CONTROL OF RED MITE ON APPLE-TREES.

New Zealand Journal of Agriculture, Volume XX, Issue 3, 20 March 1920, Page 176

CONTROL OF RED MITE ON APPLE-TREES.

TESTS AT PAPANUI EXPERIMENTAL ORCHARD.

G. STRATFORD,

Orchard Instructor, Christchurch

A series of experiments for the control of red mite was initiated at-the Papanui Experimental Orchard early this season, usihg various brands of red oil and lime-sulphur. The orchard is an old one,- with trees ranging from twelve to twenty-five years, and suitable in every way for the experiments. The 'trees were excellent subjects to work on, being badly infected with red mite, and it could hardly be expected to entirely eliminate the pest in one season. On the whole the experiments have been very successful, and the mite has been reduced to a minimum. A power sprayer was used throughout, a constant pressure of. from 200 lb. to 250 lb. being maintained. Careful observations were made before and after the sprayings, and the data collected afford much useful information to the fruitgrowers of the district.

OIL-SPRAYING.

The brands of red oil used for the tests were “ Orchard,” “ Dial,” “ Gargoyle,” and “ Federation.” All brands were applied at a strength of 1-8, on 20th August, 1919. The varieties sprayed were Stunner, Ribston Pippin, Adams Pearmain, Jonathan, and Rokewood. The mite was very prevalent on all these trees when spraying was done. Live mite was first noticed on the unsprayed trees on 16th October. The following are notes of the; operations and results with each brand of oil used :— ■ ' x ■

Orchard Brand : One row of eighteen Sturmers and one row of mixed apples. Mite very bad. Examined on 10th October and 20th November. Spraying had apparently destroyed the great majority of the eggs ; very few hatched out. Examined again on 12th December, and finally on 12th January. Trees practically free from mite. This brand of oil does not show on trees. so well as other brands, but appears effective.

Dial : One row of eighteen Sturmers and one row of mixed apples and plums. Mite very prevalent, especially on Sturmers. Spray did its work well, and appeared to have destroyed the majority of eggs when examined on 20th November. Trees examined again in December, and finally on 12th January. Results very good, practically no mite being visible.

Gargoyle : One row of Sturmer and Ribston Pippin. Mite bad. When examined on 20th November there appeared to be quite a number of mites not destroyed. Examined again in December and January. Results very satisfactory, but not quite so good as with other brands.

. Federation : One row of Sturmer. Trees very bad with mite when spraying was done. Examined on-10th October and 12th December, and finally 12th January. Results very good, trees, being practically

free from mite. This oil did not emulsify as readily as other oils, but showed up well on the trees and appeared to last for a long time.

LIME-SULPHUR SOLUTION.

Further experiments were carried out, using lime-sulphur at different strengths at different periods. The following notes indicate the practice followed and the results :—

(r.) One row of Lord Wolseley sprayed on 18th September at strength of 1-6, at bud-movement. Trees about the worst in the orchard for. mite. Examined 10th October. Much evidence of mite on trees apparently not affected by spray. Sprayed again on 14th October, 1-25, at open cluster-bud. Slight burning of tips of foliage, but not sufficient to do any damage. Mite still noticeable. Sprayed again on .15 th, November, with 1-80, at formation of fruit. No injury to fruit or foliage. Examined 21st November. Practically no mite visible. Further examinations in December and January. Results excellent considering state of trees when first sprayed.

(2.) One row of Lord Wolseley sprayed, on 18th September, 1-6, at bud-movement. Sprayed again 14th October, 1-25, at cluster-bud. Results from these trees were practically the same as No. 1. On 15th November trees were sprayed, 1-100, at formation of fruit, as against 1-80 in No. 1. This strength appeared to give , as good results as 1-80, and the trees were practically free from mite when examined on 21st November. ' Further examinations in December and January confirmed this.

(3.) One row of Rokewood sprayed on 23rd September, 1-25, at cluster-bud, the bud-movement spraying being omitted. No dormant dressing was given. This spray burnt the tips of the foliage slightly, and‘When examined on 9th October the eggs of the mite appeared sound. Live mite was noticed on 16th October, and on 29th October mite was bad. Sprayed, 1-100, ,8th November, mite being prevalent at time of spraying. Mite checked considerably, and trees appeared as good as others when examined on 21st November. Examined again in December and January, when trees were found practically clean.

(4.) One row of Sturmer sprayed 6th August, 1-6, at bud-movement, and again 1-25 on 10th October, at cluster-bud. The fruit-formation spray, was omitted so that comparisons could be made with other trees. When examined on 21st November red mite was bad. These trees were left as long as possible in order to watch results, but as the mite was on the increase a spraying at 1-80 was given early in December. On examination in January live mite was found, although not bad.

CONCLUSIONS.

As previously stated, the trees experimented with were very bad with mite. Considering this, all the brands of- red oil used were very successful in the destruction of the winter eggs, reducing them to a minimum, so that very few hatched out. There was very little distinction between the different brands used, and no damage was done by any . of the oils. From these experiments it appears that a delayed 'spraying, using the oil at strength 1-8, as late as possible, will do much to control red mite when .in the egg stage.

Where lime-sulphur was used the 1-6 and 1-25 sprays appeared to have very little effect on the eggs, which presented a healthy appearance some days afterwardsin fact, these sprays did not prevent the hatching of the. eggs. The lime-sulphur sprays at 1-80 and 1-100, at fruit-forma-tion period, were most successful, clearing up the newly hatched mite to a remarkable degree. This was very noticeable on the row of trees sprayed at 1-6 and 1-25 only, the fruit-formation spray of 1-80 being omitted. Spraying at 1-80 was delayed as long as possible on these trees, but on examination it was found necessary to apply it early in December. At the final examination in January mite was found on these trees, as well as many summer eggs. From the experiments it appears that lime-sulphur at strength 1-80 to 1-100, used at the fruitformation period, when the mite is on the move, is a most valuable spray. ■ • • . ‘ .