Method of controlling phytopathogenic diseases on turfgrass

Abstract

The present invention relates to a method of controlling pythium blight on turfgrass, in particular low to moderate disease pressure, using a fungicidally effective non-phytotoxic amount of (A) chlorothalonil and (B) acibenzolar-s-methyl.

Claims

1. A method for controlling or suppressing cool-season pythium blight in turfgrass, comprising applying to the cool-season turfgrass or to the locus of the cool-season turfgrass, a fungicidally effective non-phytotoxic amount of a combination comprising (A) chlorothalonil and (B) acibenzolar-S-methyl, wherein (A) is applied at a rate of from 2,000 to 10,000 g/ha and (B) is applied at a rate of from 4 to 20 g/ha, wherein the combination of (A) and (B) is applied pre-disease or under low to moderate pythium blight disease pressure present in the turfgrass.

2. The method of claim 1, wherein the weight ratio of chlorothalonil to acibenzolar-S-methyl is from 300:1 to 600:1.

3. The method of claim 1, wherein chlorothalonil and acibenzolar-S-methyl are applied simultaneously together, separately, or in succession.

4. The method of claim 1, wherein a fungicidally effective non-phytotoxic amount of a composition comprising a mixture of chlorothalonil and acibenzolar-S-methyl is applied to the turfgrass or to the locus of the turfgrass.

5. The method of claim 1, using a composition comprising a combination of (A) and (B).

6. The method of claim 5, wherein the composition of (A) and (B) further comprises adjuvants, solvents, carrier, surfactants or extenders.

7. The method according to claim 6, wherein the composition comprises from 0.01 to 90% by weight of the combination of (A) and (B), from 10 to 99.99% of a carrier and from 0 to 20% of a surfactant.

8. The method of claim 1, wherein chlorothalonil is applied at the rate of from 3000 to 5000 g/ha.

9. The method of claim 1, wherein acibenzolar-S-methyl is applied at the rate of from 5 to 12 g/ha.

10. The method of claim 1, wherein the combined amount of chlorothalonil and acibenzolar-S-methyl that is applied to the turfgrass or to the locus thereof is between about 3000 to 5000 g/ha.

11. The method according to claim 1, wherein the phytopathogenic disease is caused by one or more phytopathogenic fungi selected from the group consisting of Pythium spp.

12. The method according to claim 1, wherein the turfgrass is an annual or perennial Gramineae belonging to at least one of the genera Agropyron, Agrostis, Axonopus, Bromus, Buchlo, Cynodon, Eremochloa, Festuca, Lolium, Paspulum, Pennisetum, Phleum, Poa, Stenotaphrum or Zoysia.

Description

FORMULATION EXAMPLE

(1) TABLE-US-00001 Suspension concentrate Active ingredients 40% Propylene glycol 10% Nonylphenol polyethylene glycol ether (15 mol of ethylene oxide) 6% Sodium lignosulfonate 10% Carboxymethylcellulose 1% Silicone oil (in the form of a 75% emulsion in water) 1% Water 32%

(2) In preparing and SC, the finely ground active ingredients are mixed with the adjuvants, giving a suspension concentrate from which suspensions of any desired dilution can be obtained by dilution with water. Using such dilutions, living plants as well as plant propagation material can be treated and protected against infestation by microorganisms, by spraying, pouring or immersion.

(3) The following examples are for illustrative purposes only. The examples are not intended as necessarily representative of the overall testing performed and are not intended to limit the invention in any way.

BIOLOGICAL EXAMPLES

(4) Enhanced control of Pythium blight in turf is claimed when acibenzolar-S-methyl is applied in combination with chlorothalonil. Control of Pythium blight is superior to chlorothalonil applied alone.

Example 1

(5) A study was conducted to evaluate pythium blight control on Palmer IV perennial ryegrass. The trial was arranged in a randomized complete block design with four replications. Daconil Weatherstik and Daconil Action were compared at 2.0 and 3.6 ounces per 1000 square foot of turf. Daconil Action contains 54% chlorothalonil and 0.176% acibenzolar-S-methyl. Daconil Weatherstik contains 54% chlorothalonil. Rates are equivalent to the following:

(6) TABLE-US-00002 Rate - acibenzolar- fluid ounces/ Chlorothalonil S-methyl Treatment 1000 sq. ft. g ai/ha g ai/ha Daconil Action 3.6 8250 16.5 Daconil Action 2.0 4600 9.2 Daconil Weatherstik 3.6 8250 Daconil Weatherstik 2.0 4600

(7) Treatments were applied on 17 June, 1 July and 15 July. Percent turf area exhibiting pythium blight symptoms were assessed six times throughout the trial period (Table 1).

(8) TABLE-US-00003 TABLE 1 Pythium Blight Severity in Daconil Action and Daconil Weatherstik Trial. Pythium blight severity.sup.y Treatment Rate Rate Unit 1 JUL 15 JUL 18 JUL 19 JUL 20 JUL 22 JUL 1 Untreated Check 3.75 ab.sup.x 14.75 a 32.0 a 35.0 a 45.25 a 49.25 a 3 Daconil Action 3.6 fl oz/1000 ft.sup.2 4.25 a 5.0 b 14.0 bc 20.25 b 29.75 bc 32.75 b 4 Daconil Weather 3.6 fl oz/1000 ft.sup.2 0.0 c 0.0 b 3.0 bc 6.0 c 11.25 d 11.25 cd Stik 8 Daconil Action 2.0 fl oz/1000 ft.sup.2 1.75 abc 2.5 b 9.5 bc 14.25 bc 26.75 bc 25.5 bc 9 Daconil Weather 2.0 fl oz/1000 ft.sup.2 2.75 abc 5.5 b 15.25 b 20.25 b 33.5 b 33.5 ab Stik LSD (P = .05) 3.05 8.63 13.92 14.19 14.99 16.12 .sup.xValues are means of four replications. Treatment means within columns followed by same letter do not significantly differ according to Fisher's LSD (p = 0.05) .sup.ySeverity assessed by percentage of disease on a scale to 0 to 100% based on treatment means.

(9) Disease progressed significantly faster in the untreated check compared to all other treatments. The 2 ounce rate of Daconil Action provided numerically greater control than the 2 ounce rate of Daconil Weather Stik. This can be explained by the nature of contact fungicides and the sporadic control associated with them when suppressing foliar diseases.

Example 2

(10) A study was conducted to evaluate pythium blight control on perennial ryegrass (Lolium perenne). The trial was arranged in a randomized complete block design with four replications. Daconil Weatherstik and Daconil Action were compared at 2.0 and 3.6 ounces per 1000 square foot of turf. All treatments were applied once on July 14th. One day after fungicide applications each individual plot was inoculated with Pythium aphanidermatum, covered with an evergreen cover, and irrigated 3 times daily to produce optimum Pythium blight conditions. Disease severity was visually assessed as percent disease 3, 5, 7, and 10 days post inoculation (Table 2).

(11) TABLE-US-00004 TABLE 2 Pythium Blight Severity in Daconil Action and Daconil Weatherstik Trial. Disease Severity.sup.a Treatment Rate Jul 18 Jul 20 Jul 22 Jul 25 1 Non-treated 10.0a 47.5a 48.8a 80.0a control 2 Daconil 3.6 FL OZ/ 5.0bcd 18.8cd 35.0ab 37.5c WeatherStik 1000 FT2 3 Daconil 2.0 FL OZ/ 6.3ab 20.0bc 28.8bcd 36.3cd WeatherStik 1000 FT2 4 Daconil Action 3.6 FL OZ/ 0.0e 8.8de 26.3bcd 17.5ef 1000 FT2 5 Daconil Action 2.0 FL OZ/ 1.3cde 7.5e 22.5b-e 18.8def 1000 FT2 .sup.aDisease severity was visually assessed as percent disease. Means followed by the same letter do not significantly differ (P = .05, Waller-Duncan).

(12) Disease progressed significantly faster in the untreated check compared to all other treatments. By July 25.sup.th 80% disease severity was observed in the untreated check. On July 25.sup.th the 2 ounce rate of Daconil Action provided significantly greater control than the 2 ounce rate of Daconil Weather Stik. On July 25.sup.th there was 18.8% disease severity in the 2 ounce rate of Daconil Action and 36.3% disease severity in the 2 ounce rate of Daconil Weatherstik.

Example 3

(13) A study was conducted to evaluate pythium blight control on perennial ryegrass. The trial was arranged in a randomized complete block design with four replications. Daconil Weatherstik and Daconil Action were compared at 2.0 and 3.6 ounces per 1000 square foot of turf. Treatments were applied on a 14 day schedule on 17 June, 24 June, 1 July, 15 July, 29 July, and 12 August. Percent turf area exhibiting pythium blight symptoms were assessed five times throughout the trial period (Table 3).

(14) TABLE-US-00005 TABLE 3 Pythium Blight Severity in Daconil Action and Daconil Weatherstik Trial. Product rate/ Pythium Blight (%).sup.1 Trt Chemical 1000 sq ft July 11 July 15 July 22 July 28 Aug 5 1 Untreated Check 28.1 a 33.8 a 87.8 a 78.0 a 84.5 a 2 Daconil Action 6SC 3.6 fl oz 11.3 c-f 6.3 d-i 35.0 h-l 50.0 c-g 39.0 g-k 3 RU 192514-11ZI ME 3.6 fl oz 12.0 c-j 26.3 ab 46.3 e-i 52.5 c-f 39.0 g-k 4 Daconil Action 6SC 2.0 fl oz 13.1 b-f 10.0 c-i 35.8 h-l 60.5 bc 63.0 b-d 5 Daconil Weather Stik 2.0 fl oz 16.3 b-d 26.3 ab 60.8 b-e 59.8 bc 59.3 c-e 6SC .sup.1Values are means of four replicates. Means followed by the same letter are not significantly different according to Waller-Duncan k-ratio t-test (k = 100).

(15) Disease progressed significantly faster in the untreated check compared to all other treatments. By July 22.sup.nd 87.8% disease severity was observed in the untreated check. On July 15.sup.th the 2 ounce rate of Daconil Action provided significantly better control of Pythium blight than the 2 ounce rate of Daconil Weatherstik. There was 10% incidence of Pythium blight in the Daconil Action and 26.3% incidence in Daconil Weatherstik. On July 22.sup.nd the 2 ounce rate of Daconil Action provided numerically greater control than the 2 ounce rate of Daconil Weather Stik. On July 22.sup.nd there was 35.8% disease severity in the 2 ounce rate of Daconil Action and 60.8% in the 2 ounce rate of Daconil Weatherstik.

(16) These data support the claim of enhanced control of Pythium blight in turf when acibenzolar-S-methyl is applied in combination with chlorothalonil. Control of Pythium blight is superior to chlorothalonil applied alone. Daconil Action is a unique blend of a multiple-site contact fungicide (chlorothalonil) with acibenzolar-S-methyl a systemic compound used for control of disease through induction of host plant resistance. The mode of action of acibenzolar-S-methyl mimics the natural systemic activated resistance (SAR) response found in most plant species. This SAR response does not involve direct activity against the target pathogens but relies on the plants natural defense mechanism.

(17) Although the invention has been described with reference to preferred embodiments and examples thereof, the scope of the present invention is not limited only to those described embodiments. As will be apparent to persons skilled in the art, modifications and adaptations to the above-described invention can be made without departing from the spirit and scope of the invention, which is defined and circumscribed by the appended claims. All publications cited herein are hereby incorporated by reference in their entirety for all purposes to the same extent as if each individual publication were specifically and individually indicated to be so incorporated by reference.