ORCHARD SPRAYS IN NEW ZEALAND.

New Zealand Journal of Agriculture, Volume 48, Issue 1, 20 January 1934, Page 1

ORCHARD SPRAYS IN NEW ZEALAND.

VII. COMBINATION SPRAYS.

G. H. Cunningham,

Mycologist, Plant Research Station, Palmerston North.

In New Zealand it is customary to combine orchard sprays with a view to reducing the number of applications. This practice is of advantage owing to the large number of individual sprays comprising the spray programme, necessary to control the different types of insects and fungi present in the orchard. Judicious combination may halve the number of applications, and thus reduce the total spray costs considerably, since application costs are actually greater than the cost of materials. Certain combinations possess the additional advantage of improving the therapeutant value of the individual sprays. The major factors which determine the advantages or disadvantages of combination are : (a) The chemical nature of the spray compounds employed; (&) their physical properties; (c) the

risk of injury to foliage and fruit; ((/) the concentrations employed ; (e) the fungous diseases and insect pests -present ; (/) previous or subsequent sprays applied to the plant; and (g) the effects of additive compounds of the nature of spreaders, activators, dr adhesives. Of these, the aspects of disease and pest control, and of safety to the plant, are of primary importance ; consequently combinations are discussed principally from these viewpoints. The sprays in current employment are (r) lime sulphur, (2) colloidal sulphur, (3) lead arsenate, (4) bordeaux (or burgundy) mixture, (5) nicotine or nicotine sulphate, and (6) petroleum oils. Lime sulphur is employed as a fungicide and, to a lesser extent, as an insecticide. A r-per-cent. concentration is moderately effective (though inferior to petroleum oil) as a controllant of scale insects when applied during the dormant period. It is principally employed as a summer fungicide, being applied to pome fruits, stone fruits, vegetables, &c., at concentrations of from 0-083 P er cent, to- o-i per cent, (the former concentration . for less tolerant varieties) for control of. black-spot of apples, and leaf-rust and brown-rot of peaches, &c. The spray is also of value in combating soft-bodied insects, though seldom used alone for the purpose. Colloidal sulphur is the most efficient fungicide to employ against mildews. It is also effective against leaf-rust and brown-rot of

stone fruits, and tomato leaf-mould. The spray is applied in the orchard at the concentration of 4 lb. of the paste to 100 gallons of water ; under glass 2 lb. give comparable results.

Bordeaux mixture is the most efficient fungicide for the control of fungi other than mildews. Two concentrations are employed, 5-4-50 at green tip on pome fruits and bud movement on stone fruits ; 3-4-50 for summer applications to pears, tomatoes, and other small fruits, potatoes, and other vegetables.

Lead arsenate is a stomach poison used to combat chewing insects such as codling-moth, leaf-roller caterpillar, bronze-beetle, and cherry slug. The standard concentration employed in the Dominion is 11 lb. powder or 3 lb. paste per 100 gallons of water. It may be applied with safety to pome fruits, small fruits, potatoes, and most garden vegetables and flowers ; but is unsafe to use on stone fruits other than English plums.

Nicotine or nicotine sulphate may be employed during the growing season on most plants, without risk of injury, to combat soft-bodied insects, such as aphides, leaf-hopper, mealy-bug, and red-mite. The standard concentration recommended is 0-05 per cent, nicotine.

Petroleum oil is employed to destroy insect eggs during the dormant season, and against soft-bodied insects during the growing period. For dormant applications winter oil is applied at a concentration of 4 per cent, against San Jose scale, and 3 per cent, against other scales. Summer oils are applied at concentrations of 2 per cent, on citrus, and from i-o to 1-5 per cent, on pome and stone fruits. Simple Combinations. 1. Lime Sulphur. (a) Plus Colloidal Sulphur. — During the past three seasons this combination has been widely used throughout the Dominion. It has proved to be effective in combating black-spot and powderymildew of apples, and leaf-rust and brown-rot of stone fruits. At concentrations of 2 lb. of colloidal sulphur to 100 gallons of 0-083 per cent, lime sulphur, satisfactory control of these diseases may be secured without risk of leaf scorch. A “ spreader ” is unnecessary with the combination. (&) Plus Acid Lead Arsenate.- This combination has been employed for many years in the Dominion —since the introduction of commercial lime sulphur, in —for control of black-spot and chewing insects of the apple. Unless prepared in the manner outlined below, the combination is liable to cause severe leaf scorch and fruit russet. Several opinions have been published as to the nature of the changes which take place when these sprays are combined (q.v., Bradley and Tartar, 1910 ; Robinson and Tartar, 1915 ; Robinson, 1919 ; Goodwin ■and Martin, 1925 ; Andrew and Garman, 1926; Young, 1926 ; &c.). The most probable view is that partial exchange occurs between the lime, the sulphur, and the lead, leading finally to the liberation of water-soluble arsenic* and the formation, of lead sulphide. The

former is responsible for injury to plant tissues; the latter gives the combined spray a characteristic colour, indicating that change has occurred. . If prepared in the following manner the combination may be rendered as safe to plant tissues as lime sulphur or lead arsenate alone: First fill the spray-tank with lime sulphur solution. To the required quantity of lead arsenate powder add double the quantity of hydrated lime. Mix into a thin paste with water, and, with the agitator running, pour slowly into.the tank. Apply the combined spray as rapidly as possible after its preparation. The use of hydrated lime with this combination to alleviate injury was advocated by the Department of Agriculture in 1918, and became a regular practice until superseded by lime casein* “ spreader.” The lime should be of good quality and possess a high Ca(OH) 2 content, since, as Farley (1925) has .shown, a sample containing much carbonate of lime tends actually to increase the soluble arsenate content of the spray. Thatcher and Streeter (1924) claimed that comparable results were secured when casein (4 oz. per 100 gallons of combined spray) were added to the lime sulphur, the lead arsenate, or to the mixture. Their work led ultimately to the substitution of commercial lime casein for hydrated lime. This has proved a retrograde step, however, since in recent tests this “ spreader ” has been found to be less satisfactory and more expensive than hydrated lime.

(c) Plus Bordeaux Mixture. —-No advantage is gained, so far as is known, by combining lime sulphur and bordeaux mixture. The possible effects of combination are discussed, however, owing to the belief prevalent in certain localities that severe injury is liable to follow when lime sulphur is applied to apple trees sprayed a few days previously with bordeaux mixture.

As is shown elsewhere (Cunningham, 1934), when equivalent amounts of lime sulphur and copper sulphate are combined, a darkbrown precipitate of copper polysulphides is formed ; and an apparently similar precipitate is produced when bordeaux mixture (containing the same amount of copper, in the form of copper hydroxide) is used in place of copper sulphate. This precipitate may be applied to apple trees without injury to fruit or foliage, provided equivalent amounts of the copper salt and lime sulphur are used and the lime sulphur is used at summer concentrations. If, however, the lime sulphur is in excess, the precipitate is redissolved, and a spray produced which contains quantities of soluble copper, which increases with the increase in the excess lime sulphur. When this is applied as a spray to apple trees, slight leaf scorch and somewhat severe fruit russet follows.

It is apparent that increased injury is liable to occur only when the concentrations of copper hydroxide and lime sulphur are such that soluble copper compounds are produced—that is, when the copper of the bordeaux is decreased below a certain amount, or the lime sulphur is increased. Soluble copper is not produced when 5-4-50 or 3-4-50 bordeaux is combined with 0-2 per cent, lime

sulphur. Consequently, there is no likelihood of injury occurring when these concentrations are employed in the field. Theoretically, the risk of injury is increased by an increase in the time interval between the bordeaux and lime sulphur applications, owing to weathering and consequent loss of copper salts from the former spray. No method is available for ascertaining this loss, but field tests have shown that no injury follows the use of these sprays when the bordeaux is applied at green tip and followed by lime sulphur at pink or pre-pink stages.

(<7) Plus Nicotine or Nicotine Sulphate. This combination may be used for combating fungi and soft-bodied insects attacking pome fruit and stone fruit trees. It is safe to employ, since no reaction occurs which is liable to affect the efficacy of either spray, or to induce injury in excess of that caused by lime sulphur alone, either with nicotine sulphate (Andrew and Garman, 1926), or, as we have ascertained,. with nicotine. It is unnecessary to employ with the combination an activator to liberate the nicotine from the nicotine sulphate, the lime sulphur acting in this capacity (Worthley, 1927). No advantage is to be gained by the addition of commercial lime casein “ spreader ” to the combination ; and soap —recommended by manufacturers for use with nicotine or nicotine sulphate when applied aloneshould not be employed, as it reacts with the lime sulphur to form insoluble calcium soap. (0) Plus Petroleum Oils. — No advantage is to be gained by combining lime sulphur with winter oil. The' oil is most effective in destroying insect eggs when applied during early dormancy (Cunningham and Muggeridge, 1933), whereas lime sulphur has little, if any, value as a fungicide if applied at this period. The latter may be used alone to destroy insect eggs (at 1 per cent, concentration), but in such a case there is no point to be gained by using the oil spray.

It is unsafe to combine lime sulphur with summer oils emulsified or stabilized with soaps or ammonium compounds. . When ammonium compounds have been employed for the purpose, soluble sulphur compounds are produced which are highly toxic to plant tissues (Cutwright, 1929 ; Gross and Fahey, 1930). If soaps are used as emulsifiers, they , react with the lime sulphur,, leading to the formation of insoluble calcium soaps and breaking of the emulsion. ■

Injury is also liable to follow when lime sulphur is applied to trees sprayed previously with summer oil emulsified or stabilized with ammonium compounds, or vice versa. The obvious method of avoiding this injury is to employ an oil which does not contain ammonia in free or combined form. This we have demonstrated by applying to apple trees without injury a combined spray of lime sulphur and a straight summer oil emulsified with lime casein. Alternatively, this injury may be avoided by applying the oil spray from five to seven days in advance of the lime sulphur (or colloidal sulphur) spray; or, if sulphur sprays have been applied previously to the trees, by allowing ten days to elapse before applying the oil. Gross and Fahey (1930) claimed that the addition of 5 lb. of hydrated lime per 100 gallons of oil spray (075 per cent, concentration) made it safe to apply within a day or so following lime sulphur.

(/) Plus Iron Sulphate. The practice of adding iron (ferrous) sulphate to lime sulphur or the lime sulphur plus lead arsenate combination, with a view to minimizing spray injury, was originated in the United States in 1925 (Dutton, 1929). When equivalent solutions of iron sulphate and lime sulphur are combined* the mixture becomes black, and iron sulphide and sulphur are precipitated. When this precipitate is applied to the tree, within... an hour or so the iron sulphide is oxidized to free (colloidal) sulphur and a rust-colured basic sulphate. Therefore the effect of the iron sulphate is to convert the lime sulphur to colloidal sulphur. Our experiments have shown that this is accomplished at the expense of the wetting and spreading properties of the lime sulphur, a loss of portion of the sulphur, and a decrease in the fungicidal efficiency of the spray. Consequently this combination is not recommended.

(g) Plus Aluminium Sulphate. Aluminium sulphate has been employed in Nova Scotia (Taylor, 1929 ; Hockey, 1931) with lime sulphur or the combined lime sulphur plus lead arsenate or calcium arsenate sprays. Reduction of injury is claimed when 3-5 lb. of the salt are added to a spray containing 1 gallon of concentrated lime sulphur (polysulphide content not specified). The combination is not recommended, as it is somewhat costly, and produces H 2 S gas which is inflammable, toxic to man, and corrodes the brass parts of the spray outfit.

(A) Plus “Spreaders.” — Our experiments have shown that lime sulphur, being a caustic alkali applied as a liquid, has excellent wetting and spreading properties which are not materially improved by the addition of casein or lime casein “ spreaders.” Soaps cannot be employed, as they are precipitated as insoluble calcium soaps. Consequently no advantage is to be gained by the addition of available commercial “ spreaders ” to lime sulphur or the lime sulphur combinations discussed above.

2. Lead Arsenate.

(n) Plus Lime Sulphur. (See section 1 (&).)

(&) Plus Colloidal Sulphur. — This combination may be used when it is necessary to combat chewing insects and mildews. Our experiments indicate that no increase in injury follows the application of 11 lb. lead arsenate and 4 lb. colloidal sulphur per 100 gallons. A “"spreader ” is unnecessary with the combination, since the colloidal sulphur contains appreciable quantities of a protective colloid which serves this purpose.

(c) Plus Bordeaux Mixture. — This provides a good stock spray for combating chewing insects and endoparasitic fungi attacking plants which will tolerate summer applications of bordeaux mixture. No significant chemical reaction occurs in the combination.

The preferable method of making the combined spray is first to prepare a full tank of bordeaux mixture, then with the agitator running, to add slowly the lead arsenate mixed with water to a thin cream.

As the combination has poor spreading and adhesive properties, owing to the physical nature of both components, applications would be materially improved by the addition of a “ spreader.” Soaps cannot be employed, as they react with lead arsenate to form water soluble arsenic, and with the excess lime of the bordeaux to produce insoluble calcium soaps (Tartar and Bundy, 1913 ; Morris and Parker, 1914). Casein or lime casein improves spreading, but adversely affects the adhesive properties of the combined spray. Improvement in both factors may be secured by the addition of a low concentration (0-25 per cent.) of a highly refined unemulsified summer oil.

The combination of burgundy mixture with acid lead arsenate is not recommended, for the soda of the burgundy reacts with the lead arsenate to produce appreciable quantities of water soluble arsenic.

(</) Plus Nicotine or Nicotine Sulphate.— A combination of acid lead arsenate plus nicotine may be used to combat both chewing insects and soft-bodied insects. The combination is safe to apply to all plants which will tolerate lead arsenate, as no significant reaction occurs when the two sprays are combined.

An activator is necessary when nicotine sulphate is employed. For the purpose hydrated lime may be used at the rate of 5 lb. per 100 gallons of spray. Soaps cannot be used, for, as has been shown, they react with the lead arsenate to produce water soluble arsenic.

(e) Plus Petroleum Oils.— Petroleum oil and lead arsenate may be combined with advantage to produce an insecticide which is effective in combating both soft-bodied insects and chewing insects. The oil additionally improves the adhesive and spreading properties of the arsenate. For this reason the combined spray has recently been widely used in the United States for the control of codling-moth. In fact, adhesion is so improved that removal of spray residues has become a serious problem in that country, necessitating the use of costly washing machinery. Consequently, in the Dominion, the use of the combination is advisable only during the earlier part of the season against chewing insects (as bronze-beetle) which are difficult to combat.

The risk of injury following applications is considerable if the summer oil contains ammonium compounds, owing to the reaction of these with the arsenate to liberate appreciable volumes of water soluble arsenic (Robinson, 1932; Murray, 1932). Oils containing soaps as emulsifiers cannot be employed for the same reason. Consequently the combination is recommended only if prepared as follows : Emulsify a straight (unemulsified) summer oil by stirring into it the lead arsenate, mixing vigorously to form a stiff paste. To this add small quantities of water, stirring continuously until a thin cream is produced. Pour this slowly into the spray-tank (having Filed this previously with water), with the agitator running. The spray should be applied as rapidly as possible, without stoppage, for, if agitation ceases, the emulsion will break and the oil form a him on the surface.

According to Pinckney (1923), if the oil is emulsified with soap prepared entirely from oleic acid, no reaction occurs with the arsenate. Unfortunately such a product is not available on this market.

(/) Plus. “ Spreaders." lead arsenate has poor spreading and adhesive properties, it is advisable to apply it combined with a spreader.” Soaps cannot be used for the purpose, as they react chemically to produce water soluble arsenic. Casein and lime casein are efficient spreaders, but unfortunately do not materially improve adhesion; on the contrary, they tend rather to reduce the volume of lead arsenate remaining on the tree, this loss being excessive when the casein content is in excess of 4 oz. per 100 gallons of spray.

The most efficient of the available “ spreaders ” are low concentrations of highly refined summer oil or fish-oil. The former may be employed at a concentration of 0-25 per cent., the latter at 4 fluid ounces per pound of arsenate powder (Hood, 1929). Injury is liable to occur if either is emulsified or stabilized with ammonia or soap compounds. It is therefore advisable to use unemulsified oils, and to emulsify them with the arsenate immediately before application in the manner outlined in the previous section.

3. Bordeaux Mixture.

(a) Plus Lime Sulphur. (See section 1 (c).) (&) Plus Colloidal Sulphur Little is to be gained by the use of this combination, as when both ectoparasitic and endoparasitic fungi are present a preferable spray would be the lime sulphur plus colloidal sulphur combination discussed above. (Section 1 (a).) (c) Plus Lead Arsenate. (See section 2 (c).) (d) Plus Nicotine or Nicotine Sulphate. This combination may be used for combating fungous diseases (excluding mildews) and softbodied insects on plants to which bordeaux may be applied during the growing season. At standard concentrations no increased injury is likely to occur, for according to Safro (1915) nicotine (as the sulphate) may be combined with bordeaux without chemical change.

No activator is necessary with this combination, the excess lime of the bordeaux acting in this capacity. A “ spreader ” is advisable, however. (See section 3 (g).) The bordeaux may be replaced with burgundy mixture without risk of increased injury.

(e) Plus Petroleum Oils.—NAxh. winter oil no advantage is to be gained by use of this combination, for the oil should be applied during early dormancy for effective destruction of insect eggs (Cunningham and Muggeridge, 1933), whereas bordeaux is useless if applied before green tip on pome fruits or bud movement on stone fruits.

Summer oil may be combined with bordeaux for combating fungous diseases and insect pests of citrus. This combination has been employed in the United States since 1919, first with kerosene emulsion, subsequently with petroleum oils. The oil should be used at a concentration of 2 per cent., and unemulsified, for if an

ammonium or soap emulsifier or stabilizer is present it reacts with the excess lime of the Bordeaux, leading to the production of insoluble calcium soap and the liberation of free oil. To prepare the combination, fill the tank with 3-4-50 bordeaux, and then add the oil, first emulsified with 3 lb. of hydrated lime. The oil and lime, should be mixed into a stiff paste, and small quantities of water then added until the mixture assumes the consistency of thin cream. This is poured slowly into the tank while the agitator is running.

(/) Plus Hydrocyanic-acid Gas. — American workers have shown that severe injury is liable to follow when citrus trees sprayed with bordeaux mixture are fumigated subsequently with hydrocyanicacid gas (Fawcett, 1914 ; Woglum, 1923 ; Butler and Jenkins, 1930). This injury is liable to occur at any time up to six months after an application of bordeaux, and even after eleven months should the spray have been heavy and complete (Woglum,. 1929). Although fumigation is not practised in the citrus orchards of the Dominion, the matter is nevertheless of significance as the process is employed for combating insect pests of the glasshouse, where under similar conditions severe injury may occur (Guba, 1926). Butler and Jenkins (1930) have shown that injury is correlated with the ratio of copper sulphate to lime employed in making the bordeaux mixture. When this ratio is 1 : 0-2 (approximately neutral) injury does not occur, as an insoluble cuprous cyanide is produced; but as the amount of lime is increased the degree of injury is also increased. Beyond the neutral point, soluble cupric cyanide is produced; and in mixtures with ratios greater than 1:1, increasing quantities of a soluble double cupric cyanide is formed, injury increasing proportionately. They considered that injury from this source should not occur if a neutral bordeaux spray was employed. This spray is liable to cause foliage injury to plants grown under glass, so that it is advisable to replace bordeaux with sulphur sprays when fumigation is to be practised. (g) Plus “ Spreaders.”—When properly prepared, bordeaux mixture has good adhesive but poor spreading properties. Although both factors may be improved by the use of a suitable spreader,” it is difficult to procure a type which will improve coverage without reacting adversely with the bordeaux. Soaps cannot be employed, as they are converted into insoluble calcium soaps by the action of the excess lime of the bordeaux. Casein and lime casein improve its spreading properties, but. actually decrease the adhesion of bordeaux. Recent experiments have shown that a satisfactory agent to employ for the purpose is a low concentration (0-25 per cent.) of a summer oil. ' This should be unemulsified, and the combination prepared in the manner outlined under section 3 (g).

4. Nicotine or Nicotine Sulphate.

(a) Plus Lime Sulphur. (See section 1 (</).) (&) Plus Colloidal Sulphur.- —This combination may be employed without risk of injury to combat mildews and soft-bodied insects, being especially useful under glass. An activator is necessary when

nicotine sulphate is used. For . the purpose soft soap (i lb. for each pound of colloidal sulphur) may be used with advantage, being additionally an efficient wetting agent. (c) Plus Lead Arsenate. (See section 2 (d).') ■ (d) Plus Bordeaux Mixture. (See section 3 (</).) (e) Plus Petroleum Oils.— No advantage is to be gained by combining nicotine with winter oil, since the former is effective only against soft-bodied insects. With summer oil nicotine may be combined with advantage, the combination being superior to either spray when employed against such pests as woolly-aphis, mealy-bug, thrips, or red-mite under glass, both the wetting and spreading properties of the nicotine being improved. If the summer oil is emulsified or stabilized with soaps or ammonium compounds, no activator is necessary with either nicotine or nicotine sulphate. (/) Plus “ Spreaders.” When nicotine or nicotine sulphate is employed alone it is of advantage with the former, and essential with the latter, to employ an activator. This increases the volatility of the nicotine and liberates it from nicotine sulphate. For the purpose manufacturers recommend soft soap, at from 4 lb. to 5 lb. per 100 gallons of spray. This material is satisfactory for the purpose and possesses the additional advantage of increasing the wetting properties of the spray. It has, however, the disadvantages of being somewhat costly and variable in composition. Cheaper and equally efficient activators are hydrated lime (5 lb. per 100 gallons) or washing-soda (3 lb.). When soap or washing-soda is employed, an interval of ten days should elapse before a lead arsenate spray is applied to the plant.

5. Colloidal Sulphur.

(a) Plus Lime Sulphur. (See section 1 (a).) (&) Plus Lead Arsenate. (See section 2 (&).) (c) Plus Bordeaux Mixture. (See section 3 (&).) (d) Plus Nicotine or Nicotine Sulphate. (See section 4 (&).) (e) Plus Petroleum Oils.— So far as I am aware, this combination has not been tested. With winter oil no advantage would be secured by the combined . spray. It may be worth testing the efficacy of low concentrations (from o-i to 0-25 per cent.) of summer oil as a wetting and spreading agent to improve the efficacy of colloidal sulphur against such diseases as tomato leaf-mould. " At present, however, the combination is not recommended, for nothing is known as to the possible reactions which may occur in the spray or subsequently on the tree.

(/) Plus “ Spreaders.”— The manufacturers of colloidal sulphurs recommend the employment of soft soap (1 lb. for each pound of the paste) to improve its spreading properties. As the brands we have tested contain appreciable volumes of a protective colloid (one containing 15 per cent, of sulphite lye), this addition appears to be unnecessarv.

6. Petroleum Oils.

(a) Plus Lime Sulphur. (See section i (e).) (&) Plus Colloidal Sulphur. (See section 5 (e).) (c) Plus Lead Arsenate. (See section 2 (e).) (d) Plus Nicotine or Nicotine Sulphate. (See section 4 (e).) Triple and Quadruple Combinations. The complexity of the chemistry of these is such that it is difficult, and frequently impossible, to state what reactions take place. Consequently, the only safe guides are (a) efficacy of disease and pest control, and (&) safety to plant tissues. Field tests have shown that the following combinations may be applied during the growing season, at the concentrations recommended, without increased injury or decreased efficiency. (a) Lime Sulphur plus Lead Arsenate plus Nicotine. This produces, at standard concentrations, a combined spray which will combat endoparasitic fungi, soft-bodied and chewing insects. The lime sulphur and lead arsenate should be combined in the manner outlined under section 1 (&), and the nicotine (or nicotine sulphate) added immediately before spraying is commenced. As hydrated lime is used, no activator is necessary. (&) Lime Sulphur plus Lead Arsenate plus Colloidal Sulphur.— This forms a spray which will combat ectoparasitic and endoparasitic fungi and chewing insects. It may be employed as a standard summer spray for the apple orchard in localities where mildew is prevalent. The colloidal sulphur should be added to the spraytank after the lime sulphur and lead arsenate sprays have been combined, in the manner outlined in section I (&). A "spreader” is unnecessary. (c) Lime Sulphur plus Colloidal Sulphur plus Nicotine. — A possible combination which is safe to employ, but purposeless, as it does not appear to have a place in the programme. (rf) Lime Sulphur plus Lead Arsenate plus Colloidal Sulphur plus Nicotine. — This produces a combined insecticide-fungicide which should effectually combat most . diseases and pests of the apple, its employment being dictated by the prevalence of black-spot, powdery-mildew, chewing insects, and leaf-hopper or . other softbodied insect pest. Use standard concentrations ; combine the lime sulphur and lead arsenate in the manner specified in section 1 (d) ; add the colloidal sulphur, and finally the nicotine (or nicotine sulphate). No "spreader” is necessary. (e) Lead Arsenate plus Colloidal Sulphur plus Nicotine. — A possible combination which might be employed safely where black-spot was absent from the apple orchard. (/) Lead Arsenate plus Bordeaux Mixture plus Nicotine. — This may be employed safely on potatoes and tomatoes to combat endopara-, sitic fungi, chewing insects, and soft-bodied insects. Prepare the spray as indicated under section 2 (c), adding the nicotine last. An adhesive, such as a low concentration of an unemulsified summer oil, should materially improve wetting and adhesive properties of the combination.

(g) Lead Arsenate plus Summer . Petroleum . Oil plus Nicotine.— This combination is safe to employ, provided consideration is given to particulars set out in section 2 (e). It does not appear to have a place in the spray programme, however.

This lists the possible complex combinations safe to employ with standard sprays. Improvements, both in efficacy of disease and pest control, and in safety to plant tissues, will come mainly through improvements in spray applications and in so-called “ spreaders,” by the aid of which the wetting and adhesive properties of the sprays may be improved. That there is need for improvement in “ spreaders ” has been repeatedly suggested in the preceding pages.

The effects of hard waters on the preparation of sprays and combinations must not be overlooked, for, according to Heddon (1908), de Ong (1922), Yothers and Winston (1924), &c., these may indirectly cause severe injury. For, if mixed with lead arsenate, water-soluble arsenic may be formed in appreciable quantities ; and if used with oil emulsions, may cause these to break, with consequent liberation of free oil.

Hard waters contain bicarbonates and sulphates of magnesium and/or calcium. Temporary hardness is due to the bicarbonates of these alkalies held in solution by excess carbonic acid. This temporary hardness may be removed by boiling the water, the carbonic acid being then liberated and carbonates of the alkalies precipitated. Permanent hardness is due chiefly to the presence of sulphates and chlorides of magnesium and calcium, and cannot be removed by boiling the water. Soaps may be employed for the purpose, but are somewhat costly, and water so treated cannot be employed for the preparation of lead arsenate, lime sulphur, or bordeaux mixture if the soap is used in excess of the amount required to precipitate the alkalies inducing hardness. De Ong (1922) considered that caustic soda was superior to soaps for the purpose; but the same objection applies with its employment, though the water may be used safely for the preparation of oil emulsions. Robinson (1932) recommended the use of hydrated lime to overcome the difficulty of mixing hard waters with lead arsenate, summer oil, or the combination. If the procedures outlined for the preparation of the different combinations are followed, then there is little likelihood of trouble being experienced with the hard waters present in thg Dominion. These have little significant effect on lime sulphur, bordeaux mixture, nicotine sulphate, and colloidal sulphur; and if lead arsenate plus hydrated lime is used in combinations little trouble should follow. Breaking of oil emulsions should not occur if the directions given are followed.

Literature cited. Andrew, R. E., and Garman, P. (1926) : Connecticut Agricultural Experiment Station Bulletin 278, pp. 491-508. Bradley, C. E., and Tartar, H. V. (1910) : Jour. Industrial and Engineering Chemistry, Vol. 2, pp. 328-331.-Butler, O., and Jenkins, R. R. (1930) : Phytopathology, Vol. 20, pp. 419-429. Cunningham, G. H. (1934) : This Journal, pp. 15-17. Cunningham, G. II., and Muggeridge, J. (1933) : N.Z. Journal of Agriculture, Vol. 47, pp. 8-18, 89-96.

Cutright, C. R. (1929) : Ohio Agric. Experiment Station Bimonthly Bulletin 14, PP- 42-44. ■ - ' ' . de Ong, E. R. (1922) : Journal of Economic Entomology, Vol. 15, pp. 339~345Dutton, W. C. (1929) : American Fruit Grower Magazine, Vol. 49, pp. 3, 32-33-Farley, A. J. (1925) : American Fruit Grower Magazine, Vol. 45, pp. 12, 15. Fawcett, . H. S. (1914) : California Monthly Bulletin, State Comm. Horticulture, Vol. 5, pp. 41-43- . Gross, C. R., and Fahey, J. E. (1930): North-west Fruit Grower, May and June, pp. 7, 22. Guba., E. F. (1926) : Phytopathology, Vol. 16, pp. 633- 634. Heddon, W. P. (1908) : Colorado Agric. Experiment Station Bull. 131, 27 pp. Hockey, J. F. (1931) : Canada Debt: Agriculture, Kept. Dominion Botanist (1930). P- Io6 Hood, C. E. (1929) : United States Dept. Agric. Technical Bulletin in, 28 pp. Goodwin, W., and Martin, H. (1925) : Journal of A gricultural Science, Vol. 15, pp. 307-326. . Morris, H. E., and Parker,. J. R. (1914) : Montana Agric. Exp. Station Circular 16, 56 pp. Murray, C. W. (1932I : Proc. Washington State Hort. Assn., Vol. 27, pp. 52-56. Pinckney, R. M. (1923) : Jour. Agricultural Research, Vol. 24, pp. 87-95. Robinson, R. H. (1919) : Jour. Economic Entomology, Vol. 12, pp. 429-433. (1932) : Jour. Economic Entomology, Vol. 25, pp. 995-1001. ' Robinson, R.. H., and Tartar, H. V. (1915) : Oregon Exp. Stn. Bulletin 128, 32 ppSaero, V. I. (1915) : Jour. Economic Entomology, Vol. 8, pp. 199-203. Tartar, H. V., and Bundy, L. A. (1913): Jour. Industrial Engineering Chemistry, Vol. 5, pp. 561-562. Taylor, C. F. (1929) : Quebec Soc. Protection of Plants, 21st Annual Report, pp. 28-32. Thatcher, R. W., and Streeter, L. R. (1924) : New York State Hort. Society. Proc. 69th Annual Meeting, pp. 50-56. Woglum, R. S. (1923) : United States Dept. Agr. Farmers’ Bulletin 1321,. 5 8 pp- . r „ ' ' (1929) : California Citrograph, Vol. 14, p. 180. Worthlf.y,- H. N. (1927) : Jour. Econ. Entomology, Vol. 20. pp. 615-625. Mothers, W. W., and Winston, J. R. (1924) : United States Dept. Agriculture Bulletin 1217, 5 pp. Young, H. C. (1930) : Ohio Agric. Experiment Stn. Bulletin 448, 22 pp.

LAMB-FATTENING WITH WHEAT.

SOME POINTS ON ITS ECONOMIC USE IN CANTERBURY.

A. H. Flay,

Canterbury Agricultural College.

Experience shows that lamb-fattening with wheat has a place in Canterbury farm economy, and that the practice is sound only under certain conditions. The object of this article is to specify some of these conditions and to indicate the main points to be considered before commencing to feed wheat to lambs. Green Feed—It is essential that some green feed should be available to lambs being fattened by the aid of wheat. A thriving lamb requires about 2 lb. of dry matter per day. This cannot be supplied satisfactorily by wheat alone, even though . some very small quantity of other feed may be available. Generally, wheat should not supply more than half of the: feed. The remainder may be new grass, specially saved top-dressed pasture, fresh growth on old grass, red

clover grazing, or any fair to good stubble. It must be realized, of course, that, provided there is abundance of any of these feeds, lambs will fatten on them without wheat. rr If the quality of the feed is low, or the quantity limited, then wheat feeding has much to recommend it. On succulent new grass mixing good-quality oat-straw chaff with wheat assists in preventing undue scouring which sometimes occurs. Condition of Lambs. — The condition of the lambs is a most important consideration before wheat feeding is commenced. It is readily realized that young, backward, or stunted lambs, would require many weeks of feeding at a cost of approximately 2d. per week for grainnot to mention the farmer’s timeto make such lambs prime. Lambs should be in a good forward condition before feeding supplementary grain. The feeds mentioned above would be suitable for putting them in good forward condition. Wheat has its greatest value as a “finishing off’’ feed.

Cost of Wheat. The average price received by Canterbury farmers for Solid Straw Tuscan wheat last year (1933) was 3s. qd. per bushel. The price of seconds of wheat at lamb-fattening time last autumn was (approximately) 2s. qd. to 2s. 6d. per bushel. When second-grade wheat is worth pd. to is. a bushel less than first grade it is obvious that farmers—certainly those growing their own wheat — use second-quality grain. Price of Lambs— price of store lambs and of fat lambs, or the margin between these, is most important when any lamb-fattening by the aid of supplementary feeds is being considered, and especially so when a feed such as grain, that has a certain and direct cash value, is to be used.

If a line of store lambs worth, say, 12s. per head were fattened in eight weeks on suitable feed and then realized 16s., the margin would be qs. per head. There is, of course, always the risk of a small percentage of deaths during this fattening period. With something less than qs. therefore to be made out of fattening these lambs, it is obvious that fattening costs must not reach this figure— i.e., if the necessary green grass or fresh stubble, and the farmer’s time have no value, then about 3s. 6d. worth of wheat can be fed to each of the lambs without loss. At last year’s prices this would be about i| bushels of second-grade wheat. It would be as well to state here that fresh green grass and the farmer’s time do have some value, so that it is desirable for good lamb-fattening that not more than, say, 2s. worth of wheat per lamb be used. At last year’s prices this would be about q8 lb. of second-grade wheat. Amount to Feed. At last year’s prices as much as q8 lb. of seconds of wheat, or 33 lb. of first-grade wheat, may be fed per lamb. It is usually unwise to feed more than | lb. wheat per lamb daily.. For an eight-week fattening-period the total grain used then would be 28 lb. per lamb. In reality,- for the first seven to ten days very little grain is eaten, and it is not until two weeks’ feeding has been carried out that lambs, on average, eat as much as | lb. per day. In fact it is essential to start feeding with only small quantities, which can be gradually increased to the desired ration by the end of ten to fourteen

days. After each feed troughs should be emptied so that lambs taking readily to wheat will not gorge themselves. This means that the maximum grain required to fatten a lamb in an eight-week period would be about 20 lb. to 25 lb. ; at 2s. 6d. per bushel for second-grade wheat this would cost (taking the larger quantity) approximately is. per lamb.

During the last two summers several farmers have successfully supplemented their lamb-fattening feed with 10 lb. to 20 lb. of wheat grain. The lambs would have been sold as stores had grain not been used.

Alternatives to Wheat Feeding. — Where rape, turnips, kale, or young grass are grown they can be used for lamb-fattening purposes. They form a good rotation with grain crops and are sometimes essential in maintaining soil fertility. Cultivation and sowing are carried out at a time of the year when the team and teamster have least to do. On many farms, therefore, lamb-fattening by these crops will continue to be the most suitable and profitable method.

It is suggested, however, that if the greatest net returns are to be realized special crops for lamb-fattening, though important on many Canterbury farms, should be kept at a minimum and grain be used along with fresh permanent pastures, new grass, stubble feeds, &c., for finishing off good forward lambs. When good grazing is available, as in the late autumn, and other feeds are finished, the “ finishing off ” of lambs with grain is most profitable. Store lambs at this time usually have a low value. The main points as experienced by many Canterbury farmers, fattening lambs by the aid of wheat, may be summarized as follows - (1) Green feed : Fresh good grass, red clover, or fair to good stubble must be available. (2) Condition of lambs : Only good forward stores should be “ finished off ” with wheat. (3) Value or price of grain : Only second-quality grain, if possible. (4) Margin between store and fat lamb prices : For good and profitable fattening it is recommended that the difference between the prices of store and fat lambs be about double that of the value of grain used per lamb. (5) Quantity fed per day : About | lb. wheat per lamb daily should be used. . Lambs must not be allowed to gorge themselves at any time, especially when commencing wheat feeding. (6) Fattening. period : It is desirable that this be not more than eight weeks, but ten weeks or more may be profitable. A six-week period is more economical.

(7) Other feeds available on farm : If good-quality red clover, grass, or stubble are available in abundance, or rape, turnips, &c., that have no direct cash value, can be used, then it would be more profitable to fatten all the lambs or a portion of them on these, and to sell the wheat, or not buy it for fattening purposes.

My thanks are due to all those farmers, especially Mr. H. T. Reeves, Hororata, who kept details for the last four years concerning their lamb-fattening.

* Water-soluble arsenic : The exact form in which this occurs is unknown ; it is most probably present as soluble arsenic pentoxide (As 2 Os).

* Lime casein ; frequently sold under the name of “ calcium caseinate.”

' !ii * To precipitate completely the polysulphides in 100 gallons of o-i. per cent, lime sulphur, approximately 2-6 lb. of iron sulphate are required.