JPH06271404A - Process for promoting growth of plant and imparting plant with disease resistance - Google Patents

Abstract

(57) [Summary] (Corrected) [Composition] Having an endophytic mycorrhizal fungus (VAM) and growth promoting action on growing plants, preferably after soil disinfection by solar heat treatment in the presence of corrosive organic substances. Rhizosphere bacteria (PGP
R) and other plant disease antagonistic bacteria, etc., which are treated with dichlorodiisopropyl ether in the presence of a microorganism having a disease-controlling effect or a growth-promoting effect on the plant, thereby imparting plant growth-promoting and disease resistance. Method. [Effect] The method of the present invention promotes the proliferation and activity enhancement of VAM and PGPR by applying DCIP, and restores the soil fertility in soil where soil strength has declined or soil microbial ecosystem is unbalanced. It is effective in restoring and maintaining the ecosystem of soil microorganisms, and as a result, it is possible to suppress plant diseases, promote growth, and increase yield.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for promoting the growth of plants and imparting disease resistance, and more particularly to dichlorodiisopropyl plants which are grown in the presence of microorganisms which have a disease suppressing action or a growth promoting action on the plants. The present invention relates to a method for imparting disease resistance to a plant, which is characterized by performing a chemical treatment with ether (trade name: Nemamol, registered trademark of SDS Biotech Co., Ltd., hereinafter referred to as DCIP).

[0002]

2. Description of the Related Art The prevention or control of plant diseases caused by the action of harmful microorganisms is a basic proposition of agricultural and horticultural industry regardless of old, modern, east and west, but with the demand for increased food production and the modernization of agriculture. Chemicals such as pesticides and fertilizers are used extensively, and due to the development of science and technology and at the same time social needs such as environmental concern and the pursuit of safety, excellent pesticides with higher medicinal efficacy and safety than before. Although many developments have been made, on the other hand, like the cultivation of vegetables and flowers in relatively small farmlands near large cities in Japan, such as large amount application of chemicals and greenhouse cultivation, As cultivation methods in different environments have become popular, adverse effects such as soil diseases, continuous cropping defects, and stunted growth also increase, which also causes a serious problem of promoting large-scale application of drugs.

So-called natural farming, which does not use chemicals such as pesticides or fertilizers, is also practiced among some serious farmers, but stable cultivation of high quality crops with high yields. From the viewpoint of economical economic and horticultural industry, there is a limit on its own due to the fact that the conventional method requires a great deal of work and that there are restrictions on natural conditions such as target crops, soil and climate. , It's not always general.

In recent years, various studies have been conducted on the control of plant diseases focusing on the action of microorganisms in soil, and in particular, microorganisms such as endophytic mycorrhizal fungi (VAM) and plant growth promoting rhizobacteria (PGPR). There is a lot of research on
Conventionally, application to various plant cultivations utilizing the action of these microorganisms has been studied in various places, but VAM cannot currently be artificially cultivated, and the original inoculum is also reasonably expensive, and PGPR As for the above, there is a problem that even if it is applied to the soil for cultivating crops, it is difficult for bacteria to grow with existing microorganisms, and it is undeniable that there is a feeling that it will be a step forward for practical use.

VAM, which is a kind of mold symbiotic with many terrestrial plants, is bacteriologically
belongs to Ndone), which makes phosphates and minerals in the soil soluble and sends them to the roots of plants. On the other hand, the nutrients required by plants absorbed by VAM hyphae are the dendritic bodies of the fungi formed in the root cells. At that time, it exchanges with the substances necessary for the growth of the bacteria, and the remaining nutrients are stored in the capsule. VAM has the function of protecting the roots of plants from diseases because they die when the plants with which they live die, and VAMs also produce certain hormones to enhance root growth and enhance plant growth. Promotes growth. However, it does not symbiosis with roots invaded by pathogenic bacteria or roots with disabilities, and VAM disappears in many places where fertilizers and pesticides (for example, herbicides and fungicides) are used. Was a cause of frequent occurrence. As described above, VAM cannot be artificially cultivated at present, and no effective method can be found for artificial growth other than using economically expensive charcoal powder.

[0006] Some soil bacteria have a function of promoting the growth of plants and suppressing pathogenic bacteria, and particularly rhizosphere bacteria on the surface of roots of plants or in the vicinity (rhizosphere) are well known. ing. That is, rhizobacteria are propagated with nutrients such as plant secretions and bald root tissues, and are divided into plant growth-promoting rhizobacteria (PGPR) and harmful rhizobacteria (DRB) by their action on plants. Has been. This PGP
When R is used for controlling plant diseases and promoting growth, V
As with AM, its ability to settle in the rhizosphere along with its ability to antagonize pathogenic microorganisms is an important requirement,
A strain excellent in these capabilities is required.

Various attempts have been made in the past to control plant diseases by these microorganisms, but the effect is not always sufficient, and it is currently not widely used that various microorganisms exist in the soil. They coexist in balance with each other, and it is difficult to selectively grow only specific bacterial species even if they are beneficial to agriculture and horticulture. Even if a large amount of fungus is added, it will be naturally culled if the conditions for growth in the plant rhizosphere in the soil and establishment in the plant root are not properly prepared, and it is always necessary to maintain high-concentration reproduction as intended. It is said that this is due to things that cannot be done. In addition, for the purpose of proliferating bacteria, organic substances are added or watering operation is performed,
Various attempts have been made to use chemical substances, but no report has been found that a remarkable effect was obtained.

[0008]

DISCLOSURE OF THE INVENTION The object of the present invention is to promote the growth of microorganisms having the above-mentioned VAM, PGPR and other plant disease-controlling or growth-promoting actions, the establishment in the plant rhizosphere and the action on the roots. In order to ensure that these useful microorganisms act on growing plants and exert an excellent effect on the healthy growth of plants, it is intended to develop means for artificially controlling, Furthermore, by solving this problem, we will reduce the amount of fertilizers and pesticides used and contribute to environmental conservation.
It is to restore the balance of the natural ecosystem that was damaged by the heavy use of these artificial chemicals.

[0009]

The above object of the present invention is achieved by treating a growing plant with DCIP in the presence of a microorganism. That is, the present invention provides a method for imparting plant growth promotion and disease resistance, which comprises treating a growing plant with DCIP in the presence of a microorganism having a plant disease suppression action or a growth promotion action. It is intended to be provided. The present invention further provides a method characterized by treating with DCIP after soil disinfection using solar heat and a method characterized by treating with DCIP in the presence of corrosive organic substances. To do.

The method for promoting the growth of plants and imparting disease resistance according to the present invention will be described in more detail below. DCIP used in the method of the present invention has been conventionally marketed as a nematicide, and it was confirmed that it has an effect of promoting the growth of crops and an effect of increasing the yield in the process of actual application. ing. However, it promotes the growth of microorganisms such as VAM and PGPR that have disease inhibitory action or growth promoting action on plants, colonization in the plant rhizosphere, and the action on the roots, and these useful microorganisms can be reliably applied to growing plants. It has been confirmed that the present inventor has an effect of exerting an excellent effect on healthy growth of plants by acting on, and is effective in a method of promoting growth of plants and imparting disease resistance. This is the first time that I know. Incidentally, the method of the present invention is not a method for directly preventing or suppressing plant diseases, but for the growth of disease-resistant plants through microorganisms having a useful action on plants, that is,
The feature is to realize a method for promoting plant growth and imparting disease resistance.

However, as has been attempted in some fields of agriculture and horticulture, it is not sufficient to simply apply DCIP to a growing plant of interest,
In order to obtain the excellent effects of the present invention described below, it is an important requirement to treat with DCIP in the presence of a specific microorganism having a disease control action or a growth promotion action on plants.

In this case, VAM and PGPR are desirable as the types of microorganisms to coexist as described above. Specifically, for VAM, for example, Glomus (Glomu) is used.
s spp. ), Gigaspora s
pp. ), Sclerocystis
is spp. ), Scutellospora (Scutell
ospora spp. ), Enterofospora (En
terophosspora spp), Acaulospora spp, etc., and PG
Regarding PR, for example, Pseudomonas fluoresce (Pseudomonas fluoresce)
ns), Pseudomonas
s putida), Pseudomonas cepacia (Ps
As a typical example, eudomonas sepia) and the like can be mentioned. As a matter of course, other microorganisms are not particularly limited as long as they are microorganisms having a plant disease suppressing action or a growth promoting action.

It should be noted that VAM and PGP are present in the cultivated soil for crops.
In many cases, R is already present, but in such a soil it may be treated with DCIP, but in order to expect a reliable effect, a strain confirmed to have an excellent effect on each crop Is preferably applied separately, and when DCIP treatment is carried out after soil disinfection as described below, or when these microorganisms are not present or when their reproduction is suppressed by heavy use of fertilizers and pesticides, DCIP treatment At the same time or before or after the supply of these microorganisms from the outside, for example, freeze-dried or aqueous suspension P
It is necessary to add GPR bacterial cells and VAM spores or mix soil in a place with a high PGPR effect.

The amount of DCIP to be applied is not particularly limited, but if it is too small, the desired effect cannot be expected, while if it is too large, the effect itself has its own limit. The optimum concentration varies depending on the type of target crop, leaf age, natural conditions, etc. Also, since VAM and PGPR differ in the optimum concentration and the concentration that causes growth inhibition, it cannot be specified unconditionally, but give one guideline. For example, for VAM, the DCIP component amount is about 5 to 10 kg / 10a, and spore germination is promoted even at a concentration of 10 to 100 ppm.
Although PGPR has the same amount of components, the concentration of PGPR is about 1 ppm, the growth of the bacterium becomes vigorous.
If it is more than ppm, there is also a risk of growth failure.

DCIP has a high volatility, and if it is left as it is, the components are volatilized into the atmosphere. Therefore, it is necessary to cover the soil immediately after spraying it as a granule. Also, since the effect is poor in soil with low water content, the soil water content when applied is 50-
It is preferably about 60%. However, when irrigating as an emulsion, the amount may be less than this. In order to further bring out the effect of DCIP, soil pH, soil temperature, E
It is desirable that C and the like be in an appropriate range. That is, soil p
For h, it can be widely used from acidic soil to alkaline soil, but in VAM there is a lot of spore formation near 5.3 to 6.2,
In addition, in PGPR, it is recognized that the effect tends to be exhibited around 6.0 to 8.0.

Regarding the soil temperature and the time of use, it is said that the activity of VAM is active at about 20 to 35 ° C., but about 20 to 25 ° C. for glomus, which is one of the most typical VAMs. It has a suitable temperature. Although it varies depending on the region depending on the season, the cultivated land in the open field of Japan is generally suitable from the middle of May to the middle of October. Further, in PGPR, it can be said that the proper period is around July to late September (about 20 to 25 ° C.) where the ground temperature is high in the open field, and it is desirable that the temperature is at least 15 ° C. Of course, this is not the case if the ground temperature is high in greenhouses and heating houses. Also, EC is 0.3 to 0.5
The degree is appropriate.

The method of the present invention is a method of subjecting a growing plant to DCDC treatment as it is or by introducing useful microorganisms. Further, in order to obtain a more reliable and excellent effect, the soil is disinfected once. A method of killing contaminated bacteria and phytopathogenic fungi and then performing DCIP treatment again is preferable. In this case, useful VAM, PGPR and the like are also killed, but it is sufficient to re-introduce an excellent strain suitable for the crop by the above-mentioned method or the like.

As a soil disinfection method, it has been conventionally said that treatment with chloropicrin, methyl bromide, or the like is surely performed. However, these agents are highly toxic to the human body and therefore, in order to avoid danger in using them. In addition to being forced to take various troublesome preventive treatments, and highly effective in combating pathogenic soil bacteria and filamentous fungi, harmful soil nematodes, etc., in addition to these, other useful There is a problem that it destroys natural ecosystems by slaughtering various microbes and micro organisms. Therefore, in the present invention, treatment with solar heat, which has been popular in recent years in closed houses and the like, is recommended from the viewpoints of reduction of work labor, avoidance of danger to human bodies, prevention of destruction of soil microbial ecosystem. Further, when the solar heat treatment is performed, the effect becomes more reliable if the treatment is performed in the coexistence of a corrosive organic substance. The soil disinfection method by solar heat treatment in the presence or absence of corrosive organic substances is well known in the art, and there are no special requirements when applied in the method of the present invention. The conventional method can be used as it is.

The method of the present invention is not limited to the target plant and can be applied to various plants. In particular, seedlings just before germination, seedlings, bots, cells, etc., during seedling raising or during transportation. And these are used together with the above-mentioned useful microorganisms.
By treating with CIP, disease resistance is imparted to these plants, and the subsequent growth is more active and the yield of crops is increased as compared with untreated seeds and seedlings.

[0020]

INDUSTRIAL APPLICABILITY The method of the present invention can be applied to V by applying DCIP.
It promotes the growth of AM and PGPR and enhances the activity, and is also effective in restoring soil fertility and restoring and maintaining the soil microbial ecosystem in soil with weakened soil and soil with an unbalanced soil microbial ecosystem. Therefore, as a result, it is possible to suppress plant diseases, promote growth, and increase yield. The method of the present invention is particularly difficult to control than before, and a controllable disease such as chloropicrin or methyl bromide having a method of dealing only with thorough soil disinfection using highly toxic agents, such as tomato, Pseudo-monas solanac of eggplant, bell pepper, potato, tobacco, etc.
Earum), wilt disease such as tomato, cucumber, melon, watermelon, potato, spinach, Fusarium wilt (Fusar)
ium oxysporum), cucumber, eggplant, etc., seedling blight, spinach, etc., strain rot (Rhizoton)
ia spp, Pythium spp), tomato, eggplant, etc. half body wilt disease (Verticillium sp.
p), etc. are effective in prevention, and when compared with soil disinfection methods using chloropicrin, methyl bromide, etc., they are not only easy and cheap to handle, but especially for human safety and environmental protection. The significance is immeasurable.

[0021]

EXAMPLES Hereinafter, the method of the present invention will be described more concretely by showing representative examples. However, these examples are shown as a single frame for facilitating the understanding of the method of the present invention, and are merely examples for the purpose of explanation, and thus the method of the present invention is not limited to these. Needless to say, these are not restrictive.

Example 1 Objective: Contrary to chlorpicrin, which has been conventionally used for preventing bacterial wilt and wilt disease in a tomato continuous cropping house Variety: House Momotarou Treatment method: 10a large-scale diseased by continuous tomato cultivation until the previous year Soil disinfection using solar heat for 20 days from July 15th at the house, and DCIP at 9 ai amount on August 20th.
After treatment with kg / 10a, seedlings were planted on August 27. Fertilization and other management was based on the general house. Test results: The diseased strains 80 days after planting were investigated to determine the diseased strain rate.

[0023] Comment: After the sun heat treatment, a slight illness was also observed in the chlorpicrin treatment area. It is considered that the drug did not reach the tip (1 m or more) of the root extension,
The high effect of DCIP was due to the growth of antagonistic bacteria in the soil after solar heat treatment.

Example 2 Purpose: Control effect against eggplant half body wilt disease compared with commercially available soil fumigant Variety: Senryo No. 2 Treatment method: D-D92% as a reagent agent at the place of occurrence in the previous year,
Carbum 50%, Chlorpicrin, DCIP 80% 8
Predetermined amount (10a / 301 for each drug) 30cm on the 5th of each month
The dots were staggered. Except for DCIP plots, they were covered after post-injection, degassed on Aug. 17, and planted on Aug. 29 under the condition of 1 plot of area of 10 m ² and 4 stations. Test results: The survey was conducted on October 1. Comment: Although no nematode damage was observed in any of the plots, the nematicide DCIP showed growth similar to that of chlorpicrin, and the number of hemitrophic wilt disease strains was also less than that of chlorpicrin.

[0025]

Example 3 Purpose: Examination of carnation wilt bacterial disease control effect and phytotoxicity Varieties: Nora Treatment method: Vinyl house cultivation (in the disease house: All the plants that died of all the diseases due to this disease in the previous work were used. 1
Probably due to the effect of positive heat treatment by the polyethylene coating for 0 days, the occurrence was moderate. Fertilization: General management), planting August 16
Sun, stock distance 15cm, line spacing 25cm, 1 ward 2.1m
² (1.4 × 1.5m), 32 shares / ward, 3 consecutive systems, DCI
The chemical treatment with P is carried out on August 2 (14 days before planting),
DC of predetermined amount (261 per 10a, ai20.8kg)
After injecting IP at a distance of 30 cm and a depth of 15 cm, it was covered with a polyethylene film. The soil temperature at a depth of 15 cm at the time of treatment was 32 ° C, and the soil water content was 17.5%. Degassing was carried out twice on August 12 (immediately after removing the coating) and August 16 (before planting). The untreated section was covered with polyethylene for 10 days in order to make the same conditions as the treated section. Test results: On October 17, the diseased strains were investigated by surveying wilting strains and investigating bacteria flowing out into water. Comments: Carnation wilt disease (Fusarium) and wilt bacterial disease (Pseu) due to soil treatment with DCIP
It was confirmed that the disease was prevented, and there was no phytotoxicity.

[0027]

Example 4 Purpose: Controlling effect on tomato wilt disease by treatment after soil disinfection by solar heat treatment Chlorpicrin and shark variety: Fukuju No. 2 Treatment method: Tomato wilt disease on July 13 by using solar heat The soil was disinfected, and thereafter, 10/10 of DCIP emulsion was diluted 200 times with 101 / 10a and irrigated. The chloropicrin plot and the untreated plot were set to be the same and used as a control plot. Chlorpicrin Ward, July 20, 301 / 10a, 3
It was poured in a 0 cm zigzag pattern, covered with polyethylene, and degassed on August 7. For planting, seedlings grown in pots were planted on August 20 and planted on September 20 in a greenhouse. 1 ward 100 shares,
2 consecutive system. Test result: October 20 Survey of the number of diseased strains Comment: DCIP treatment area showed few diseases, vigorous growth, and early harvest. DC after solar heat treatment
Disease onset in the IP-treated group was similar to that in the chlorpicrin group in the control group.

[0029]

Example 5 Purpose: Examination of growth promoting effect on Chinese cabbage Varieties: Gold general Treatment method: Seeding date September 3rd, drug treatment date September 21st, provisional planting date October 1st Setting of test zone and amount of drug (1 ward 6 people 4 repetitions) 1. Chlorpicrin 30 1 / 10a 2. DCIP 30 〃 3. DCIP 20 〃 4. Untreated plot Survey results: Harvest on November 27 The stock weight was examined. Unit k
g Comment: When Chinese cabbage was cultivated in a field treated with DCIP emulsion, the growth was fast and the head size was large. It should be noted that it is necessary to harvest as early as about 2 weeks to 10 months because the heading becomes large during the normal harvesting period and becomes a problem as a product.

[0031]

Example 6 Purpose: Examination of the effect of DCIP application on soil growth and yield of strawberries Varieties: Onamine Treatment method: Complete soil treatment in flatland forcing cultivation General seedlings July 15th, September 15th DCIP granules (30 g /
m ²⁾ the application KokoOkoshi-Saxe, ridge width 1.1m, strains 21c
2 m high ridge of m, planting on September 30th, starting heat retention on October 20, fertilization / cultivation management is by conventional method. Test scale 1 ward system (1 ward 6m ² , 50 shares). Survey result: Early harvest and yield Comments: 1) About 1 flowering period and 1 harvest period
Early on day 0, there were many harvests as well as growth, and the index was 192, and the average fruit weight was heavy. 2) The transition of 1 fruit weight is DCI
P ward was light until mid-January, but tended to be heavier in eki fruits. It is considered that this is because the number of fruits was large in relation to the yield. 3) As a result, although DCIP application improved the initial growth and increased the yield, the effect of application was high until mid January (around the severe cold season), but decreased from mid February.

[0033]

Example 7 Purpose: Examination of the effect of PGPR on the growth of spinach Variety: Mahoroba Test method: Rhizo among the bacteria isolated from the root surface of the spinach strain, which promoted remarkable growth using DCIP
The test bacteria were those having a strong antagonistic effect against C. tonobacteria. The test bacteria were cultivated for 48 hours and then suspended (10 ⁹ CFU / ml)
Was adjusted, and the seeds were soaked in this bacterial solution overnight and then seeded. 1
Ward 0.3 × 10 m, 2 repeats (August 2) Survey method: The survey counted the number of strains growing to 0.3 × 10 m. (September 7th) a) Number of growing strains, b) Number of growing strains in which true leaves are fully developed, c) Average weight Comment: A certain number of seeds per certain area were sown, but N
o. 1 bacterium and No. In the area where seeds were coated (bacteri- zation) with 2 fungi, no disease was observed due to Rhizoctonia, growth was vigorous, and yield was high.

[0035]

Example 8 Purpose: Examination of influence of application of DCIP on growth and yield of tea Test method: Test in kindergarten (variety: Yabukita young tree) Test section 1: Untreated section 2: DCIP Granules 15 kg / 10a applied from mid to late June 3: In addition to the above, also applied from early to mid September (total 30 kg /
10a) 4: 30 kg / 10a of DCIP granules was applied from the middle to the middle of September Test in a natural garden (variety: Yabukita 20th grader,
Machine picking) Test section 1: Untreated section 2: DCIP granules 15 kg / 10a applied from early to mid September 3: DCIP granules 30 kg / 10a applied from early September to mid September Survey results: 1st tea and 2nd tea The yield of rice (4th consecutive year)

[0037]

[0038]

Example 9 Purpose: Examination of VA mycorrhizal growth of Satsuma mandarin orange by DCIP and its effect on growth and yield Test method: DCIP emulsion 101, 30 per 10a
It was diluted to 0 times and irrigated on May 16 into a soil containing fertilizer mixed with sterilized soil in a wooden frame. One week after the treatment, mandarin orange seedlings were inoculated with mycorrhizal fungi (Glomus mossey) in roots and planted, and six months after planting, the number of spores in soil and the degree of symbiosis of fine roots were examined. DCIP in the middle of May every 5th year after planting
The emulsion was diluted 101/300 times per 10a and irrigated, and the growth of the tree and the yield per tree after 3 years were investigated. Averaged for 5 shares in 1 ward. Test results:

[0040]

[0041] Comment: When DCIP was used together with the soil inoculated with Glomus, the number of bacteria increased remarkably. In addition, in the mandarin orchard treated with the DCIP emulsion, the tree volume expanded 3 years after the treatment, and the number of fruits set and the yield increased. It is considered that this is because the VA mycorrhizal fungi increased due to the DCIP treatment.

Example 10 Purpose: Examination on the growth promotion effect of VA bacteria and the growth promoting effect of young trees when DCIP emulsion was applied to the soil of citrus garden Varieties and scales: 2nd grade Okitsu early age, 2 repeats for each ward, 3 repeats

Test method: The constitution of the treatment section and the treatment method are as follows. Note) For soil disinfection, use chlorpicrin on April 9 for 30 days.
After processing 3 ml per hole at 1 cm intervals, vinyl mulch is applied and 1
After 0 days, mulch was removed and degassing was performed by medium tillage. The planting was carried out on April 24, and 30 g of VAM was adhered to the roots of the early-growing Okitsu young trees per tree in the VA inoculation area. Survey method: Trunk circumference and tree volume of the test tree on May 1st and January 22nd of the following year Summary of survey results: Trunk circumference and tree volume of Okitsu Waso Wenzhou

[0044] Comment: In the previous year's test, DCIP was found to grow VA mycorrhizal fungi, but it was confirmed that it promotes the growth of mandarin oranges.

Example 11 Purpose: Examination of influence of treatment time / concentration of DCIP on yield of figs Variety: Masui Dauphin Test method: DCIP emulsion 101 / 10a in early June, 9
At the beginning of the month, dilute 200-fold or 300-fold, respectively, and investigate the difference in yield between the one-time treatment group and the two-time treatment group. Cultivation is conventional cultivation of paddy field cropping, 1 ward, 3 strains, 2 consecutive systems. Result: Survey the total amount taken by the end of October.

[0046] Comment: The treated plot showed a significant increase in revenue compared to the untreated plot. In particular, the two-treatment area had a high yield increase. However, the difference between the 200 times and 300 times once treatment areas was not clear,
We think that double processing is practical.

Claims (6)

[Claims] 1. A method for imparting plant growth promotion and disease resistance, which comprises treating a growing plant with dichlorodiisopropyl ether in the presence of a microorganism having a disease control action or a growth promotion action on the plant. . 2. The plant according to claim 1, wherein the microorganism is at least one of plant disease antagonistic bacteria, endophytic mycorrhizal fungi, and soil microorganisms belonging to rhizobacteria having a growth promoting action. Method. 3. The method according to claim 1, which is treated with dichlorodiisopropyl ether after soil disinfection. 4. The method according to claim 1 or 3, wherein the soil disinfection is a solar heat treatment. 5. The method according to claim 1, wherein the treatment with dichlorodiisopropyl ether is carried out in the presence of a corrosive organic substance. 6. A method for promoting the growth of a plant, which comprises treating the seedlings in a growing box, pot, cell, etc. with dichlorodiisopropyl ether in the presence of a microorganism having a disease-controlling effect or a growth-promoting effect on the plant. A method for imparting disease resistance.