Safe long-acting weeding method for phoebe nursery

Abstract

This invention belongs to the field of forest tree seedling technology and relates to a safe and long-lasting weed control method for *Phoebe zhennan* nurseries. The method uses 70-100 mesh moist river sand as a carrier, employing a two-step premixing process to uniformly adsorb ethoxyflufenicol and pendimethalin onto the sand surface before application to the seedbed. Comparative experiments show that the leaf residue rate of 70-100 mesh river sand (1.2%) is significantly lower than that of >100 mesh ultrafine sand (8.7%), with a phytotoxicity rate of 0. The effective period (52 days) is significantly longer than that of 20-40 mesh coarse sand (28 days), and there is no significant difference compared to ultrafine sand, achieving an excellent combination of "safe coarse sand-like effect + long-lasting ultrafine sand-like effect". The annual weed control cost per acre is 150 yuan, a 92.5% reduction compared to manual weeding and a 25% reduction compared to conventional chemical spraying. This invention solves the problems of easy phytotoxicity from chemical weeding in nurseries and the high cost of manual weeding, offering advantages such as safety, long-lasting effect, low cost, and ease of operation.

Description

Technical Field

[0001] This invention belongs to the field of forest tree seedling technology, specifically relating to a safe and long-lasting weed control method for use in Phoebe zhennan nurseries, using 70-100 mesh river sand as a carrier. Background Technology

[0002] *Machilus chinensis* is a precious timber species unique to my country and a national second-class protected plant. Its seedling cultivation is a crucial link in afforestation and resource conservation. In nurseries, weeds fiercely compete with seedlings for sunlight, water, and nutrients, severely impacting seedling growth. Currently, the following two weeding methods are mainly used:

[0003] 1. Manual weeding: Weeding requires 4 people for 1 day per acre (local labor cost is 100 yuan / day), and 5 weedings are needed per year, with an annual cost of about 2,000 yuan / acre. This method is labor-intensive and inefficient, and the roots of seedlings are easily damaged during weeding, affecting the survival rate of seedlings.

[0004] 2. Conventional chemical spraying: The herbicide is diluted with water and sprayed directly onto the seedbed. Although the cost of each application is low, it has the following drawbacks: (1) Because the seedlings of Phoebe bournei are sensitive to a variety of herbicides, the drift or dripping of the herbicide can easily cause leaf burn, deformed heart leaves, or even death of the whole plant, resulting in a very high risk of herbicide damage; (2) The effective period is short, usually only 25 to 30 days, and it is necessary to apply the herbicide 3 times a year, with a total annual cost of about 200 yuan / mu (not including seedling losses caused by herbicide damage); (3) It has strict requirements for weather (no wind and no rain), and is difficult to operate. Therefore, manual weeding is still the main method in production.

[0005] While existing technologies include the application of pesticides mixed with solid carriers (such as sand) (commonly known as the "pesticide-soil method"), inappropriate carrier particle size selection often leads to the following problems: excessively coarse particles (e.g., 20-40 mesh) result in a small specific surface area, weak pesticide adsorption capacity, and a short duration of effectiveness; excessively fine particles (e.g., >100 mesh) result in slow sedimentation and easy retention on leaf surfaces, posing a risk of phytotoxicity. Therefore, it is urgent to screen for carriers with the optimal particle size that can ensure good adsorption to prolong the duration of effectiveness while also allowing for rapid sedimentation to avoid leaf residue. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a nursery weeding method that is highly safe for *Machilus pungens* seedlings, has a long-lasting effect after a single application (45-60 days), and is significantly less expensive than manual weeding. This method overcomes the technical shortcomings of existing "soil-based herbicide methods," which suffer from short-lasting effects or the risk of phytotoxicity due to improper selection of carrier particle size. The method specifically includes the following steps:

[0007] Step 1: River sand pretreatment

[0008] Select 70-100 mesh river sand, sieve it to remove coarse particles and impurities, and adjust the moisture content of the river sand to 50%-60% (it should clump together when squeezed in the hand and crumble when dropped). Prepare 25kg of moist river sand per acre of nursery.

[0009] Step 2: Stepwise premixing

[0010] Mix 25g of the contact herbicide ethoxyflufen (24% EC) with 2.5kg of the moist river sand prepared in step 1 to form premixed sand A;

[0011] Mix 25g of the pre-mixed herbicide pendimethalin (33% emulsifiable concentrate) with another 2.5kg of moist river sand to make premixed sand B.

[0012] Step 3: Overall Mixing

[0013] Add premixed sand A, premixed sand B, and the remaining 20 kg of moist river sand into a mixer and mechanically stir at 60-80 rpm for 5-10 minutes until the river sand turns a uniform brown color. This will give you the drug-containing river sand carrier.

[0014] Step 4: Nursery Site Preparation

[0015] The nursery was irrigated the day before the application of the medicated river sand to moisten the soil.

[0016] Step 5: Application

[0017] Choose a sunny, windless day. After the dew on the leaves of the *Phoebe zhennan* seedlings has dried, evenly spread the medicated river sand on the surface of the seedbed. The spreading density should be such that 50-80 sand grains are visible per square meter.

[0018] Step 6: Clean the leaf surface

[0019] Immediately after application, gently sweep the seedling leaves with a soft broom to remove any remaining medicated river sand from the ground.

[0020] Step 7: Timing of application

[0021] It should be done when the weed seedlings have grown to 2-3 true leaves.

[0022] The present invention has the following advantages:

[0023] 1. High safety: Comparative experiments (Table 2) demonstrate that the leaf residue rate of 70-100 mesh river sand is only 1.2%, significantly lower than the 8.7% of >100 mesh ultrafine sand (p<0.01), and the incidence of phytotoxicity is 0, while the phytotoxicity rate in the ultrafine sand treatment area reaches 6.5%. This is because the particle size of 70-100 mesh river sand is moderate, which can ensure good adsorption of the pesticide while allowing it to settle quickly and not easily remain on the leaf surface.

[0024] 2. Long-lasting efficacy: 70-100 mesh river sand has a moderate specific surface area (approximately 0.15-0.21 mm), exhibiting good adsorption capacity for pesticides and exhibiting minimal agglomeration. A single application provides efficacy for 45-60 days, significantly longer than the 25-30 days of 20-40 mesh coarse sand (p<0.01), and not significantly different from the 50-60 days of >100 mesh ultrafine sand (Table 2). Only two applications are required throughout the growing season.

[0025] 3. Low cost: The total cost of pesticide, river sand and labor per mu is about 75 yuan. The cost of two pesticide applications per year is 150 yuan. This is 92.5% lower than manual weeding (2000 yuan / mu / year) and 25% lower than conventional chemical spraying (200 yuan / mu / year).

[0026] 4. Easy to operate: No special equipment is required. Two people can work together to quickly complete large-area operations. The weather requirements are lower than those for spraying (as long as there is no rain and no dew on the leaves). Detailed Implementation

[0027] The technical solutions in the embodiments of the invention are described clearly and completely below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] Step 1: River sand pretreatment

[0030] Select 70-100 mesh river sand, sieve it to remove coarse particles and impurities, adjust the moisture content of the river sand to 55% with water (it can be formed into a ball when squeezed in the hand, but crumbles when dropped), and prepare 25 kg of moist river sand per acre of nursery.

[0031] Step 2: Stepwise premixing

[0032] Mix 25g of the contact herbicide ethoxyflufen (24% EC) with 2.5kg of the moist river sand prepared in step 1 to form premixed sand A;

[0033] Mix 25g of the pre-mixed herbicide pendimethalin (33% emulsifiable concentrate) with another 2.5kg of moist river sand to make premixed sand B.

[0034] Step 3: Overall Mixing

[0035] Premixed sand A, premixed sand B, and the remaining 20 kg of moist river sand are put into a mixer and mechanically stirred at 70 rpm for 7.5 minutes until the river sand turns a uniform brown color, thus obtaining the drug-containing river sand carrier.

[0036] Step 4: Nursery Site Preparation

[0037] The nursery was irrigated the day before the application of the medicated river sand to moisten the soil.

[0038] Step 5: Application

[0039] Choose a sunny, windless day. After the dew on the leaves of the *Phoebe zhennan* seedlings has dried completely, evenly spread the medicated river sand on the surface of the seedbed. The spreading density should be such that 65 sand grains are visible per square meter.

[0040] Step 6: Clean the leaf surface

[0041] Immediately after application, gently sweep the seedling leaves with a soft broom to remove any remaining medicated river sand from the ground.

[0042] Step 7: Timing of application

[0043] It should be done when the weed seedlings have grown to 2-3 true leaves.

[0044] Experimental Example 1

[0045] 1. Test conditions

[0046] The experiment was conducted in 2024 at the *Machilus chinensis* seedling nursery of Jiangxi Longhua Health Development Co., Ltd., covering an area of ​​10 mu (including a comparison area for different particle sizes). The tested *Machilus chinensis* seedlings were one-year-old container seedlings, with an average height of 30 cm and a ground diameter of 0.5 cm. The main weeds in the nursery included *Digitaria sanguinalis*, *Eleusine indica*, *Cyperus rotundus*, and *Barnyardgrass*. The experiment included three treatments: coarse sand (20–40 mesh), the present invention (70–100 mesh), and very fine sand (>100 mesh). Each treatment was replicated three times in a randomized block design, with each plot covering 1 mu.

[0047] 2. Materials and Operation

[0048] River sand: For each treatment, use 25 kg per acre according to the designed particle size, and adjust the moisture content to 55% (it should clump together when squeezed in the hand, but crumble when dropped).

[0049] Herbicides: 25g of 24% ethoxyfluorfen EC and 25g of 33% pendimethalin EC.

[0050] Perform the above steps 2-6 twice (on May 15th and July 20th).

[0051] In addition, a manual weeding control area (1 mu, 5 times a year) and a conventional chemical spraying control area (1 mu, the same agent diluted with water and sprayed, 3 times a year) were set up.

[0052] 3. Measurement Indicators and Methods

[0053] Leaf residue rate: After application and cleaning, 10 seedlings were randomly selected from each plot, and the residual sand particles on the leaves were collected, weighed, and calculated as a percentage of the total applied amount.

[0054] Duration of effect: The number of days from the application of the herbicide until the weed germination rate reaches 50% of that in the control area.

[0055] Incidence of pesticide damage: The proportion of plants with scorched leaves, deformed leaves, or necrotic growing points was investigated 30 days after pesticide application.

[0056] Seedling survival rate: Statistical analysis at the end of the growing season.

[0057] Cost accounting: calculated based on local actual labor and material prices.

[0058] 4. Results

[0059] Table 1 Comparison of physical properties of river sand carriers with different particle sizes

[0060] Particle size range Specific surface area Adsorption capacity Settlement velocity clumping tendency Leaf adhesion coarse sand 20-40 mesh Small weak quick none weak This invention 70-100 mesh Moderate good Moderate none medium Extra fine sand 100 mesh big powerful slow have powerful

[0061] Table 2 Results of field comparative experiments with river sand carriers of different particle sizes

[0062] Leaf residue rate (%) Shelf life (days) Incidence of pesticide damage (%) Seedling survival rate (%) coarse sand 0.8±0.3a 28±3a 0a 97.2±1.2a This invention 1.2±0.4a 52±4b 0a 98.5±0.8b Extra fine sand 8.7±1.2b 55±5b 6.5±1.5b 91.3±2.1c Manual weeding - 18±2 0 94.8±1.5 Chemical spraying - 28±3 13.5±2.5 86.4±3.1

[0063] Note: Different letters in the same column indicate significant differences (p<0.01, n=5). Experimental conditions: One-year-old seedlings of *Machilus chinensis*, 25 kg of medicated river sand per mu (667 square meters) was applied, with the pesticides being ethoxyflufenican + pendimethalin. Leaf residue rate refers to the percentage of sand particles remaining on the leaves after application and cleaning, relative to the total amount applied.

[0064] Table 3 Comparison of annual costs and effectiveness of different weed control methods

[0065] Manual weeding Conventional chemical spraying Method of the present invention Number of assignments per year 5 weeding trips 3 sprays 2 times of giving Labor required per instance (person-days / acre) 4 0.5 0.5 Cost per application of pesticide + carrier (yuan / mu) 50 30 (pharmacy) 5 (River Sand) Labor cost per mu (yuan / mu, 100 yuan / day) 400 50 50 Total annual cost (yuan / mu) 2000 200 (excluding pesticide damage) 150 Cost of replanting seedlings (yuan / mu, based on a 5% replanting rate) 50 100 (Replanting after pesticide damage) 0 Total annual cost (including replanting) 2050 300 150 Safety of seedlings Safe but prone to damaging the root Unsafe, high risk of pesticide damage Highly safe, zero pesticide damage Shelf life (days) 15-20 25-30 45-60

[0066] Table 4. Comprehensive Costs for Each Treatment Year (Yuan / Mu)

[0067]

[0068] in conclusion:

[0069] The 70-100 mesh river sand carrier used in this invention exhibits excellent efficacy duration, reaching up to 52 days, significantly superior to coarse sand carriers (28 days); and shows no significant difference compared to ultrafine sand carriers (55 days). Regarding safety indicators, the leaf residue rate of this invention is only 1.2%, with no phytotoxicity (0% phytotoxicity), significantly better than the ultrafine sand scheme (8.7% residue rate, 6.5% phytotoxicity rate), and essentially equivalent to the coarse sand scheme. These technical effects demonstrate that this invention achieves a synergistic unity of "safety (coarse sand-like) and long-lasting effect (ultrafine sand-like)" through a specific particle size combination, achieving technical effects that a single particle size carrier cannot achieve, possessing outstanding substantive characteristics and significant progress.

[0070] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A safe and long-lasting weed control method for *Phoebe zhennan* nurseries, characterized in that, Includes the following steps: (1) Adjust the moisture content of 70-100 mesh river sand to 50%-60%, and prepare 25 kg per mu for later use; (2) Take 2.5 kg of moist river sand and mix it evenly with 25 g of 24% ethoxyfluorfen EC to make premixed sand A; take another 2.5 kg of moist river sand and mix it evenly with 25 g of 33% pendimethalin EC to make premixed sand B; (3) Mix premixed sand A, premixed sand B and the remaining 20 kg of moist river sand at 60-80 rpm for 5-10 minutes until the color is uniformly brown to obtain drug-containing river sand; (4) Irrigate the soil to retain moisture the day before applying the pesticide; (5) On a sunny and windless day, when the seedling leaves are free of dew, spread the medicated river sand evenly on the seedbed. The spreading density is 50 to 80 visible sand grains per square meter. (6) Immediately after sprinkling, use a soft broom to sweep away any remaining sand particles from the seedling leaves; (7) The effective period of a single application of the drug is ≥45 days.

2. The method according to claim 1, characterized in that, The optimal time for application is when the weed seedlings have 2-3 true leaves.

3. The method according to claim 1, characterized in that, The river sand has a moisture content of 55%.

4. The method according to claim 1, characterized in that, The method was applied in a nursery of 1-2 year old *Phoebe zhennan* seedlings.

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