Application of Schiff base-containing compound in resisting plant pathogenic fungi and bactericide

Abstract

The invention provides application of a compound containing Schiff base in resisting plant pathogenic fungi and a bactericide, and belongs to the technical field of plant disease control. The compound L2 containing Schiff base provided by the invention has a good inhibition effect on plant pathogenic fungi, and plays a bactericidal role by destroying the integrity of hypha cell walls, inducing membrane lipid peroxidation, mitochondrial dysfunction and other multi-target mechanisms, thereby inhibiting the growth of pathogenic bacteria or killing the pathogenic bacteria. The result of the embodiment shows that the compound L2 shows remarkable broad-spectrum antibacterial activity, and the inhibition effect on fusarium graminearum is remarkably improved (EC50 is equal to 8.954 mg / L); the disease index of a compound L2 treatment group is only 6.67%, the prevention and treatment effect is 85.85%, and the prevention and treatment effect is obviously higher than that of a control agent carbendazim treatment group (69.15%) and a compound DSA treatment group (72.74%).

Description

Technical Field

[0001] The present invention relates to the technical field of plant disease prevention and control, in particular to application of a Schiff base-containing compound in resisting plant pathogenic fungi and a fungicide. Background Art

[0002] Wheat fusarium head blight is a global wheat disease caused by pathogenic fungi such as Fusarium graminearum. Its devastating effects include a 20% to 50% yield reduction in prevalent years, and in severe cases, even total crop failure, making it difficult to control. The pathogen can be spread through soil, straw, and seeds. Currently, commonly used chemical agents for wheat fusarium head blight control in my country include thiram, carbendazim, hexaconazole, and prothioconazole. However, after years of use, these agents have developed resistance to a certain degree. Therefore, the development of new, highly effective, low-resistance, and environmentally friendly antimicrobial agents is urgent.

[0003] Currently, biogenic fungicides are well known and developed in large quantities. Common biogenic fungicides include active molecules such as salicylic acid and coumarin derivatives, which have attracted much attention due to their environmental friendliness. However, the active molecules of existing common biogenic fungicides are insufficient in activity (EC 50 >25μg / mL) or poor chemical stability (e.g., easy photolysis or hydrolysis). To address these issues, the research team previously discovered an antibacterial active substance, 4-(diethylamino) salicylaldehyde (DSA), from the metabolites of Streptomyces KN37. Toxicity assays revealed that DSA was effective against Rhizoctonia solani but less effective against wheat fusarium, limiting its practical application. Summary of the Invention

[0004] The object of the present invention is to provide an application of a Schiff base-containing compound in resisting plant pathogenic fungi and a fungicide. The Schiff base-containing compound provided by the present invention has excellent broad-spectrum antibacterial effect, especially has a good inhibitory effect on wheat fusarium, and can be used to resist plant pathogenic fungi.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides an application of a Schiff base-containing compound in resisting plant pathogenic fungi. The Schiff base-containing compound has a chemical structure as shown in Formula I:

[0007]

[0008] Preferably, the plant pathogenic fungi include one or more of cotton wilt pathogen, cucurbit anthracnose pathogen, wheat fusarium sphaeroides, rice blast pathogen and cotton verticillium dahliae.

[0009] Preferably, the method for using the Schiff base-containing compound in combating plant pathogenic fungi comprises: applying a Schiff base-containing compound solution to cotton, melons, wheat or rice.

[0010] Preferably, the Schiff base compound solution is applied to the wheat and rice during the flowering stage and / or full flowering stage.

[0011] Preferably, the method of applying the Schiff base compound solution is spraying; the application amount of the Schiff base compound in the Schiff base compound solution is 750 to 3000 mg / hm2. 2 .

[0012] Preferably, the Schiff base compound solution is applied to cotton before the disease occurs or at the early stage of the disease.

[0013] Preferably, the method of applying the Schiff base-containing compound solution is root irrigation; the application amount of the Schiff base-containing compound in the Schiff base-containing compound solution is 0.2 to 2.4 mg per plant.

[0014] Preferably, the Schiff base compound solution is applied to melons before the disease occurs or at the early stage of the disease.

[0015] Preferably, the application amount of the Schiff base-containing compound in the Schiff base-containing compound solution is 0.5 to 2 g / mu.

[0016] The present invention also provides a fungicide, comprising a pesticide adjuvant and a Schiff base-containing compound; the Schiff base-containing compound has a chemical structure as shown in Formula I in the above technical solution.

[0017] The present invention provides a use of a Schiff base-containing compound in resisting plant pathogenic fungi, wherein the Schiff base-containing compound has a chemical structure as shown in Formula I. The Schiff base-containing compound provided by the present invention has a good inhibitory effect on plant pathogenic fungi, exerting a fungicidal effect through multiple target mechanisms such as destroying the integrity of the mycelial cell wall, inducing membrane lipid peroxidation and mitochondrial dysfunction, thereby inhibiting the growth of pathogens or killing pathogens. The results of the examples show that compound L2 exhibits significant broad-spectrum antibacterial activity, and the inhibitory effect on wheat fusarium is significantly improved (EC 50 =8.954 mg / L); The results of the potted plant test showed that compound L2 had a certain therapeutic effect on wheat fusarium head blight. Applying the drug after infection could prevent the fusarium head blight from further infecting the wheat ears. The disease index of the compound L2-treated group was only 6.67%, and the control effect was 85.85%, which was significantly higher than that of the control drug carbendazim-treated group (69.15%). At the same time, the control effect of the compound L2-treated group was significantly better than that of the compound DSA-treated group (72.74%). BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the NMR spectrum of compound L2 prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0019] The present invention provides an application of a Schiff base-containing compound in resisting plant pathogenic fungi. The Schiff base-containing compound has a chemical structure as shown in Formula I:

[0020]

[0021] In the present invention, the Schiff base-containing compound is (Z)-2-(4-diethylamino)-2-hydroxybenzylidene)amino)pyridin-4-ol, referred to as compound L2. Compound L2 has a good inhibitory effect on plant pathogenic fungi and can be used to resist plant pathogenic fungi.

[0022] In the present invention, the preparation method of the compound L2 preferably comprises: mixing 4-(diethylamino) salicylaldehyde, 2-amino-4-hydroxypyridine and an alcohol solvent, and performing a dehydration condensation reaction to obtain the compound L2.

[0023] In the present invention, the molar ratio of 4-(diethylamino)salicylaldehyde to 2-amino-4-hydroxypyridine is preferably 1 to 3:1, more preferably 1 to 2:1. Controlling the molar ratio of 4-(diethylamino)salicylaldehyde to 2-amino-4-hydroxypyridine within the above range is more conducive to improving the yield and purity of compound L2.

[0024] In the present invention, the alcohol solvent is preferably methanol. Methanol is used as the alcohol solvent in the present invention, which has good solubility for 4-(diethylamino)salicylaldehyde and 2-amino-4-hydroxypyridine.

[0025] In the present invention, the ratio of the amount of 4-(diethylamino)salicylaldehyde to the volume of the alcoholic solvent is preferably 5 mmol:(10-50) mL, more preferably 5 mmol:(20-30) mL. By controlling the ratio of the amount of 4-(diethylamino)salicylaldehyde to the volume of the alcoholic solvent within the above range, the present invention can fully dissolve 4-(diethylamino)salicylaldehyde and 2-amino-4-hydroxypyridine.

[0026] The present invention does not particularly limit the method for mixing the 4-(diethylamino) salicylaldehyde, 2-amino-4-hydroxypyridine and alcoholic solvent, as long as the 4-(diethylamino) salicylaldehyde and 2-amino-4-hydroxypyridine are completely dissolved in the alcoholic solvent. In an embodiment of the present invention, the method for mixing the 4-(diethylamino) salicylaldehyde, 2-amino-4-hydroxypyridine and alcoholic solvent can be: mixing 4-(diethylamino) salicylaldehyde with an alcoholic solvent to obtain a 4-(diethylamino) salicylaldehyde solution; and adding 2-amino-4-hydroxypyridine dropwise to the 4-(diethylamino) salicylaldehyde solution. The present invention does not particularly limit the rate of the addition.

[0027] In the present invention, the dehydration condensation reaction temperature is preferably 25 to 60° C., more preferably 30 to 40° C.; the dehydration condensation reaction time is preferably 2 to 12 hours, more preferably 4 to 6 hours. At the above temperature and time, the present invention can fully react 4-(diethylamino)salicylaldehyde and 2-amino-4-hydroxypyridine.

[0028] In the present invention, the system obtained after the dehydration condensation reaction is preferably dried and then purified by column chromatography to obtain compound L2.

[0029] In the present invention, the drying method is preferably evaporation under reduced pressure. The present invention has no particular limitation on the operation method of evaporation under reduced pressure, and a conventional evaporation under reduced pressure method can be used. In an embodiment of the present invention, the evaporation under reduced pressure method can be a rotary evaporator that spin-dries the system obtained after the dehydration condensation reaction.

[0030] In the present invention, the solid phase extraction column for column chromatography purification is preferably neutral alumina. The present invention uses neutral alumina for column chromatography purification, which is more conducive to improving the purity of compound L2.

[0031] In an embodiment of the present invention, the eluent for column chromatography purification is preferably petroleum ether and ethyl acetate. In an embodiment of the present invention, the volume ratio of petroleum ether to ethyl acetate is preferably 20:1.

[0032] In the present invention, the plant pathogenic fungi preferably include one or more of cotton wilt pathogen, cucurbit anthracnose pathogen, wheat head blight pathogen, rice blast pathogen, and cotton verticillium dahliae pathogen. Compound L2 provided by the present invention has a good inhibitory effect on plant pathogenic fungi and thus has a broad-spectrum antifungal effect against the above-mentioned multiple plant pathogenic fungi.

[0033] In the present invention, the method for using the Schiff base-containing compound in resisting plant pathogenic fungi preferably comprises: applying a Schiff base-containing compound solution to cotton, melons, wheat or rice.

[0034] In the present invention, the Schiff base compound solution is preferably applied to wheat and rice during the flowering stage and / or the peak flowering stage. The present invention can reduce the incidence of wheat scab by applying the Schiff base compound solution to wheat and rice during the flowering stage and / or the peak flowering stage.

[0035] In the present invention, the method of applying the Schiff base compound solution is preferably spraying. In the present invention, the application amount of the Schiff base compound in the Schiff base compound solution is preferably 750 to 3000 mg / hm2. 2 As an embodiment of the present invention, the dosage of the Schiff base-containing compound in the Schiff base-containing compound solution can be 750 mg / hm 2 , 800mg / hm 2 , 850mg / hm 2 , 900mg / hm 2 , 950mg / hm 2 , 1000mg / hm 2 , 1500mg / hm 2 , 2000mg / hm 2 , 2500mg / hm 2 or 3000mg / hm2 2 The present invention has no particular limitation on the concentration of the Schiff base compound solution, and the concentration can be adjusted as needed to achieve an application amount of 750 to 3000 mg / hm2 of the Schiff base compound solution. 2 The present invention controls the concentration and application amount of the Schiff base-containing compound solution within the above ranges, which can achieve a good antibacterial effect. In an embodiment of the present invention, the concentration of the Schiff base-containing compound solution can be 100 mg / L.

[0036] In the present invention, the Schiff base compound solution is preferably applied to cotton before or at the early stage of the disease. The present invention can reduce the incidence of cotton damping-off and cotton Verticillium wilt by applying the Schiff base compound solution to cotton before or at the early stage of the disease.

[0037] In the present invention, the method of applying the Schiff base-containing compound solution is preferably root irrigation. The present invention does not specifically limit the operation method of the root irrigation, and the conventional root irrigation method can be used. In the present invention, the application amount of the Schiff base-containing compound in the Schiff base-containing compound solution is preferably 0.2 to 2.4 mg / plant. As an embodiment of the present invention, the application amount of the Schiff base-containing compound in the Schiff base-containing compound solution can be 0.2 mg / plant, 0.5 mg / plant, 1 mg / plant, 1.5 mg / plant, 2 mg / plant or 2.4 mg / plant. The present invention controls the application amount of the Schiff base-containing compound solution within the above range, which can have a better antibacterial effect.

[0038] In the present invention, the Schiff base-containing compound solution is preferably applied to melons before or in the early stages of a disease. Applying the Schiff base-containing compound solution to melons before or in the early stages of a disease can reduce the incidence of anthracnose in melons. The present invention does not specifically limit the specific type of melon; any conventional melon plant can be used.

[0039] In the present invention, the application amount of the Schiff base-containing compound in the Schiff base-containing compound solution is preferably 0.5 to 2 g / mu. As one embodiment of the present invention, the application amount of the Schiff base-containing compound in the Schiff base-containing compound solution can be 0.5 g / mu, 1 g / mu, 1.5 g / mu, or 2 g / mu. By controlling the concentration and application amount of the Schiff base-containing compound solution within the above ranges, the present invention can achieve a good antibacterial effect.

[0040] The present invention also provides a fungicide, comprising a pesticide adjuvant and the Schiff base-containing compound; the Schiff base-containing compound has a chemical structure as shown in Formula I.

[0041] The present invention has no particular limitation on the mass ratio of the pesticide adjuvant to the Schiff base-containing compound, and the ratio can be adjusted as needed.

[0042] In the present invention, the pesticide adjuvant preferably includes one or more of sodium carboxymethyl cellulose, hydroxypropyl methyl cellulose, lignin sulfonate, sodium dodecyl sulfonate, alcohol ether carboxylates, alkyl phosphonates, alkyl naphthalene sulfonates, silicon dioxide, clay, kaolin and diatomaceous earth.

[0043] The present invention can achieve the prevention and treatment effects of multiple plant diseases by combining the pesticide adjuvant with the Schiff base-containing compound.

[0044] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0045] Example 1

[0046] A Schiff base-containing compound is used in resisting plant pathogenic fungi, wherein the Schiff base-containing compound has a chemical structure as shown in Formula I:

[0047]

[0048] Hereinafter, the Schiff base-containing compound represented by Formula I is referred to as Compound L2;

[0049] The preparation method of the compound L2 is as follows: 4-(diethylamino) salicylaldehyde (0.97 g, 5 mmol) is dissolved in 30 mL of methanol, and then 2-amino-4-hydroxypyridine (0.55 g, 5 mmol) is added dropwise to dissolve and then condensed and refluxed for 4 hours. After the reaction is completed, the product is dried using a rotary evaporator, and the obtained crude product is purified by column chromatography on neutral alumina, and the eluent is petroleum ether and ethyl acetate, and the volume ratio of the petroleum ether and ethyl acetate is 20:1, to obtain 0.5 g of a bright yellow solid, which is compound L2.

[0050] The NMR spectrum of compound L2 prepared in this example is as follows Figure 1 As shown. Figure 1 It can be seen that the compound L2 prepared in the present invention has a chemical structure as shown in Formula I, and its name is (Z)-2-(4-diethylamino)-2-hydroxybenzylidene)amino)pyridin-4-ol.

[0051] Test Example 1

[0052] Inhibitory effect of compound L2 prepared in Example 1 on five pathogenic fungi (in-dish test)

[0053] After the PDA solid culture medium is melted, it is cooled to 45°C and mixed with the filter-sterilized (0.22 μm filter membrane) compound L2 solution to prepare drug-containing culture medium plates with concentrations of 5 mg / L, 10 mg / L, 15 mg / L, 20 mg / L and 25 mg / L as the treatment group. Among them, the culture medium plate with a compound L2 solution concentration of 0 mg / L is used as the control group. A 5 mm diameter pathogen cake is inoculated in the center of each culture medium plate and cultured in the dark at 28°C for 3 to 7 days until the mycelium of the control group fills the culture dish. The colony diameter is measured by the cross-cross method, the mycelium growth inhibition rate is calculated, and then the EC is calculated. 50The calculation of the inhibition rate is shown in formula (1):

[0054] Inhibition rate (%) = ((diameter of control group - 5 mm) - (diameter of treatment group - 5 mm)) / ((diameter of control group

[0055] -5mm))×100 type (1)

[0056] The inhibitory effect of compound L2 on five pathogenic fungi was determined, as shown in Table 1.

[0057] Table 1 Toxicity of compound L2 to five plant pathogenic fungi

[0058] pathogens Toxicity curve <![CDATA[R 2 ]]> <![CDATA[EC 50 (mg / L)]]> 95% confidence interval Cotton wilt pathogen y=1.237x-1.803 0.978 28.663 25.260-32.855 Cucurbit anthracnose y=1.033x-1.290 0.999 17.741 15.245-20.541 Wheat Gibberella y=1.379x-1.313 0.999 8.954 7.697-10.213 Rice blast fungus y=1.390x-1.702 0.999 16.752 14.919-18.736 Verticillium dahliae y=1.390x-1.8005 0.997 19.861 17.746-22.225

[0059] As can be seen from Table 1, compound L2 has the strongest toxicity to wheat fusarium, EC 50 The value is 8.954 mg / L, while the toxicity to cotton wilt is relatively weak, EC 50 The value was 28.663 mg / L. It also had a good inhibitory effect on the other three pathogenic fungi.

[0060] Example 2

[0061] Control effect of compound L2 prepared in Example 1 on wheat scab (pot test)

[0062] The wheat variety used for the test was Xindong No. 18. After sowing, the wheat was watered normally until the flowering stage. The fusarium graminearum conidia concentration was 1×10 3 Each ear was inoculated with 20 μL of the compound (100 mg / mL). Twenty ears were treated per pot. 80 mL of the compound (80 mL / pot) was sprayed 24 hours after inoculation. The concentration of compound L2 was 100 mg / L, and three pots were replicated per treatment. The disease status of the wheat ears was investigated 14 days later, and the control efficacy was calculated.

[0063] Grading method:

[0064] Level 0: no symptoms;

[0065] Level 1: Only the inoculated spikelets are diseased, or some adjacent spikelets are diseased, but the lesions do not extend to the spike axis;

[0066] Level 2: The spikelets are diseased and the diseased spikelets account for less than 25% of the total spikelets;

[0067] Level 3: The spikelets are diseased, and the diseased spikelets account for 25% to 50% of the total spikelets;

[0068] Level 4: The spikelets are diseased, and the diseased spikelets account for more than 50% of the total spikelets.

[0069] The disease index was calculated according to formula (2); the control effect was calculated according to formula (3). The results are shown in Table 2.

[0070]

[0071] Comparative Example 1

[0072] The difference from Example 2 is that L1 is used instead of L2, and the rest of the operation method is the same as Example 2. Wherein, L1 is a bis-Schiff base compound, 5-diethylamino-2-[(Z)-{2-[(E)-4-diethylamino-2-hydroxybenzylideneamino]cyclohexylmethylene}amino]phenol, having a chemical structure shown in Formula II:

[0073]

[0074] Comparative Example 2

[0075] The difference from Example 2 is that DSA is used instead of L2, and the rest of the operation method is the same as Example 2. Wherein, DSA is 4-(diethylamino) salicylaldehyde, which has a chemical structure shown in Formula III:

[0076]

[0077] Comparative Example 3

[0078] The difference from Example 2 is that carbendazim is used instead of L2, and the rest of the operation method is the same as that of Example 2.

[0079] Comparative Example 4

[0080] The difference from Example 2 is that clean water is used instead of L2, and the rest of the operation method is the same as Example 2, which serves as a blank control.

[0081] Test Example 2

[0082] After the treatment using the methods of Example 2 and Comparative Examples 2 to 4, the control effect test results obtained are shown in Table 2.

[0083] Table 2 The control effect of different pesticides on wheat scab (pot test)

[0084]

[0085] Note: The numbers in Table 2 are the averages of three replicates, and different lowercase letters after the numbers indicate significant differences (p < 0.05).

[0086] The results of the potted test showed that compound L2 has a certain therapeutic effect on wheat ergot. Applying the drug after infection can prevent the ergot fungus from further infecting the wheat ears. The disease index of the group treated with compound L2 was only 6.67%, and the prevention and control effect reached 85.85%, which was significantly higher than that of the group treated with the control agent carbendazim (69.15%). At the same time, the prevention effect of the group treated with compound L2 was significantly better than that of the group treated with compound DSA (72.74%).

[0087] Example 3

[0088] Field efficacy test of compound L2 prepared in Example 1 for controlling wheat scab

[0089] The test site was a wheat field at the Shihezi University Experimental Field in Shihezi City, Xinjiang. The field experiment was conducted with four treatments, namely compound L2, DSA, carbendazim, and water control. The area of ​​each area was 20m 2 Each treatment was replicated four times in a randomized block arrangement. The first application occurred during the wheat flowering stage and the second application occurred during the peak flowering stage, with a water rate of 50 L / mu. Wheat was surveyed in the late milky stage, with five diagonal sampling points in each plot and 100 ears surveyed at each point. The number of diseased ears and disease grade were recorded, and control efficacy was calculated.

[0090] Grading standards:

[0091] Level 0: All ears are disease-free;

[0092] Level 1: The diseased ear area accounts for less than one-quarter of the entire ear area;

[0093] Level 3: The diseased ear area accounts for one quarter to one half of the entire ear area;

[0094] Level 5: The diseased ear area accounts for one-half to three-quarters of the entire ear area;

[0095] Level 7: The diseased ear area accounts for more than three-quarters of the entire ear area;

[0096] The diseased ear rate was calculated according to formula (4). The results are shown in Table 3.

[0097]

[0098] Table 3 Results of field trials on the efficacy of different pesticides in controlling wheat scab

[0099]

[0100] As shown in Table 3, compound L2 exhibited a significant control effect against wheat scab, achieving a 78.15% efficacy, significantly superior to the control group treated with carbendazim (64.75%) and the precursor DSA (62.79%). Furthermore, compound L2 significantly reduced the incidence of wheat scab, with the L2-treated group exhibiting only a 7.85% incidence, significantly lower than the blank control group and the control group.

[0101] Test Example 3

[0102] In order to compare the inhibitory effect of compound L2 on five pathogenic fungi, compounds L1, L3, L4, DSA and CK (blank control) were used as agents to replace L2 respectively, and the operation steps were the same as those in Test Example 1. Among them, L3 has a chemical structure shown in Formula IV, and L4 has a chemical structure shown in Formula V:

[0103]

[0104] The inhibition rate was calculated according to formula (1) and the results are shown in Table 4.

[0105] Table 4 Inhibitory effects of different agents on wheat fusarium

[0106] deal with Average colony diameter (mm) Average inhibition rate (%) L1 45.36±0.65 32.51 L2 21.39±1.08 68.17 L3 42.09±1.14 37.38 L4 34.16±1.09 49.17 DSA 49.06±0.60 27.01 CK 67.21±0.79 /

[0107] As can be seen from Table 4, only one compound, L2, showed a significantly improved inhibitory effect (68.16%) on wheat fusarium head blight, which was 2.5 times higher than the inhibition rate of DSA (27.01%). This shows that compound L2 has a good inhibitory effect on wheat fusarium head blight.

[0108] From the above results, it can be seen that the compound L2 provided by the present invention has excellent antibacterial activity against plant pathogenic fungi, such as cotton wilt, cucurbit anthracnose, wheat scab, rice blast and cotton verticillium dahlia, showing significant broad-spectrum antibacterial activity. In particular, the inhibitory effect on wheat scab was significantly improved (EC 50 =8.954mg / L); compounds containing Schiff bases can effectively inhibit the growth of pathogenic mycelium, and the control effect on wheat fusarium is>85%, which can significantly reduce the incidence of wheat fusarium.

[0109] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. Use of a Schiff base-containing compound in resisting plant pathogenic fungi, characterized in that: The Schiff base-containing compound has a chemical structure as shown in Formula I:

2. The use according to claim 1, characterized in that The plant pathogenic fungi include one or more of cotton wilt pathogen, cucurbit anthracnose pathogen, wheat fusarium sphaeroides, rice blast pathogen and cotton verticillium dahliae pathogen.

3. The use according to claim 1 or 2, characterized in that The method for applying the Schiff base-containing compound in resisting plant pathogenic fungi comprises: applying a Schiff base-containing compound solution to cotton, melons, wheat or rice.

4. The use according to claim 3, characterized in that The Schiff base compound solution is applied to the flowering stage and / or full flowering stage of wheat and rice.

5. The use according to claim 4, characterized in that The method of applying the Schiff base compound solution is spraying; the application amount of the Schiff base compound in the Schiff base compound solution is 750 to 3000 mg / hm 2 .

6. The use according to claim 3, characterized in that The Schiff base compound solution is applied to the cotton before the disease occurs or at the early stage of the disease.

7. The use according to claim 6, characterized in that The method for applying the Schiff base-containing compound solution is root irrigation; the application amount of the Schiff base-containing compound in the Schiff base-containing compound solution is 0.2-2.4 mg / plant.

8. The use according to claim 3, characterized in that The Schiff base compound solution is applied to melons before the disease occurs or at the early stage of the disease.

9. The use according to claim 8, characterized in that The application amount of the Schiff base-containing compound in the Schiff base-containing compound solution is 0.5 to 2 g / mu.

10. A fungicide comprising a pesticide adjuvant and a Schiff base-containing compound; the Schiff base-containing compound has the chemical structure shown in Formula I of claim 1.

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