about the order of the droplets produced by a XR8001 nozzle.
Further, it is preferable that the travel speeds of the droplets are in the range of about 0.4 km per hour to about 2 km per hour, more preferably between 0.55 and 1.10 km per hour. As would be evident to someone of skill in the art, travel speeds outside this range also may be used in accordance with the method of tire present invention, but that the travel speed and droplet size should not be such that physical damage occurs to plants.
Retention and biocontrol et~'icacy of fungal biocontrol agent 94-409A
Refernng now to Figure 3, there is shown the effect of application method, spore concentration and droplet size on the efficacy of fungal biocontrol agent 94-409A on green foxtail. As shown by the results in Figure 3, application of between about 106 and aboutl0' spores/ml of fungal biocontrol agent 94-409A onto the foliage of green foxtail weeds reduces the weight of the weeds, regardless of the method used to apply the composition. The results shown in Figure 3 also suggest that fungal isolate 94-409A may be applied to green foxtail weeds by a variety of application methods, such as, but not limited to by airbrush,or broadcast spraying. Further, broadcast spraying of the biocontrol composition of the present invention in an amount of about 2000L/ha, there was little difference between the two application methods (data not shown). At higher spore concentrations, there was no significant difference between application treatments, and the average plant fresh weight was reduced by about 85°lo to about 91%
compared to the control. At lower doses, however, the XR8004 nozzle appeared to be slightly more effective than the airbrush spray, but was comparable to the XR8002.
Preferably, the biocontrol composition of the present invention comprises between about 106 and about 10' spores of fungal biocontrol agent 94-904A.
Reduction of application volume by increasing inoculum concentration Referring now to Figure 4, there is shown the effect of application dose of biocontrol agent 94-409A on the fresh weight and % disease of green foxtail plants.
As suggested by the results of Figure 4, increasing the spore concentration of biocontrol agent 94-409A in a biocontrol composition offsets the efficacy loss that results from reducdion of application volume. Further, little difference in biocontrol efficacy is observed with all the volumes applied based on the measurement of disease severity and plant fresh weight. Compared with the control, the average reduction of fresh weight ranged from about 58 to about 67% with different application volume treatments.
Thus, the use of high spore concentrations of biocontrol agent 94-409A in a biocontrol composition may reduce the application volumes without compromising the efficacy of weed control. In addition, a high spore concentration increases the number of propagules contained in the spray, avoiding large numbers of 'empty' droplets (Jones 1998).
The above description is not intended to limit the claimed invention in any manner, furthermore, the discussed combination of features might not be absolutely necessary for the inventive solution.
The present invention will be further illustrated in the following examples.
However, it is to be understood that these examples are for illustrative purposes only, and should not be used to limit the scope of the present invention in any manner.
EXAMPLE 1: Preparation of Plants - 1=1 -Mature green foxtail seeds are harvested from a weed nursery on the research farm of Agriculture and Agri-Food Canada near Saskatoon. Seeds are planted in a layer of Redi-Earth on top of a layer of soil-less mix with fertilizer in 7.5-cm plastic pots, and grown at 20 ~ 3°C with 14-h supplementary lighting for about 3 weeks until the 3-leaf stage.
EXAMPLE Z: Preparation of Inoculum and Inoculation of Plants Mycelium plugs (5x5 mm) were cut from the edge of growing cultures of fungal agent 94-409A, placed on a modified oatmeal agar in petri plates, and incubated at 26°C with 14 h of near-UV lighting. Sporulating cultures are Hooded with 5 ml of sterilized water and a 0.1-ml aliquot of the suspension is plated on oatmeal agar and incubated under the same conditions for approximately 1 week.
This method usually produces about 10~ spores/plate.
For inoculation, sporulating cultures are flooded with water containing 0.1~/o Tween 80 (surfactant) and the spores are scraped off the medium.
Concentrations of spore suspensions are estimated using a haemocytometer and adjusted accordingly. An airbrush sprayer and broadcast cabinet sprayer are used to apply spore suspensions of the fungal biocontrol agent 94-904A. Constant air pressure at approximately 250 kPa is used in both airbrush and broadcast spraying.
Approximately 3 ml of suspension is required to achieve visible runoff for plants at the 3-leaf stage in a 7.5-cm-diameter pot. For broadcast application, several types of TeeJet nozzles according to rates and spray quality are tested. Inoculated plants are placed immediately in an environment-controlled dew chamber at 20°C ~ 2 °C and 20 hours dark/4 hours light prior to being placed in the green house.
EXAMPLE 3: Disease Assessment of Plants Plant reactions are assessed 7 days after inoculation. The efficacy of the fungal biocontrol agent 94-904A is estimated using disease severity measured on the basis of percent diseased areas on a whole plant. A C)-11 scale adopted from I-~orsfall-Barratt (1945; which is herein incorporated by reference) is used to facilitate the assessment, in which scale 0 indicates no visible symptoms, 11 indicates a dead plant, and the other classes represent a range of disease severity in between.
In additions, plants are cut at the soil line from each replicated plot and measured for fresh weight as an indicator of weed suppression.
EXAMPLE 4: Spray retention studies Six replicated pots, each containing 8 plants at the 3-leaf stage are used for all treatments. Plants are sprayed with a Rhodamine WT dye solution containing 0.1%
(v/v) Tween 80 surfactant, and the relative retention of the spray on plants is estimated by washing plant tissues in ethanol and measuring the dye amount on a spectrophotometer (Wolf et al, 2000; which is herein incorporated by reference).
Measurements are taken on various plant parts, as well as on the whole plant.
The top, mid, and bottom leaves are cut carefully and separated from the stem.
Spray retained on individual parts and whole plants is measured separately, and reported in ~,I dye/mg plant dry matter.
To compare spray retention on plants using different application methods and droplet sizes, an airbrush sprayer and broadcast sprayer with a series of TeeJet t7at fan nozzles are used. For airbrush application, approximately 3 ml of solution is applied to a pot of plants. The application usually results in runoff of the spray from the plants. For broadcast application, plants are placed in a spray chamber and sprayed with various volumes. Plastic petri plates are placed beside the plants in the spray chamber to collect and determine the actual spraying volumes (Wolf et al., 1997 which is herein incorporated by reference).
- 1 ~7 -Effects of droplet size and travel speed on retention A spray cabinet is used to identify spraying parameters for improvement of spray retention and reduction of carrier volume. Retention Efficiency is used to compare the effect of variables, in which retention on plants is measured in relation to actual application volumes determined using petri plate collection as described above.
TeeJet XR 8001, 8002, and 8004 nozzles are used to create different droplet size spectra and their effect on retention is examined at travel speeds of 0.55 and 1.1 km/h.
Retention and biocontrol efficacy:
For comparison of the biocontrol efficacy of airbrush and broadcast applications at volumes resulting in a similar level of retention on the plant. In broadcast spraying, a single XR 8004 tip or two XR 8002 tips in a Lurmark Twin Cap are used to assess the effects of droplet size and spray trajectory. Spore suspensions of 94-409A at concentrations of 106 and 10' spores/ml are applied to plants. The experiment is a completely randomized factorial design with 4 replicates (pots) for each treatment.
Application volume and concentration dose: A broadcast sprayer with a single or two XR 8002 tips operated at 250 kPa is used to apply the mycoherbicide agent at approximately 250, 500, 1000, and 2,000 L/ha. Carrier volume is altered by changing the sprayer travel speed between 0.28 and 1.1 km/h. Spore concentrations for the lower application volumes is increased so all treatments have the same applied fungal propagule dose. The experiment is arranged in a completely randomized design with 6 replicates for each treatment Data analysis: All data is subjected to analysis of variance (ANOVA) using STATISTICA
1999 software. LSD (P _< 0.05) was used to separate treatment means when a significant difference (P <_ 0.05) was indicated in ANOVA.
The results presented herein suggest that:
1. A broadcast spray delivering approximately ?000 Uha provides similar spray retention amounts and biocontrol efficacy on green foxtail in comparison to an airbrush spray to the point of runoff.
The invention relates to biocontrol agents for suppressing weed growth. More specifically the present invention relates to fungal biocontrol agents for suppression of weed growth.
BACKGROUND OF THE INVENTION
Control of weeds is an important aspect of crop management. Due to several undesirable properties associated with the use of chemical herbicides, alternative weed control practices, including the use of biological herbicides, are desired.
For example, rising economic, environmental and social costs associated with agricultural inputs, spray drift, pesticide residues, gove~~nment legislation for reduced pesticide use, along with the development of herbicide resistance in weeds, make biocontrol agents attractive strategies for weed control.
Biological control of weeds with microorganisms (bioherbicides), preferably involves the production and application of a weed -specific pathogen to a target weed.
The weed specific pathogen is typically a fungus or bacterial pathogen that inhibits or suppresses root, shoot or both root and shoot growth, development, or both growth and development, thereby reducing weed competition. The development of biological crop protection products (bioherbicides) for economically important weed problems in agricultural field crops may help to facilitate harvests, secure yields, and protect the environment. Biological control provides an additional tool to complement an integrated weed management system and helps sustainable agricultural systems by maintaining the ecosystem balance through the preservation of plant and microbial diversity in the field.
There are several documents disclosing the use of fungi as biocontrol agents.
For example, U.S. 5,993,802 teaches methods for suppressing the growth of Calamagrostis canadensis using an isolate of a low temperature basidiomycete fungus, Coprinus psychromorbidus. U.S. 5,472,690 teaches of a mycoherbicide (including at least one or both of Fc~sarium nivalis and Colletotrichum calamagrostidis) effective in the control _ 7 _ of Calamagrostis canadensis and/or related grasses. The control of crabgrass using fungi is disclosed in U.S. 5,92,264, using the fungus Cochliobolees internzedizcs, and U.S.
5,635,444 using a fungus selected from the genus Curvularicc. U.S. 5,747,029, teaches the control of sicklepod weeds using the fungus MyrotlzeciuzYZ verrzecaria.
The control of nutsedge weeds using the fungus Dactylaria lziggimsii is disclosed in WO
98/08389.
U.S. 4,606,751 teaches the biocontrol of Johnson grass using Bipolaris sorghicola spores that are suspended in a solution of water and surfactant, and sprayed onto a field in which the weed is growing.
Annual grassy weeds such as Setaria viridis (L.) Beauv. (commonly known as green foxtail, pigeongrass, wild millet, green bristlegrass, and bottlegrass) develop dense competitive stands and have heavy seed production in spring sown crops. Green foxtail is a principal weed of corn, soybean, cereals, flax, canola, sugar beets, and pastures. The amount of damage to the crop depends on the density of the stand, time of emergence, and length of time the weed and crop are competing. Weed surveys for herbicide-resistant green foxtail have revealed that many of these plants exhibit some degree of herbicide resistance (Beckie, H.J., A. L.egere, A.G. Thomas, L.T. Juras, and M.D.
Devine. 1996 Survey of Herbicide-Resistant Wild Oat and Green Foxtail in Saskatchewan:
Interim Report. AAFC Report, 22 pp.). Therefore, biocontrol of these plants is highly desirable.
However, at present for most of these weeds there are no known satisfactory biocontrol agents for control of green foxtail.( need more types of weeds) An important aspect in the development of a successful biological control agent is an effective delivery system. For biocontrol agents delivered onto target weeds by spraying, it is common for the erect top leaf to survive the attack due to the poor retention of the biocontrol agent on this portion of the plant. Thus, new methods of applying biocontrol agents are desired in the art. Further, traditional application methods such as run-off spraying are generally not suitable for treatment of large areas and thus there is a need in the art for methods to reduce the application volumes of biocontrol agents without reducing the efficacy of the biocontrol agent on the target weeds. To date, variable efficacy has been observed with boipesticide agents at reduced application volumes (Jones 1994, Smith and Bouse, 1981) Previous attempts to control green Foxtail weeds with biocontrol compositions have been relatively poor. In particular, it was noted in other studies that the top leaf of green foxtail consistently exhibited the least amount of disease development following biocontrol application, and reduced spray retention is speculated as a cause because of the erect leaf architecture of green foxtail weeds. Further, the surviving leaf often contributes to regrowth from the apical meristem, reducing the effectivity of the biocontrol agent. Other factors, such as but not limited to age (Green and Bailey 2000) and mineral nutrient content (Filippi and Prabhu 1998) of the leaves, may affect the susceptibility of green foxtail weeds to fungal pathogens.
In field crops, application volumes over 600 L/ha are considered high (Matthews, 1992), and the trend is generally toward volume reduction. In previous experiments, when applied at volumes between 100 to 800 L/ha, the agent 94-409A showed significantly lower efficacy in comparison to the runoff airbrush spray using the same spore concentration. Commonly the erect top leaf developed little disease and survived the attack. It is believed that the poorer eFFicacy is related to a lower amount of fungal propagules received and retained on the plant.
_4_ It is an object of the present invention to overcome drawbacks of the prior art.
The above object is met by a combination of the features of the main claims.
The sub claims disclose further advantageous embodiments of the invention.
SUIVINIARY OF THE INVENTION
The invention relates to biocontrol agents for suppressing weed growth. More specifically the present invention relates to fungal biocontrol agents for suppression of weed growth.
The present invention provides an isolated fungal biocontrol agent Pyricularia IS setariae isolate 94-904A that exhibits weed suppressive activity. Also provided by the present invention is the use of biocontrol agent for controlling green foxtail (Setaria viridis [L.] Beauv.) weeds.
Also provided by the present invention is a biocontrol composition comprising fungal biocontrol agent 94-904A in an acceptable medium and the use of the biocontrol composition for controlling green foxtail weeds. The acceptable medium may comprise a liquid culture medium, a solid culture medium or a combination thereof.
Preferably the acceptable medium is a liquid culture medium.
Also according to the present invention there is provided a method for suppressing weed growth by applying a fungal biocontrol agent 94-904A to a weed.
Preferably the weed is green foxtail (Setaria viridis [L.] Beauv.). Also according to the present invention there is provided a method for suppressing weed growth by applying a biocontrol composition comprising biocontrol agent 94-904A to a weed.
Preferably the weed is green foxtail (Setaria viridis [L.] Beauv.).
_ j _ Further, according to an embodiment of the present invention, there is provided a method of suppressing weeds during crop growth comprising;
a) adding an effective amount of a biocontrol composition comprising fungal biocontrol agent 94-904A formulated in an acceptable medium, to soil to produce a treated soil;
b) planting crops in the treated soil and;
c) growing the crops.
Also according to the present invention, there is provided a method of suppressing weeds during crop growth comprising;
a) spraying an effective amount of a biocontrol composition comprising biocontrol agent 94-904A formulated in an acceptable medium, to an area of plants comprising green foxtail weeds, and;
b) growing said plants.
The biocontrol agent or biocontrol composition may be applied to weeds by any method known in the art, but is preferably applied by spraying, for example, but not limited to airbrush spraying or broadcast spraying. Broadcast application may be effected using a nozzle which enhances the reduction of the size of the droplets which are emitted during application of the biocontrol agent or composition as defined above.
Preferably the nozzles are selected from the group consisting of X8001, X8002 and X8004.
However, other nozzles may also be employed to deliver the biocontrol agent or composition of the present invention.
Also, according to the present invention as defined above, there is provided a biocontrol composition and the use of a biocontrol composition comprising fungal biocontrol agent 94-409A wherein fungal biocontrol agent 94-409A is present in the composition in an amount of about 106 to about 10' spores per ml.
Also, according to the present invention as defined above there is provided a method of inhibiting green foxtail weeds in a desired area, said method comprising, spraying the desired area with between about 250 L/Ha to about 2000 LJHa of a biocontrol composition comprising between about 106 to about 10' spores of fungal biocontrol agent 94-904A.
This summary does not necessarily describe all necessary features of the invention but that the invention may also reside in a sub-combination of the described features.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the invention will become more apparent from the following description in which reference is made to the appended drawings wherein:
FI(TURE 1 shows retention volumes on different parts of green foxtail with airbrush sprayer (runoft~ and broadcast sprayers (1,960 L./ha). The measurements were taken from different plant parts and expressed as ftl/mg dry matter.
FIGURE 2 shows the effect of spray droplet size and travel speed on the retention efficiency of spray on treated plants.
FIGURE 3 shows the effect of application method, spore concentration, and droplet size on the efficacy of 94-409A as a biocontrol agent on green foxtail weeds.
FIGURE 4 shows the effect of increased concentration doses of biocontrol agent 409A on the efficacy of green foxtail weed control with reduced application volumes.
_g_ The invention relates to biocontrol agents for suppressing weed growth. More specifically the present invention relates to fungal biocontrol agents for suppression of weed growth.
The following description is of a preferred embodiment by way of example only and without limitation to the combination of features necessary for carrying the invention into effect.
According to an aspect of the present invention, there is provided fungal biocontrol agent Pyriculria s~~tariae isolate 94-904A. In a preferred embodiment fungal biocontrol agent 94-904A is used to control green foxtail (Setaria viridis) weeds.
By the term "biocontrol agent" it is meant a microorganism which suppresses the growth of, or kills, a target pest, for example, but not limited to a plant or a weed. More specifically, the biocontrol agents of the present invention may be used to suppress the growth of one or more target pests. Without wishing to be bound by theory, the biocontrol agent suppresses the growth of a target pest, for example, a plant or weed (i.e.
exhibits weed suppressive activity), by interfering with the normal growth and development of the target plant or weed. For example, but not wishing to be limiting, the biocontrol agent may inhibit root growth, shoot growth, reduce biomass, inhibit seed production, reduce competitiveness of the target plant or weed for a crop's water and nutrients, or a combination thereof.
As someone of skill in the art will understand, in order for the biocontrol agent of the present invention to be grown, cultured or used in accordance with the embodiments of the present invention, it is preferable that the biocontrol agent be grown in a suitable medium to produce a biocontrol composition or formulation. By the term "suitable medium" or "acceptable medium" it is meant any liquid, semi-liquid or solid substrate which allows biocontrol agent 94-904A to grow, or to remain viable, or both grow and remain viable. Thus, the present invention contemplates a biocontrol composition comprising fungal biocontrol agent 94-904. Preferably, the composition permits an effective amount of fungal biocontrol agent 94-409A to remain viable prior to, and after, being applied to a crop. More preferably, the composition permits fungal biocontrol agent 94-409A to remain viable for a period between about 1 day to about 1 month following application of the biocontrol composition of the present invention onto a plant, or soil.
The biocontrol agent or biocontrol composition of the present invention may be applied to plants, soil or both plants and soil. Preferably, the biocontrol agent or composition is applied to plant foliage, for example the foliage of the target weed.
Alternatively, the biocontrol agent or composition may be applied directly to soil, either before, during or after seeding a crop. The biocontrol agent may be applied by any method known in the art, for example, but not limited to spraying, pouring, dipping or the like. Preferably, the biocontrol composition of the present invention is applied by spraying.
Therefore, the present invention provides for the use of fungal biocontrol agent 94-904A grown and formulated in a suitable composition for the suppression of green foxtail weeds. However, as someone of skill in the art will understand, the amount of the biocontrol composition required for suppression of green foxtail weeds may be dependent on the medium in which fungal biocontrol agent 94-904A is formulated and the method in which it is formulated. For example, but not wishing to be limiting, a formulation and medium which permits a greater percentage of the fungal agent to remain viable may require less biocontrol composition to suppress weed growth than does another formulation and medium in which biocontrol agent 94-904A is less viable.
Further, the amount of a biocontrol composition required for suppression of weeds may be influenced by environmental factors such as but not limited to temperature, humidity, soil pH, and soil type.
Refernng now to Table l, there is shown spray retention on plants by airbrush and broadcast application. The results shown in Table 1 suggest that the retention of spray on whole green foxtail plants generally increases with broadcast application volume. Also suggested by Table 1 is that spray retention on plants following broadcast application at a volume of about 1,960 L/ha produces a similar level to that of airbrush spraying. Thus, the present invention contemplates airbrush and broadcast application of fungal biocontrol agent 94-904A or a biocontrol composition comprising biocontrol agent 94-904A. However, application of biocontrol agent 94-904A or a biocontrol composition comprising 94-904A is not limited to airbrush and broadcast application.
Table 1. Spray retention achieved by airbrush and broadcast applications at different volumes on green (oxtail.
Volumes AirbrushBroadcast Application Volume (IJha)3 ml/pot171 474 477 885 1187 1960 *
Retention Volume (~l/plant) 25.8 3.2 9.8 7.4 11.2 18.3 26.4 * Application volume resulting in runoff on 8 plants at the 3-leaf stage.
Refernng now to Figure l, there is shown the results of spray retention on different plant parts following airbrush or broadcast application using nozzles that vary the droplet size of the spray. As shown by Figure 1, spray retention is slightly higher on leaves than on the stems of plants when spray retention is measured on a dry matter basis.
The results shown in Figure 1 also suggest that broadcast application of the biocontrol composition of the present invention with the XR 8002 nozzle results in greater retention of spray on whole plants and leaves compared to broadcast application using a XR 8004 nozzle or by airbrush spraying. Without wishing to be bound by theory, smaller spray droplets may be better retained on plant leaves than are larger droplets.
Thus modulation of the spray droplet size during application of the fungal biocontrol agent or composition of the present invention may enhance retention of the biocontrol control agent on target weeds.
Effects of droplet size and travel speed on retention efficiency of biocontrol agent Retention efficiency is a term comparing the amount of a biocontrol agent on a plant following application relative to total application volume delivered.
Referring now to Figure 2, there is graphically depicted the retention efficiency of spray following broadcast application using nozzles XR 8001, XR 8002 and XR 8004 and using spray application speeds of 0.5 and 1.1 km per hour. Nozzles XR 8001, XR 8002 and XR
produce progressively greater size droplets. The results shown suggest that application of smaller droplets result in a relatively higher proportion of spray being retained on the target weed. For example, but not wishing to be limiting, broadcast application of a biocontrol composition using a small droplet size nozzle (XR8001) results in greater retention efficiency of the biocontrol composition on plants than do larger droplet size nozzles XR8002 and XR8004 under the specific conditions under which the three nozzles were tested. Also suggested by the results shown in Figure 2 is that the travel speed of the droplets has little effect on the retention efficiency of the biocontrol composition and thus the fungal biocontrol compositions of the present invention may be applied in a wide range of droplet sizes and travel speeds. Preferably, the droplet sizes are small, for example in about the order of the droplets produced by a XR8001 nozzle.
Further, it is preferable that the travel speeds of the droplets are in the range of about 0.4 km per hour to about 2 km per hour, more preferably between 0.55 and 1.10 km per hour. As would be evident to someone of skill in the art, travel speeds outside this range also may be used in accordance with the method of tire present invention, but that the travel speed and droplet size should not be such that physical damage occurs to plants.
Retention and biocontrol et~'icacy of fungal biocontrol agent 94-409A
Refernng now to Figure 3, there is shown the effect of application method, spore concentration and droplet size on the efficacy of fungal biocontrol agent 94-409A on green foxtail. As shown by the results in Figure 3, application of between about 106 and aboutl0' spores/ml of fungal biocontrol agent 94-409A onto the foliage of green foxtail weeds reduces the weight of the weeds, regardless of the method used to apply the composition. The results shown in Figure 3 also suggest that fungal isolate 94-409A may be applied to green foxtail weeds by a variety of application methods, such as, but not limited to by airbrush,or broadcast spraying. Further, broadcast spraying of the biocontrol composition of the present invention in an amount of about 2000L/ha, there was little difference between the two application methods (data not shown). At higher spore concentrations, there was no significant difference between application treatments, and the average plant fresh weight was reduced by about 85°lo to about 91%
compared to the control. At lower doses, however, the XR8004 nozzle appeared to be slightly more effective than the airbrush spray, but was comparable to the XR8002.
Preferably, the biocontrol composition of the present invention comprises between about 106 and about 10' spores of fungal biocontrol agent 94-904A.
Reduction of application volume by increasing inoculum concentration Referring now to Figure 4, there is shown the effect of application dose of biocontrol agent 94-409A on the fresh weight and % disease of green foxtail plants.
As suggested by the results of Figure 4, increasing the spore concentration of biocontrol agent 94-409A in a biocontrol composition offsets the efficacy loss that results from reducdion of application volume. Further, little difference in biocontrol efficacy is observed with all the volumes applied based on the measurement of disease severity and plant fresh weight. Compared with the control, the average reduction of fresh weight ranged from about 58 to about 67% with different application volume treatments.
Thus, the use of high spore concentrations of biocontrol agent 94-409A in a biocontrol composition may reduce the application volumes without compromising the efficacy of weed control. In addition, a high spore concentration increases the number of propagules contained in the spray, avoiding large numbers of 'empty' droplets (Jones 1998).
The above description is not intended to limit the claimed invention in any manner, furthermore, the discussed combination of features might not be absolutely necessary for the inventive solution.
The present invention will be further illustrated in the following examples.
However, it is to be understood that these examples are for illustrative purposes only, and should not be used to limit the scope of the present invention in any manner.
EXAMPLE 1: Preparation of Plants - 1=1 -Mature green foxtail seeds are harvested from a weed nursery on the research farm of Agriculture and Agri-Food Canada near Saskatoon. Seeds are planted in a layer of Redi-Earth on top of a layer of soil-less mix with fertilizer in 7.5-cm plastic pots, and grown at 20 ~ 3°C with 14-h supplementary lighting for about 3 weeks until the 3-leaf stage.
EXAMPLE Z: Preparation of Inoculum and Inoculation of Plants Mycelium plugs (5x5 mm) were cut from the edge of growing cultures of fungal agent 94-409A, placed on a modified oatmeal agar in petri plates, and incubated at 26°C with 14 h of near-UV lighting. Sporulating cultures are Hooded with 5 ml of sterilized water and a 0.1-ml aliquot of the suspension is plated on oatmeal agar and incubated under the same conditions for approximately 1 week.
This method usually produces about 10~ spores/plate.
For inoculation, sporulating cultures are flooded with water containing 0.1~/o Tween 80 (surfactant) and the spores are scraped off the medium.
Concentrations of spore suspensions are estimated using a haemocytometer and adjusted accordingly. An airbrush sprayer and broadcast cabinet sprayer are used to apply spore suspensions of the fungal biocontrol agent 94-904A. Constant air pressure at approximately 250 kPa is used in both airbrush and broadcast spraying.
Approximately 3 ml of suspension is required to achieve visible runoff for plants at the 3-leaf stage in a 7.5-cm-diameter pot. For broadcast application, several types of TeeJet nozzles according to rates and spray quality are tested. Inoculated plants are placed immediately in an environment-controlled dew chamber at 20°C ~ 2 °C and 20 hours dark/4 hours light prior to being placed in the green house.
EXAMPLE 3: Disease Assessment of Plants Plant reactions are assessed 7 days after inoculation. The efficacy of the fungal biocontrol agent 94-904A is estimated using disease severity measured on the basis of percent diseased areas on a whole plant. A C)-11 scale adopted from I-~orsfall-Barratt (1945; which is herein incorporated by reference) is used to facilitate the assessment, in which scale 0 indicates no visible symptoms, 11 indicates a dead plant, and the other classes represent a range of disease severity in between.
In additions, plants are cut at the soil line from each replicated plot and measured for fresh weight as an indicator of weed suppression.
EXAMPLE 4: Spray retention studies Six replicated pots, each containing 8 plants at the 3-leaf stage are used for all treatments. Plants are sprayed with a Rhodamine WT dye solution containing 0.1%
(v/v) Tween 80 surfactant, and the relative retention of the spray on plants is estimated by washing plant tissues in ethanol and measuring the dye amount on a spectrophotometer (Wolf et al, 2000; which is herein incorporated by reference).
Measurements are taken on various plant parts, as well as on the whole plant.
The top, mid, and bottom leaves are cut carefully and separated from the stem.
Spray retained on individual parts and whole plants is measured separately, and reported in ~,I dye/mg plant dry matter.
To compare spray retention on plants using different application methods and droplet sizes, an airbrush sprayer and broadcast sprayer with a series of TeeJet t7at fan nozzles are used. For airbrush application, approximately 3 ml of solution is applied to a pot of plants. The application usually results in runoff of the spray from the plants. For broadcast application, plants are placed in a spray chamber and sprayed with various volumes. Plastic petri plates are placed beside the plants in the spray chamber to collect and determine the actual spraying volumes (Wolf et al., 1997 which is herein incorporated by reference).
- 1 ~7 -Effects of droplet size and travel speed on retention A spray cabinet is used to identify spraying parameters for improvement of spray retention and reduction of carrier volume. Retention Efficiency is used to compare the effect of variables, in which retention on plants is measured in relation to actual application volumes determined using petri plate collection as described above.
TeeJet XR 8001, 8002, and 8004 nozzles are used to create different droplet size spectra and their effect on retention is examined at travel speeds of 0.55 and 1.1 km/h.
Retention and biocontrol efficacy:
For comparison of the biocontrol efficacy of airbrush and broadcast applications at volumes resulting in a similar level of retention on the plant. In broadcast spraying, a single XR 8004 tip or two XR 8002 tips in a Lurmark Twin Cap are used to assess the effects of droplet size and spray trajectory. Spore suspensions of 94-409A at concentrations of 106 and 10' spores/ml are applied to plants. The experiment is a completely randomized factorial design with 4 replicates (pots) for each treatment.
Application volume and concentration dose: A broadcast sprayer with a single or two XR 8002 tips operated at 250 kPa is used to apply the mycoherbicide agent at approximately 250, 500, 1000, and 2,000 L/ha. Carrier volume is altered by changing the sprayer travel speed between 0.28 and 1.1 km/h. Spore concentrations for the lower application volumes is increased so all treatments have the same applied fungal propagule dose. The experiment is arranged in a completely randomized design with 6 replicates for each treatment Data analysis: All data is subjected to analysis of variance (ANOVA) using STATISTICA
1999 software. LSD (P _< 0.05) was used to separate treatment means when a significant difference (P <_ 0.05) was indicated in ANOVA.
The results presented herein suggest that:
1. A broadcast spray delivering approximately ?000 Uha provides similar spray retention amounts and biocontrol efficacy on green foxtail in comparison to an airbrush spray to the point of runoff.
2. Reductions in carrier volume may be offset by increasing spore concentration, suggesting that spore dose, not carrier volume, may govern bioherbicide efficacy.
3. Spray retention on plants may be improved by using finer sprays and angling the spray trajectory forward, backward or both forward and backward from the vertical.
4. Pyricularia can be used as an effective bioherebicide against weeds, for example green foxtai I.
All citations are herein incorporated by reference.
The present invention has been described with regard to preferred embodiments.
However, it will be obvious to persons skilled in the art that a number of variations and modifications can be made without departing from the scope of the invention as described herein.
References:
Filippi, M.C. and Prabhu, A.S. 1998. Relationship between panicle blast severity and mineral nutrient content of plant tissue in upland rice. J. Pl Nutr. 21: 177-78.
Graham-Bryce, LJ. 1977. Crop Protection: a consideration of the effectiveness and disadvantages of current methods and scope for improvement. Phil. Traps. Roy.
Soc. of Britain. 281: 163-179.
Greaves, M.P., Duton, L. and Lawrie, J. 2000. Formulation of microbial herbicides.
Aspects of Applied Biology 57 (Pesticide Application): 171-178.
Green, S. and Bailey K.L. 2000. Effects of leaf maturity, infection site, and application rate of Alternaria cirsino.~ia conidia on infection of Canada thistle (Cirsiurr2 arvense).
Biological Control 19: 167-174.
Groves, R., Caldwell, B.C., Maybank, J, and Wolf, T.M. 1997. Airborne off-target losses and ground deposition characteristics from a Spra-Coupe using 'low drift" nozzle tips. Can. J. Plant Sci. 77:493-500.
Hartley, G. S. and R. T. Brunskill. 1958. Reelection of water drops from surfaces. Pages 214-223 In: Surface Phenomena in Chemistry and Biology J. F. Danielli, et al.
eds .
Pergannon Press, London.
Himel, C.M., Loats, H. and Bailey, G.W. 1990. Pesticide sources to the soil and principles of spray physics. In: Pesticides in the Soil Environment, Impact and Modeling.
Soil Science of America Book Series 2 (ed. H.H. Cheng), pp7-50. Soil Sci. Soc.
of Am., Wisconsin.
_ 1 C~ _ Horsfall, J.G. and Barratt, R.W. 1945. An improved grading system for measuring plant diseases. Phytopatholog~~ 35:665 (Abstr.).
Jones, K. A. 1994. Use of baculoviruses for cotton pest control. In: Insect Pest of Cottoc2 (eds. G.A. Matthews and J. P. Tunstall), pp. 477-504. CAB
International, Wallingford, UK.
Jones, K.A. 1998. Spray application criteria. In: Fonneclatioci ofMicrobial Biopesticides led. H.D. Burges), pp. 367-375. Academic Press, London.
Jones, K.A and Burges, H.D. 1998. Technology of formulation and application.
In:
Formcclatiort of Microbial Biopesticides, pp. 7-30.
Knoche, M. 1994. Effect of droplet size and earner volume on performance of foliage-applied herbicides. Crop Prot. 13:163-178.
Matthews, G. A. 199?. Pesticide Application Methods, 2°'' edition.
Longman Scientific and Technical, Harlow, UK.
Nordbo, E., K. Kristensen, and E. Kirknel. 1993. Effects of wind direction, wind speed and travel speed on spray deposition. Pestic. Sci. 38:33-41.
Reichard, D. L. 1988. Drop formation and impaction of the plant. Weed Technol.
2:82-87.
Richardson, R. G. 1987. Effect of drop trajectory on spray deposits on crop and weeds.
Plant Prot. Quarterly 2:108-111.
- 'J ~ -Smith, D. B. and Bouse, L. F. 1981. Machinery and factors that affect the application of pathogens. In: Microbial Control of Pest arad Plant DiSecc,res, pp. 635-653.
Spillman, J. J. 1984. Spray impaction, retention and adhesion: an introduction to basic characteristics. Pestic. Sci. 15:97-106.
Wolf, T.M., Liu, S.H., Caldwell, B.C., and Hsiao, A.I. 1997. Calibration of greenhouse spray chambers - the importance of dynamic nozzle patternation. Weed Technol.
11:428-435.
Wolf, T.M., Harc-ison, S.K, and Hall, F.R. ?000. Optimizing postemergence herbicide deposition and efficacy through application variables in no-till. Weed Science 48:761-768.
All citations are herein incorporated by reference.
The present invention has been described with regard to preferred embodiments.
However, it will be obvious to persons skilled in the art that a number of variations and modifications can be made without departing from the scope of the invention as described herein.
References:
Filippi, M.C. and Prabhu, A.S. 1998. Relationship between panicle blast severity and mineral nutrient content of plant tissue in upland rice. J. Pl Nutr. 21: 177-78.
Graham-Bryce, LJ. 1977. Crop Protection: a consideration of the effectiveness and disadvantages of current methods and scope for improvement. Phil. Traps. Roy.
Soc. of Britain. 281: 163-179.
Greaves, M.P., Duton, L. and Lawrie, J. 2000. Formulation of microbial herbicides.
Aspects of Applied Biology 57 (Pesticide Application): 171-178.
Green, S. and Bailey K.L. 2000. Effects of leaf maturity, infection site, and application rate of Alternaria cirsino.~ia conidia on infection of Canada thistle (Cirsiurr2 arvense).
Biological Control 19: 167-174.
Groves, R., Caldwell, B.C., Maybank, J, and Wolf, T.M. 1997. Airborne off-target losses and ground deposition characteristics from a Spra-Coupe using 'low drift" nozzle tips. Can. J. Plant Sci. 77:493-500.
Hartley, G. S. and R. T. Brunskill. 1958. Reelection of water drops from surfaces. Pages 214-223 In: Surface Phenomena in Chemistry and Biology J. F. Danielli, et al.
eds .
Pergannon Press, London.
Himel, C.M., Loats, H. and Bailey, G.W. 1990. Pesticide sources to the soil and principles of spray physics. In: Pesticides in the Soil Environment, Impact and Modeling.
Soil Science of America Book Series 2 (ed. H.H. Cheng), pp7-50. Soil Sci. Soc.
of Am., Wisconsin.
_ 1 C~ _ Horsfall, J.G. and Barratt, R.W. 1945. An improved grading system for measuring plant diseases. Phytopatholog~~ 35:665 (Abstr.).
Jones, K. A. 1994. Use of baculoviruses for cotton pest control. In: Insect Pest of Cottoc2 (eds. G.A. Matthews and J. P. Tunstall), pp. 477-504. CAB
International, Wallingford, UK.
Jones, K.A. 1998. Spray application criteria. In: Fonneclatioci ofMicrobial Biopesticides led. H.D. Burges), pp. 367-375. Academic Press, London.
Jones, K.A and Burges, H.D. 1998. Technology of formulation and application.
In:
Formcclatiort of Microbial Biopesticides, pp. 7-30.
Knoche, M. 1994. Effect of droplet size and earner volume on performance of foliage-applied herbicides. Crop Prot. 13:163-178.
Matthews, G. A. 199?. Pesticide Application Methods, 2°'' edition.
Longman Scientific and Technical, Harlow, UK.
Nordbo, E., K. Kristensen, and E. Kirknel. 1993. Effects of wind direction, wind speed and travel speed on spray deposition. Pestic. Sci. 38:33-41.
Reichard, D. L. 1988. Drop formation and impaction of the plant. Weed Technol.
2:82-87.
Richardson, R. G. 1987. Effect of drop trajectory on spray deposits on crop and weeds.
Plant Prot. Quarterly 2:108-111.
- 'J ~ -Smith, D. B. and Bouse, L. F. 1981. Machinery and factors that affect the application of pathogens. In: Microbial Control of Pest arad Plant DiSecc,res, pp. 635-653.
Spillman, J. J. 1984. Spray impaction, retention and adhesion: an introduction to basic characteristics. Pestic. Sci. 15:97-106.
Wolf, T.M., Liu, S.H., Caldwell, B.C., and Hsiao, A.I. 1997. Calibration of greenhouse spray chambers - the importance of dynamic nozzle patternation. Weed Technol.
11:428-435.
Wolf, T.M., Harc-ison, S.K, and Hall, F.R. ?000. Optimizing postemergence herbicide deposition and efficacy through application variables in no-till. Weed Science 48:761-768.
Claims (21)
PROPERTY OF PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An isolated fungal biocontrol agent 94-904A.
2. The use of the biocontrol agent of claim 1 for controlling green foxtail (Setaria viridis [L.] Beauv.) weeds.
3. A biocontrol composition comprising fungal biocontrol agent 94-904A in an acceptable medium.
4. The use of the biocontrol composition of claim 3 for controlling green foxtail weeds.
5. The biocontrol composition of claim 3, wherein said acceptable medium comprises a liquid culture medium, a solid culture medium or a combination thereof.
6. The biocontrol composition of claim 5, wherein the acceptable medium is a liquid culture medium.
7. A method for suppressing weed growth comprising applying the isolated biocontrol agent of claim 1 to a weed.
8. The method of claim 7, wherein the weed green foxtail (Setaria viridis [L.]
Beauv.).
Beauv.).
9. A method of suppressing weed growth comprising, applying a biocontrol composition compring fungal biocontrol agent 94-904A.
10. The method of claim 9, wherein the weed is green foxtail (Setaria viridis [L.]
Beauv.).
Beauv.).
11. A method of suppressing weeds during crop growth comprising;
a) adding an effective amount of a biocontrol composition comprising fungal biocontrol agent 94-904A formulated in an acceptable medium, to soil to produce a treated soil;
b) planting crops in said treated soil and;
c) growing said crops.
a) adding an effective amount of a biocontrol composition comprising fungal biocontrol agent 94-904A formulated in an acceptable medium, to soil to produce a treated soil;
b) planting crops in said treated soil and;
c) growing said crops.
12. A method of suppressing weeds during crop growth comprising;
a) spraying an effective amount of a biocontrol composition comprising biocontrol agent 94-904A formulated in an acceptable medium, to an area of plants comprising green foxtail weeds, and;
b) growing said plants.
a) spraying an effective amount of a biocontrol composition comprising biocontrol agent 94-904A formulated in an acceptable medium, to an area of plants comprising green foxtail weeds, and;
b) growing said plants.
13. The method of claim 9, wherein said applying is performed by spraying.
14. The method of claim 13 wherein said spraying comprises airbrush or broadcast spraying.
15. The method of claim 14 wherein said broadcast spraying is performed with a nozzle selected from the group consisting of X8001, X8002 and X8004.
16. The biocontrol composition of claim 2, wherein said fungal biocontrol agent is present in said composition in an amount of about 10 6 to about 10 7 spores per ml.
17. A method of inhibiting green foxtail weeds in a desired area, said method comprising,spraying said desired area with between about 250 L/Ha to about 2000 L/Ha of a biocontrol composition comprising between about 10 6 to about 10 7 spores of fungal biocontrol agent 94-904A.
18. A use of a Pyricularia as a bioherbicide.
19. The use as defined in claim 18, wherein said Pyricularia is Pyricularia setariae.
20. The use of the Pyricularia of claim 18 for controlling green foxtail (Setaria viridis [L.] Beauv.) weeds.
21. The use of the Pyricularia of claim 19 for controlling green foxtail (Setaria viridis [L.] Beauv.) weeds.
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002345503A CA2345503A1 (en) | 2001-04-30 | 2001-04-30 | Pre-emergent biological control agents |
| CA002357889A CA2357889A1 (en) | 2001-04-30 | 2001-09-26 | Biological control agents |
| CA2445959A CA2445959C (en) | 2001-04-30 | 2002-04-30 | Control of weed with a fungal pathogen |
| PCT/CA2002/000637 WO2002087343A1 (en) | 2001-04-30 | 2002-04-30 | Control of weed with a fungal pathogen |
| US10/476,219 US7449428B2 (en) | 2001-04-30 | 2002-04-30 | Control of weed with a fungal pathogen |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002345503A CA2345503A1 (en) | 2001-04-30 | 2001-04-30 | Pre-emergent biological control agents |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2345503A1 true CA2345503A1 (en) | 2002-10-30 |
Family
ID=4168922
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002345503A Abandoned CA2345503A1 (en) | 2001-04-30 | 2001-04-30 | Pre-emergent biological control agents |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2345503A1 (en) |
-
2001
- 2001-04-30 CA CA002345503A patent/CA2345503A1/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |