CA1075598A

CA1075598A - Dithiocarbamate fungicide systems of enhanced effectiveness

Info

Publication number: CA1075598A
Application number: CA269,909A
Authority: CA
Inventors: Sol J. Barer; Arnold J. Rosenthal; Norman W. Thomas
Original assignee: Celanese Corp
Current assignee: Celanese Corp
Priority date: 1976-01-19
Filing date: 1977-01-18
Publication date: 1980-04-15
Also published as: AU2140577A; JPS52105212A; IT1075802B; BR7700341A; AU504522B2; FR2337998A1; DE2702096A1; AR219911A1; ES455309A1

Abstract

ABSTRACT: Effectiveness of dithiocarbamate salt foliar fungicides, e.g., Maneb, enhanced with vinyl acetate polymer dispersions.

Description

7~598 1 This invention relates to foliar fungicide applications and more particularly, systems for enhanced fungicidal effectiveness of dithiocarbamate salts utiliz-ing film forming poly(vinyl acetate) emulsions.
: 5 Foliar fungicides i.e. chemical agents having fungicidal or fungistatic properties employed in direct application e.g. sprayed onto the foliage of plant species for control or eradication of fungal infestation are well~
j known. Maneb (manganous ethylene bis[dithiocarbamate~), 10 and Zineb (zinc ethylene bis~dithiocarbamate]) are typical, and are widely used in the control o~ a broad class of fungi including molds, mildews, rusts, yeasts and smuts, ln cultivation of tomato, potatoes, or vine crops for example.
Maneb is normally applied to foliage as an aqueous dispersion in water of an 80~o wettable powder ( 80 WP i . e. 80% Maneb plus 20% of an inert inorganic sub-strate with a surfactant). Despite its relati~ely low solubility in water, it is readily removed from the foliage 20 by rainfall, necessitating reapplication as many as eight times in one season for effective fungus control. Fungicides especially must be able to withstand weathering since it is during rainy periods that infection potential is maximized.
The problem is discussed in U.S. 3~592,910, pro-25 posing a liquid polyterpene as a sticking agent forfungicides such as Maneb. In general, it has long been known that many substances having low water solubility and which are also sticky, gummy or varnish-like at high ~p .

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~0755~8 concentrations or when dry have the ability to enhance the tenaciousness of pesticides to the protected locus, e.g. leaves. Examples of such 'sticking agents' include proteinaceous materials such as glue, gelatine, casein, ; 5 flour and skim and dried milk; or petroleum, fish, soy-bean and linseed oils; or miscellaneous materials such as bentonite, bentonite-sulfur, Bordeaux mixture, resins from sugar, coumarin resin, rubber latex, vinyl latex, polyvinyl acetate, polyvinyl chloride and acrylic 10 adhesives. (See "Laboratory and Field Comparisons of Tenacity Agents for Agr~cultural Spray Fungicides", Harry, J.B. pH. D. Thesis, Univ. Pa. (1948): ~niversity Microfilms, Ann Arbor, Michigan, Publ. ~2139; "Analysis of the basic processes involved in the deposition, degra-15 dation, persistence and effectiveness of pesticides"Ebeling, W. Residue Rev. 3, p. 35-163 (1963)~.
The selection of such adjuvants involves a number of factors beyond the resistance to weathering of the combination or the phytotoxicity thereof, including 20 interference by reaction or otherwise with the operatlon of the active fungicidal agent, the clogging of leaf stomata, and the issue of persistent residues. Moreover, the material utilized must be easily handled, operate consistently with the spray schedule, be economical and 25 be consistent with environmental concerns.
In general, the synthetic resins improve tenacity~
but without increases in efficacy of the fungicidal agent.
In fact Harry, supra reports that standardized tests showed , 3~

1 that certain synthetic resins interfered with the normal inhibiting effect of a tribasic copper sulfate fungicide.
Other reports, in experiments with copper oxychloride and small amounts of e.g. surfactant containing polyvinyl 5 acetate emulsions, are in conflict: 'Some observations on size and biological activity of spray deposits produced by various formulations of copper oxychloride' Evans, E.
et al Ann. appl. Biol, 58, p. 131-144 (1966)). See also Somers, E. J. Sci. Fd. A~ric. (1956) p. 160 ff, ibid 10 10 (1959) p. 548 ff.
In a particular application of Parzate (65% zinc ethylene bis[dithiocarbamate~) with sticXing agents for control of coffee rust, it was found that althou~h the inherent tenacity of the active agent could be improved, 15 the differences in effieacy for the respective systems were statistieally insignificant. {'A Field Evaluation of six stickers in combination with Parzate for the Control of Coffee Rust' Valdez, R.B. et al. Plant Dis. Reptr. 43 p.
562-~ (1959)).
Moreover, a comparative study ('For Foliar Application of Chemicals' Billard, R.W. and Campbell, D.L.
Forest Science 14 (1) pp. 39-43 (1968)) ranking polymeric species as stieking agents for sueh materials as zinc dimethyl dithioearbamate show none as effective as the 25 aerylies in eommon use (particularly Rhoplex AC-33), and vinyl acetate - based adhesives exhibited less weather resistance than the other classes tested. At best, it is apparent from the art that enhancement of pesticide tenaeity ~` 30 `

D~ ~ ~RIc .:

1 and fungitoxicity is empirical and agent specific.
Although polyvinyl acetate emulsions constitu~-ing the selected agent and vehicle for the co~positions and delivery systems of the invention have been used in 5 agriculture heretofore as noted above, no known applica-- tion has evidenced enhanced and retained fungicidal efficacy for dithiocarbamate salts. U.S. 3,873,689 shows the use of a small proportion of polyvinyl acetate disper-sion in a multi-component system for plant agents such as 10 Maneb, but no enhancement of activity of any agent ~s disclosed.
In accordance with this invention, there are provided foliar fungicide compositions of enhanced and retained activity comprising a minor proportion of at 15 least one dithiocarbamate salt, a ma~or proportion of polyvinyl acetate and an agriculturally acceptable carrier.
The dithiocarbamate material, usually a wettable powder, is typically dispersed in a concentrate for spraying by dilution with water in conventional apparatus for the 20 purpose and can therefore be conveniently adapted for combination with polyvinyl acetate, as in an emulsion com-prising a stable milky dispersion of solid resin in water.
Thus, the present invention also provides a method of improving the fungicidal activity of dithiocarbamate salts 25 by providing the salt in combination with a maJor proportion of vinyl acetate polymer.
Levels of poly(vinyl acetate) to fungicide ranging from l:l to 30:1 (weight ratio) may be used or, 1 (at a nominal 50% solids level) from 2:1 to 60:1 based upon emulsion, although best results are often secured at intermediate levels e.g. 12:1 emulsion basis.
;~ ~he foliar fungicide/polyvinyl acetate emulsion 5 is usually applied to the crop to provide 1/12 to 4 lbs. of dithiocarbamate/acre. Thus, Maneb/PVAc may be provided e.g. as concentrates containing 6% Maneb with 37.59% to -~ 93.75% of poly(vinyl acetate) (55% emulsion), and diluted and applied at a rate to supply 1 to 4 lbs. Maneb/acre.
10Although analysis of leaf tissue at the low application levels applicable is exceedingly difficult, it is believed that the active fungicide component is carried within and deposited on ~he plant surfaces in combination with the film forming polymer. Thus, pockets or patches 15 of appliea material form sections of generally discontinu-ous but sometimes interconnected film segments. The fast set property and excellent leveling of polyvinyl acetate emulsions, taken together with their soft, flexible and water resistant film properties together make the polymer 20 uniquely suited to utilization in accordance with the invention.
Without wishing to be bound by an essentially hypothetical elucidation of the~underlying mechanisms, it is believed that the foliar fungicide is on the one hand 25 physically isolated by the film barrier from contact with conditions leading to degradation and loss of effectiveness, while on the other hand offering sufficient availability to counter ~ungus infestation~ and at the same time benefiting ''~

1~75598 1 from tenacious adherence to the substrate. Possibly, a combination of factors including permeability or porosity of the film as well as its more complex barrier and mem-brane transfer properties interplay to offer the large 5 increases in fungicidal effectiveness seen in this system.
It is not known with certainty which mechanisms pertain in the utilization of dithiocarbamate fungicide i.e. whether the initially applied compounds or breakdown products con-stitute the active agent, and whether passage into the plant 10 tissue or access to the mycelia is a limiting factor in effectiveness. Thus, the ratio o~ lipid to water solubility of the combined delivery system may give rise to preferential ~bsorption into fungus spores or mycelium pads. Since leaf tissue is typically negatively charged, as are such materials 1~ as Zineb, fungicidal effectiveness in this system due to improved deposition and retention may be at least in part aue to a minimization of repellant charge by coating with the emulsified polymer. (See 'Dynamics of Deposltion and Tenacity of Fungicides' Rich, S. Phytopathology, 44 (1954) 20 ~p. 203-213)-The effect of the dithiocarbamate salt-pol~vinyl acetate system also appears specialized by comparison to combinations that might have been expected to exhibit similar performance. Thus, systems utilizing polyvinyl 25 acetate emulsions in combination with (1) Karathane 25 WD
(2,4- and 2,6- Dinitro 6-octylphenyl crotonate) for protec-tant control of powdery mildew in cucumber (Cucumis sativa)

(2) Hinosan 40% EC (o-ethyl-S,S-diphenyl phosphorodithiolate)

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: ~075598 :
1 for control of rice blast disease in rice (Or~za sativa);
and (3) Glyphosate (N-(phosphonomethylglycine)), for pos~-emergence herbicidal control of yellow nutsedge (Cyperus esculentus) were generally ineffective under standard rain-5 fall conditions.
An advantage of the present invention is the~inimization of reapplication fre~uency for the fungicide.
Obviously, loss of e.g. Maneb from the foliar region leads to potentially undesirable concentrations of the substance 10 in the soil, particularly with iterated treatments required by rainy weather. Retention on the leaves also maintains effectiveness levels at relatively reduced material cost.
This is particularly advantageous for fungal disease con-trol in long growing season tropical and subtropical crops 15 such as banana, coffee and yams, since fewer applications of fungicide with retained effeckiveness may be envisaged using a weathering or rain resistant formulation according to the invention.
The film forming polymer delivery system is also 20 beneficial for application to leaf crops e.g. lettuce, cabbage and the like since the coherent film deposits tend to be discharged by the plant before harvest by the loss of tenaciousness through plant growth. In this instance, or even where removal from the leaf of the composite system 25 may be accomplished by weather conditions, the present fungicidal compositions are seen as more effective soil drenches. Moreover, residual soil levels can be controlled more effectively by the use of the present invention with , 1 ecological limits.
In accordance with a preferred embodiment, an ethylene bis[dithiocarbamate] salt is applied to tomatoes for control of late blight in combination with about 3:1 5 up to about 8:1 parts by weight of a polyvinyl acetate emulsion, at a level of fungicide to provide 2 lb./acre.
As seen from Examples III-IV, better than 90% control is B achieved with Maneb and two different PVAc emulsions, even with substantial simulated rainfall.
In addition to Maneb and Zineb~ other fungicides of the class may be used, such as Ferbam (ferric dimethyl dithiocarbamate); Ziram~(zinc dimethyl dithiocarbamate);
Vapam (sodium N-methyl dithiocarbamate~; Polyram (mixture of 5.2 pts. weight (83.9%) of ammoniates of [ethylene bis-15 (dithiocarbamate)] zinc, 1 pt. wgt. (16.1%) of ethylene bis-[dithlocarbamic acid], bimolecular and trimolecular cyclic anhydrosulfides and disulfides); and the coordina-tion product of zinc (2%) and manganese (16%) ethylene : bis-~dithiocarbamate] (62%). The usually employed 20 toxicologically acceptable salts of these materials are suitable ~or the present purposes. (See U.S. Patents 1,972,961 or Re: 22,750; 2,317,765; 2,504,404; 2,974,156;
3,248,400 and 3,379,610) i~rporatod hor~in by roferenoo.) The polyvinyl acetate conveniently takes the ; 2~ form of an emulsion both for its ready compoundability ~rith the principal fungicidal agent, and its simple adaptability to spraying operations. Surfactants of course may be employed where desired to facilitate emulsification.

~ Trod~ rna~ _g_ . .

107559~3 1 Aqueous emulsions comprising homopolymers and copolymers of vinyl acetate of the well-known type may be conveniently utilized in accordance with the invention.
The procedures used to prepare such polymer emulsions 5 generally involve adding, with rapid stirring, one or more of the monomers to water which contains or to which ls added, either simultaneously or subsequently, surfactants or emulsifying agents, a polymerization catalyst or initia-tor and, in many cases, a protective colloid-forming sub-10 stance. This mixture is then heated to polymerizationtemperature with continued stirring~ and held at that temperature until substantially complete polymerization of the monomer or monomers has occurred. Delayed add~tion of one or more monomers may be practiced, and pre-emulsion 15 techniques utilized to maximize solids levels (See U.S.
3,637,563, 3,423,352-3.) Fine particle size (0.1-0.2 micron) poly(vinyl acetate) emulsions with anionic or nonionic surfactants, are commercially available, as are the large particle size 20 (0 5-3.0 micron) variants stabilized by a protective colloid.
The polymer may be internally plasticized or modified with lO to 30 percent comonomer units based upon the unsaturated esters, such as the acrylates e.g. ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, the methyacrylates 25 and the dialkyl e.g. dibutyl or dioctyl maleates and fumarates. Poly(vinyl alcohol) and hydroxyethylcellulose are conventionally used as protective colloids. The use of coalescing agents to improve film formation (e.g. Butyl ~075S98 1 Carbitol and the Cellosolves) is also contemplated.
Preferred for the purpose of this invention, are the homopolymer, and copolymers which dry rapidly to a soft flexible, relatively clear film. Best results have been 5 achieved with Stein, Hall Vin Rez 7R-15 comprising an B internally plasticized poly(vinyl acetate) copolymer and an anionic surfactant, of 55% solids, l micron particle size providing a permanently soft flexible water resistant film; or Vin Rez 202A (Stein Hall) comprising a homopolymer 10 of poly(vinyl acetate) and an anionic surfactant of 5~%
solids, 2-lO micron particle size, providing a film of good flexibility and fair water resistance. Similar emulsions are availableg as SB-5, SB-9 or SB-ll (~B. Feller), Flexbond 800 (Air Reduction), 40 124 ~Jalpol (Reichhold) 15 P529 or P763 (Borden) and Elv ~ t--81 900 (duPont).
The application of the emulsion in the absence/
of fungicide of course shows some favorable effect as a protectant, but the result is believed due to little more than surface coverage and chemical and physical surface 20 modification, per se, rather than any significant level of fungicidal activity.
It is, of course, understood that the dithiocarba-mate may form only part of a multipurpose spray. Thus, Maneb or Zineb may be formulated with Methoxych~r or Sevin, $ ~ ~
25 and Rotenone or Malathion for vegetables; Ferbam may be mixed with Methoxychlor or Sevin, and Malathion for fruits;
and Zineb or Ferbam may be used with sulfur or Karathane, DDT, lindane or Sevin, and Malathion for flowers, trees and shrubs.

~ rr6.DI~ M~rK -11-,' 1 Of course, combinations with inorganic pesticides are also contemplated where compatible as formulations with sulfur, copper sulfate tbasic), copper oxide (brown), Bor-deaux mixture tdry), copper hydroxide, lime sulfur and the 5 like. Obviously, other plant agents such as insecticides, acaricides, minerals and hormones commonly used in agricul-ture for the maintenance or nurture of plant life, or the control or eradication of pests or disease therein, or the pres$nce of undesired species thereabout may be incorporated 10 in the compositions of the inventi~n wherever compatible.
C-enerally speaking the dithiocarbamate fungicides are protective rather than eradicant in nature: thus Zineb, Polyram, or Ziram are used essentially to keep the spores or mycelia of disease causing fungi from entering treated 15 plants. Maneb or Ferbam have some eradicant character, but the class typically is applied before infestatlon, which has given rise to the frequent reapplication this invention seeks to minimize.
While the invention has been described hereinabove 20 by particular reference to foliar application where its advantages are best illustrated, it is to be understood that the system is also effective as a fungicide in other conven-tional usages in lawns and gardens, or for agricultural crops.
Thus, Zineb is commonly used as a soil drench ~or control of a 25 number of turf diseases.
The various dithiocarbamate fungicides have vari-able, preferred7 or specific applications in recognized use, and response levels vary, as between mildews and rusts, for ~75~98 1 example. The practice of this invention is accordingly go~erned in some respects by the conventional skill of the artisan in selecting agents treatment levels and the like for optimum control.
It is intended that the active foliar fungicide component will be utilized within reco~mended dosage limits for the species and infestations as listed in the EPA
Compendium of Registered Pesticides and believed that reduced levels of fungicide will be rendered useable for 10 efficient control in accordance with the practices of this invention. Thus, Maneb will be typically employed at a level of l.2 to l.6 lb./lO0 gal./acre in control of fungus infestation in fruit, vegetables~ and ornamentals. For tomatoes, dosages may range from 0.4 to 3.2 lb./lO0 gallons.

Appllcation levels may vary with applicable ecosystems, and especially for tropical and subtropical environments a higher level of application to provide effective control may be required, as in the treatment of banana diseases (such as banana leaf spot (Mycosphaerella 20 musicola), Sikatoka disease (Cercospora musae~, Black leaf streak (Mycosphaerella Fi~iensis), banana rust (Uromyces musae), Cordana leaf spot (Cordana musae), Johnson spot (Piricularia grisea), and Anthracnose (Colletotrichum musae) or coffee diseases, such as coffee rust (Hemileia 25 vastatrix or coffele~ola).
The fungicidal system of the invention may be readily prepared by admixture of the agents in preformed concentrates or in the field. Conveniently, the dithiocar-bamate salt is diluted in water to about a lO:l ~eight )75598 1 ratio, and the diluted agent admixed with the poly(vinyl acetate) emulsion by routine shaking at room temperature to effect interdispersion for application.
As a measure of the effectiveness of the present 5 fungicid~l systems under rainfall condltions in the field, simulated rainfall equipment has been employed as disclosed in Chemistry and Industry, March 29, 1969, p. 414. Basically, the apparatus employs a spray of tap water at 20 psi directed ; normally against a leaf held at a distance of about 3 inches 10 from the nozzle. The spray head is traversed slowly across the leaf, and applies about 3 ml of water/sec. The water i3 collected every 50 seconds and the spray reapplied to reach the intended total dosage. A course T ~et noz~le was employed, of the type available from ~praying Systems.
The invention is further illustrated without limitation in the following Examples. Maneb was utilized in each instance as the wettable powder comprising 80%
active agent and 20% inert inorganic substrate with surfac-tant. Percent fungus control represents a calculation of 20 percentage total infection loci on treated plants compared to total infection loci on untreated inoculated controls.
EXAMPLE I
Poly(vinyl acetate) homopolymer (Vin Rez 202A:
Stein, Hall, 55% solids) alone at 600 ppm (emulsion, 26 equivalent to 0.5 lb./acre at 100 gal. or about .25 lb./acre of poly(vinyl acetate) was applied to 9 tomato plants which were removed to the greenhouse, after drying. Four hours after PVAc treatment, 6 of these plants were placed in the ~07559l3 1 rain chamber, subjected to one inch simulated rainfall, allowed to dry and then returned to the greenhouse. Twenty-four hours after the PVAc treatment 3 of the 6 plants subjected to simulated rainfall were placed in the rain 5 chamber, sub~ected to one inch additional simulated rainfall and allowed to dry. At this time all 9 PVAc 202A-treated plants were removed from the greenhouse to the treatment area, spray-inoculated with a mixed sporangial and zoospore suspension of Phytophthora infestans (commonly, late blight) 10 and immediately placed in an incubation chamber maintained at 70F. and 95% plus RH. After 40 hours in the incubation chamber, the plants were removed and observed for total infection lesions of the top three leaves. Effectiveness of treatments was determined by direct comparison with 15 inoculated untreated controls.
By the same procedure, tomato plants were treated with Maneb (manganous ethylene bis~dithiocarbamate], 80 WP) alone at lO0 ppm and compared to the untreated inoculated control.
2~ Tomato plants were also treated in the same manner -~ with a fungicidal system according to the inven~ion, comprising lO0 ppm Maneb dispersed in Vin Rez 202A poly(vlnyl acetate) emulsion at 600 ppm.

~075598 1 The results, expressed as % fungus control relative to the untreated inoculated controls, are tabulated as follows:
Treatment Simulated Rainfall% Fungus Control 5 A. PVAc 202A, 0 0 600 ppm. 1" at 4 hours 17 1" at 4 hours & 24 hrs. 49 B. Maneb, 0 54 100 ppm. 1" at 4 hours 51 1" at 4 hours & 24 hrs. 52 C. Maneb, 0 77 100 ppm. & 1" at 4 hours 77 PVAc 202A, 1" at 4 hours & 2~ hrs. 61 600 ppm.
Thus, even at relatively low levels of Maneb, a significant degree of fungus control was achieved by the fungicidal system of the invention, evidencing con-1~ siderably more effecti~eness than either treatment alone.
! Superior effectiveness levels were retained even after substantial and repeated rainfall.
EXAMP~E II
Poly(vinyl acetate) copolymer (Vin Rez 7R-15:
20 Stein, Hall, 55~ solids) alone at 600 ppm (emulsion, equivalent to 0.5 lb./acre at 100 gal. or about .25 lb./
acre of poly(vinyl acetate) was applied to 9 tomato plants which were removed to the greenhouse, a~ter drying. Four hours after PVAc treatment, 6 of these plants were placed 25 in the rain chamber, subjected to one inch simulated rainfall, allowed to dry and then returned to the greenhouse.
Twenty-four hours after the PVAc treatment 3 of the 6 plants sub~ected to simulated rainfall were placed in the rain chamber, subjected to one inch additional simulated rainfall .

10'75598 :

1 and allowed to dry. At this time all 9 P~Ac 7R-15 ^ treated plants were removed from the greenhouse to the treatment area, spray-inoculated with a mixed sporangial and zoospore suspension of Phytophthora infestans (commonly, 5 late blight) and immediately placed in an incubation chamber maintained at 70F. and 95% plus RH. After 40 hours in the incubation chamber, the plants were removed and observed ~or total in~ection lesions o~ the top three leaves. Effective-ness of treatments was determined by direct comparison with 10 inoculated untreated controls.
By the same procedure, tomato plants were treated ; with Maneb (manganous ethylene-bis~dithiocarbamateJ~ 80 WP) alone at 100 ppm and compared to the untreated inoculated control.
Tomato plants were also treated in the same manner with a fungicidal system according to the invention, compris-ing 100 ppm Maneb dispersed in Vin Rez 7R-15 poly(vlnyl acetate) copolymer emulsion at 60o ppm.
The results, expressed as % fungus control relative 20 to the untreated inoculated controls, are tabulated as follows:
Treatment Simulated Rainfall ~ Fungus Control A. PVAc 7R-15, 0 0 ; 600 ppm. 1" at 4 hours 0 1" at 4 hours & 24 hrs. 42 ; B. Maneb, 0 54 100 ppm. 1" at 4 hours 51 1" at 4 hours & 24 hrs. 52 C. Maneb, 0 58 100 ppm. 1" at 4 hours 84 PVAc 7R-15, 1" at 4 hours & 24 hrs. 87 600 ppm.

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-- 1.075598 1 Thus, even at relatively low levels o~ Maneb, a significant degree of fungus control was achieved by the fungicidal system of the invention~ evidencing con-siderably more effectiveness than either treatment alone.
5 Superior effectiveness levels were retained even after substantial and repeated rainfall.
EXAMPLE III
The procedure of Example I was repeated, except that the proportion of Vin Rez 202A in each instance was 10 increased to 1200 ppm, equivalent to 1 lb./acre at 100 gal. or about .5 lb./acre of poly(vinyl acetate). The follow~ng results were obtained:
Treatment Simulated Rainfall% Fungus Control A. PVAc 202A, 0 0 1200 ppm. 1" a~ 4 hours 17 1" at 4 hours & 24 hrs. 49 B. Maneb, 0 77 100 ppm. 1" at 4 hours 81 1" at 4 hours & 2~ hrs. 27 C. Maneb, ~ 0 99 100 ppm.& 1" at 4 hours 100 PVAc 202A 1" at 4 hours & 24 hrs. 96 -2Q Although in such testing relative differentiation is attributed more significance than absolute values which commonly vary from test to test, the relative degree of control obtained here for the combined system is remarkàble, and the effect of Maneb wash-off with repetitive rainfall apparent.
EXAMPLE IV
The procedure of Example II was repeated, except that the proportion of Vin Rez 7R-15 was increased in each :

1 instance to 1200 ppm. The following results were obtained:
Treatment Simulated Rain~all % Fungus Control - A. PVAc, 7R-15, 0 1200 ppm. 1" at 4 hours 19 1" at 4 hours & 24 hrs. 31 5 B. Maneb, 0 77 100 ppm. 1" at 4 hours 81 1" at 4 hours & 24 hrs. 27 C. Maneb, 0 98 100 ppm. & 1" at 4 hours 97 PVAc, 1200 ppm. 1" at 4 hours & 24 hrs. 95 The same observation may be made for the copolymer 10 as in Example III, relative to the homopolymer, indicating the general equivalence of the species.
EXAMPLE V
The procedure of Example I-II was repeated, except ; that the concentration of vinyl acetate emulsion was increased 15 to 4800 ppm, with the following results:
Treatment l Applied ppm Simulated Rainfall % Fungus Control ; PVAc 202A,4800 0 8 1" at 4 hours 30 1" at 4 hours & 2ll hrs. 0 PVAc 7R-15,4800 0 3 1" at 4 hours 0 1" at 4 hours & 24 hrs. 9 Maneb, 100 0 46 1" at 4 hours 37 1" at 4 hours & 24 hrs. 20 Maneb, 100 0 62 PVAc 202A, 4800 1" at 4 hours 34 1" at 4 hours & 24 hrs. 44 Maneb, 100 0 71 PVAc 7R-15,4800 1" at 4 hours 18 1" at 4 hours & 24 hrs. 41 1 Although some increase in efficacy is evidenced, it is apparent that performance at the intermediate ratios (12:1) of Examples III-IV is preferred.
EXAMPLE VI
: 5 The fungicidal system of the invention may also be applied in the cultivation of fruits and nuts such as almonds, apples, apricots, bananas, cranberries, figs, grapes, nectarines, papaya, and peaches, vegetables such as asparagus, beans, broccoli, brussel sprouts, cauliflower, 10 cabbage, celery, corn, cucumber, lettuce, melons, peppers and spinach or other cultivars such as yams, coffee and tobacco, ~or effective control of fungal infestation therein.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the foliar treatment of plants susceptible to fungal infestation comprising applying to the foliage a poly(vinyl acetate) emulsion comprising a minor pro-portion of a dithiocarbamate salt foliar fungicide at a rate sufficient to control said infestation.

2. The process of claim 1, wherein said dithiocarbam-ate salt is manganous ethylenebis [dithiocarbamate].

3. The process of claim 2, wherein the weight ratio of vinyl acetate polymer to salt is between about 3:1 and 30:1.

4. A composition comprising an aqueous dispersion of a dithiocarbamate salt foliar fungicide and a poly(vinyl acetate) the weight ratio of said poly(vinyl acetate) to said dithiocarbamate salt being from 3:1 up to 30:1.

5. A poly(vinyl acetate) emulsion comprising a fung-icidally effective amount of manganeous ethylenebis [diothiocarbam-ate].

6. A process for the protectant control of fungus infestation in plant foliage comprising applying to said foliage a fungicidal composition comprising a fungicidally effective pro-portion of a dithicarbamate salt and an excess by weight of poly (vinyl acetate) sufficient to enhance the control of fungal in-festation.

7. A process for the protectant control of late blight in tomatoes comprising applying to the tomato foliage the composition of claim 4.

8. A process for the protectant control of late blight in tomatoes comprising applying to tomato foliage a composition comprising an aqueous dispersion of manganeous ethy-lene bis[dithiocarbamate] and poly(vinyl acetate) the weight ratio of said poly(vinyl acetate) to said dithiocarbamate being from 3:1 up to 30:1.