Fungicide for the treatment of fungal pathogens causing mycotoxins

Abstract

Fungal diseases and resulting mycotoxins are reduced or eliminated from plant tissues during crop growth or post-harvest during storage by treatment with an aqueous spray solution prepared from a fungicide composition of a bicarbonate salt containing a surfactant system to reduce the surface tension and contact angle of the spray solution on the plant surface thereby controlling the crystal size of the bicarbonate and re-distribution and adherence of the crystals to the crop vegetation and/or grains.

Claims

1. A method for treatment of crop vegetation to control, reduce or eliminate mycotoxins comprising: applying to the crop vegetation from 0.5 to 10 kilograms per hectare, an aqueous spray solution of a fungicide composition comprising a bicarbonate salt and a surfactant system comprising two or more surfactants including sodium dodecyl sulphosuccinate and sodium lauryl sulfate which, when applied to the crop vegetation, results in crystals of the bicarbonate salt on a plant surface of the crop vegetation of a particle size of less than 0.4 mm upon evaporation of water of the aqueous spray solution; and wherein one surfactant of the surfactant system acts as a dispersant and controls the particle size of the crystals of the bicarbonate salt and another surfactant of the surfactant system acts as a spreader and sticker to distribute the aqueous spray solution and the bicarbonate salt crystals that derive therefrom across the plant surface of the crop vegetation.

2. The method according to claim 1, wherein the crop vegetation comprises cereals or rice.

3. The method according to claim 2, wherein the crop vegetation comprises wheat and the mycotoxins comprise Fusarium species.

4. The method according to claim 1, wherein the aqueous spray solution has a surface tension in a range of 25-45 nN/m and has a contact angle of less than 60.

5. The method according to claim 4, wherein the surface tension is from 28 to 32 nM/m.

6. The method according claim 1, wherein the bicarbonate salt is an alkali metal bicarbonate.

7. The method according to claim 6, wherein the alkali metal bicarbonate is sodium bicarbonate or potassium bicarbonate or mixtures thereof.

8. The method according claim 1, wherein the bicarbonate salt is used in combination with an alkali metal or ammonium carbonate.

9. A method for treatment of crop vegetation comprising wheat to reduce or eliminate Fusarium species, the method comprising: applying to the crop vegetation comprised of wheat from 0.5 to 10 kilograms per hectare of an aqueous spray solution of a fungicide composition comprising a bicarbonate salt and a surfactant system comprising sodium dodecyl sulphosuccinate and sodium lauryl sulfate.

10. The method according to claim 9, wherein the aqueous spray solution has a surface tension in a range of 25-45 nN/m and has a contact angle of less than 60.

11. The method according to claim 10, wherein the surface tension is from 28 to 32 nM/m.

12. The method according to claim 9, wherein the bicarbonate salt is an alkali metal bicarbonate.

13. The method according to claim 12, wherein the alkali metal bicarbonate is sodium bicarbonate or potassium bicarbonate or mixtures thereof.

14. The method according to claim 9, wherein the bicarbonate salt is used in combination with an alkali metal or ammonium carbonate.

15. The method according to claim 4, wherein the contact angle is in the range of 35-60.

16. The method according to claim 10, wherein the contact angle is in the range of 35-60.

17. The method according claim 4, wherein the bicarbonate salt is an alkali metal bicarbonate.

18. The method according claim 5, wherein the bicarbonate salt is an alkali metal bicarbonate.

19. The method according claim 10, wherein the bicarbonate salt is an alkali metal bicarbonate.

20. The method according claim 11, wherein the bicarbonate salt is an alkali metal bicarbonate.

Description

EXAMPLE 1

(1) Potassium bicarbonate was dissolved in water at a concentration of 4.25 wt % and droplets were deposited on an artificial hydrophobic (para-film) surface.

(2) A formulation was prepared containing 85 wt % potassium bicarbonate and 15 wt % of a surfactant combination of sodium dioctylsulfosuccinate and sodium laurylsulfate. The formulation was dissolved in water at a concentration of 5.0 wt %. Again, droplets were deposited on the artificial hydrophobic surface.

(3) FIGS. 1 and 2 show the residual crystals of potassium bicarbonate remaining on the surface after evaporation of the water. Comparison of the Figures clearly shows the smaller more evenly distributed crystals derived from the formulation containing the surfactant mixture.

EXAMPLE 2

(4) Spring wheat, Triticum aestivum was grown in pots and sprayed, at ear stage, with the surfactant containing formulation used in Example 1 at three different concentrations, 1000, 3000 and 5000 ppm, shortly before spraying the plants were inoculated with a Fusarium graminearum spore suspension. The efficacy of the treatment was assessed using a photographic scale and compared with untreated ears.

(5) The sprayers were roughly calibrated and amount per pot was weighed to ensure that each pot received around the same amount of spray solution. For the treatments this varied from 24.2 to 27.1 g.

(6) Fusarium graminearum spore suspension from Arbiotech, Saint Gilles, France was allowed to melt (supplied frozen), diluted to 105 mL- and Tween 20 added and sprayed onto the plants, the average dose per pot was 25.2 mL.

(7) The plants were placed in the dark in a controlled environment room after inoculation and remained there for 2 days. The temperatures were between 24.6 and 25.8 C. and the humidity was between 77 and 90%. After this the plants were placed in a greenhouse and supported by canes and string lines.

(8) When effects were visible visual estimations of % effect were carried out for every mature ear (small immature ears were ignored) using a scale which categorised ears into 9, 5, 10, 20, 30, 50, 60, 80 and 100% affected. This was done at 18, 21, 24 and 28 days after application of the fungicide. Finally the ears were cut and weighed on the assumption that dead ears would have lower weight.

(9) The following parameters were measured. Number of ears per pot. Total infection score per pot. Number of infected ears per pot. Average disease % per ear per pot and pre-treatment Disease incidence per treatment Fresh weight of ears per pot, per ear per pot and per ear per treatment Ear weight is also given for extra non-inoculated pots. % incidence and % infection are also given as graphs. The results are plotted in FIGS. 3 and 4.

EXAMPLE 3

(10) The spray solution of the surfactant containing fungicide composition employed in Example 2 was tested for the control of mycotoxins formed due to ear blight (Fusarium spp.) in winter wheat. The fungicide composition was applied to Cubus winter wheat at various treatment rates and the number of healthy ears of wheat per 200 plants was determined 36 days after application of the fungicide composition.

(11) The results were as follows.

(12) TABLE-US-00002 Treatment Level Kg/ha Healthy Ears per 200 plants 0 141 3 155 5 150 7.5 162

(13) The crop plots were harvested and the samples analysed for the presence of the mycotoxins Deoxynivalenol (DON) and Zearalenone (ZEA) with the following results.

(14) TABLE-US-00003 Treatment Level DON ZEA Kg/ha Mg/kg Mg/kg 0 4.2 4000 3 4 5000 5 4.5 2200 7.5 1.5 1100

EXAMPLE 4

(15) A trial was conducted in the field to evaluate the efficacy and crop safety of the product of the invention, in relation to Fusarium ear bight on winter wheat. Trials were performed with the product as employed in Example 1 stand-alone and in a mixture with the commercial fungicide FOLICUR. The performance was compared to the commercial fungicides FOLICUR and DON Q. The trial site was inoculated with Fusarium culmorum spore suspension at the beginning of flowering.

(16) The assessment was conducted on 100 randomly chosen ears of wheat per plot. The untreated control showed a visual assessed pest severity of 21% (calculated 20.49%) and a calculated pest incidence of 30.3% with Fusrium culnorum (FUSACU).

(17) The following treat levels were tested.

(18) TABLE-US-00004 Treatment Name Form Cone/Form Unit Rate Unit Untreated control Invention 850 g/kg 3 kg/ha Invention 850 g/kg 5 kg/ha Invention 850 g/kg 7 kg/ha FOLICUR 250 g/l 1 l/ha DON Q 704 g/kg 1.1 kg/ha Invention 850 g/kg 3 kg/ha FOLICUR 250 g/l 1 l/ha

(19) The product of the invention applied at 7 kg/ha exhibited 64.542% control of Fusarium culmorum. The reference product DON Q applied at 1.1 kg/ha gave 56.0% control of FUSACU and Folicur at 1 l/ha gave 52.4% control.

(20) At assessment time clear symptoms of Fusarium culmorum were observed.

(21) The highest control of Fusarium culmorum was obtained with the product of the invention mixed with FOLICUR applied at l/ha the product of the invention applied at 3 kg/ha. The control was 64.61%, followed closely by the product of the invention applied at 7 kg/ha with 64.52%. The reference DON Q applied at 1.1 kg/ha controlled FUSACU with 56.0%.

(22) The results were as follows.

(23) TABLE-US-00005 Form Disease EFFICACY Disease Treatment Cone/Form Rate Incidence % Severity Name Unit Unit % untreated % Untreated 30.3 0.00 20.49 Control Invention 850 g/kg 3 kg/ha 22 41 11.89 Invention 850 g/kg 5 kg/ha 23 44 11.37 Invention 850 g/kg 7 kg/ha 18 64 7.23 FOLICUR 250 g/l 1 1/ha 20 52 9.75 DON Q 704 g/kg 1.1 kg/ha 21 56 9.00 Invention 850 g/kg 3 kg/ha 21 53 9.47 Invention 850 g/kg 3 kg/ha Invention 850 g/kg 3 kg/ha 17 64 7.01 FOLICUR 250 g/l 1 1/ha

(24) After harvest samples were analysed for mycotoxin levels Vomitoxin (DON) and Zaeraleone (ZEA). The untreated sampled showed a Voritoxin level of 1.87 mg/kg. The lowest mycotoxin level was measured for the reference FOLICUR with 0.26 mg/kg for DON. The level of ZEA in the untreated control was under the measurable range 10.00 g/kg.

(25) The results were as follows.

(26) TABLE-US-00006 Form Treatment Cone/Form DON ZEA g/kg lower Name Unit Rate Unit (mg/kg grain than Untreated 1.87 10.00 Control Invention 850 g/kg 3 kg/ha 0.82 10.00 Invention 850 g/kg 5 kg/ha 0.57 10.00 Invention 850 g/kg 7 kg/ha 0.76 10.00 FOLICUR 250 g/l 1 l/ha 0.26 10.00 DON Q 704 g/kg 1.1 kg/ha 0.43 10.00 Invention 850 g/kg 3 kg/ha 0.86 10.00 Invention 850 g/kg 3 kg/ha Invention 850 g/kg 3 kg/ha 0.6 10.00 FOLICUR 250 g/l 1 l/ha