WO1991007869A1

WO1991007869A1 - Liquid coating formulation containing solid particulate materials to increase efficacy of biological treatments with beneficial microorganisms

Info

Publication number: WO1991007869A1
Application number: PCT/US1990/006946
Authority: WO
Inventors: Alan G. Taylor; Tai-Gi Min; Gary E. Harman
Original assignee: Cornell Research Foundation, Inc.
Priority date: 1989-12-04
Filing date: 1990-12-03
Publication date: 1991-06-13

Abstract

Seeds having a continuous, adhered coating comprising in combination a microorganism for biological control of plant pathogens and a carbonaceous particulate solid matter including soft coal, lignateous shales, sphagnum moss, muck soil, activated charcoal or mixtures protect the seed and plant from soil-borne pathogens including Pythium spp. Bioprotective compositions comprising Trichoderma strain 22 (ATCC No. 20847) are particularly effective in protecting a variety of crops including tomato, cucumber, cabbage, sugar beets, table beets, field corn, sweet corn, cotton, dry bean, snap bean and soybean.

Description

LIQUID COATING FORMULATION CONTAINING SOLID PARTICULATE MATE^RIALS TO INCREASE EFFICACY OF BIOLOGICAL TREATMENTS WITH BENEFICIAL MICROORGANISMS

The present invention relates to improved seed treatments for biological control. Background of the Invention

It is known to treat plant seeds with biological control agents to protect against Pythium spp. and Rhizoctonia solani (cf Harman et al, Phytopathology, 21 No. 6, 569-572 (1981)).

Biological control of plant pathogens requires that delivery systems be designed to permit the bioprotectant to rapidly grow and proliferate. The first 24-48 hours after sowing are critical, since the bioprotectant must occupy the ecological niche on which it is applied. Other microflora in agricultural environments compete for these niches, and so the bioprotectant must be protected while it becomes established. Further, seed treatment systems may fail if seed rotting pathogens gain entry into seeds before biocontrol agents become established. Pythium spp., in particular, attack very quickly, and can infect seeds in as little as 4 hours after planting. Trichoderma spores require 12 hours to germinate after planting, so timing becomes critical. There are many approaches for the development of seed treatment systems, including the use of selective food bases, pH control, and the use of colonized substrate (Harman et al, (1989) in Baker, H. and P. Dunn (ed.) "New Directions in Biological Control," Alan R. Liss, NY). Regardless of the method, it is clear that for effective and reliable biological control, the delivery system must be such that it allows full expression of the biological ability of the organism in question. Simply treating seeds with viable spores or otherwise delivering biocontrol agents in systems developed for the delivery of toxicants, may fail. More commonly, activity will be both more variable and less effective than that of chemical pesticides (Harman et al, Plant Disease. 73._631-637 (1989)). Solid matrix priming (SMP) developed by J. Eastin is a seed treatment that reliably gave adequate levels of protection with Trichoderma or other bioprotectants (Harman and Taylor, Phytopathology. 78;520-525 (1988)). It is effective not only in treating seeds, but also results in long-term plant benefits, particularly with rhizosphere competent organisms. However, as a batch process, it is a relatively expensive treatment for most agronomic seeds.

Consequently, there is a need for alternative seed treatment systems that provide levels of activity equivalent to that obtained with SMP, but with processes that are more adapted to continuous flow seed treatment systems. The present invention relates to improved seed treatment processes and protective coatings.

Brief Summary of the Invention

The invention relates to an improved process for treating seeds for the biological control of plant pathogens, and to the protected seed prepared thereby, which comprises treating the seed with a coating mixture comprising as a biocontrol agent, an organism adapted to grow and to control plant pathogens pathogenic to the seed; an adhesive binder; and a carbonaceous particulate solid adapted to provide a hospitable environment for the multiplication of the biocontrol agent.

One object of the invention comprises a method for applying to a seed a coating comprising a biocontrol agent, such as for example Trichoderma spp. strain 22, one or more adhesive binders, and one or more carbonaceous particulate solid carriers, adapted to provide an hospitable environment for the multiplication of the biocontrol organism. Examples of such particulate solids include soft coal, lignateous shales, lignite sphagnum moss, activated charcoal or mixtures thereof. The coating is applied from an aqueous solution or suspension in an amount sufficient to form a continuous uninterrupted, adhered solid coating on said seed and to protect the seed from at least one pathogenic organism present in the seed growing environment. Another object relates to the above method for coating a seed which further includes incubating the coated seed under conditions of high relative humidity to foster growth of the biocontrol organism within the seed coating prior to planting the seed. A further object relates to a process and coated seed where the biocontrol agent and binder mixture is applied as a first coating and thereafter a second coating comprising a particulate solid carrier is applied. A yet further object is a protective coated seed wherein no binder is used and the coating comprising biocontrol agent and solid particulate carrier is applied to the seed as a dry powder coating. Brief Description of the Drawings Figure 1 is a graph of the influence of

Trichoderma quantity in seed treatments on percent stand of cucumber sown in a Pythium infested soil. Figure 2 shows a photograph comparing surface characteristics of traditionally coated seeds with seeds coated according to the liquid coating of the present invention. Detailed Description of the Invention

The invention relates to improved seed treatments for biological control which are superior to conventional slurry techniques. In the present method, the aqueous suspension or solution of a mixture of biocontrol agent and carbonaceous particulate solid preferably with an adhesive binder are applied to the seed to form an uninterrupted solid coating over the surface of the seed.

One aspect of the invention is a seed having a continuous, uninterrupted, adhered, solid coating thereon which comprises: a bioaφntrol agent comprising an organism selected from the group consisting of fungi and bacteria for the biological control of at least one organism pathogenic to the seed or plant derived therefrom; a parbj-culate solid material selected from the group consisting of carbonaceous particulate solids and inorganic particulate solids adapted to provide an hospitable environment for the multiplication of the biocontrol agent; said biocontrol agent and said particulate solid carrier being combined in an amount sufficient to form a continuous, uninterrupted, adhered coating on said seed and to protect the seed from at least one antagonistic pathogenic organism present in the seed-growing environment.

Another aspect of the invention relates to a process for coating the above-described seed as hereinafter detailed. The amount of active biocontrol agent needed to protect the seed will vary somewhat with seed type, properties and dimensions. Generally suitable amounts will range from about 10⁵ to 10⁸ colony forming units (CFU) per gram weight of seed.

In a preferred method, seeds are treated with a mixture of biocontrol agent, adhesive binder and carbonaceous particulate solid, and these seeds are then incubated in a humid atmosphere that allows growth of the biocontrol agent. An important aspect of this preferred method is to provide seed treatments which prevents seeds from drying for several days following treatment. In another suitable method, the coating process is effected in two steps. The seeds are first coated with an aqueous suspension of biocontrol agent and binder and then a second coating of particulate solid and binder is applied to insulate the active biocontrol agent from the competitive microflora in the soil. The second coating provides an environment conducive to growth of the biocontrol agent and delays or prevents the ingress of pathogens, especially during the germination stage.

The high moisture content of the freshly coated seed is preferably maintained in an amount sufficient to maintain the hospitable environment for the multiplication of the biocontrol organism by exposing the coated seed to an atmosphere of high relative humidity. An alternative method of producing coated seeds of the instant invention is to add moisture to the uncoated seed and thereafter apply the coating composition to the moistened seed. In either case the moisturized seed and coated seed is preferably dried to allow storage and handling.

Choice of ingredients for the seed coating aqueous suspension will depend on various factors. It is preferred that the pH of the seed coating be maintained at a pH conducive to the growth of the particular biological control agent employed. For Trichoderma spp a pH of from about 3.0 to about 7.5, preferably a pH of about 4 to 6, is recommended.

The term "biocontrol agent" as used herein means a microorganism including a variety of fungi and bacteria which act, in combination with the carbonaceous particulate solid and with an adhesive binder to form an uninterrupted coating, to protect a plant seed from one or more organisms pathogenic to the seed in a seed growing environment. By "uninterrupted coating" is meant a coating that is continuous and without breaks over the surface of the seed. The coating comprises a biocontrol organism, a solid particulate and an adhesive binder in amounts sufficient to provide a hospitable environment for the multiplication of the biocontrol organism sufficient to protect the seed from one or more pathogens in the environment in which the seed is to be grown.

Table 1.

Materials and processes for effective biological seed treatments.

Amount per Material Source gram of seed

T. harzianum Geneva 1 mg (10⁶ CFU) strain 22

Binder: Pelgel Nitragin Corp. 0.5 ml (10% aqueous soln)

Polyox N-10 Union Carbide Corp. 0.5 ml (5% aqueous soln)

Solid: Agro-Lig American Colloid Co. 200 mg Carlisle Muck Soil Oswego, N.Y. 120 mg Nuchar SA Westvaco Co. 120 mg Process Duration of Level

High Relative Humidity^'incubation 4 days Pre-moistening of seeds 24% moisture content

(fresh wt basis) Although the best mode examples utilize

Trichoderma spp. Strain 22 as biocontrol agent and

Pythium spp. as the pathogen, one skilled in the art will recognize that the invention applies generally to a wide variety of fungi and bacteria bioprotectants and to other pathogenic organisms that affect crop plants. Examples of seeds protected are, for example, tomato, cucumber, cabbage, sugar beets, table beets, sweet corn, field corn, cotton, dry bean, snap bean, soybean and other crops.

The amount of biocontrol agent applied to the seed to protect against pathogens will vary somewhat with the application system i.e. pathogen, adhesive binder, particulate solid and carrier liquid. Typical useful amounts of biocontrol agent will range from about 10⁵ (Colony Forming Units) to about 10⁸ CFU per gram of seed. Useful biocontrol agents in the practice of this invention include for example, Trichoderma spp such as T. harzianum T12 (ATCC 20737) and T. virid ; T. koningjj T8 (ATCC 20736) ; Pseudomonas spp. ; Enterobacter spp. including Enterobacter cloacae (ATCC 39979 and ATCC 39978); Gliocladium spp., such as for example G. viride; Bacillus spp., such as B__. subtilus. and Pseudomonas spp. , for example P^. putida.

The coatings of the present invention, as prepared by the improved process, will protect seeds against a wide variety of pathogens in addition to Pythium spp. These include for example, Alternaria spp. ; Rhizoctonia spp. such as Rhizoctonia solani; Sclerotiu spp. such as S_. rolfsii and S. cepivorum; Armillaria spp. such as A. mellea; Verticillium spp. such as V. dahliae; and Phytophthora spp. such as P. parasitica.

Although the invention is not meant to limit use of any one species of biocontrol agent to any particular pathogen, certain specific advantageous combinations are noted. These include for example: Trichoderma spp. with Pythium spp. , Phytophthora spp. and Armillaria spp. ; Gliocladium spp. with Phytophthora spp. and Pseudomas spp. which control pathogenic fungi.

It is advantageous for preparing the improved uninterrupted coatings to incorporate an agriculturally acceptable adhesive binder into the coatings comprising biocontrol agents and carbonaceous particulate solid matter. Such binders, when indicated, are required in attaching the biocontrol agent and carbonaceous particulate solid to the seed by forming a continuous, uninterrupted solid layer over the surface of the seed, thus isolating the seed from attack by one or more pathogenic organisms present in the seed growing environment which are otherwise detrimental to seed growth. The adhesive binders are preferably soluble in the liquid medium used to apply the coating to the seed but at the least are suspendible in such medium. Although other liquid medium, such as organic liquids, can be used, aqueous solutions or suspensions are preferred.

Useful adhesive binders include for example, polyvinyl alcohol, polyalkylene oxide, polyvinyl acetate, starch, cellulose esters such as methylcellulose and hydroxypropyl cellulose, organic silicates including organosilicon esters, gums, alginate, and the like. With Trichoderma spp. neutral or acid binders are preferred so that the pH of the coating will be in the range of from about 3.0 to about 7.5, a pH of about 4.0 to 6.0 being preferred. Preferred adhesive binders include Pelgel (The

Nitragin Company) ; Polyox N-10 polyethylene oxide (Union Carbide) ; Maltrin starch (Grain Processing Company) ; and Gelvatol polyvinyl alcohol (Monsanto) . Although adhesive contents may vary depending on the type and size of seed and the particulate solid, useful amounts range from about 5 ul to about 5000 ul binder solution per gram weight of seed treated.

Useful carbonaceous particulate solid matter for the practice of the instant invention include, for example, peat and peat-like substances; peat moss;

Sphagnum moss; shale such as Leonardite shale, organic soils, muck soil activated carbon and charcoal, soft coal and the like. Preferred particulate solids, especially for use with Trichoderma spp. biocontrol agents, include Agro-Lig (American Colloids) and muck soil (muck soil from Oswego, NY) .

Other particulate solids or fillers useful in the present invention which, depending on the particular biocontrol agent/pathogen system, can often be substituted in whole or in part for the carbonaceous particulate solids include ver iculite, talc, clays, diatomaceous earths, silicates, silica, cellulose, chitin and the like. In coatings comprising the biocontrol agent or organisms, these particulate solids may be used alone, in combination with the carbonaceous particulate solid carriers or in addition to the carbonaceous particulate solids merely as fillers to fortify and improve the seed coating. These particulates are believed to be advantageous to provide an hospitable environment for the multiplication of the biocontrol agent in the seed coating, by allowing water adsorption into the coating and in providing overall insulation from the environment.

The thickness of the coating on the seed will be such that a continuous uninterrupted coating encapsulates the seed without voids thus insulating the seed from viable soil-borne pathogens. Depending on the organism and type of seed, useful coatings typically range from about 0.015 to about 1.5 mm in thickness with a coating of about 0.07 mm being preferred. Preferred coatings for Pythium spp. control are those using Trichoderma spp. Strain 22, Pelgel or Polyox N-10 binders and solid particulates such as Agro-Lig, muck soil and/or Nuchar SA.

Although the coating mixture can be applied in a single application as an aqueous suspension of the biocontrol agent, binder and particulate solid, the most preferred system is one where the seed is first treated with an aqueous suspension of biocontrol agent and binder followed by a top coating of particulate solid, also as an aqueous suspension. Useful concentrations to provide 10 ⁵ to 10⁸ colony forming units (CFU) per gram of seed treated are from 0.01 mg to about 10 mg bioprotectant; from 5 μl to about 5000 μl binder solution; and from about 1 mg to about 5,000 mg particulate solid.

The following examples are given to generally illustrate the invention and should not limit the broader scope of the invention.

EXAMPLE 1 Crops and Bioassav: The crop used was cucumber fCucumis sativus) 'Poinsett 76', a slicing cultivar. The target pathogen was Pythium ultimum strain P4.

Trichoderma harzianum strain 1295-22 (ATCC No. 20847) was the biocontrol agent employed and was formulated as a dry powder.

The bioassay consisted of sowing treated seeds in a Pythium infested sandy loam in enclosed plastic containers. The initial soil moisture content was adjusted to 6-10 percent (dry weight basis) and the bioassay was conducted at room temperature. Florescent tubes provided supplemental lighting with a 12 hour photoperiod. Seedling emergence was recorded approximately 7 days after sowing. The Trichoderma numbers were quantified in spore preparations used to treat seeds. Standard microbial techniques were followed and the number of propagules are expressed as Colony Forming Units (CFU) . Percent stand was recorded at 4 days (MAXIMUM) emergence and at 7 days (FINAL) post-emergence damping-off.

Liquid Coating Formulation: The liquid coating formulation consisting of a mixture of a binder in solution, biocontrol agent and fine-sized solid particulate material to form an aqueous suspension. The suspension, which was of low viscosity, could easily be sprayed onto seeds with an airbrush. The solid particulate was no larger than 100 mesh but a finer particle size (ca. 10 microns) was found to be best suited. The solid particulate such as Agro-Lig formed a uniform coating around the seeds, also the biocontrol agent was uniformly applied in this process. After coating, seeds were dried and a durable coating resulted which could easily be handled and planted.

Coating Equipment; Seeds were treated in a Gustafson Batch Lab Treater. A 16 oz. plastic container was adapted to the unit since the manufactured drum size was too large for our application. In general, a 10 gram sample of cucumber seeds was treated at one time. The airbrush provided good atomization and accurately delivered low volumes of liquids. All coatings were allowed to air dry overnight prior to sowing.

EXAMPLE 2 Using the application methods shown in Example 1, seeds were coated by application of Trichoderma harzianu strain 22 and Agro-Lig either as a single component or in combination. Strain 22 was applied at the rate of 5 mg/g seed and Pelgel served as the binder. Treated seeds were sown in a Pvthium infested soil in a laboratory bioassay. The results are shown in Table 2. Table 2. The influence of different combinations of strain 22 and Agro-Lig on percent stand of cucumber seeds.

Percent stand ea ent axi um Fi al

z - Mean separation within columns by LSD (least significant difference) at 5 percent level. Means followed by common letters are not significantly different.

No improvement in stand was attributed to either strain 22 or Agro-Lig applied separately compared to the non-treated seeds. An unexpected result was obtained when strain 22 was applied in a liquid coating with Agro-Lig. This data shows that Trichoderma applied in slurry alone is ineffective as a protectant in Pythium infested soil. Further studies have shown that strain 22 applied in a slurry at approximately 100 fold concentration results in 30-50% healthy seedlings in this bioassay. Therefore, the liquid coating formulation greatly improves the efficacy of the Trichoderma.

EXAMPLE 3 Solid Particulates

The effect of solid particulate materials in the liquid coating formulation was studied using Agro- Lig, muck soil and Nuchar SA (activated carbon) . The pH of aqueous suspensions of each material was 4.1, 6.1 and 5.0 respectively. The coatings produced from Nuchar SA were brittle and easily flaked from the seed surface. Muck soil produced uniform coating and required less material per gram of seed than Agro- Lig. Results are shown in Table 3. Table 3.

The influence of different solid particulates in liquid coatings on percent stand of cucumbers. All treatments contained 1 mg strain 22 per gram of seed and Pelgel was the binder. Percent stand

Solid particulate Maximum Final

Non-treated 4 c^z 0 c^z

Agro-Lig 62 a 40 a

Muck soil 56 a 36 a Nuchar SA 30 b 16 b

All liquid coated treatments with solid particulate materials performed better than the non- treated seeds in the bioassay. Plant stands obtained from seeds treated with Agro-Lig and muck soil were greater than the plant stands from the Nuchar SA treated seeds. EXAMPLE 4

Using muck soil as the solid particulate material, rate studies were preformed using different amounts of strain 22 applied per gram of seed. Pelgel was used as the binder in the liquid coating formulation. As shown in Figure 1, a general linear increase in plant stand was recorded with logarithmic increase in strain 22. One mg of strain 22 per gram of seed is equivalent to 1.6 oz of biocontrol agent per 100 pounds of seeds. EXAMPLE 5

Binder Study

By screening approximately 20 candidate binders, two compounds, Polyox N-10, and Pelgel were found to be well suited. These binders were used in seed coating formulations with Agro-Lig or muck soil. Results are shown in Table 4. Table 4.

The influence of Polyox vs. Pelgel on percent stand of cucumber. All liquid coating treatments contained strain 22 at 1 mg per gram of seed.

Solid Percent stand d articulate t e Maximum F nal

z - mean separation within columns by LSD (least significant difference) at 5 percent level. Means followed by common letters are not significantly different. Both binders resulted in similar performance, however Polyox was shown to improve efficacy compared to Pelgel when muck was used as the solid particulate. Polyox was easy to apply during coating and less tacky in the coating drum. As previously shown, no differences were observed between solid particulates within binder types.

EXAMPLE 6 High Humidity Incubation The effect of maintaining high seed moisture content by incubating the seeds after liquid coating was studied. Since water is the carrier in the liquid coating process, the seed moisture content would increase during treatment. Immediately after the liquid coating process, seeds were placed at high humidity (hiRH) , over water vapor, for a period of 4 days. After this incubation treatment, seeds were dried under ambient conditions and then sown in Pythium infested soil. Results are given in Table 5. Table 5.

The influence of hiRH incubation of liquid coated cucumber seeds on percent stand. Liquid coating formulation contained strain 22, Pelgel and muck soil.

Percent stand Treatme Maximum Final

The high humidity incubation of liquid coated seeds significantly increased the percent total and healthy seedlings compared to liquid coated seeds only. The incubation was equally effective when conc .cted either in light or dark. A 100-fold increase in colony forming units (CFU) was recovered from seeds after the 4 day incubation. Thus, it appears that Trichoderma can proliferate on the seed coat/coating at the higher water potential. The solid particulate provides inorganic and organic nutrients and the binder such as Pelgel provide carbon source. High humidity incubation was not effective in improving plant stands from slurry treated seeds (data not shown) .

EXAMPLE 7 Adding Solid Particulate as Dry Powders

The role of water from the liquid coating and high humidity incubation were characterized. In a new procedure, strain 22 and solid particulate are mixed and added as dry powders, no binder or water was added. This type of formulation is known in the trade as a planter or hopper box treatment and we have termed this process 'powder coating¹. In this experiment, three components are studied singly or in combination; binder in solution, solid particulate and high humidity incubation. The results are shown in Table 6. Table 6. The influence of binder, solid particulate and hiRH incubation on percent stand of cucumber. Pelgel was used as the binder in the liquid coating formulation treatments and strain 22 was added to all treatments.

Percent stand Treatment Maximum Final

Regarding solid particulate and aqueous binders, the powder coating with Agro-Lig plus strain 22 was effective in improving stands compared to slurry treatment (binder plus strain 22) . However, powder coating was less efficacious than liquid coating.

High humidity incubation was only effective on liquid coated seeds, so it appears that the seed moisture content must initially be high before incubation for the treatment to be successful.

EXAMPLE 8

Comparison of SMP with high moisture content biological seed treatments

To improve the efficacy of biological seed treatments, the influence of premoistening seeds prior to application of powder coating was investigated.

Other treatments included comparisons with and without high humidity incubation and SMP. Results are given in Table 7. Table 7.

The influence of high moisture content and SMP treatments on percent stand of cucumbers. Pelgel served as the binder and strain 22 was incorporated into each treatment at 1 mg per g seed.

Percent

Treatment Maximum Total liquid coating 72 b^z premoistened + powder coating (PC) 74 b liquid coating + hiRH 98 a premoistened + PC + hiRH 90 a

SMP 94 a

z - mean separation within columns by LSD (least significant difference) by 5 percent level. Means followed by commons letters are not significantly different. Premoistening seeds prior to powder coating resulted in improved biocontrol similar to liquid coating. Combining either of these treatments with high humidity incubation further improved efficacy. Results from liquid coating plus high relative humidity or premoistened plus powder coating (PC) plus high humidity.

EXAMPLE 9

Two Step Seed Coating Treatment (double coat) It is important for effective biocontrol that a high percentage of spores of the bioprotectant germinate rapidly after sowing. Compounds which leak from seeds during imbibition serve as a nutrient source for the bioprotectant. The nutritional status of spores may be enhanced by changing the spatial arrangement between the spores and the seed surface. This can be accomplished by first applying the bioprotectant and the binder as a slurry. The second step is to apply the solid particulate such as Agro- Lig suspended in the binder such as Polyox which will form an uninterrupted coating around the seeds. Table 8.

The influence of single and double coating on percent stand of cucumbers Treatment Percent stand liquid coating alone 0 liquid coating with strain 22 24 slurry with strain 22 followed 52 by liquid coating (double coat)

The two step (double coat) procedure greatly improved performance compared to the liquid coating treatment (binder, bioprotectant and solid particulate applied in one step) . No seedlings survived without the bioprotectant.

EXAMPLE 10 The actual amount of material required for uniform coatings is dependent in part on the type of seed coating equipment employed. Table 8 shows a relative guide useful in producing uniform coating for various crops. Table 8. The amounts of Agro-Lig required to produce a uniform coatings for several crops.

Agro-Lig Percent of

Crops (mg per g seed) seed wt

Tomato 280 28 Cucumber 200 20

Cabbage 200 20

Sugar beets 160 16

Sweet corn 160 16

Cotton 64 6.4 Navy bean 40 4.0

Snap bean 20 2.0

Soybean 20 2.0

EXAMPLE 11 Repeating the procedure of Example 3, but substituting non-carbonaceous particulate solids (100- 200 mg per gram of seed) for the carbonaceous particulate solids, cucumber seeds were coated using a 5 percent solution of Polyox N-10 as the binder and Trichoderma harzianum as biocontrol agent added at the rate of 1 mg per gram of seed. The coated seeds were sown in Pythium infested soil. Percent stand was evaluated at 4 days. The results known in Table 9 show that the inorganic particulate solids are effective in increasing plant viability although they were somewhat less effective than the carbonaceous particulate solid Agro-Lig.

EXAMPLE 12 Comparison of conventional seed treatments with the liquid coating treatment of the present invention was made. Photographs of the respective seeds are shown in Figure 2. It is noted that the liquid coated seeds have an uninterrupted external protective coating while the conventional coated seeds show gaps and interruptions on the seed surface.

Table 9.

The influence of other non carbonaceous solid particulates in liquid coating on percent stand of cucumbers.

Solid particulate Percent stand

Control 22

Aluminum silicate 18 Cellulose 28

Vermiculite 30

Talc 34

Agro-Lig 46

Claims

WHAT IS CLAIMED IS:

1. Seeds having a continuous, uninterrupted, adhered coating thereon which comprises a biocontrol agent comprising an organism selected from the group consisting of fungi and bacteria for the biological control of at least one organism pathogenic to the seed or plant derived therefrom; a particulate solid material adapted to provide an hospitable environment for the multiplication of the biocontrol organism; said biocontrol agent and said particulate solid being present in an amount sufficient to form a continuous uninterrupted adhered solid coating on said seed and to protect the seed from said pathogenic organism present in the environment in which the seed is to be grown.

2. The coated seed of claim 1 wherein said coating further comprises an adhesive binder in an amount sufficient to bind the said biocontrol agent and said particulate solid to the seed in a continuous uninterrupted solid layer over the surface of the seed and to isolate the seed from attack by said pathogenic organism.

3. The coated seed of claim 2 wherein the particulate solid is a carbonaceous particulate solid; and wherein the biocontrol agent is present in an amount sufficient to provide from about 10 ⁵ to about 10 ⁸ Colony Forming Units (CFU) or about 0.1 to about 10 mg per gram of seed.

4. The coated seed of claim 3 wherein the particulate solid is selected from the group consisting of lignite, lignateous shales, soft coal, sphagnum moss, muck soil and peat.

5. The coated seed of claim 3, wherein the particulate solid is Agro-Lig, muck soil, or mixtures thereof and the adhesive binder is Pelgel, Polyox N- 10 or mixtures thereof.

6. The coated seed of claim 4 wherein the particulate solid is lignateous shale and the adhesive binder is polyethylene oxide.

7. The coated seed of claim 3, wherein the particulate solid is a muck soil.

8. The coated seed of claim 4 wherein the biocontrol agent in Trichoderma species fungi and the plant pathogen is Pythium species.

9. The coated seed of claim 4 wherein the biocontrol agent is Trichoderma harzianum strain 22 (ATCC No. 20847) .

10. The coated seed of claim 4 wherein the biocontrol agent, adhesive and particulate are applied to the seed in a single coating by means of an aqueous solution or suspension.

11. The coated seed of claim 6 having multiple coating wherein a first coating comprising biocontrol agent and adhesive is applied to the seed prior to application of a second coating comprising particulate solid.

12. The coated seed of claim 8 wherein the adhesive is Polyox-N-10 and the particulate solid is Agro-Lig.

13. The coated seed of claim 12 wherein the biocontrol agent, adhesive and solid particulate are applied in a single coating.

14. The coated seed of claim 4 wherein the treated seed is incubated at high relative humidity to foster growth of the bioprotectant organism.

15. The coated seed of claim 1 wherein the coating is applied to the seed as a dry powder coating.

16. A seed having a continuous, uninterrupted, adhered solid coating thereon, which comprises in combination; a) a biocontrol agent comprising an organism selected from the group consisting of bacteria and fungi, said biocontrol agent adapted to grow on the surface of the seed and to control at least one organism pathogenic to the seed and seed growth; and b) a carbonaceous particulate solid selected from the group consisting of lignite,lignateous shales, muck soil,soft coal, sphagnum moss, peat, and activated charcoal or mixtures thereof, said particulate solid adapted to form with said biocontrol agent a continuous, uninterrupted, adhered coating on said seed and to provide an hospitable environment for the multiplication of said biocontrol agent to protect said seed from said pathogenic organism; and wherein said control seed is incubated at high relative humidity to foster growth of the bioprotectant organism; and c) an adhesive binder.

17. The coated seed of claim 16 wherein the biocontrol is a fungus organism present at a concentration of from about 10 ⁵ to about 10 ⁸ Colony Forming Units (CFU) and the particulate solid is present in an amount of from 1 mg to about 5000 mg. per gram of seed.

18. The coated seed of claim 17 where the biocontrol agent is a Trichoderma species, the adhesive binder is Pelgel or Polyox N-10 polyethylene oxide and the particulate solid is Agro-Lig, muck soil or Nuchar SA.

19. The coated seed of claim 18 wherein the plant pathogen is Pythium species.

20. The coated seed of claim 19 wherein the biocontrol agent is Trichoderma harzianum strain 22 (ATCC No. 20847) .

21. A process for treating plant seeds to protect the seed from one or more pathogenic organisms present in the seed growing environment which comprises applying to the seed a coating comprising in combination a biocontrol agent organism adapted to grow and to control at least one pathogen pathogenic to the seed; a solid particulate carbonaceous particulate solid material selected from the group consisting of lignite, muck soil, lignateous shales, sphagnum moss, soft coal, and peat; said biocontrol agent organism and said carbonaceous particulate solid being present in an amount sufficient to form a continuous uninterrupted adhered coating on said seed and to thus protect the seed from said pathogenic organisms present in the environment in which the seed is to be grown.

22. The process of Claim 21, wherein said biocontrol agent is Trichoderma species fungi and the pathogen is Pythium species.

23. The process of Claim 22, wherein the biocontrol agent is Trichoderma harzianum strain 22 (ATCC No. 20847) .

24. The process of Claim 22, wherein the coating is applied to the seed as a single coating from an aqueous solution or suspension and the coated seed is incubated at high relative humidity to foster growth of the biocontrol agent.

25. A process of controlling Phytophthora spp. caused plant diseases which comprises coating the plant seed to be protected according to the process of Claim 21 wherein the biocontrol agent is selected from the group consisting of: Trichoderma viride Trichoderma koningii Trichoderma harzianum Gliocladium virens

26. The coated seed of Claim 2 wherein the biocontrol agent is present in an amount to provide from about 10⁵ to about 10⁸ Colony Forming Units (CFU) per gram of seed and the particulate solid is an inorganic particulate solid selected from the group consisting of clay, powdered silica, metal and metalloid silicates, chalk, talc, diatomaceous earth, gypsum, vermiculite and kaolin and the adhesive binder is selected from the group consisting of polyvinyl alcohol, polyalkylene oxide, polyvinyl acetate, methylcellulose, cellulose acetate, dextrin, sugar, alginate and gums.