Green planting method for reducing damage of ipiuna variabilis (moore) to sweet potato

Abstract

The present application relates to sweet potato planting technical field, especially to a kind of green planting method for reducing the damage of sweet potato narrow margin moth, according to the rule of narrow margin moth damage sweet potato, a set of narrow margin moth prevention and treatment planting strategy for sweet potato land is summarized, mainly in, by strictly controlling the use of paclobutrazol, so that sweet potato dwarf, control tuberous stem overgrowth, reduce the degree of stem and leaf dense, create an environment that is not suitable for narrow margin moth growth, while improving the chlorophyll content of leaf, leaf still can carry out sufficient photosynthesis, also will improve sweet potato yield;When paclobutrazol is applied, a variety of biological pesticides are mixed, and the biological pesticides that can effectively control narrow margin moth are found out to form a leaf environment with paclobutrazol, so as to effectively control the damage of narrow margin moth, the control effect reaches more than 90%, and other underground pests are also treated, the yield-increasing effect is obvious, the commodity nature of sweet potato is improved, and the efficient and cost-saving green planting of sweet potato is realized.

Description

Technical Field

[0001] This invention relates to the field of sweet potato cultivation technology, and in particular to a green cultivation method to reduce damage from the narrow-edged cutworm in sweet potatoes. Background Technology

[0002] Sweet potatoes are high-yielding and stable-yielding. They are widely adaptable, nutritious, and have many uses. In the 21st century, the uses of sweet potatoes have further diversified and become specialized, making them an important food, feed, industrial raw material, and new energy crop. However, following the discovery of a new potato pest—the narrow-edged cutworm (Schrankia costestrigalis)—in 2015, this insect was also found to be damaging sweet potatoes in 2019, with an increasing trend. The larvae of the narrow-edged cutworm mainly damage the sweet potato tubers, causing single or multiple holes in the affected tubers. Severely damaged tubers exhibit a honeycomb-like pattern of holes, affecting both yield and quality (e.g., ...). Figures 1-3 (As shown). Research indicates that this insect prefers to live in dark, damp environments, usually staying in nearby damp grassy areas. After the sweet potato vines and leaves close in, the dense, shady plants allow the adults to migrate from the grass to the sweet potato field, where they lay their eggs in the soil at the base of the lush green plants. Before tuber formation, the larvae primarily feed on the roots or newly grown roots or adventitious roots on the stem nodes. After tuber formation, the adults burrow into the plant's roots through gaps to lay their eggs. After hatching, the larvae damage the tubers; larvae on the ground surface can also burrow into the tubers through cracks.

[0003] Observations during rearing revealed that this insect has one generation every 25 days from April to October, with overlapping generations in the field. It causes earlier and more severe damage in clay soil fields. In sandy soil, it mainly occurs when the tubers are swelling, after the ridges (beds) crack, allowing the insect to enter the roots and damage the tubers through the cracks or gaps. High humidity levels result in more severe damage; delayed harvesting prolongs the infestation period and exacerbates the damage.

[0004] Currently, there are no reported methods for controlling this insect on sweet potatoes, and directly applying control methods used on potatoes is not suitable for sweet potatoes. Specifically, the under-foliage environment of sweet potato plants is different from that of potato plants. Sweet potato vines have longer and denser creeping parts compared to potato vines, more and longer branches, and more, larger, and denser leaves, making it easier to create a dense and concealed environment. In addition, sweet potato tubers are larger than potato tubers, making them more likely to cause soil cracks and providing a breeding ground for the narrow-edged cutworm. Therefore, it is necessary to summarize a set of green control methods for the narrow-edged cutworm in sweet potato cultivation, so as to effectively control the damage caused by the narrow-edged cutworm in a highly efficient, cost-effective, and environmentally friendly manner. Summary of the Invention

[0005] In view of the above, it is necessary to summarize a set of green control methods for the narrow-edged cutworm in sweet potato cultivation, so as to effectively control the damage caused by the narrow-edged cutworm, and achieve high efficiency, cost-saving and green results.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A green planting method to reduce damage from the narrow-edged cutworm in sweet potatoes, the method comprising the following steps:

[0008] (1) Site selection: Select sandy loam or loam soil with loose soil, deep soil layer, flat terrain and convenient irrigation and drainage as the sweet potato planting site;

[0009] (2) Land preparation and ridging: Deep plowing and turning the soil, breaking up the clods, making deep furrows and high ridges;

[0010] (3) Weeding: After ridging and before planting sweet potatoes, apply herbicide to the planting plot and weed manually.

[0011] (4) Hilling and topdressing: Before the stems and leaves cover the ridge, open a trench on the lower half of the ridge to apply fertilizer. After applying fertilizer, hill the soil to cover the fertilizer tightly. At the same time, weeding is carried out in conjunction with hilling.

[0012] (5) Spraying paclobutrazol to control seedlings: 40 days after planting and 5-7 days after topdressing, spray paclobutrazol once after the stems and leaves have closed the canopy; spray paclobutrazol again after 20-30 days; the amount of paclobutrazol sprayed per mu each time is 60-80 grams.

[0013] (6) Tuber management: During the tuber enlargement period, if cracks are found on the ridge surface, cover and seal the cracks on the ridge surface with fine soil, leaving no gaps; control the field humidity throughout the planting process, stop irrigation 15 to 20 days before harvest, and harvest the sweet potatoes in time after they mature.

[0014] Furthermore, in step (5), the dilution factor of paclobutrazol is 600 to 1200 times.

[0015] Furthermore, in step (5), when applying paclobutrazol, a mixture of Metarhizium anisopliae, chlorantraniliprole, thiamethoxam, and Bacillus thuringiensis (Bt) is applied simultaneously.

[0016] Furthermore, the effective ingredient content of Metarhizium anisopliae is 10 billion / g, and the effective ingredient content of Bacillus thuringiensis (Bt) is 8000 IU / mL; the mass ratio of Metarhizium anisopliae, Bacillus thuringiensis (Bt), and chlorantraniliprole in the biopesticide is 5:5:1; the dilution factor of Metarhizium anisopliae is 150-250 times, the dilution factor of Bacillus thuringiensis (Bt) is 200-400 times, and the dilution factor of chlorantraniliprole (Bt) is 4000-4500 times.

[0017] Furthermore, the dilution factor of Metarhizium anisopliae is 250 times, the dilution factor of Bacillus thuringiensis (Bt) is 300 times, and the dilution factor of chlorantraniliprole and thiamethoxam is 4500 times.

[0018] Furthermore, the application rate of the biological pesticide is 1100 mL / mu.

[0019] The present invention has the following beneficial effects:

[0020] 1. Based on the pattern of damage to sweet potatoes by the narrow-edged cutworm, this application summarizes a set of green control planting strategies for the narrow-edged cutworm in sweet potato fields. The main methods adopted are: (1) Using paclobutrazol to control the growth of sweet potato leaves, prevent the leaves from growing excessively, and create a leaf environment unsuitable for the growth and reproduction of the narrow-edged cutworm. However, in actual work, we found that applying too much paclobutrazol would seriously affect the growth of sweet potato leaves, thereby reducing the photosynthetic capacity of the leaves and leading to a reduction in sweet potato yield. Therefore, in order to effectively control the yield and also achieve the purpose of creating a leaf environment, paclobutrazol needs to be diluted to 300-1200 times before use. If the concentration is too high, it will lead to a reduction in sweet potato yield. If the concentration is too low, it will create an overly shady leaf environment suitable for the growth and reproduction of the narrow-edged cutworm, thereby causing serious sweet potato pests and also reducing the yield of sweet potatoes and the commercial rate of sweet potatoes. (2) Combine the use of biological pesticides and minimize the application of chemical pesticides. During planting, we found that the insect control ability of biological pesticides, Metarhizium anisopliae and Bacillus thuringiensis, is not as good as that of chemical pesticides. When used alone, their effect is lower than that of chemical pesticides. Therefore, in order to effectively improve the control effect against the narrow-edged cutworm, we combined the above two biological pesticides with the low-toxicity chlorantraniliprole and thiamethoxam. The insect control effect was greatly improved. Through exploration of application conditions, we found that when Metarhizium anisopliae was diluted to 250 times, chlorantraniliprole and thiamethoxam was diluted to 400 times, and Bacillus thuringiensis (Bt) was diluted to 300 times, they were mixed in a mass ratio of 5:5:1 and applied to the sweet potato planting area by spraying. This can effectively control the narrow-edged cutworm, and the control effect can even reach more than 98%. The effect is better than that of all chemical pesticides, and the amount of chemical pesticides used is very small, and the control effect is significantly improved. (3) Harvest sweet potatoes in time after they mature to shorten the damage period and reduce pests. Therefore, in summary, this application effectively controls the damage caused by the narrow-edged cutworm by integrating multiple green methods, achieving a control effect of over 90%, while also controlling other underground pests, resulting in a significant increase in yield and improving the marketability of sweet potatoes, thus realizing efficient and cost-effective green planting of sweet potatoes. Attached Figure Description

[0021] Figures 1-3 The condition of sweet potato tubers after they have been damaged by the narrow-edged leafminer moth. Detailed Implementation

[0022] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0023] Unless otherwise stated, each feature disclosed in this specification (including any appended claims and abstract) is merely one example of a series of equivalent or similar features.

[0024] Example 1:

[0025] This embodiment describes a method for controlling the damage caused by the narrow-edged cutworm using agricultural measures. The method primarily employs agricultural measures and includes the following steps:

[0026] Studies have shown that the narrow-edged cutworm prefers to live in dark, damp underground environments, usually staying in nearby damp grass. After the sweet potato vines and leaves close the canopy, the dense foliage provides cover, and the adults migrate from the grass to the sweet potato field, laying their eggs in the soil beneath the lush green plants. Before tuber formation, the larvae primarily feed on exposed roots or newly emerging adventitious roots. After tuber formation, the insect burrows into the plant's roots through the gaps, damaging the tubers. If the soil is highly clayey and poorly broken up during tillage, resulting in larger gaps between soil clods, the insect can easily burrow into the roots and damage the tubers. Alternatively, as the tubers enlarge, the ridge surface may crack, allowing the insect to enter the roots through these cracks. Fields with high field moisture, poorly broken up soil, and more gaps between soil clods tend to have more severe infestations.

[0027] Based on the insect's occurrence patterns, several key agricultural measures can be implemented through improvements in the planting process. These include selecting sites away from damp, weed-infested areas to reduce insect populations; minimizing or reducing the formation of underground voids and lowering field humidity; timely weeding; and timely application of paclobutrazol to control seedling growth and reduce shading, thereby disrupting its suitable habitat and achieving effective control of the narrow-edged cutworm infestation with minimal or no pesticide use. The key measures are:

[0028] 1. Site selection: Choose sandy loam or loam soil with loose soil, deep soil layer, flat terrain, and convenient irrigation and drainage. At the same time, try to stay away from damp places with weeds and winter potato planting sites.

[0029] 2. Land preparation: Deep plow and turn the soil, break up the clods and rake them to ensure that the soil has small gaps after ridging.

[0030] 3. Ridging: Dig deep furrows to make high ridges. The bottom width of the ridge (including the furrow) is 110cm, the ridge width is 0.7-0.8cm, the ridge height is 30cm, and the furrow width is 30cm. The ridge surface and the bottom of the furrow should be straight, and the soil clods should be fine and broken.

[0031] 4. Weed control: After ridging, 1-2 days before sweet potato planting, apply pre-emergence herbicides such as acetochlor, metolachlor, or pendimethalin evenly to the soil surface, ensuring the herbicide is evenly mixed into the soil. During the early growth stage of sweet potatoes, when weeds have 2-3 leaves, spray with quizalofop-P-ethyl, or manually weed in conjunction with cultivation, hilling, and fertilization.

[0032] 5. Hilling and topdressing: Generally, before the stems and leaves close the ridge (about 35 days after planting), topdressing is done by digging a trench on the lower half of the ridge. After topdressing, the fertilizer is covered tightly with soil. At the same time, weeding is done manually in conjunction with hilling.

[0033] 6. Spray paclobutrazol to control seedling growth: Spray paclobutrazol 1-2 times during the vigorous growth period of sweet potato stems and leaves. About 40 days after planting, and 5-7 days after topdressing, spray paclobutrazol once after the stems and leaves have closed the canopy. If the stems and leaves are still growing vigorously 10-20 days after spraying, spray again after 20-30 days. Spray 60-80 grams of paclobutrazol per acre, diluted in 50-60 kg of water, and spray evenly. When spraying paclobutrazol, it can be mixed with biological pesticides to control pests on the stems and leaves.

[0034] 7. Covering cracks with soil during tuber enlargement: When cracks appear on the ridge surface during the tuber enlargement period, cover the cracks with fine soil to seal them tightly without leaving gaps. This prevents adult insects from flying into the soil to lay eggs or larvae from burrowing into the roots to damage the tubers and reduces the exposure of the tuber heads.

[0035] 8. Control field humidity throughout the process: use moist irrigation as the main method to prevent waterlogging or excessive moisture; stop irrigation 15 to 20 days before harvest.

[0036] 9. Harvest promptly: Harvest sweet potatoes promptly after they mature to reduce the time they are harmful.

[0037] demonstration:

[0038] The demonstration site was located in Renhou Village, Renhou Town, Yuzhou District, in 2022. The demonstration area was 5 mu (approximately 0.33 hectares). The demonstration was conducted according to the above-mentioned agricultural measures, including pesticide application: 500x dilution of acetochlor and 500x dilution of quizalofop-P-ethyl were sprayed before and after budding, respectively. 600x dilution of paclobutrazol was sprayed 40 days and 65 days after planting to control seedling growth. Simultaneously with the paclobutrazol application, a 300x dilution of Bacillus thuringiensis (Bt) was also sprayed. The acetochlor was purchased from Shandong Shengbang Luye Chemical Co., Ltd., the quizalofop-P-ethyl from Shanghai Hulian Biopharmaceutical (Xiayi) Co., Ltd., the paclobutrazol from Sichuan Run'er Technology Co., Ltd., and the Bacillus thuringiensis (Bt) mixture from Shandong Lukang Biological Pesticide Co., Ltd.

[0039] A control field (conventional control) of 0.8 mu was set up. The selected field was sandy loam with slightly sticky soil. The land preparation quality and soil clod crushing were average, with some gaps between the clods. Paclobutrazol was not sprayed, and the cracks were not covered with soil. Saturated irrigation was carried out. During the mid-growth stage, 40 days and 60 days after planting, a 300-fold dilution of Bacillus thuringiensis 8000 IU / mL suspension was sprayed on the leaves once. During the tuber enlargement stage, 75 days and 90 days after planting, a 1000-fold dilution of 12% chlorfenapyr suspension was sprayed on the leaves once.

[0040] When the sweet potatoes were ripe and harvested, a survey was conducted on each of the aforementioned demonstration fields. Three points were randomly selected from each plot, and a 4.5m sample was taken at each point. 2 All tubers were dug up from the sampling points, and the pest rate was counted. When calculating the yield, 1.5% of the total harvested tuber weight of impurities and soil was removed.

[0041] Insect infestation rate (%) = (Number of tubers infested with insects / Total number of tubers) × 100%

[0042] Control efficacy (%) = (Pest rate in control area - Pest rate in treatment area / Pest rate in control area) × 100

[0043] Pest damage loss rate (%) = (Yield loss per unit area due to pests / Yield per unit area) × 100

[0044] Demonstration effect

[0045] The average pest infestation rate in the demonstration field, which mainly used agricultural measures for pest control, was 1.56%, and the loss rate was 1.42%, while the pest infestation rate in the control field was 15.69%, and the loss rate was 13.56%. The control effect of agricultural measures in the demonstration field was 90.06% (Table 1).

[0046] Table 1. Demonstration effect of agricultural-based control of narrow-edged cutworm.

[0047]

[0048] Example 2:

[0049] This embodiment studies the effects of spraying paclobutrazol and different pesticides and spraying methods on pest control.

[0050] 1. Test materials

[0051] The experimental site was selected in a sweet potato field in Renhou Village, Renhou Town, Yuzhou District, Yulin City, Guangxi Province. The experiment was conducted in 2022, and the variety used was Xiguahong (also known as Pushu 32), which has a large local planting area.

[0052] Choose sandy loam soil, plow and turn the soil deeply, break up the soil clods and level the soil, then plant sweet potatoes after ridging.

[0053] The experiment selected seven pesticides and paclobutrazol growth regulators, including chlorfenapyr, chlorfenapyr, phoxim, thiamethoxam, chlorpyrifos, Bacillus thuringiensis (Bt), Beauveria bassiana, and Metarhizium anisopliae (Table 2).

[0054] Table 2. Test Pesticides and Application Methods

[0055]

[0056] The aforementioned chlorfenapyr was purchased from Jinan Tianbang Chemical Co., Ltd., chlorantraniliprole and thiamethoxam were purchased from Syngenta Nantong Crop Protection Co., Ltd., Bacillus thuringiensis (Bt) was purchased from Shandong Lukang Biological Pesticide Co., Ltd., Beauveria bassiana and Metarhizium anisopliae were purchased from Beihai Yiqiang Biotechnology Co., Ltd., thiamethoxam and chlorpyrifos were purchased from Shanghai Hulian Biopharmaceutical Co., Ltd., and phoxim was purchased from Tongda Chemical Plant in Jining City, Shandong Province.

[0057] 2. Test methods

[0058] A total of 16 treatments were set up, with each pesticide applied using both spraying and drenching methods (7 pesticides applied using two methods, totaling 14 treatments). Treatment 15 involved sealing cracks in the seedbed with soil after they appeared during the tuber enlargement stage, without any pesticide application. Treatment 16 served as a blank control without pesticide application. All 15 treatments were uniformly sprayed once at 45 and 65 days after planting with different concentrations of paclobutrazol (80 g / mu) to control excessive vegetative growth. The specific concentrations of paclobutrazol were 300, 600, 900, 1200, and 1500 times dilution, with three treatments per concentration. Each treatment had three replicates. Plot design: Randomized arrangement, each plot was 36.6 m². 2 A total of 48 processes were processed.

[0059] Apply the pesticide approximately 40 days before harvest (during the tuber enlargement period), when the ridge surface cracks due to tuber enlargement. Repeat the application 15 days later. For spraying, evenly distribute the pesticide solution onto the leaves. For rinsing, first evenly spray the solution onto the leaves, then lower the nozzle and slowly spray along the cracks, allowing the solution to fully penetrate the plant base and roots, ensuring the soil at the base of the plant is thoroughly moistened.

[0060] 3. Survey Methods

[0061] (1) Investigation on the effect of paclobutrazol spraying on insect population density and yield

[0062] Twenty days after spraying paclobutrazol, the insect population density of the 15th and 16th treatments was investigated, with a 10-day interval between investigations, for a total of three investigations. At the end of the period, yield and other experimental results were investigated. The specific investigation methods and the calculation formulas for insect infestation rate, control effect, and insect loss rate are as follows:

[0063] Survey on insect infestation rate, loss rate, control effect and yield of tubers under different treatments

[0064] When the sweet potatoes were ripe and harvested, investigations were conducted on the above-mentioned experiments. Three points were randomly selected from each plot, and each point was 4.5m wide. 2 All tubers were dug up from the sampling points, and the pest rate was counted. When calculating the yield, 1.5% of the total harvested tuber weight of impurities and soil was removed.

[0065] Insect infestation rate (%) = (Number of tubers infested with insects / Total number of tubers) × 100%

[0066] Control efficacy (%) = (Pest rate in control area - Pest rate in treatment area / Pest rate in control area) × 100

[0067] Pest damage loss rate (%) = (Yield loss per unit area due to pests / Yield per unit area) × 100

[0068] The experimental results are shown in Table 3.

[0069] Table 3. Effects of paclobutrazol spraying on population density of narrow-rimmed cutworm in Renhou Village, Renhou Town, Yuzhou District.

[0070]

[0071] Table 3 shows that the investigation of the 15th paclobutrazol-sprayed treatment and the 16th control treatment revealed that after paclobutrazol spraying, the excessive growth of sweet potato stems and leaves in the treated area was inhibited, internodes shortened, leaves became dark green, leaves thickened, and the density of stems and leaves decreased. The optimal concentration of paclobutrazol was 600-1200 times. Too high a concentration (300 times) resulted in severe dwarfing of sweet potato plants, which was detrimental to sweet potato growth. The yield was not significantly different from the control group, and the restricted growth of sweet potatoes also led to more severe pest infestations. Too low a concentration (1500 times) failed to effectively intervene in dwarfing of sweet potatoes, resulting in excessive leaf growth, larger plant size, and more vigorous growth compared to other experimental groups. This favored the growth of the narrow-edged cutworm, exacerbating pest infestations and leading to a decrease in yield. Therefore, the optimal application rate of paclobutrazol in sweet potato cultivation is 600-1200 times.

[0072] (2) Effects of different pesticides on tuber pest rate and yield

[0073] Using the same survey method, the pest infestation rate, loss rate, control effect, and yield of tubers were investigated under different pesticide application conditions. The specific results are shown in Table 4.

[0074] Table 4. Results of experiments on the control of narrow-edged cutworm using different pesticides and application methods.

[0075]

[0076] Table 4 shows that the tested pesticides, when applied by spraying, all achieved control efficacy above 87%, with no significant differences among the various pesticides. The control efficacy, from highest to lowest, was as follows: chlorfenapyr / thiamethoxam, thiamethoxam / chlorfenapyr, chlorfenapyr / fenflurfen, phoxim, Bacillus thuringiensis (Bt), Metarhizium anisopliae, and Beauveria bassiana. The pest loss rate for each pesticide treatment ranged from 1.29% to 1.59%, significantly lower than the control's 14.23%. The control efficacy of the pesticides applied by spraying ranged from 42.01% to 43.77%, showing some effect, but significantly lower than that of spraying; the loss rate ranged from 5.95% to 7.62%. Although the three biological pesticides were slightly less effective than the others, they all achieved efficacy rates of 87% to 89.89%. The method of sealing cracks with soil by hilling up achieves a control effect of 89.59%, which is no different from pesticide spraying. However, this method is labor-intensive, and the vines are easily damaged during the hilling process, affecting the transport of nutrients from the vines to the tubers and hindering the accumulation of dry matter in the tubers later. Large-scale use will affect sweet potato yield. Taking all factors into consideration, several biological pesticides such as Metarhizium anisopliae, Beauveria bassiana, and Bacillus thuringiensis (Bt) can be selected.

[0077] In addition, the survey also showed that the various pesticide treatments also had good concurrent control effects on underground pests such as sweet potato weevils, grubs, and mole crickets, with the control effect of spraying reaching about 80%.

[0078] The research group conducted experiments on the combination of several biological pesticides, as detailed below:

[0079] Metarhizium anisopliae 10 billion / g powder, Beauveria bassiana 20 billion / g powder, and Bacillus thuringiensis (Bt) 8000 IU / mL suspension were mixed in pairs and applied to sweet potato fields by spraying. The control efficacy and yield were statistically analyzed, and the specific results are shown in Table 5.

[0080] Table 5. Effects of different biological pesticides on sweet potato cultivation

[0081]

[0082] As shown in Table 5, the control efficacy and yield were not significantly improved by using mixed or compound biological pesticides compared to applying biological pesticides alone. Observations revealed that adding Beauveria bassiana to the mixture was less effective than applying a single biological pesticide. In order to achieve a control efficacy of over 90%, the research team chose to add some low-toxicity pesticides to the biological pesticides and conducted further experiments to observe whether it could significantly improve the control efficacy.

[0083] Example 3:

[0084] Based on the experimental results of Example 2, a mixture of 10 billion CFU / g Metarhizium anisopliae powder, 8000 IU / mL Bacillus thuringiensis (Bt) suspension, and 20% chlorantraniliprole·thiamethoxam water dispersible agent was selected and applied to sweet potato fields by spraying. An orthogonal experiment was used to study the application conditions of the mixture. To improve the environmental friendliness of the overall compound system, Metarhizium anisopliae, Bacillus thuringiensis (Bt) suspension, and 20% chlorantraniliprole·thiamethoxam water dispersible agent were mixed at a mass ratio of 5:5:1. Three different multiples were set for each factor. Nine biopesticide treatment schemes were designed using the orthogonal experimental method, as shown in Tables 6 and 7.

[0085] Table 6. Biopesticide Factor Levels

[0086]

[0087] Table 7 Orthogonal Design of Biological Pesticide Treatment Schemes

[0088]

[0089] As shown in Table 7, the range analysis using pest infestation rate as an indicator shows that the order of importance of the factors is: chlorpyrifos-thiamethoxam > Metarhizium anisopliae > Bacillus thuringiensis (Bt), with the optimal condition being A2B3C1. Similarly, the range analysis using control effect as an indicator shows the same order: Metarhizium anisopliae > Bacillus thuringiensis (Bt) > chlorpyrifos-thiamethoxam, with the optimal condition being A2B3C1. Finally, the range analysis using yield per unit area also shows the same order: Metarhizium anisopliae > chlorpyrifos-thiamethoxam > Bacillus thuringiensis (Bt), with the optimal condition being A2B3C1. Range analysis using loss rate as an indicator showed the following order of importance of factors: Metarhizium anisopliae > Chlorantraniliprole / Thiamethoxam > Bacillus thuringiensis (Bt). The optimal conditions were A2B3C1. Overall, when Metarhizium anisopliae was diluted 150-250 times, chlorantraniliprole / Thiamethoxam was diluted 4000-4500 times, and Bacillus thuringiensis (Bt) was diluted 200-400 times, and the mixture was applied at a mass ratio of 5:5:1, the pest rate was significantly reduced, all below 2.50%, with control efficacy exceeding 90.0%, yield exceeding 2100 kg / mu, and loss rate below 2.7%. Therefore, the optimal solution for each factor is to mix Metarhizium anisopliae diluted 250 times, Bacillus thuringiensis (Bt) 200 times, and chlorantraniliprole / Thiamethoxam diluted 4500 times at a mass ratio of 5:5:1, and then apply the mixture to the sweet potato planting area via spraying.

[0090] Example 4:

[0091] This example study investigated the effect of using the same pesticide formulation without sweet potato dwarfing treatment on the damage caused by the narrow-edged cutworm, as detailed below:

[0092] The experimental group, control group 1, control group 2, and control group 3 were set up. The specific planting method for the experimental group was as follows:

[0093] Refer to Example 1 for routine planting management. The difference is that, during planting, the specific method for controlling seedling growth with paclobutrazol in step 6 is as follows:

[0094] Spraying paclobutrazol to control seedlings: Spray paclobutrazol (80 g / mu) evenly once each at 45 days and 65 days after sweet potato planting to control seedlings. The specific concentration of paclobutrazol is 900 times.

[0095] After the second spraying of paclobutrazol, the mixed biological pesticides were applied to the sweet potato field by spraying. The total application rate of the biological pesticides was 1100 mL / mu. The optimal biological pesticide formulation was to mix Metarhizium anisopliae diluted to 250 times, Bacillus thuringiensis (Bt) diluted to 200 times, and chlorantraniliprole diluted to 4500 times at a mass ratio of 5:5:1.

[0096] The specific planting method for control group 1 was as follows:

[0097] The same planting management was performed as in Example 1, except that paclobutrazol was applied only once in step 6 during planting. Specifically:

[0098] Spraying paclobutrazol to control seedlings: Spray paclobutrazol (80 g / mu) evenly once 45 days after sweet potato planting to control seedlings. The specific concentration of paclobutrazol is 900 times.

[0099] On the 45th day after sweet potato planting, the mixed biological pesticides were applied to the sweet potato field by spraying. The total application rate of the biological pesticides was 1100 mL / mu. The optimal biological pesticide solution was to mix Metarhizium anisopliae diluted to 250 times, Bacillus thuringiensis (Bt) diluted to 200 times, and chlorantraniliprole and thiamethoxam diluted to 4500 times in a mass ratio of 5:5:1.

[0100] The specific planting method for control group 2 was as follows:

[0101] The same planting management was performed as in Example 1, except that paclobutrazol was applied only once in step 6 during planting. Specifically:

[0102] Spraying paclobutrazol to control seedlings: Spray paclobutrazol (80 g / mu) evenly once 65 days after sweet potato planting to control seedlings. The specific concentration of paclobutrazol is 900 times.

[0103] On the 65th day after sweet potato planting, the mixed biological pesticides were applied to the sweet potato field by spraying. The total application rate of the biological pesticides was 1100 mL / mu. The optimal biological pesticide solution was to mix Metarhizium anisopliae diluted to 250 times, Bacillus thuringiensis (Bt) diluted to 200 times, and chlorantraniliprole and thiamethoxam diluted to 4500 times in a mass ratio of 5:5:1.

[0104] The specific planting method for control group 3 was as follows:

[0105] Refer to Example 1 for routine planting management, except that step 6, which involves not using paclobutrazol to control seedling growth, is as follows:

[0106] On day 0, day 15, day 45, and day 65 of sweet potato planting, the mixed biological pesticide was applied to the sweet potato field by spraying. The total application rate of the biological pesticide was 1100 mL / mu. The optimal biological pesticide solution was to mix Metarhizium anisopliae diluted to 250 times, Bacillus thuringiensis (Bt) diluted to 200 times, and chlorantraniliprole and thiamethoxam diluted to 4500 times in a mass ratio of 5:5:1.

[0107] The control efficacy and yield of the two groups of experiments were statistically analyzed and calculated, as shown in Table 8:

[0108] Table 8. Effects of paclobutrazol seedling suppression on sweet potato planting

[0109]

[0110] As shown in Table 8, the control efficacy and yield of the experimental group were significantly higher than those of the control group 1-3; this indicates that the combined planting method of "paclobutrazol + biological pesticide" significantly increases the control efficacy against the narrow-edged cutworm.

[0111] The control efficacy and yield of control groups 1 and 2 were lower than those of the experimental group, indicating that a single application of paclobutrazol was insufficient to effectively suppress seedling growth, creating an environment conducive to the survival of the narrow-edged cutworm, thus failing to significantly improve control efficacy and yield. Furthermore, within the two control groups, control group 1 showed higher control efficacy and yield than control group 2. This suggests that applying paclobutrazol for seedling suppression on day 65 was no longer effective in controlling the excessive growth of sweet potato seedlings. Moreover, the timing of pesticide application on day 65 indicated that pest damage had already occurred, making it difficult to further improve control efficacy. Therefore, applying seedling control and biological pesticide treatment on day 65 would significantly increase the damage caused by the narrow-edged cutworm.

[0112] In control groups 1-3, control group 3 showed significantly higher efficacy and yield than control group 2, and slightly higher than control group 1, but not significantly. This indicates that if this application only involves early intervention with biological pesticides without combining it with seedling control treatment, the efficacy against the narrow-edged cutworm will not be significantly improved. The reason for this may be that, due to the need for green planting, the concentration of biological pesticides and low-toxicity pesticides will not be too high. If pesticides are applied without effective seedling control, the sweet potato leaves will grow excessively, creating a shady environment, and the improvement in efficacy will not be obvious. Therefore, in the process of sweet potato planting, in order to reduce the damage of the narrow-edged cutworm to sweet potatoes, high-quality biological pesticides combined with low-toxicity pesticides and paclobutrazol seedling suppression efficiency are indispensable.

[0113] Example 5:

[0114] This embodiment studies the effect of different harvest times on damage caused by the narrow-edged cutworm, as detailed below:

[0115] The results obtained from selecting the sweet potato planting base in Renhou Village, Renhou Town, Yuzhou District in 2022 are shown in Table 9:

[0116] Table 9. Comparison of pest rates between fields harvested in a timely manner and fields not harvested in a timely manner.

[0117]

[0118] Table 9 shows that surveys of planting bases during the sweet potato harvest season (July-August and November-December) revealed that the pest rate was lower for sweet potatoes harvested promptly after maturity than for those harvested late. Delayed harvesting after maturity prolongs the infestation period. The average pest rate was 3.06% for sweet potatoes harvested in early to mid-July, 3.21% for those harvested in early to mid-November, and 12.67% for those harvested in early August and early December. The survey indicates that regardless of whether sweet potatoes are spring or summer-grown, timely harvesting results in less pest damage, while delayed harvesting after maturity leads to more severe pest infestations.

[0119] Example 6:

[0120] This embodiment studies the effects of different soil types on the damage caused by the narrow-edged cutworm, as detailed below:

[0121] 1. Select location and time: Select sweet potato planting bases in Renhou Village, Renhou Town, Yuzhou District and Wanglao Village, Zhangmu Town, Fumian District, in 2022.

[0122] 2. Soil selection: Each planting base should have 2 clay soil samples and 4 sandy loam or loam soil samples. Planting should be done in mid-July, and fertilizer and water management conditions should be basically the same.

[0123] 3. Effect Survey: The survey method was the same as above. The experimental results are shown in Table 8:

[0124] Table 10 Damage caused by the narrow-margined cutworm in sweet potatoes under different soil types

[0125]

[0126] The survey results in Table 10 show that the pests occurred earlier and were more severe in clay soil fields, while they occurred later and were less severe in sandy loam or loam fields.

[0127] Based on the above experiments and demonstrations, the optimal green control method for sweet potato narrow-edge application of insecticide is as follows:

[0128] 1. Site selection: Choose sandy loam or loam soil with loose soil, deep soil layer, flat terrain, and convenient irrigation and drainage. At the same time, try to stay away from damp places with weeds and winter sweet potato planting sites.

[0129] 2. Land preparation: Deep plow and turn the soil, break up the clods and rake them to ensure that the soil has small gaps after ridging.

[0130] 3. Ridging: Dig deep furrows to make high ridges. The bottom width of the ridge (including the furrow) is 110cm, the ridge width is 0.7-0.8cm, the ridge height is 30cm, and the furrow width is 30cm. The ridge surface and the bottom of the furrow should be straight, and the soil clods should be fine and broken.

[0131] 4. Weed control: After ridging, 1-2 days before sweet potato planting, apply pre-emergence herbicides such as acetochlor, metolachlor, or pendimethalin evenly to the soil surface, ensuring the herbicide is evenly mixed into the soil. During the early growth stage of sweet potatoes, when weeds have 2-3 leaves, spray with quizalofop-P-ethyl, or manually weed in conjunction with cultivation, hilling, and fertilization.

[0132] 5. Hilling and topdressing: Generally, before the stems and leaves close the ridge (about 35 days after planting), topdressing is done by digging a trench on the lower half of the ridge. After topdressing, the fertilizer is covered tightly with soil. At the same time, weeding is done manually in conjunction with hilling.

[0133] 6. Spray paclobutrazol to control seedling growth: Spray paclobutrazol 1-2 times during the vigorous growth period of sweet potato stems and leaves. About 40 days after planting, and 5-7 days after topdressing, spray paclobutrazol once after the stems and leaves have closed the canopy; spray paclobutrazol again after 20-30 days. The application rate of paclobutrazol is 60-80 grams per acre, spray evenly. When spraying paclobutrazol, it can be mixed with biological pesticides such as Bacillus thuringiensis BT, chlorantraniliprole, and Metarhizium anisopliae to control pests on stems and leaves.

[0134] 7. Covering cracks with soil during tuber enlargement: When cracks appear on the ridge surface during the tuber enlargement period, cover the cracks with fine soil to seal them tightly without leaving gaps. This prevents adult insects from flying into the soil to lay eggs or larvae from burrowing into the roots to damage the tubers and reduces the exposure of the tuber heads.

[0135] 8. Control field humidity throughout the process: use moist irrigation as the main method to prevent waterlogging or excessive moisture; stop irrigation 15 to 20 days before harvest.

[0136] 9. Harvest promptly: Harvest sweet potatoes promptly after they mature to reduce the time they are harmful.

[0137] In step 6, the spraying ratio of paclobutrazol is 600-1200 times.

[0138] The application ratio of Metarhizium anisopliae 10 billion / g powder, Bacillus thuringiensis (Bt) 8000 IU / mL suspension and 20% chlorantraniliprole·thiamethoxam water dispersible agent was 5:5:1. The dilution ratio of Metarhizium anisopliae was 250 times, the dilution ratio of Bacillus thuringiensis was 300 times, and the dilution ratio of chlorantraniliprole·thiamethoxam was 4500 times.

[0139] In step 9, the harvesting time is when the potato tubers are mature.

[0140] In summary, based on the damage patterns of the narrow-edged cutworm to sweet potatoes, this application presents a set of planting strategies for the control of the narrow-edged cutworm in sweet potato fields. The main strategy involves strictly controlling the use of paclobutrazol to dwarf the sweet potatoes, control excessive leaf growth, and create an unsuitable under-foliage environment for the narrow-edged cutworm's growth. Simultaneously, the leaves can still perform sufficient photosynthesis, preventing yield reduction. Furthermore, when applying paclobutrazol, combined research on the mixing of various biological pesticides is conducted to identify effective biological pesticides that work in conjunction with the under-foliage environment created by paclobutrazol. This effectively controls the narrow-edged cutworm's damage, achieving a control rate of over 90%, while also controlling other underground pests. This results in a significant increase in yield and improves the marketability of the sweet potatoes, realizing efficient and cost-effective green cultivation of sweet potatoes.

[0141] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A green planting method for mitigating damage by Spodoptera exigua Hubner to sweet potato, characterized by, The method comprises the following steps: (1) Selection: select loose soil, deep soil, flat terrain, convenient irrigation and drainage sandy loam or loam as sweet potato planting land; (2) Land preparation and ridging: deep plowing, raking, deep ditching, high ridge, and ridging; (3) Weeding: after ridging, apply herbicide to the planting plot before planting sweet potatoes, and manually weed; (4) Cultivation and topdressing: before stem and leaf ridge sealing, open ditch for topdressing on the lower half of the ridge slope, cover the fertilizer tightly after topdressing, and combine ditching and manual weeding; (5) Spray paclobutrazol to control seedlings: spray paclobutrazol once 40 days after planting and 5-7 days after topdressing after stem and leaf ridge sealing; spray paclobutrazol again after 20-30 days; the amount of paclobutrazol sprayed per mu is 60-80 grams; (6) Management of tubers: during the tuber expansion period, cover the cracks on the ridge surface with fine soil to seal and block the cracks on the ridge surface without leaving gaps; control the field humidity throughout the planting process; stop watering 15-20 days before harvesting; harvest sweet potatoes in time after they mature; The dilution ratio of paclobutrazol in step (5) is 600-1200 times; In step (5), green muscadine, chlorothalonil, thiamethoxam and Bacillus thuringiensis (Bt) mixed biological pesticides are applied at the same time; The effective component content of green muscadine is 100 billion / g, and the effective component content of Bacillus thuringiensis (Bt) is 8000 IU / mL; the mass ratio of green muscadine, Bacillus thuringiensis (Bt) and chlorothalonil in the biological pesticide is 5:5:1; the dilution ratio of green muscadine is 150-250 times, the dilution ratio of Bacillus thuringiensis (Bt) is 200-400 times, and the dilution ratio of chlorothalonil is 4000-4500 times.

2. The green planting method for reducing the damage of spodoptera exigua hubner to sweet potato according to claim 1, characterized in that, The dilution ratio of green muscadine is 250 times, the dilution ratio of Bacillus thuringiensis (Bt) is 300 times, and the dilution ratio of chlorothalonil is 4500 times.

3. The green planting method for reducing the damage of spodoptera exigua hubner to sweet potato according to claim 1, characterized in that, The application amount of the biological pesticide is 1100 mL per mu.

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