THE LIME-SULPHUR SPRAYING COMPOUND.

New Zealand Journal of Agriculture, Volume XIII, Issue 1, 20 July 1916, Page 52

THE LIME-SULPHUR SPRAYING COMPOUND.

J. A. CAMPBELL,

Assistant Director, Horticulture Division

Commercial lime-sulphur solution has now been in fairly general use by New Zealand fruitgrowers for three seasons, and it is safe to say that it has gained in favour each year.

As an insecticide lime-sulphur is not equal to oil emulsion for winter use, nor is it equal to some of the other special sprays for summer use; nevertheless, it is very useful in summer for the control of red mite, scab, &c.

As a winter fungicide ‘ it does not equal either bluestone solution, or Bordeaux mixture, but when used sufficiently strong it is not to be despised for this purpose. The same may be said of the solution as a summer fungicide. It is . not equal to Bordeaux mixture for the control of black-spot, particularly after the disease has made its appearance; but it is infinitely preferable to Bordeaux for summer use, being far less liable to damage the fruit. In addition, lime-sulphur has a direct advantage over Bordeaux mixture in the control of powdery mildew. Bordeaux is of little or no use • against this disease, while limesulphur . (apart from atomic sulphur, which, although so far satisfactory, has had only one season's trial) is the 1 best remedy for mildew we have.

The fact that emulsified oil and other solutions are recognized to be superior insecticides, and that Bordeaux is a more effective fungicide than lime-sulphur, should on the face of it leave the latter spray at a disadvantage. But this .is compensated for, particularly for summer use, by the fact that lime-sulphur possesses both insecticidal and fungicidal qualities, and, when properly applied, covers both these purposes quite satisfactorily, thereby doing away with the extra amount of labour required in spraying with separate solutions for the different purposes. Lime-sulphur can be safely combined with arsenate of lead; in fact, the general opinion is that the good effect of lime-sulphur is increased by the combination. ' '

■ Lime-sulphur when used at too great a strength is liable to damage foliage badly, and the action of the material in this way appears to be somewhat inconsistent. A diluted mixture which

can be safely used one season may, at the same strength, scorch the foliage more or less the next, season. Similar inconsistencies may be experienced at. different times during the same season or in different orchards in the same district. Again, the, strength 1-100, which has been found to give general satisfaction in the North Island, will at times severely scorch the foliage when used in the South Island. In the southern districts. 1 in 120 is considered to be the greatest strength at which the mixture can be safely used as a general summer spray. This peculiarity, however, although calling' - for careful attention,' is not sufficient to greatly affect ' the popularity of the lime-sulphur spray.

In combining lime - sulphur with arsenate of lead there. are two matters worthy of attention. Either the full quantity of arsenate of lead to which the lime-sulphur is to be . added should be first prepared, or the ingredients should be prepared separately and poured simultaneously into a third vessel, as in preparing Bordeaux mixture. When combined the mixture should not .be allowed to stand longer than can be avoided before using, otherwise the danger of scorching is increased. ...

Lime-sulphur as a late winter or spring fungicide is of . particular interest at present owing to . the greatly increased price of bluestone. This fact will, no doubt, mean a large increase in the use of lime-sulphur. . ‘ .

HOME-MADE LIME-SULPHUR SOLUTION.

When used ■at winter strength . and even when somewhat reduced, commercial lime-sulphur becomes a fairly expensive spray. This cost can, however, be reduced considerably by the orchardist preparing his own solution. If good materials are available, this can be done satisfactorily according to the following formula:— '

Sulphur . . . . . . .. 100 lb. Roche-lime (95 per cent, pure) ... . . 50 lb. Water . . . . . . - . . . . 50 gallons.

Slake the lime with hot water, mix the sulphur to a paste and add it to the lime, also sufficient water to make up to 50 gallons. Boil vigorously in an iron boiler of sufficient capacity to. prevent waste from boiling over, and add water to replace waste from boiling, so that there will be about 50 gallons when cooked. Solutions made in this way usually register 27 0 to 28° Beaume. In order to secure a standard strength corresponding with the commercial . solution that is, 33 0 —it is essential to ascertain the specific gravity of the mixture before dilution.- . For

this purpose a Beaume hydrometer is recommended. Test the mixture, compare with the accompanying table compiled by Mr. A. B. Mansfield, Orchard Instructor, Auckland, and dilute accordingly.

Referring to the chart, it may be explained that the top line of figures represents spray mixtures, varying in strength from 1 in 10 to 1 in 125. . The column of figures on the left represents lime-sulphur solution, varying in density from 25 0 to 35 0 Beaume. ■

To prepare a spray of any standard strength first find the specific gravity of the solution by means of a Beaume hydrometer. Mark the figures in the column on the left of the chart corresponding with the reading of the hydrometer. Next select the figures in the top line representing the strength of the spray required. The figures where this column and the cross - line denoting the specific gravity of the solution intersect represent the quantity of water required to make a spray mixture of equal strength to that given at the top of the column.

For instance, suppose the specific gravity to be 28° Beaume, and the strength of spray required is 1 in 80 standard. The figures at the intersection are 67-9. This ' means that one part of the 28° Beaume solution with 67-9 (say, 68) parts of water added is of equal strength to 1 part of a 33 0 Beaume solution with 80 parts of water added.

STRENGTH OF SOLUTION RECOMMENDED.

The various strengths at , which lime-sulphur based on a 33 Beaume test is recommended for use is as follows :

Sucking-insects and' Fungoid Diseases.

Pip-fruits: 1-10, applied preferably just as the buds begin to swell.

Stone-fruits: 1-15, applied in autumn and as the buds begin to swell.

Spring. —Fungoid ' Diseases. Pears : 1-15 to 1-20. .

Apples : 1-25 to 1-30

. Applied as the buds show colour or as the . most advanced burst into bloom.

Summer. —Sucking-insects and Fungoid Diseases.

Pip - fruits: i-ioo to 1-120 throughout the season, combined with arsenate of lead. ' • ' . .. .

Beaume. -IO. i-i5-1-20. J 1-40. 1-50. 1-60. 1-70-1-80. • 1 1-90. J I-IOO. ! 1-no. I—120. 1-125. .1 1-40. 1-50-1-60. 1-70. 1-80. ■ • 1 1-90. I-IOO. I-IIO. 1-120. 1-125. 0 25 7-6 | n-4 15-2 19-0 227 30-3 37’9 457 53-o 6o-6 68-2 75'8 83-3 90-9 947 26° ... 7-9 ii-8 15-8 197 23-6 31’5 39'4 47'3 .55-2 63-0 70-9 78-8 867 '■ 94'5 9 ' : . . 8-2 12-3 16-4 20-5 247 327 40-9 49-1 577 65'5 73'6 8i-8 90-0 98-2 102-3 28° 8 ; 127 17-0 21-2 25'5 33'9 42-4 ' 50-9 ; 59’4. 677 767 84-8 937 ioi-8. 106-1 9° 8-8 13-2 17-6 22-0 26-4 35-2 43'9 527 61-5 70'3 79-1 877 96-7 105-5 109-8 30° 9-i 13-6 18-2 227 27’3 36-4 45'5 547 63-6 727 8i-8 90-9 100-0 109-1 113-6 3i° 9’4. 14-1 i8-8 23'5 28-2 37-6 47-o 56-4 65-8 75-2 847 93'9 103-3 112-7 117-4 32° •- 97 147 19-4 24-2 29-1 38-8 487 58-2 677 77-6 873 97'0 106-7 116-4 I2I-2 33° io-o i5-o : 20-0 25-0 30-0 40-0 50-0 6o-o 70-0 8o-o 90-0 100’0 iio-o 120-0 I25-O 34° io-3 15 20’6 25’8 30-9 41-2 5i-5 61-8 72-1 82-4 7 9 103-0 113-3 123-6 128-8 35° •• • io-6 ' *5'9 21-2 26-5 31-8 42-4 53 63-6 74’2 ' 84-8 957 106-1 116-7 127-3 132-6

REFERENCE CHART FOR STANDARDIZING HOME-MADE LIME-SULPHUR SOLUTION BASED ON A 33 BEAUME STANDARD.