WORK FOR THE COMING MONTH.

New Zealand Journal of Agriculture, Volume XV, Issue 3, 20 September 1917, Page 163

WORK FOR THE COMING MONTH.

THE ORCHARD.

J. A. CAMPBELL,

Assistant Director, Horticulture Division.

THE BLOSSOMING AND SETTING PERIOD.

The success of the fruit crop is particularly affected by the climatic conditions prevailing during the blossoming-period and immediately subsequent to the setting of the fruit. - With pip-fruits the blossomingperiod, taken in conjunction with'different districts of New . Zealand and the various varieties of trees, covers a considerable, range. A few varieties of pears come into blossom as early as August, while a number of apples bloom well into November. The actual date of the blossoming of any, particular variety of apple or pear may vary several days according to the nature of the season, but the variation of the same variety between districts is often very slight, and at times, contrary to what is generally supposed, varieties in Central Otago, instead of blossoming later, are . simultaneous with and in some cases earlier than the same varieties grown in the Auckland District. ‘ In the. season of 1913 the Sturmer and Jonathan trees came into bloom as follows : Sturmer—Otago, 27th to 30th September ; Nelson, Ist to 4th October ;■ Hastings, Ist to 3rd October ; Auckland, 2nd to 4th October. Jonathan —Otago, 25th to 29th September Nelson, 25th September to 6th October ; Hastings, 28th September to 6th October ; Auckland, Ist to 9th October. . Generally speaking, however, the blossoming-period of the majority of pears extends from 15th September to 25th October, and that of apples from 25th September to the first week in November.

Fine sunny weather is what, is hoped for during this period. Not only are such conditions adverse to the development of fungus diseases, but the dispersal of pollen and fertilization of the blossoms is also assured through the diligent labours of the. bee. Conditions, however, -are not always what ,we would wish them to be. What the orchardist is concerned in is how to “ come out on top ” when climatic conditions are much,less-bright. \-S; ' ' * . ..

PREPARATORY WORK.

Little early preparatory work can be done to ensure the setting of fruit in a wet season other than arranging to have in the vicinity of the orchard an adequate number of bees to ensure the maximum advantage being gained for the work done by these voluntary orchard assistants during the fine days that may occur, and by assisting them in their work—or, rather, by controlling it to the advantage of a more complete fertilization —by reducing where practicable the number of blossoms the tree would otherwise bear. Profuse blossom does not

necessarily mean under any circumstances a corresponding heavy crop of fruit; in fact, the reverse is almost- invariably the case. Therefore the pruning-away of surplus blossom-buds • not only has the effect of strengthening and making more fertile those that remain, but it also reduces the number of blossoms to be visited by bees, which in a season when suitable working-weather is limited is of no small advantage.

In preparing to meet attacks of fungus diseases and insect pests the orchardist has more scope. The modus operandi in each case is governed by circumstances, .but . the guiding principle throughout should be cleanliness and - thoroughness. Cleanliness consists in the complete removal from the orchard or the destruction of all rubbish, &c., likely to harbour disease, particularly coarse bark, old dead leaves, and fruit; also the pruning-away of all dead and diseased wood and the destruction of alb prunings. Thoroughness pertains to all seasonal matters, particularly in cultivation, and in the application of reliable spraying-compounds not after but before the particular diseases aimed at become active, also the renewal of such spraying as circumstances demand. ' -

■■ Much of the preparatory work for the coming summer campaign should already have been attended to, one of the most critical periods of the year having already opened There is little doubt that the most effective treatment for the control of black-spot, as far as spraying is concerned, is when the buds show colour, and although a large number of varieties will have already passed this stage of development there are still a number that have not yet done so. In addition to the completion of this spraying there is also the calyx-spraying to attend to. " £

CALYX-SPRAYING.

Calyx-spraying (or spraying when the fruit has set, as it is generally termed among New Zealand growers) is considered of the utmost importance in many parts of North America. It is there estimated that the codlin-grub enters the eye of the apple in the proportion of 75 per cent, of affected fruits, and the orchardists aim at overcoming this by carrying out what they term the single-spray process. The single spray in this case, however, is really a term applying to the calyx-spraying period, and not to the number of applications required. As a matter of fact two applications are required. The object aimed at is to fill the calyx-cup with a poisonous mixture, the poison to be held in place by the closing of the calyx, thereby forming a toxic trap for the destruction of all grubs that endeavour to enter the fruit at this point.

For applying this method thoroughly a high pressure is needed to force the spray well into the calyx-cups. This, of course, cannot be done after they close, which they do a very short time after the blossoms fall. Therefore, owing to the period over which a tree sets its fruit, at least two applications of the spray are required to make the work effective. The first of these is recommended to be given when two-thirds of the blossoms have fallen, the second when the remainder have fallen.

Although the percentage of infection through the eye of the fruit does not appear to be anything nearly so high in New Zealand as is stated to be the case in America, calyx-spraying is held to be an important feature of our orchard-work. This is not only in connection

with codlin-moth control; at this stage fungus diseases are also liable to be troublesome, rendering spraying for these alone of the Utmost importance. Therefore if a combined insecticide.and fungicide is used both purposes can be served at the same time. *At this stage of growth, however, the tender nature of the skin of the fruit must be taken into consideration, and a spray' somewhat weaker than is required for either purpose later in the season should be used.

POWDERY MILDEW.

Of recent years powdery mildew has been increasingly troublesome to many of the weaker varieties of apples. Not only does this disease by affecting the foliage very detrimentally influence the growth and general health of the tree attacked, but it also renders the leaves more liable to spray-scorching, with the result that the tree receives a further check. Such constitutionally weak trees as the Jonathan, when called upon to withstand a bad attack of this kind—particularly when combined with other neglect, such as underpruning, overbearing, &c.are often rendered quite useless by the time they are ten years old. If taken in hand, however, powdery mildew is not a difficult disease to deal with. An affected tree should be pruned in the winter and otherwise treated so as to encourage growth. All affected . growths that escape the winter spraying should be removed as soon as fresh growth commences, when such parts become plainly evident by the white powdery appearance of the foliage. Also, as soon as the buds burst the tree should be sprayed with either lime-sulphur or atomic sulphur at the strengths mentioned further on.

BROWN-ROT.

A good deal has been written recently with reference to this disease (see last month’s Journal'), but it may be well to repeat that a systematic thinning, which is essential in any case to good-quality fruit, will materially lessen the difficulty of keeping the disease in hand, particularly when combined with the careful destruction of all affected fruit at frequent intervals.

SPRAYING AND SPRAYS RECOMMENDED.

Black-spot (colour-bud spray).Pears : 6-4-50 Bordeaux, or 1-20 lime - sulphur. Apples 3-4-40 Bordeaux, or 1-25 to 1-30 limesulphur. . . Ditto (when fruit has set).-Pears : 2-3-40 Bordeaux, or 1-125 limesulphur. Apples : 2-3-40 Bordeaux, or 1-125 lime-sulphur. ' Ditto (subsequent' sprayings).—Pears: 3-4-40 Bordeaux, or 1-100 lime-sulphur. 'Apples : North Island, 1-100 ,to 1-120 lime-sulphur ; South Island, 1-120 to 1-130 lime-sulphur. - t ... Codlin-moth. — When fruit has set, paste arsenate of lead, 1 lb. to 50 gallons of water, combined with either Bordeaux or lime-sulphur at the above strengths. Powdery Mildew (colour-bud spray).Lime-sulphur, 1-25 to 1-30, or atomic sulphur, 10 lb. to 100 gallons water. Ditto (subsequent sprayings).- —Lime-sulphur as for black-spot, combined with arsenate of lead. Atomic sulphur, 8 lb. to 10 lb. to 100 gallons water, with 3 lb. of arsenate of lead added. . -

. Mixing Lime-sulphur and Arsenate of Lead. When using these sprays in combination it is preferable to mix the ingredients separately, using half the total quantity of water for each and then pouring them simultaneously into a third vessel, as in making bordeaux. ' Otherwise remove sufficient water from the bulk in which to thoroughly mix the arsenate. Add the lime-sulphur to the bulk of the water, and follow with the arsenate-of-lead mixture. Stir well, and in either case use as soon after mixing as possible.