Peanut Seed Treating

This invention relates to the treatment of peanut seeds and particularly the method of treating such peanut seeds.

Peanut seeds have presented some exceedingly difficult problems as relates to the application of pesticides or fungicides to the seed prior to planting.

The testa of the seed is a very important and essential part of the peanut seed, but is subject to damage, depending upon the method of materials used in treating the seed.

The testa will be recognized as the thin and delicate membrane which embraces the peanut and oftentimes flakes off or is intentionally removed when peanuts are eaten. The testa provides the peanut embryo protection and also supplies essential nutrient enzymes to the germinating seed. Partial loss of the seed coat or testa reduces the likelihood that the peanut seed will germinate; and complete loss of the seed coat or testa makes it unlikely that there will be normal germination of the seed.

The susceptibility of seed coat damage and loss is dependent upon the type of the peanuts. Spanish and Bunch Type peanuts are more susceptible to damage than Runner Types.

The seed coat or testa also varies considerably in different types of peanuts. In the Spanish peanuts, which are some of the smaller peanuts grown in the United States, the seed coats or testa are relatively smooth and considerably smoother than the testa or seed coat of the Runner Types of peanuts which are generally somewhat larger or of an intermediate size as compared to the smaller Spanish peanuts. The largest peanuts are the Bunch Type peanuts, and these Bunch Type peanuts have seed coats which are considerably more wrinkled and less smooth than the testa of the Runner Type peanuts.

In order to minimize the likelihood of damage to the seed coat or testa during treating of peanut seeds, the seeds have been exclusively treated by applying a dry dust to the seed. Applying chemical treatments by a dust presents formidable problems in the application as well as in the handling of treated seeds prior to planting. The dust products have been finely ground or micronized so that it is very difficult to control the dust during application and handling. The recommended rates of usage of these dust products are 20 percent to 30 percent higher than the amount of chemical that the peanut seed can actually retain on its outside surface. The chemicals present in the dust have contact activity only, and as a result, this massive use of the dry chemicals on the peanut seeds does assure complete coverage and good chemical performance.

These chemical dusts used in treating peanuts are considered to be dust toxicants and are therefore the subject of intense interest by safety and governmental authorities. Many of the people who work with the peanut seeds have allergies responsive to the dust or skin conditions which are sensitive to the dust. Of course, the constant exposure to these dust conditions can present a very serious health hazard to the workers who must work with these peanut seeds. All of the people who handle or work with the seeds at various stages of treatment, handling and planting, including processors, truck drivers, dealers and farmers, are subject to these serious health hazards.

When it is considered that approximately 500,000 pounds of dust chemical seed protectants are required in order to adequately treat the amount of seed to plant the U.S. acreage, the excessive use of treatment by approximately 30 percent of this amount of dust chemical seed protectant is a sizable amount of chemical exposure for people involved in the peanut planting industry.

In a processing plant for treating peanut seeds, the actual treating area should have a dust-collecting system so as to remove the excessive dust from the treating area and ducting the dust outside. Clean air standards, established by both Federal and state and local governments require the air in both the treating area and the bagging area of a processing plant be treated and cleaned for minimum employee exposure. In order to fully comply, a totally enclosed air control system would be necessary at a projected cost of $50,000 to $100,000, depending upon the plant size. In view of the fact that the peanut seed processors operate on a very low gross profit margin, expenditures of this magnitude cannot be justified.

In addition, the chemical dust which is used for treating presents considerable problems to the seed processor in terms of applying the correct amount of the treating dust to the seed. Much of this seed treating is carried on in the southern states where high humidity is a frequent occurrence. High humidity causes the chemical dust to become sticky due to the fact that these dust products hydrate quite rapidly when exposed to high humidities. When the dust becomes sticky, measuring of the dust and causing of the dust to flow freely is extremely difficult and of course the amount applied to seeds becomes rather erratic.

When atmospheric conditions are extremely dry, then the problems of static electricity become extremely important in the handling of chemical dusts. Of course, static electricity also inhibits the flow of dust and the application of exact correct amounts to the seeds is extremely difficult.

Accordingly, unless the humidity conditions during processing is substantially exactly correct, flow problems are continually experienced in handling of dust.

The peanut grower who buys the treated seed is presented with varying problems by the problems of the processor. In many cases, the peanut seeds carry either an inadequate or excessive amount of dust. Inadequate amounts of treating dust on the seed result in a lower rate of germination of the seed in the field, and of course a reduced production. When the peanut seeds carry excessive amounts of chemical dust, the excessive amounts of dust present substantial problems to the grower in planting the seeds.

As indicated above, the chemical dusts become sticky under high humidity ambient conditions, which occur frequently during planting time for peanuts. The dust therefore causes the planting equipment to clog to the point of being inoperable or at least erratic in operation. The planter plates used to place individual seeds in the ground will clog to the point where the openings in the plates will not accept a seed so that the spacings between the seeds planted in the ground become non-uniform. Of course, such non-uniform plant spacing in the field will reduce the overall production of the field.

In the past, some attempts have been made to use slurry treatments with wettable powders and water to treat peanut seeds. These attempts proved quite unsuccessful, primarily because of the effect of the water on the very fragile seed coat or testa which, upon being wetted, becomes hydrated quite rapidly. Later, when the testa is permitted to dry, it shrinks substantially and flakes off the peanuts so as to substantially damage the peanut seed for planting purposes. It is believed that this occurs because when a peanut seed is treated with water and/or an organic solvent, these accumulate between the testa and the cotyledons faster than the liquid is absorbed by the cotyledon. As the liquid dries, the testa shrinks and becomes brittle and will shed very easily.

The remaining seed with a partial seed coat or testa loss is referred to as a "Bull-Head"; and a peanut seed which has suffered complete seed coat loss is termed a "Bald-Head".

Because of the marked failure to adequately treat peanut seeds with the water based slurry, the treatment of seed by dusting has been the exclusive way of applying fungicides in recent years.

An object of the invention is to produce a method of treating peanut seeds which will eliminate health hazards to persons associated with processing, handling and planting such seed.

Another object of the invention is to produce a method of treating peanut seeds which will materially reduce the quantity of treatment applied to the seed, and thereby reduce the cost and hazards associated with obtaining necessary protection from the excess toxic dust during the treating of peanuts.

Another object of the invention is to produce for peanut seeds, a seed treatment which will be effective against principal pathogens and will eliminate health hazards to persons associated with processing, handling, testing, and planting such seed.

A principal feature of the invention is the application of the treatment chemical to peanut seeds in the form of an oil based slurry or colloidal suspension, and wherein the active ingredients or particles in the suspension are exceedingly small.

Another principal feature of the invention is a method of treating peanut seeds through the use of an oil base carrier containing finely ground particles of active ingredients which uniformly cover the peanut seed to provide thorough protection.

Still another feature of the invention is the method of treating peanut seeds by utilizing a liquid as a carrier for the active ingredients and wherein the liquid is an oil.

Another principal feature of the invention is a seed treatment for peanut seeds which is dustless and which is an oil based slurry or colloidal suspension containing the active ingredients.

A principal advantage of the present invention is the elimination of toxic dust on peanut seeds and the elimination of related dust problems at application and bagging stations in a processing plant and at other locations of seed handling, trucking and planting. The dust on the seeds is essentially eliminated as to minimize environmental and physical problems related to processing, handling and planting the seeds which have previously been caused by the effect of humidity and static electricity and the extreme toxic nature of these chemical dusts.

Another principal advantage of the invention is the uniform application of treatment material to peanut seeds so as to thoroughly protect the seeds, but without using excessive amounts of the treatment material.

Still another advantage of the invention is the uniform coating of peanut seeds with non-dusting seed treatment which will not interfere with germination and sprouting of the seed but which will protect the seed against seed-borne pathogens.

A significant advantage obtained by the present invention is, in addition to obtaining treatment of peanut seeds with efficacy at least as good as with prior treatments, the elimination of dust associated with prior peanut seed treatments, which dust presents a severe health hazard to persons associated with processing, handling and planting peanut seeds, including processing plant employees, truck drivers, warehouse workers, and farmers.

In addition to the elimination of health hazards, the overriding advantages obtained by the present invention are that the treating is accomplished with an oil base slurry which is not affected at all by humidity, and therefore the high humidity problems of sticking of the dust are eliminated, and the low humidity problems related to static electricity are also eliminated; and further, the clogging of the growers planting machinery is essentially eliminated as a result of treating the seeds according to the present invention. The processor will be able to apply uniform and carefully controlled amounts of treating material to the seeds so that the peanuts received by the grower will be of standard quality, all being treated with the proper amount of the treating material. And finally, the treatment will result in uniform spacing of plants in the field because the planting machinery of the grower will not be clogged up and will continue to operate efficiently as designed.

The usual purpose of treating peanut seeds is to control and effectively eliminate the fungi and bacteria on the peanut seeds to be planted.

Some of the more important seed-borne pathogens that must be controlled include Aspergillus niger, Aspergillus flavus-oryzae, Bacteria, Penicillium spp., Rhizopus arrhizus, and Trichoderma spp. Other fungi which need to be controlled in certain situations include Alternaria sp., Chetomium sp., Curvularia sp., Fusarium oxysporum, Fusarium roseum, Fusarium solani, Mucor sp., Mucor haemalis, Rhizoctonia solani, Sterile fungi, Thielavia terricola, and Zygorhynchus sp. A number of different active chemical products are useful in controlling the seed-borne pathogens related to peanut seed. Since these products are contact fungicides, the dust formulations used are applied at excessive rates to permit total seed coverage. The non-retained excess toxic dust relates to the environmental and physical problems in the peanut seed industry.

The present invention deals principally with the manner of application of active chemical ingredients serving as pesticides to the peanuts.

According to the present invention, peanut seeds are treated by mixing the active ingredients or treating chemicals into a homogeneous oil based slurry of suspension which is then applied to the peanut seeds. The peanut seeds are actually thoroughly covered with the oil based suspension carrying the treating chemicals with the result that a homogeneous coating including the treating chemicals remain on the seed. The suspension may be applied to the seeds in any of a number of ways, but is preferably applied by producing a mist of the suspension, and then passing the seed through the air-borne mist as by gravity. The treating chemicals are in the form of finely ground particles which adhere to the peanut seed treated by the slurry and contained in the homogeneous coating which remains on the seeds. The slurry which is applied to the peanut seeds migrates around the entire periphery of each of the peanut seeds so that the coating covers the entire outer periphery of the seeds. In the process of applying the slurry, all of the outer surface of the testa or seed coat including all of the wrinkles or irregularities is coated with the oil based slurry or suspension.

It has been found satisfactory to use a refined and distilled mineral oil as the oil base of the slurry.

The treating chemicals known as Captan, Botran and Vitavax have been found to be effective in treating peanut seeds, as against the principal seed-borne pathogens. Botran is a registered trademark of The Upjohn Company, Kalamazoo, Mich.; and Vitavax is a registered trademark of Uniroyal Chemical, a division of Uniroyal, Inc. of Naugatuck, Conn. These chemicals are initially in the form of a dry dust, and are formulated into a colloidal suspension with oil. These formulated chemical products all contain approximately three pounds of active dry dust per gallon of product, and are all formulated under the same formulation technology at Gustafson Chemicals, Inc., Marcene, Idaho.

It has been found that approximately twelve to sixteen fluid ounces of the treatment-carrying oil slurry per hundred weight of peanut seeds treated is satisfactory to give adequate coverage.

Several different chemicals and combinations have been used as seed treatments in the suspension to produce the coating for the peanuts. After the suspension is applied to the peanut seeds, as to produce a coating on the peanut seeds, the seeds are allowed to dry. The end product of this treatment is the peanut seed with a dried coating embracing and thoroughly covering the testa. The coating extends into the wrinkles of the testa and at least partially penetrates the testa. The coating contains at least one contact type fungicide, as described, effective against seed-borne pathogens.

Captan 30-DD flowable has been used as a seed treatment, utilizing 3.0 fluid ounces of the seed treatment per hundred weight of peanut seeds. The Captan was mixed into an oil base slurry, adding oil sufficient to apply 6.0 fluid ounces of the total slurry including the Captan, per hundred weight of seeds treated. The oil used as a base for the slurry is a mineral oil, refined and distilled from crude. Typical of the oil used is an oil produced by Witco Chemical Company of Bakersfield, Calif., identified as Product 9093LM with a specific gravity at 60.degree. F. of 0.8751 and a flash point, COC of 320.degree. F.

There are a number of other similar oils available which would also be suitable, all mineral oils refined and distilled from crude, such as Shell 68-S oil product code 86625 produced at Shell Refinery, Martinez, Calif., with a flash point of 320.degree.; Sun Oil Product 8070 Neutral, product code KM133-714 with a flash point of 350.degree. to 360.degree. F., sold by Kerr-McGee Refining Corporation of Oklahoma City, Okla.; or other Kerr-McGee products identified as product name 8070 E-2 with a product code KM133-998, or product name 8070 E-1 with a product code KM133-996, both with flash points of approximately 350.degree. to 360.degree. F.

In this example, the Terra Coat L-205 seed treatment was used in a concentrate of 4.0 fluid ounces per hundred weight of peanut seeds treated, and also mixed into an oil based slurry, wherein six fluid ounces of the slurry including the Terra Coat L-205 was applied per hundred weight of seed treated.

The fungicide treated seed and controls were plated ten per Petri dish and were incubated in the dark for seven days after which the colonies of fungi and bacteria were enumerated; with the exception of the enumeration of the Rhizopus and Trichoderma colonies which were enumerated after three days because these grow so rapidly.

The effectiveness of the chemical treatment of the seed is found in Table 1 which compares to the non-treated control seeds, and the seeds treated with the standard Difolatan-Botran (60-20).

Also as a part of this example, laboratory germination tests were made of the seeds which were treated with the oil based slurry seed treatment and compared against non-treated seeds and seeds treated with the standard dust control treatment of Difolatan and Botran (60-20). The germination checks are reported in Table 2.

Treatment of the seeds in this example was effective and the oil based slurry did not cause damage to the seeds. Although the actual chemical treatments used were lacking in some respects, the Captan 30-DD seed treatment alone with the oil based slurry produced outstanding performance based on the expectancies of this Captan seed treatment.

In this example, numerous seed treatment chemicals were applied alone in an oil based slurry and various mixtures of chemical seed treatment were applied in an oil based slurry, each being applied to one hundred peanut seeds of the Florunner variety and another one hundred of Florigiant variety.

Although the various chemical treatments used in the oil based surries had varying efficacy as relates to the seed-borne pathogens counted, the coatings produced on the seeds by the treating slurries did not produce Bull-heads or Bald-heads. In each of the seed treatments, nine fluid ounces of the total slurry, including the active ingredients, was used per hundred weight of seeds being treated. Table 3 and Table 4 show the actual fluid ounces of the treating chemical used in the slurry. The oils used were again mineral oils refined and distilled from crude, as explained in Example 1.

The Treatment No. 7 indicated in Tables 3 and 4 is the standard Difolatan-Botran (60-20) dust which is the standard used in the industry prior to this time.

Tables 3 and 4 indicate the colonies of fungi and bacteria of various identifications counted on the plated seeds.

As a part of this example, a number of the Florunner peanut seeds treated with varying seed treatments applied with the oil slurry were laboratory germinated in comparison with non-treated control seeds and seeds treated with the standard dust treatment of Difolatan-Botran (60-20). Germination of these seeds treated with various treatments applied with the oil slurry is reported in Table 5. It will be recognized that the number of seeds germinated is closely comparable between the seeds treated with the standard dust treatment and certain of the seeds to which treatment is applied with the oil based slurry.

In Example 3, the results of which are found in Tables 6 and 7, additional quantities of one hundred Florunner peanut seeds were again treated with the flowable Captan 30-DD and the flowable Botran 30 in an oil based slurry, and the second seed treatment also included the flowable Vitavax. The oils used were as explained in Example 1. The total slurry including the active ingredients was applied at a rate of nine fluid ounces per hundred weight of seeds treated. Again, the colonies of fungi and bacteria were counted, and germination tests were performed, and the results were quite favorably comparable to the results obtained with the dust chemical treatment provided by the Botec standard dust treatment. The treatment with the oil based slurry and chemical treatments carried thereby caused no Bull-heads or Bald-heads in the peanuts treated.

In Example 4, numerous concentrations of Captan and Botran flowable are demonstrated in comparison with the non-treated control peanut seeds and the peanut seeds treated with the standard dust treatment of Difolatan-Botran (60-20).

All of the flowables were applied in a slurry with fourteen fluid ounces total slurry per hundred weight of peanut seeds treated. Several of the treatments with different combinations of active ingredients produced results very comparable to those produced with the standard dust treatment. The same type of oil described in connection with Example 1 was used in the treatments of Table 8, Treatment No. 2, and Treatment No. 6 showed results extremely comparable with the standard dust treatment in Treatment No. 10. In Treatment No. 2, three fluid ounces of each of Captan 30 and Botran 30 were mixed in the oil slurry and applied with fourteen fluid ounces of total slurry per hundred weight of peanuts treated.

Field emergence as demonstrated in Table 9 was actually better than for the seeds treated with the standard dust treatment.

In addition to the oils specified in connection with Example 1 and used throughout the testing, other oils may also be used such as Penreco Oil 2251 and Penreco Oil 2263, which are white mineral oils with flash point of 165.degree. to 170.degree. F. These oils are produced by Pennzoil of Butler, Pa., and facilitate quick drying during the processing of the peanut seeds.

It should be pointed out that the treating chemicals or active ingredients must be finely divided in producing the flowable product. Technical Captan, for instance, has particle sizes in the range of 50 to 300 microns. This technical Captan is micronized, preferably to the particle sizes of 3 to 30 microns in producing a flowable product.

Here, seed treatments with various amounts of the oil based slurry or suspension were applied to several batches of peanut seeds, and the number of colonies of disease pathogens were counted. In batches II, III and IV, the treatments were applied at rates of 8, 10, and 12 ozs., respectively, per hundred weight of peanut seed treated. Comparison was made to untreated peanut seeds, and to seeds treated with Vitavax 300 dust, according to Table 10; and to seeds treated with Difolatan-Botran (60-20) dust according to Table 11. The effectiveness of the treatment will be recognized in the rates of treatment applied. Application of 14 or 16 ozs. per hundred weight will also produce effective protection. The oil based extender uses the same type of oil specified in Example 1.

Field emergence of peanut seeds to which 12 oz. of seed treatment per hundred weight of seeds treated, is seen to be very satisfactory according to Table 12. The oil used in the slurry or suspension is the same type as indicated in Example 1.

The effects of applying peanut seed treatments at rates of twelve and fourteen ounces of treatment per hundred weight of peanut seed as relates to elimination fungicide colonies on the seeds and as relates to rate of germination, are evident in Tables 13 and 14. These are compared with the percentages of clean seed and germination of peanut seeds treated with the standard Difolatan-Botran (60-20) dust, and of untreated seeds. The effectiveness of the treatment applied as an oil based suspension or slurry is clear. The oils used in the treatment is of the same type as described in Example 1.

It will be seen that applying seed treatments in the form of an oil based slurry or suspension containing the active contact type chemicals at rates of six to sixteen ounces of total treatment per hundred weight of peanut seed provides effective protection against the pathogens which are of primary concern in the planting and growing of peanuts.