Commercial Vegetable Growing in the Pukekohe District

New Zealand Journal of Agriculture, Volume 84, Issue 4, 15 April 1952, Page 301

Commercial Vegetable Growing in the Pukekohe District

By

T. C. R. DAWE,

Vegetable Instructor,

Department of Agriculture, Pukekohe

CULTURAL practices on an 80-acre commercial vegetable garden in the Pukekohe district, 32 miles south of Auckland, on the main North Island railway line, are described in this article. The gardening area, which is dominated by the wellknown feature Pukekohe Hill, is almost frost free and admirably suited for the production of early vegetables.

THE district is specially noted for early potatoes, which are grown mainly on the “Hill”, and for longkeeping onions. Most of the staple vegetables are produced in large quantities. Other miscellaneous vegetables such as radish, silver beet, turnips, red beet, lettuce, and celery are not grown in appreciable quantities. They are supplied by gardens closer to the principal markets.

Since 1911, when the main trunk railway from Wellington to Auckland was completed; vegetable growing at Pukekohe has increased steadily, until now approximately 2000 acres are producing vegetables each year. Originally, potatoes and onions were the main crops, but the rapidly increasing population of Auckland City and improved rail and road transport facilities have led to Pukekohe district becoming the centre of a more general gardening industry.

The land used for vegetable growing is more or less undulating, with adequate natural drainage. The soil of the “Hill” is a red-brown volcanic loam, and that of the surrounding country a medium to heavy clay loam. These soils respond well to applications of fertilisers.

The climate is mild, with a well-dis-tributed rainfall of about 50in. per annum. Temperatures do not fluctuate to a great extent and relative humidity is usually in the vicinity of 70 to 75 per cent. These conditions are equally favourable for plant diseases and for vegetable growing, and consequently producers are obliged to maintain a vigorous programme for disease control. Modern methods and equipment enable growers to deal successfully with most of the problems, but they must be continually on the alert and ready to meet the unexpected as well as the normal attacks of diseases and pests.

The areas of individual gardens range from 5 to 100 acres. Most of the land produces two crops; from the more favourably situated parts it is possible to take three crops annually.

Crop rotation is practised, but green crops are seldom grown, although some humus is provided by ploughing under weed growth, crop residues, and trash from harvested crops.

Mechanical units of various types, according to the size of individual gardens, are employed to do most of the cultivation. Horses are still used to a limited extent, mainly on the

smaller areas, but also for urgent work on larger gardens when unfavourable weather prevents the use of . mechanical power. , The programmes and practices described are those used in an 80-acre garden on the north-west side of the “Hill”, including areas on both of the soil types previously mentioned. While it is inevitable that methods used in other gardens should a differ to some extent in detail, those described have been found successful and may be considered fairly representative of sound practice in the district. Potatoes Potatoes are still one of the major crops. Planting begins in June, and with successional plantings, early and mid-season potatoes are supplied from September to January. This out-of-season potato production calls for heavy fertilising and rigorous disease control. Weather conditions, particularly during the spring and early summer, are very humid and attacks of blight are frequent. Control measures consist of spraying at intervals of from 7 to 10 days with copper compounds. Varieties grown are Arran Chief and Gamekeeper, planted in rows 2ft. 3in. apart with 9 to 12in. between sets. Harvesting begins at 3| to 4 months from planting, when the tubers are large enough to ensure a profitable return but before they are fully mature. Cultural and disease control operations begin when the plants are about 3in. high. In some instances surface cultivation is carried out as the plants are just emerging, by the use of saddle-back harrows, which leave the soil in a good tilth and suppress weeds. Hand hoeing, scarifying, and moulding are continued until the

haulms become too large for convenient working, when a final high moulding is given. Bordeaux and Burgundy mixtures and copper oxychloride are used for blight control. In recent years the lastnamed has been most favoured. During very wet seasons better control of blight is obtained by alternate applications of Bordeaux and copper oxychloride sprays. During January, February, and March preventive sprays are applied for the control of potato tuber moth, and lib. of D.D.T. wettable powder (50 per cent.) to 100 gallons of water has given satisfactory control. D.D.T. may be mixed with the copper'sprays. Fertiliser Mixture Good results have been obtained by the application of the following fertiliser mixture applied at the rate of 20 to 25cwt. per acre: Superphosphate, 4cwt.; dried blood, 4cwt.; potash, 2cwt.; blood and bone, 6c wt.; bonedust, 2cwt.; and sulphate of ammonia, 2cwt. Seed potatoes are selected from the November-harvested crop and are replanted within a month to be lifted in the following March and April. Yields of from 5 to 7 tons are usual from crops sown for seed. The early and midsummer per acre crop yields vary with the time of digging. They are usually: September, 4 tons; October, 5 tons; November, 7 tons; and December and January, 8 tons. Heavier yields have been recorded when the weather has been very favourable during the growing season. Onions Onions are grown in large quantities both as transplant and as seedling crops. Transplant crops, the plants for which are grown in a seed-bed sown

in February, are planted out in the field during May and June for harvest during the following J anuary ana February. - In seasons when a shortage of household onions occurs some of these are harvested early as green onions. Usually transplants are sold directly off the field, as they are of doubtful keeping quality. Yields of 12 tons per acre are usual. Seedling crops are sown directly into the field by single or multiple seeding units at the rate of 4 to 51b. of seed per acre. Rarely is it necessary to thin this crop. Onions are harvested in March or April, graded, and the best types stored for winter and spring sales. The seedling crop produces bulbs of excellent keeping quality. Yields are generally slightly lower than from transplanted crops. Varieties grown are Pukekohe Early Straw for early harvest and Pukekohe Long Keeper for transplant and seedling crops. Wheel hoeing is commenced as soon as the plants have ■ emerged and continued . at intervals until bulb growth prohibits this operation. The most costly item in onion production is hand weeding of the small plants. Successful weed control among the young plants has been obtained recently by spraying the rows of seedlings with a 10 per cent, solution of commercial sulphuric acid. When the crop has fully matured the onions are lifted and allowed to lie in the field to cure, being turned at intervals by hand raking. Topping of onions is at times carried out in the field by manual labour or by mechanical onion toppers, but on some occasions the bulbs are stored untopped until they are finally sorted for marketing. A ton of lime per acre is applied at least a month before seeding or planting out. The area used for onion growing is then fertilised with a mixture of 1 ton of bonedust, lewt. of sulphate of ammonia, and lcwt. of potash per acre. Onion downy mildew and onion thrips usually affect the onion crops and control measures by fungicides and insecticides are necessary.

Control of onion mildew can be obtained by spraying with Bordeaux mixture 5 : 4: 50 to which 1 pint of summer oil is added as a spreader. Applications are first made when plants are

from 4 to 6in. high and fortnightly are generally necessary for Ideouate control The control of onion thrips Crimps tabaci) is difficult during warm weather. Some control has been obtainpd bv the aoolication of sprays consisting of' nicotine sulphate 1: 200 and D.DT. (50 per cent.) lib. to 100 gallons of water with the addition of 1 pint of summer oil to every 100 gallons of the mixture. Fortnightly applications are advisable as a normal treatment, but it is sometimes necessary to spray much more often. By spraying before infestation is apparent good control has resulted. The above sprays for onion mildew and thrips can be combined. r'kkkar.ke kyaooages Cabbages are grown for harvest throughout the year, September being the most difficult month to produce good yields, because of seed-stem development. Plants are raised in open seed-beds, where rigid disease control measures are carried out. Downy mildew in seed-beds is prevalent most months of the year, and spraying for caterpillars of the diamond-backed moth and white

butterfly is necessary during the warmer periods. Cabbage aphis is extremely difficult to control during February, and March. Spring-harvested types of cabbage are planted in June or July. The favoured varieties Greyhound, Jersey Wakefield, and Charleston Wakefield are harvested during September to December and yield from 6 to 8 tons per acre. From October to January the variety Golden Acre is planted for harvest during December to April. This quickmaturing cabbage yields up to 14 tons per acre and is harvested from 8 to io weeks from planting out. Cabbages for winter harvest are planted out during March, April, and May, the varieties being Early Market (Hendersons), Green Acre, and Copenhagen Market. These round-headed types yield excellently and successional plantings ensure supplies from May to August inclusive. The planting programme mentioned above enables the grower, by selecting ,

varieties suitable to local climatic and soil conditions, to supply cabbage the year round. Cabbage crops are fertilised with a mixture usually comprising lOcwt. of blood and bone, 2cwt. of bonedust, 3cwt. of superphosphate, 2cwt. of sulphate of ammonia, and lcwt. of potash, which is applied in bands just before .. planting out at the rate of ' 1 ton per acre. Lime is applied also at 1 ton per acre at least a month before planting. Cultural practices are hand hoeing, scarifying, and light moulding to ensure adequate drainage, particularly for the. winter crop. Spraying or dusting with insecticides for the control of diamond-backed moth and white •butterfly caterpillars is necessary during summer and autumn. Cauliflowers Cauliflower crops receive manurial, cultural, and ' disease-control treatments similar to those for cabbage crops. To stimulate the development of the curds crops are generally side dressed about a month before curd development with lcwt. of nitrate of soda mixed with lcwt. of superphosphate per acre, after-- which a light moulding is given to draw the fertiliser toward the plants. Cauliflowers for winter supply are planted from February to April and for late-summer and autumn harvest during November and December. Varieties favoured are Phenomenal Early, Phenomenal (5 months), and Phenomenal Main Crop. Tomatoes Tomato production for condiment manufacturers is also a major part of the cropping programme. Plants are purchased from nurserymen and planting out begins during .October and is completed by early November. Here again . disease control is a serious problem, and the plants are kept sprayed from the time of setting out. Copper oxychloride sprays are favoured for the early applications, with alternate sprayings of Bordeaux mixture and copper oxychloride in the

later stages of growth. Up to 10 applications have been necessary in some seasons. D.D.D. 25 at the rate of lib. of powder to 100 gallons of water is applied to tomato crops for caterpillar control after fruit has formed. D.D.D. gives adequate control of stem borer caterpillar and may be mixed with copper oxychloride sprays. Harvesting begins in late January and continues until April in most seasons. Yields of from 10 to 14 tons per acre have often been recorded. Adelaide Dwarf is the main variety grown and is very suitable for this district, being an upright bushy type, which can be easily sprayed and worked. Plants are spaced 2ft. apart in the rows, with 3ft. between rows, which provides 4000 to 5000 plants per acre. The following base application of fertiliser has produced good yields:— Superphosphate . . scwt. Dried blood .. .. scwt. Bonedust .. . . scwt. Blood and bone . . 3cwt. Potash . . .. 2cwt. Shallow inter-row cultivation is carried out during the first 3 months of growth or until the plants cannot be cultivated without damage. Carrots and Parsnips Carrots are grown the year round. Sowing in rows 12in. apart begins in July for harvesting in November and December as spring carrots. Yields of up to 6 to 8 tons are harvested from these plantings. Successional plantings continue at intervals until the following March. These later plantings can be carried over in the soil until August and September and produce yields of from 12 to 15 tons per acre. Weeding is the main cost in the growing of the carrot crop. Weeding by the use of a suitable grade of power kerosene is practised extensively and is of considerable assistance. Disease control for green carrot aphis and rust fly is usually necessary during the growing period from October to March. Little or no fertiliser is applied to main-crop carrots. They are planted

on land which has been heavily fertilised for the preceding crop. Topdressings are applied when necessary for spring crops. Varieties grown are: Early Krop, Manchester Table, and Chantenay. Small quantities of parsnips are grown, the Hollow Crown variety being favoured. They are sown in June for spring harvest and in NovemberDecember for winter supply. The cultural methods applied are similar to those for carrot crops. ' Peas and Beans Peas for canning are grown as a catch crop only. Yields of up to 30c wt. per acre of shelled peas are obtained. They are grown in rows 15in. apart and cultivated similarly to other row crops and are usually planted on land ■ which has been heavily fertilised for the preceding crop, with up to lOcwt. of lime per acre added when necessary. Plantings are made in October and November for harvesting in January and February. Greenfeast is the main variety. Beans, planted in 15in. rows during late October or early November, are grown mostly for canning. They are generally planted on land that has been heavily fertilised for the previous crop. When necessary an application of scwt. of superphosphate per acre is given. Cultural operations consist of weeding, hand hoeing, and scarifying. The principal variety grown is Asgrow Stringless, which is harvested in February in an immature state for the canneries. The yield varies from 30cwt. to 2 tons per acre. Beans are regarded as a short-term catch crop between main plantings of other vegetables. Pumpkins, . Marrows, and Kumaras ' Pumpkins are grown mostly for storage for late supply, being planted in -November. They are favoured with a long growing season in Pukekohe district, as it is not necessary to harvest them until the following April or May, before frosts are likely. They can be stored successfully in sheds until the following August, September, or October, when a good return is generally assured. Pumpkins are usually grown on land heavily fertilised for previous crops. Varieties are Triamble and Crown. Marrows are grown in small quantities, the bush type being preferred for harvesting in January and February. Kumaras are not grown to any great extent. They are planted during November for April-May harvest, and the Tauranga Red variety is generally favoured.

Busy Year

It will be realised that a Pukekohe commercial gardener with 80 acres of land producing vegetables has a very busy year. With most of the area producing two crops, and some of it even three in a year, from 10 to 15 male workers are employed. In addition more than 50 casual workers are employed, mainly on a contract basis, for weeding, when necessary, and for harvesting the large quantities of vegetables produced.