Application of fungicide in prevention and treatment of pepper sclerotinia disease and a method for preventing and treating pepper sclerotinia disease

Abstract

The application belongs to the technical field of crop disease and pest control, and particularly relates to application of a fungicide in prevention and treatment of pepper phoma disease and a method for preventing and treating pepper phoma disease. The application provides application of a fungicide in prevention and treatment of pepper phoma disease, wherein the fungicide comprises hexaconazole and / or azoxystrobin; the pepper varieties include resistant varieties and susceptible varieties; the use concentration of the hexaconazole is 20-100 mu g / mL; and the use concentration of the azoxystrobin is 20-100 mu g / mL. It is found that the hexaconazole and the azoxystrobin have good comprehensive prevention and treatment effects on the resistant and susceptible varieties, the resistant varieties can be combined with the fungicide in a joint mode to manage the disease in the prevention and treatment of the phoma disease, the disease phoma disease incidence can be effectively reduced, the use amount of the fungicide can be reduced, and the plant can be stably grown; and the root morphology and the antioxidant enzyme regulation of the resistant varieties are better than those of the susceptible varieties, and the protection activity prevention and treatment effect of the resistant varieties is significantly higher than that of the susceptible varieties.

Description

Technical Field

[0001] This invention belongs to the field of crop disease and pest control technology, specifically relating to the application of fungicides in the control of white mold disease in peppers and a method for controlling white mold disease in peppers. Background Technology

[0002] Chili peppers, belonging to the genus Capsicum, are annual or short-lived perennial herbaceous plants. The fruit is typically conical or oblong, green when immature, turning bright red, green, or purple when ripe, with red being the most common. The spiciness of chili peppers comes from capsaicin in the pericarp, which enhances appetite. Chili peppers have the highest vitamin C content among vegetables.

[0003] White mold disease of peppers, caused by *Sclerotium rolfsii* Sacc., is a serious soil-borne disease. The roots are the primary organ directly exposed to the fungus and the first and most direct site of infection. In recent years, with the continuous expansion of pepper production, the incidence and affected area have been increasing year by year, and it has now become one of the major field diseases affecting normal pepper production. There are many methods for controlling white mold disease, mainly including chemical control, field agricultural management, biological control, and planting resistant varieties. Currently, chemical control remains the primary measure for controlling white mold disease in the field. However, there are currently no pesticides registered for controlling white mold disease in peppers in China, nor are there any screened and publicly promoted resistant pepper varieties. Therefore, finding fungicides to control white mold disease is particularly important. Summary of the Invention

[0004] The purpose of this invention is to provide the application of fungicides in the prevention and control of white mold disease in peppers and a method for preventing and controlling white mold disease in peppers, so as to effectively prevent and control white mold disease in peppers.

[0005] To achieve the above objectives, the present invention provides the application of fungicides in the control of white mold disease in peppers, wherein the fungicides include hexaconazole and / or pyraclostrobin;

[0006] The chili pepper varieties include disease-resistant varieties and susceptible varieties; the disease-resistant varieties have a disease index of ≤45.8 for white rot; the susceptible varieties have a disease index of >45.8 for white rot.

[0007] The concentration of hexaconazole used is 20–100 μg / mL;

[0008] The concentration of azoxystrobin used is 20–100 μg / mL.

[0009] Preferably, the disease-resistant varieties include one or more of Qianjiao No. 8, Yanjiao 485, and Yanjiao 435;

[0010] The susceptible varieties include one or more of the following: Xiangla No. 7, Xiangla No. 14, Zunla No. 9, Layan No. 3, Layan No. 12, and Layan No. 101.

[0011] Preferably, the fungicide inhibits the growth of the pathogen causing white mold disease of pepper, thereby preventing and controlling white mold disease of pepper.

[0012] Preferably, the hexaconazole is formulated as a 95 wt.% powder; the azoxystrobin is formulated as a 98 wt.% powder.

[0013] The present invention also provides a method for preventing white mold disease of peppers by applying a fungicide to peppers when transplanting pepper seedlings to the field;

[0014] The fungicide includes hexaconazole and / or pyraclostrobin;

[0015] The chili pepper varieties include disease-resistant varieties and susceptible varieties; the disease-resistant varieties have a disease index of ≤45.8 for white rot; the susceptible varieties have a disease index of >45.8 for white rot.

[0016] The concentration of hexaconazole used is 20-100 μg / mL, and the application rate is 5 mL / plant;

[0017] The concentration of azoxystrobin used is 20–100 μg / mL, and the application rate is 5 mL / plant.

[0018] Preferably, the fungicide is applied by root irrigation.

[0019] Preferably, the disease-resistant varieties include one or more of Qianjiao No. 8, Yanjiao 485, and Yanjiao 435;

[0020] The susceptible varieties include one or more of the following: Xiangla No. 7, Xiangla No. 14, Zunla No. 9, Layan No. 3, Layan No. 12, and Layan No. 101.

[0021] The present invention also provides a method for treating white mold disease of peppers, wherein a fungicide is applied to peppers 24 hours after they are infected with the white mold disease pathogen.

[0022] The fungicide includes hexaconazole and / or pyraclostrobin;

[0023] The chili pepper varieties include disease-resistant varieties and susceptible varieties; the disease-resistant varieties have a disease index of ≤45.8 for white rot; the susceptible varieties have a disease index of >45.8 for white rot.

[0024] The concentration of hexaconazole used is 20-100 μg / mL, and the application rate is 5 mL / plant;

[0025] The concentration of azoxystrobin used is 20–100 μg / mL, and the application rate is 5 mL / plant.

[0026] Preferably, the fungicide is applied by root irrigation.

[0027] Preferably, the disease-resistant varieties include one or more of Qianjiao No. 8, Yanjiao 485, and Yanjiao 435;

[0028] The susceptible varieties include one or more of the following: Xiangla No. 7, Xiangla No. 14, Zunla No. 9, Layan No. 3, Layan No. 12, and Layan No. 101.

[0029] Beneficial effects:

[0030] This invention provides the application of fungicides in the control of white mold disease in peppers. The fungicides include hexaconazole and / or azoxystrobin. The pepper varieties include resistant and susceptible varieties. The disease index of the resistant varieties against white mold is ≤45.8; the disease index of the susceptible varieties against white mold is >45.8. The concentration of hexaconazole is 20–100 μg / mL; the concentration of azoxystrobin is 20–100 μg / mL. This invention conducted in vitro activity tests against white mold disease in peppers and determined the indoor toxicity of different fungicides against the disease. The results showed that hexaconazole and azoxystrobin have good comprehensive control effects on both resistant and susceptible varieties. Pot experiment results showed that 20–100 μg / mL of hexaconazole and / or pyraclostrobin had good overall control efficacy. When controlling white mold disease, the combined use of resistant varieties and fungicides can effectively reduce the severity of the disease, reduce the amount of fungicide used, and maintain stable plant growth. Furthermore, the root morphology and antioxidant enzyme regulation of resistant varieties are superior to those of susceptible varieties, and the protective activity and control effect of resistant varieties are significantly higher than those of susceptible varieties. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly described below.

[0032] Figure 1 Cluster diagram for disease resistance identification analysis of different chili pepper varieties based on DI value;

[0033] Figure 2 A comparison chart of disease indices for different chili pepper varieties;

[0034] Figure 3 A comparison of the growth differences of different chili varieties 4 days after inoculation;

[0035] Figure 4 The results show the potted plant efficacy test results of the fungicide against white mold disease of pepper; where P represents protective activity (preventive effect) and C represents curative activity (curative effect);

[0036] Figure 5This is a comparative graph showing the disease index and control effects of different chili pepper varieties; where a represents disease-resistant varieties and b represents disease-susceptible varieties; different lowercase letters indicate significant differences between treatments within the same variety (P < 0.05), and different uppercase letters indicate significant differences between varieties within the same treatment (P < 0.05).

[0037] Figure 6 A graph showing the difference in growth among different treatments of different chili pepper varieties 5 days after inoculation; where c represents disease-resistant varieties and d represents disease-susceptible varieties.

[0038] Figure 7 A comparative graph showing root morphology (total root length, root projected area, and root volume) data of different pepper varieties after 5 days of inoculation with the fungus; where a represents disease-resistant varieties and b represents disease-susceptible varieties; different lowercase letters indicate significant differences between treatments within the same variety (P < 0.05).

[0039] Figure 8 Comparison of root morphology and phenotypes of different pepper varieties after 5 days of inoculation; where c represents disease-resistant varieties and d represents disease-susceptible varieties.

[0040] Figure 9 The effect of fungicide application on root antioxidant enzyme activity after white mold infection of resistant varieties; different lowercase letters indicate significant differences between treatments within the same variety (P < 0.05);

[0041] Figure 10 The effect of fungicide application on root antioxidant enzyme activity after white mold disease infection of susceptible varieties; different lowercase letters indicate significant differences between treatments within the same variety (P < 0.05);

[0042] in, Figures 5-10 In the diagram, P indicates protective activity (preventive effect); C indicates therapeutic activity (therapeutic effect); A represents hexaconazole, B represents azoxystrobin, 1 represents a concentration of 50 μg / mL, and 2 represents a concentration of 100 μg / mL.

[0043] Figure 11 The results of correlation analysis between different indicators of resistant and susceptible varieties. Detailed Implementation

[0044] This invention provides the application of fungicides in the control of white mold disease in peppers, wherein the fungicides include hexaconazole and / or pyraclostrobin;

[0045] The chili pepper varieties include disease-resistant varieties and susceptible varieties; the disease-resistant varieties have a disease index of ≤45.8 for white rot; the susceptible varieties have a disease index of >45.8 for white rot.

[0046] The concentration of hexaconazole used is 20–100 μg / mL;

[0047] The concentration of azoxystrobin used is 20–100 μg / mL.

[0048] In this invention, as one embodiment, the disease-resistant variety includes one or more of Qianjiao No. 8, Yanjiao 485, and Yanjiao 435; as another embodiment, the disease-resistant variety is Qianjiao No. 8. As one embodiment, the susceptible variety includes one or more of Xiangla No. 7, Xiangla No. 14, Zunla No. 9, Layan No. 3, Layan No. 12, and Layan 101; as another embodiment, the susceptible variety is Layan 101. This invention uses the squared Euclidean distance method for cluster analysis to classify chili varieties into susceptible and disease-resistant types. It was found that the root morphology and antioxidant enzyme regulation of disease-resistant varieties are superior to those of susceptible varieties, thus making the protective activity and control effect of disease-resistant varieties significantly higher than that of susceptible varieties. As one embodiment, the disease index of the disease-resistant variety against white rot is ≤20.

[0049] In this invention, the fungicide inhibits the growth of the pathogen causing white mold of pepper, thereby preventing and controlling white mold disease in peppers. As one embodiment, the pathogen causing white mold of peppers is *Sclerotium rolfsii* Sacc.

[0050] In this invention, as one embodiment, the concentration of hexaconazole used is 20-100 μg / mL; as another embodiment, the concentration of hexaconazole used is 50 μg / mL. As one embodiment, the formulation of hexaconazole is a 95 wt.% powder. As one embodiment, the method of application of hexaconazole is root drenching. As one embodiment, the concentration of azoxystrobin used is 20-100 μg / mL; as another embodiment, the concentration of azoxystrobin used is 50 μg / mL. As one embodiment, the formulation of azoxystrobin is a 98 wt.% powder. As one embodiment, the method of application of azoxystrobin is root drenching. Indoor toxicity testing revealed that hexaconazole had the best antibacterial effect, EC... 50 The value was 0.00139 μg / mL. The inhibitory effects of the three fungicides, carbendazim, tebuconazole, and fluazinam, were the next best, with EC [value missing]. 50 The values ​​were all 0.1 μg / ml; the inhibitory effects then decreased in the following order: chlorpyrifos, azoxystrobin, pyraclostrobin, and tebuconazole, EC 100%. 50 The values ​​were 0.2, 0.3, 0.4, and 0.7 μg / mL, respectively; oxadiazine showed the worst inhibitory effect, EC50. 50The concentration was 3.3 μg / mL. Based on the different activity mechanisms and levels of fungicides against pathogens, pot experiments were conducted to determine the efficacy of azoxystrobin, carbendazim, fluazinam, pyraclostrobin, and hexaconazole. The results showed that hexaconazole and azoxystrobin had good comprehensive control effects on both resistant and susceptible varieties. This invention, through pot efficacy testing, screened hexaconazole and azoxystrobin as fungicides with good comprehensive control effects. Furthermore, in controlling white mold disease, a combined approach of resistant varieties and fungicides can be used for disease management, effectively reducing the severity of white mold disease, reducing the amount of fungicide used, and maintaining stable plant growth.

[0051] The present invention also provides a method for preventing white mold disease of peppers by applying a fungicide to peppers when transplanting pepper seedlings to the field;

[0052] The fungicide includes hexaconazole and / or pyraclostrobin;

[0053] The chili pepper varieties include disease-resistant varieties and susceptible varieties; the disease-resistant varieties have a disease index of ≤45.8 for white rot; the susceptible varieties have a disease index of >45.8 for white rot.

[0054] The concentration of hexaconazole used is 20-100 μg / mL, and the application rate is 5 mL / plant;

[0055] The concentration of azoxystrobin used is 20–100 μg / mL, and the application rate is 5 mL / plant.

[0056] In this invention, as one embodiment, the fungicide is applied by root irrigation.

[0057] In this invention, as one embodiment, the concentration of hexaconazole used is 20–100 μg / mL; as another embodiment, the concentration of hexaconazole used is 50 μg / mL. As one embodiment, the formulation of hexaconazole is a 95 wt.% powder. As one embodiment, the application rate of hexaconazole is 5 mL / plant; as another embodiment, the application rate of hexaconazole is 5 mL / plant.

[0058] In this invention, as one embodiment, the concentration of azoxystrobin used is 20–100 μg / mL; as another embodiment, the concentration of azoxystrobin used is 50 μg / mL. As one embodiment, the formulation of azoxystrobin is a 98 wt.% powder. As one embodiment, the application rate of azoxystrobin is 5 mL / plant; as another embodiment, the application rate of hexaconazole is 5 mL / plant.

[0059] In this invention, as one embodiment, the disease-resistant varieties include one or more of Qianjiao No. 8, Yanjiao 485, and Yanjiao 435; as another embodiment, the disease-resistant variety is Qianjiao No. 8. As one embodiment, the susceptible varieties include one or more of Xiangla No. 7, Xiangla No. 14, Zunla No. 9, Layan No. 3, Layan No. 12, and Layan 101; as another embodiment, the susceptible variety is Layan 101. This invention limits the chili varieties, enabling disease management in conjunction with fungicides, which can effectively reduce the severity of white mold disease, reduce the amount of fungicide used, and maintain stable plant growth.

[0060] The present invention also provides a method for treating white mold disease of peppers, wherein a fungicide is applied to peppers 24 hours after they are infected with the white mold disease pathogen.

[0061] The fungicide includes hexaconazole and / or pyraclostrobin;

[0062] The chili pepper varieties include disease-resistant varieties and susceptible varieties; the disease-resistant varieties have a disease index of ≤45.8 for white rot; the susceptible varieties have a disease index of >45.8 for white rot.

[0063] The concentration of hexaconazole used is 20-100 μg / mL, and the application rate is 5 mL / plant;

[0064] The concentration of azoxystrobin used is 20–100 μg / mL, and the application rate is 5 mL / plant.

[0065] In this invention, as one embodiment, the fungicide is applied by root irrigation.

[0066] In this invention, as one embodiment, the concentration of hexaconazole used is 20–100 μg / mL; as another embodiment, the concentration of hexaconazole used is 50 μg / mL. As one embodiment, the formulation of hexaconazole is a 95 wt.% powder. As one embodiment, the application rate of hexaconazole is 5 mL / plant; as another embodiment, the application rate of hexaconazole is 5 mL / plant.

[0067] In this invention, as one embodiment, the concentration of azoxystrobin used is 20–100 μg / mL; as another embodiment, the concentration of azoxystrobin used is 50 μg / mL. As one embodiment, the formulation of azoxystrobin is a 98 wt.% powder. As one embodiment, the application rate of azoxystrobin is 5 mL / plant; as another embodiment, the application rate of hexaconazole is 5 mL / plant.

[0068] In this invention, as one embodiment, the disease-resistant varieties include one or more of Qianjiao No. 8, Yanjiao 485, and Yanjiao 435; as another embodiment, the disease-resistant variety is Qianjiao No. 8. As one embodiment, the susceptible varieties include one or more of Xiangla No. 7, Xiangla No. 14, Zunla No. 9, Layan No. 3, Layan No. 12, and Layan 101; as another embodiment, the susceptible variety is Layan 101. This invention limits the chili varieties, enabling disease management in conjunction with fungicides, which can effectively reduce the severity of white mold disease, reduce the amount of fungicide used, and maintain stable plant growth.

[0069] The results of the embodiments of this invention show that, regardless of whether it is hexaconazole or azoxystrobin, the preventive effect on resistant varieties is better at concentrations of 20–100 μg / mL, with the best effects at 50 μg / mL and 100 μg / mL. At 50 μg / mL, hexaconazole showed better therapeutic effects on susceptible varieties than on resistant varieties. When the concentration increased to 100 μg / mL, the therapeutic effect on resistant varieties significantly increased, but the control effect on susceptible varieties did not significantly improve. At 50 μg / mL and 100 μg / mL, azoxystrobin showed significantly higher control effects on susceptible varieties than on resistant varieties.

[0070] To further illustrate the present invention, the application of the fungicide provided by the present invention in the prevention and control of white mold disease of peppers and a method for preventing and controlling white mold disease of peppers are described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0071] All data in this invention embodiment are the averages of at least three independent replicates. The analysis of variance was performed using SPSS 26.0 statistical software. A p-value ≤ 0.05 was considered statistically significant.

[0072] Example 1

[0073] 1. Materials and Methods

[0074] 1.1 Experimental Materials and Instruments

[0075] (1) Sclerotium rolfsii Sacc.: Placed on PDA plates and cultured in a constant temperature incubator at 25±1℃, and stored at 4℃.

[0076] (2) Chili varieties: Yanjiao 485 (P1) and Yanjiao 435 (P2) were produced by Chongqing Keguang Seedling Co., Ltd.; Xiangla No. 7 (P3) and Xiangla No. 14 (P4) were produced by Hunan Xiangyan Seed Industry Co., Ltd.; Qianjiao No. 8 (P5), Zunla No. 9 (P6), Layan No. 3 (P7), Layan No. 12 (P8), and Layan No. 101 (P9) were provided by the Chili Research Institute of Guizhou Academy of Agricultural Sciences. All chili peppers were transplanted into flowerpots when they had 6-8 true leaves in a greenhouse (temperature 25℃, photoperiod 16h / 8h day-night cycle, light intensity 700-1100 Lux) for the next stage of the experiment. All experimental chili pepper seedlings grew under the same conditions and showed the same growth.

[0077] (3) Test fungicides technical grade: 98wt.% azoxystrobin technical grade powder (Macklin), 98wt.% carbendazim technical grade powder (Macklin), 98wt.% propiconazole technical grade powder (Alfa), 95wt.% oxadixyl technical grade powder (Yuanye Biotechnology), 98wt.% chlorothalonil technical grade powder (Yuanye Biotechnology), ≥98wt.% tebuconazole technical grade powder (Yuanye Biotechnology), ≥98wt.% tebuconazole technical grade powder (Adamas-beta), ≥95wt.% cyclophosphamide technical grade powder (Macklin), 98wt.% fluazinam technical grade powder (Macklin), 98wt.% azoxystrobin technical grade powder (Macklin), 95wt.% hexaconazole technical grade powder (Yuanye Biotechnology), and ≥98wt.% chlorothalonil technical grade powder (Yuanye Biotechnology).

[0078] (4) Instruments and equipment: clean bench, constant temperature incubator, root scanner, microplate reader

[0079] 1.2 Test Methods

[0080] 1.2.1 Identification of resistance to white mold disease in different chili pepper varieties

[0081] Pot experiments were conducted to examine the differences in resistance to white rot disease among different pepper varieties. The inoculation method for the pot experiments followed that of Song et al. (Song D, Wen R, Chen K, et al. Application of thifluzamide to stem rot in peppers: Infection and control mechanisms of sclerotium rolfsii[J]. Pesticide Biochemistry and Physiology, 2024:105846.), with five replicates for each variety and ten pepper plants per replicate.

[0082] (1) Observe the growth of peppers 4 days after inoculation and determine their disease index (DI). The determination and classification of the disease index (DI) are as follows: Measure the length of the withered stem base (let X be the length of the browning and withering at the stem base):

[0083] 0 = No browning at the base of the stem, and the entire plant is disease-free;

[0084] 1. The base of the stem shows no browning, but the plant wilts slightly or the leaves turn yellow.

[0085] 3 = Browning and shrinkage at the base of the stem (X≤1cm), with slight wilting or yellowing of the plant's leaves;

[0086] 5 = Browning and withering at the base of the stem (X≤1cm), withered / fallen leaves;

[0087] 7 = Browning and withering at the base of the stem; 1 < X ≤ 2 cm; leaves wither / fall off.

[0088] 9 = Browning and withering at the base of the stem; 2 < X ≤ 3 cm; leaves wither / fall off.

[0089] 10 = Browning and shrinkage of the stem base 3 cm ≤ X, plant dies;

[0090] Disease Index (DI) = [∑(number of diseased plants at each level × corresponding level) / (total number of plants investigated × highest level value)] × 100.

[0091] (2) Using the DI value (disease index) of 9 chili pepper varieties as indicators, cluster analysis was performed using SPSS 26.0 software and the squared Euclidean distance method.

[0092] The identification results showed that the nine chili pepper varieties could be divided into two different resistance types: P5, P2, and P1 (DI≤45.8) were disease-resistant varieties; P3, P9, P6, P7, P4, and P8 (DI>45.8) were disease-susceptible varieties. Figure 1 The disease index shows an upward trend as resistance decreases. Figure 2 This means that different chili pepper varieties have different degrees of disease severity. Figure 3 The varieties exhibited varying degrees of resistance to white rot. Among them, the resistant variety P5 (Qianjiao 8) had the lowest disease index at 37.60, while the susceptible variety P9 (Layan 101) had the highest disease index at 74.00. The disease index of the resistant variety Qianjiao 8 was significantly lower than that of the susceptible variety Layan 101 (P<0.05).

[0093] 1.2.2 Screening of fungicides for controlling white mold disease in peppers

[0094] 1.2.2.1 In vitro activity test of fungicide against white mold disease of pepper

[0095] The mycelial growth rate method was used to test the in vitro activity of 12 fungicides against white mold disease of pepper.

[0096] (1) Before the experiment, the test strain was activated and prepared for use. On the culture dish covered with mycelium, a 0.5 cm diameter punch was used to make a mycelial cake at the edge of the mycelium. One mycelial cake was inoculated on each plate and inoculated in the center of the drug-containing / drug-free culture dish respectively. (Preparation of drug-containing / drug-free culture dish: Weigh the test fungicide and dissolve it in 0.5 mL of DMSO, then add it to 4.5 mL of aqueous solution containing 0.2% Tween 20 to prepare the drug-containing stock solution. The same aqueous solution without fungicide was used as a blank control, i.e., the drug-free stock solution. Finally, add all the drug-containing / drug-free stock solutions to the still undried conical flask containing PDA (45 mL), shake well while hot and pour into the culture dishes. Pour 3 dishes into each conical flask. After solidification, the drug-containing / drug-free culture dishes are obtained.)

[0097] (2) After inoculation, the culture dishes were placed in a constant temperature incubator at 25℃ and incubated in the dark. When the colonies of the blank control reached a diameter of about 5.5 cm, the colony diameter of each culture dish was measured using the cross-sectional method, and the inhibition rate of each fungicide treatment was calculated. For each test, three concentration gradients were set for one fungicide, with each gradient constituting one treatment, and each treatment was repeated three times. The concentration of each fungicide was progressively decreased, and adjustments were made based on the concentration results before screening continued until the half-maximum effective inhibition concentration (EC50) was determined. 50 Until then. The inhibition rate (%) = (control colony diameter - treated colony diameter) / (control colony diameter - 0.5) × 100%; based on the logarithmic values ​​of each fungicide concentration and the corresponding inhibition rate, the virulence regression equation (y = a + bx) and the effective inhibitory concentration (EC) are calculated. 50 ) and correlation coefficient (R) 2 The results are shown in Table 1.

[0098] Table 1. Results of indoor toxicity tests of fungicides against white mold on peppers.

[0099] Hexaconazole 0.00139±0.0i y = 1.3812x + 7.4738 0.9725 Corrosive agent 0.1±0.0h y = 1.0708x + 6.0417 0.9736 Tebuconazole 0.1±0.0h y = 2.0035x + 6.6908 0.9639 Cyclozazole 0.1±0.0h y = 1.2031x + 6.0022 0.9667 Fluazinam 0.1±0.0h y = 0.7853x + 5.7324 0.8346 Bai Kemin 0.2±0.0g y = 0.9397x + 5.6250 0.8268 azoxystrobin 0.3±0.1f y = 0.3088x + 5.1456 0.9657 Azoxystrobin 0.4±0.0e y = 0.9100x + 5.3650 0.9550 Tebuconazole 0.7±0.1d y = 0.8514x + 5.1402 0.9791 propiconazole 1.7±0.1c y = 1.4051x + 4.6670 0.9556 Chlorothalonil 2.7±0.3b y = 0.4506x + 4.8069 0.8947 Oxyphenidazole 3.3±0.1a y = 1.6543x + 4.1384 0.9736

[0100] Note: Different lowercase letters indicate significant differences.

[0101] As shown in Table 1, there are significant differences in the toxicity effects among different fungicide technicals. Hexaconazole showed the most significant inhibitory effect on *Sclerotium affine* hyphae in the in vitro activity test (EC50). 50 The value was 0.00139 μg / mL; the four fungicides, namely carbendazim, tebuconazole, fluazinam, and cyclophosphamide, showed the next best inhibitory effects, with EC... 50 The values ​​were all 0.1 μg / mL; the inhibitory effects then decreased in the following order: chlorpyrifos, azoxystrobin, pyraclostrobin, and tebuconazole, with EC50 values ​​of 0.2, 0.3, 0.4, and 0.7 μg / mL, respectively; oxadixyl had the worst inhibitory effect, EC50 values ​​of 0.1 μg / mL. 50The value was 3.3 μg / mL.

[0102] 1.2.2.2 Screening of fungicide efficacy against potted pepper varieties susceptible to white mold disease

[0103] The inoculation method is the same as step 1.2.2.1. Apply fungicide to the roots 24 hours before or after inoculation, using 5 mL per pepper plant.

[0104] Based on the results in 1.2.1, two chili pepper varieties with the greatest difference in disease resistance (P5 and P9, respectively, representing a resistant and susceptible variety) were selected. Considering the in vitro activity test results in 1.2.2.1 and the mechanisms of action of different fungicides, five fungicides (hexaconazole, carbendazim, fluazinam, azoxystrobin, and pyraclostrobin) were selected for pot experiments. The experimental concentration for each fungicide was 20 μg / mL. A water-treated mycelium inoculation was used as a blank control. Each fungicide was used as one treatment, with 15 seedlings per treatment and 5 replicates. Five days after inoculation, the disease index was statistically analyzed, and the relevant control effects were calculated. The disease index was evaluated as in 1.2.1. The control effect was calculated based on the disease index: Control effect (%) = [(Disease index of blank group - Disease index of treatment group) / Disease index of blank group] × 100%.

[0105] Statistical results show that, at a concentration of 20 μg / mL, the five fungicides exhibited different control effects on resistant and susceptible pepper varieties, and there were differences in the control effects between protective and curative activities. Figure 4 Specifically, it manifests as follows:

[0106] (1) Disease-resistant varieties (P5): Among the protective activities, hexaconazole has the best control effect at 40.31%; followed by oxychloride at 21.71%; and azoxystrobin has the worst effect at only 6.2%. Among the curative activities, azoxystrobin has the best effect (20.93%), followed by fluazinam (10.85%), and hexaconazole has the worst effect (2.33%).

[0107] (2) Disease-susceptible varieties (P9): Among the protective activities, azoxystrobin had the best effect (49.28%), followed by oxychlorpyrifos (33.33%), and fluazinam had the worst effect (9.42%); among the therapeutic activities, oxychlorpyrifos had the best effect (36.96%), followed by hexaconazole (34.78%), and fluazinam had the worst effect (8.7%).

[0108] 1.2.3 Effects of applying hexaconazole and azoxystrobin against white rot stress on white rot-susceptible pepper varieties

[0109] 1.2.3.1 Determination of the control effects of hexaconazole and azoxystrobin against susceptible pepper varieties infected with white mold.

[0110] According to 1.2.2.2, hexaconazole and azoxystrobin were selected as the final fungicides. Two pepper varieties (P5 and P9, respectively, a resistant and susceptible variety) were treated with hexaconazole (water treatment) and fungicides at concentrations of 50 μg / mL and 100 μg / mL for 24 hours before and after inoculation. Pepper growth was observed 5 days after inoculation to assess the control effect. The results are as follows: Figures 5-6 As shown.

[0111] according to Figures 5-6 It can be seen that different resistant pepper varieties exhibit different control effects when treated with the same fungicide. Both hexaconazole and azoxystrobin significantly (P < 0.05) reduced the disease index of white mold on peppers, and there was a significant difference in control effect between resistant and susceptible pepper varieties (P < 0.05). Specifically:

[0112] (1) Among pepper varieties resistant to / susceptible to white mold disease, different fungicide dosages showed varying control effects on the disease. For resistant varieties, the optimal control treatment was hexaconazole with a protective activity of 50 μg / mL, achieving a control efficacy of 98.12%. This was followed by hexaconazole with a protective activity of 100 μg / mL and azoxystrobin with a protective activity of 100 μg / mL, achieving control efficiencies of 92.58% and 88.60%, respectively. Azoxystrobin with a curative activity of 50 μg / mL showed the lowest control efficacy at 8.47%. For susceptible varieties, the optimal control treatment was azoxystrobin with a protective activity of 100 μg / mL, achieving a control efficacy of 85.41%. This was followed by azoxystrobin with a curative activity of 100 μg / mL and hexaconazole with a protective activity of 50 μg / mL, achieving control efficiencies of 82.97% and 74.77%, respectively. Hexaconazole with a curative activity of 100 μg / mL showed the lowest control efficacy at 31.58%.

[0113] (2) Under the same fungicide treatment, resistant and susceptible pepper varieties of white mold showed different responses to the fungicide. In terms of protective activity, both hexaconazole and azoxystrobin showed significantly higher control effects (P < 0.05) on resistant varieties than on susceptible varieties. However, in terms of curative activity, except for hexaconazole at 100 μg / mL, all other treatments showed significantly higher control effects (P < 0.05) on susceptible varieties than on resistant varieties. These results indicate that hexaconazole and azoxystrobin have good protective activity against pepper. Although there are some differences in activity among different varieties, and the curative activity is not as significant as the protective activity, they still have a control effect on white mold in pepper. Overall, the control effect of resistant varieties is better than that of susceptible varieties.

[0114] (3) Under protective and curative activities, there are differences in the control effects between resistant and susceptible white rot disease varieties. However, overall, the protective activity of fungicides has a significantly better control effect than the curative activity. Among them, there are large differences in the protective and curative control effects of resistant varieties, while the differences among susceptible varieties are smaller. At a concentration of 50 μg / mL of hexaconazole, the difference in protective and curative activity between the two treatments was the greatest in resistant varieties, with a difference of 74.84%, while the difference in protective and curative activity between susceptible varieties was only 42.25%. At a concentration of 100 μg / mL of hexaconazole, the difference in protective and curative activity between the two treatments was the greatest in susceptible varieties, with a difference of 42.32%, while the difference between Qianjiao 8 (P5) was 57.24%. At a concentration of 50 μg / mL of azoxystrobin, the difference in protective and curative activity between resistant varieties remained large at 66.55%, but the difference in control efficacy between susceptible varieties was very small, only 8.60%. At a concentration of 100 μg / mL of azoxystrobin, the differences in protective and curative activity between resistant and susceptible varieties were the smallest, but the difference in control efficacy between resistant varieties still reached 36.96%, while the difference in control efficacy between susceptible varieties was only 2.44%.

[0115] (4) When the protective activity was observed, the disease index of the resistant variety (CK) was higher than that of the susceptible variety, but the control effect of the resistant variety was significantly better than that of the susceptible variety after the application of the pesticide. However, when the therapeutic activity was observed, there was no significant difference in the disease index of the resistant and susceptible varieties, but the control effect of the susceptible variety under the application of azoxystrobin was significantly better than that of the resistant variety. This indicates that the resistant variety has a better absorption or retention effect of the pesticide in terms of protective activity, while the susceptible variety is better in terms of therapeutic activity. That is, the resistant and susceptible white mold pepper varieties respond differently to different pesticides.

[0116] (5) After conducting a significance level analysis on the interaction between different varieties of resistance, different fungicide treatments and protective / curative activities on the control effect, it was found that variety resistance, fungicide treatment, and protective / curative activities all had extremely significant effects on the control effect of white mold disease in peppers (Table 2). This indicates that there are significant differences in the control effect of fungicides between resistant and susceptible white mold disease pepper varieties, and it is feasible to use resistant varieties in combination with fungicides to control white mold disease.

[0117] Table 2. Results of the significance analysis of the effect of variety resistance, fungicide treatment, and protective / curative activity on control efficacy.

[0118]

[0119] Note: aR 2 =0.992 (adjusted R) 2 =0.989).

[0120] 1.2.3.2 Effects of hexaconazole and azoxystrobin antagonism, and the influence of inoculation on root morphology of pepper varieties susceptible to white mold.

[0121] The root system was scanned into TIF image files using an Expression 12000xl root scanner (Epson, USA). WinRHIZO image analysis software was then used for quantitative analysis of the images to obtain parameters such as total root length, root surface area, root volume, and average root diameter. The results showed significant differences in root morphology under different fungicide treatments and concentrations. Compared with the control group without fungicide application, the inhibitory effect on white mold disease increased with increasing fungicide concentration, resulting in greater control efficacy and reduced stress from white mold disease on pepper roots. Overall root morphology showed significant increases (P < 0.05) in total root length, root projected area, root volume, root surface area, and number of root tips. Figure 7 and Figure 8 Furthermore, even without the application of fungicides, the root morphology of resistant varieties after infection with white mold was still significantly better than that of susceptible varieties. This explains why, in protective activity, resistant varieties were significantly more effective than susceptible varieties, but in curative activity, susceptible varieties were better than resistant varieties. Specifically, in protective activity, the well-developed root system of resistant varieties allowed for greater absorption of pesticides, while in curative activity, the larger root area allowed for deeper infection by white mold, resulting in root damage and reduced subsequent absorption of pesticides. Susceptible varieties, on the other hand, exhibited the opposite effect.

[0122] 1.2.4 Effects of hexaconazole and azoxystrobin antagonism, and the effects of inoculation of white mold-susceptible pepper varieties on root antioxidant enzyme activity.

[0123] Following the same steps as in step 1.2.3, relevant samples were collected 5 days after inoculation, and the following antioxidant enzyme activities were measured: POD activity (peroxidase), MDA (malondialdehyde), CAT activity (catalase), and H2O2 (hydrogen peroxide), all using kits from Beijing Solarbio Biotechnology Co., Ltd.

[0124] The results showed that, under different fungicide treatments, the H2O2 content of disease-resistant varieties increased compared to the control under protective activity, while the difference was not significant under curative activity. Figure 9 (a); Under protective activity, compared with the control, CAT activity showed a decreasing trend with increasing fungicide concentration. Figure 9 (b) Except for hexaconazole (50 μg / mL), whose CAT activity increased compared to the control, all other bactericides showed a decrease in activity. In the therapeutic activity category, all were lower than the control. MDA levels were higher in the protective activity category than in the control, and the same trend was observed in the therapeutic activity category. Figure 9 (c) Under protective activity, POD activity showed a decreasing trend compared to the control, while therapeutic activity showed the opposite trend. Figure 9 (d).

[0125] Compared with the control, the H2O2 content increased under different fungicide treatments on susceptible varieties. Figure 10 In the middle (a); CAT activity decreased ( Figure 10 (b) The content of MDA increased in both cases. Figure 10 (c) In terms of protective activity, the POD activity of the treated azoxystrobin at 50 μg / mL was higher than that of the control group, while the activity of the other treated azoxystrobins was lower than that of the control group. In terms of therapeutic activity, the POD activity of the treated azoxystrobins at 50 μg / mL and azoxystrobin at 100 μg / mL was lower than that of the control group, while the activity of the other treated azoxystrobins was higher than that of the control group. Figure 10 (d).

[0126] Under the same pesticide treatment, the MDA content of resistant varieties was lower than that of susceptible varieties when the pesticide was applied in a protective activity state. However, when the pesticide was applied in a curative activity state, the MDA content of resistant varieties was higher than that of susceptible varieties when hexaconazole was applied, but lower when azoxystrobin was applied. This is positively correlated with the control effect of the pesticide application. That is, when the pesticide application has a good inhibitory effect on white mold, the degree of plant cell damage is small. This indicates that when the root antioxidant enzyme system of resistant varieties is in protective activity, it can be stimulated by the pesticide and the root system can be regulated in advance to defend against white mold, thus further enhancing the resistance to white mold. In contrast, when the pesticide is applied in a curative activity state, the antioxidant enzyme system of white mold is attacked in advance, and it is difficult for the pesticide to be absorbed and the system regulation to be restored after the pesticide action, resulting in poor resistance to white mold.

[0127] 1.2.5 Correlation Analysis

[0128] Correlation analysis was performed on different indicators after inoculation of resistant and susceptible varieties. The analysis showed that there were correlations between the disease index and different indicators between resistant and susceptible varieties. The results showed that the disease index of resistant varieties was negatively correlated with control effect, average root diameter, root volume, root surface area, and H2O2, and positively correlated with total root length, root projected area, root tip number, CAT, MDA, and POD; while the disease index of susceptible varieties was positively correlated with POD and negatively correlated with all other indicators. Figure 11 This result indicates that the difference in control efficacy between resistant and susceptible varieties is due to inconsistencies in the regulation between root morphology and root antioxidant enzyme systems.

[0129] As can be seen from the above, hexaconazole and / or azoxystrobin have good overall efficacy against white mold disease in peppers. Using a combination of resistant varieties and fungicides for disease management can effectively reduce the severity of white mold disease, reduce the amount of fungicide used, and maintain stable plant growth. Furthermore, the root morphology and antioxidant enzyme regulation of resistant varieties are superior to those of susceptible varieties, and the protective activity and control effect of resistant varieties are significantly higher than those of susceptible varieties.

[0130] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. The application of fungicides in the control of white mold disease in peppers, characterized in that, The bactericide is hexaconazole; The chili pepper varieties include disease-resistant varieties and susceptible varieties; the disease-resistant varieties have a disease index of ≤45.8 for white rot; the susceptible varieties have a disease index of >45.8 for white rot. The concentration of hexaconazole used is 20~100μg / mL; The hexaconazole is in the form of a 95 wt.% powder. The fungicide is applied by root irrigation.

2. The application according to claim 1, characterized in that, The disease-resistant varieties include one or more of Qianjiao No. 8, Yanjiao 485 and Yanjiao 435; The susceptible varieties include one or more of the following: Xiangla No. 7, Xiangla No. 14, Zunla No. 9, Layan No. 3, Layan No. 12, and Layan No.

101.

3. The application according to claim 1, characterized in that, The fungicide inhibits the growth of the pathogen causing white mold disease in peppers, thus preventing and controlling white mold disease in peppers.

4. A method for preventing white mold disease in peppers, characterized in that, When transplanting chili seedlings to the field, apply fungicide to the chili peppers; The bactericide is hexaconazole; The chili pepper varieties include disease-resistant varieties and susceptible varieties; the disease-resistant varieties have a disease index of ≤45.8 for white rot; the susceptible varieties have a disease index of >45.8 for white rot. The concentration of hexaconazole used is 20~100μg / mL, and the application rate is 5mL / plant; The hexaconazole is in the form of a 95 wt.% powder. The fungicide is applied by root irrigation.

5. The method according to claim 4, characterized in that, The disease-resistant varieties include one or more of Qianjiao No. 8, Yanjiao 485 and Yanjiao 435; The susceptible varieties include one or more of the following: Xiangla No. 7, Xiangla No. 14, Zunla No. 9, Layan No. 3, Layan No. 12, and Layan No.

101.

6. A method for treating white rot in peppers, characterized in that, Apply fungicide to the peppers 24 hours after they are infected with the pathogen of white mold disease; The bactericide is hexaconazole; The chili pepper varieties include disease-resistant varieties and susceptible varieties; the disease-resistant varieties have a disease index of ≤45.8 for white rot; the susceptible varieties have a disease index of >45.8 for white rot. The concentration of hexaconazole used is 20~100μg / mL, and the application rate is 5mL / plant; The hexaconazole is in the form of a 95 wt.% powder. The fungicide is applied by root irrigation.

7. The method according to claim 6, characterized in that, The disease-resistant varieties include one or more of Qianjiao No. 8, Yanjiao 485 and Yanjiao 435; The susceptible varieties include one or more of the following: Xiangla No. 7, Xiangla No. 14, Zunla No. 9, Layan No. 3, Layan No. 12, and Layan No. 101.

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