Growing and Storing Pumpkins in the Auckland District

New Zealand Journal of Agriculture, Volume 83, Issue 4, 15 October 1951, Page 302

Growing and Storing Pumpkins in the Auckland District

By

S. O. GILLARD,

Vegetable Instructor, Department of

Agriculture, Auckland

THE pumpkin [Cucurbita maxima) is a trailing vine which is a • native of America and it is known to have been used by the North American Indians before the advent of European settlers, If pumpkins are properly handled and stored, a supply of them can be available all the year. The culture of pumpkins and the best method of keeping them in good condition for a long period after harvest are described in this article. THE climate of the Auckland district is very suitable for the production of pumpkins and usually 400 acres are grown commercially each year. The average yield from this area is about 4000 tons, or 10 tons per acre, and in exceptionally favourable seasons yields as high as 20 tons to the acre have been recorded. Pumpkins require a long growing season, but are very frost sensitive. Because of this they can be grown extensively only in the warmer district? which do not usually experience early or late frosts. The pumpkin is an exceedingly vigorous vine and rich soil conditions are needed to produce heavy crops. It is desirable to select well-drained soils, but those which are likely to dry out in summer should be avoided, as the vine requires a plentiful supply of moisture during the hot months. Rich river flats containing sufficient sand to render them free working usually provide excellent soil conditions. The moisture-holding capacity of the soil may be improved by the addition of animal manure, compost, or green crops. _ Varieties The most popular commercial varieties include Crown, Triamble, Queensland Blue, and Warren. As the pumpkin is readily cross-pollinated, there are many mixed strains, but the best market prices are realised for true types. Crown is half round to flat, of medium size, and has a grey skin and deep orange flesh; it is an excellent keeper. A particular strain grown in the Whangaparoa district and known locally as Whangaparoa Crown is probably the most popular variety on the Auckland market. Triamble is a medium-sized pumpkin of distinct shape, having three deeply incised lobes. The smooth skin is light grey and the flesh very thick and of rich orange colour. It is an excellent keeping variety.

Queensland Blue (Beaudesert) is a medium-sized pumpkin with a serrated, dark slate skin. The flesh is thick and orange. Its keeping quality is fair.

Warren, commonly called Red Warren, is a large and very attractive pumpkin with a rich orange-scarlet, heavily warted skin. It is half round to flat with deep orange flesh. This is the earliest variety grown in the district; it does not keep well. The Crown and Triamble varieties are popular with retailers and consumers because besides being of excellent quality, they do not have thick rinds when fully mature. Being excellent storing varieties they are grown in quantity for this purpose. Queensland Blue is also a good-quality pumpkin with a thin rind. Although once popular, it is not now grown extensively in Auckland, perhaps because it is not as good a keeper as Crown or Triamble. It is also difficult to procure the true strain of this variety. The Warren variety is popular with growers because of its early-maturing qualities. It can be marketed early in the year and weeks ahead of other varieties. It has a very hard thick rind when fully mature, but is usually marketed before this stage. Importance of Good Seed The first essential in growing pumpkins is to secure good seed of a desirable strain. Many growers prefer to save their own seed by selecting the best fruits and extracting the seed from them. Provided the crop is grown in a fairly isolated area where there is little danger of crosspollination by other varieties, the strain can be kept reasonably stable for a number of years. A distance of at least half a mile between varieties is necessary to avoid crosspollination by insects. If other varieties are grown in close proximity, the grower will have to choose between accepting the possibility of his variety being cross-pollinated or procuring seed from a more reliable source. Seed Saving and Treatment To extract seed the pumpkin should be cut in halves longitudinally (an ordinary carpenter’s saw is ideal for. this purpose) and the pulp and the seed scooped out. The cnnd ic cpnarninH hv hand from th a bulk th a nnln and

may be spread out on sacks or shallow trays to dry in the sun. Pumpkin seed should not be washed, as this process removes the thin waterproof transparent skin on the outside of the seed which protects it from excess soil moisture. When seed is thoroughly dry it should be stored safe from rats and mice until required. The amount of seed required to plant an acre varies from 2 to 41b., depending on the size of the seeds and the planting distances. It is a good practice to plant plenty of seed and to thin plants out later. As a protection against soil fungi which may affect the germination or growth of the young plants seed may be treated with copper oxychloride or copper carbonate. The dosage is 1 level teaspoon to lib. of seed. The seed and dust should be mixed thoroughly in a tight container until all seeds are coated. Any excess dust should be screened off after the seed has been treated. Preparation of Land Pumpkins are often grown after crops such as cabbage, cauliflower, beetroot, parsnips, or carrots to provide a change in crop rotation. Pasture land is also used and in this case early preparation is desirable. Skim ploughing in late autumn or early winter should be followed in spring by a deep ploughing across the previous furrow. Then by the use of discs, harrow, and roller the land can be worked down to a fine tilth. If time permits, a further deep ploughing followed by cultivation just before sowing will be found to improve yields. Lime Although pumpkins are not as sensitive to soil acidity as most vegetable crops, they do best on soils which are only slightly acid, or nearly neutral, that is, pH 6.5 to 6.9. Extremely acid soils should be avoided, and moderately acid soils should be limed at the rate of J ton to 1 ton of carbonate of lime per acre, depending on the degree of acidity. The type of lime to be applied must be determined by conditions. If quick results are desired, the use of burnt shell or hydrated lime may be found advisable, but under most conditions finely ground carbonate of lime will be found satisfactory. Manuring As soon as the risk of damaging frosts is pastusually by mid-October— crop may be sown. Planting should be delayed, however, until the soil has warmed up and is in good condition to promote the germination of seed. The seed germinates best at a relatively high temperature and is likely to decay if set in a wet, cold soil. The general practice adopted when using artificial fertilisers is to incorporate in the seed row a fertiliser mixture consisting of equal parts by weight of blood and bone and superphosphate to which is added sulphate of potash at the rate of lcwt. to each ton of the mixture. The rate of application varies from lOcwt. to 1 ton to the acre, according to the fertility of the soil.

The general practice is to mark the field out into lines Bft. apart along which the fertiliser is sown in a band approximately 12in. wide. Furrows are then ploughed on either side of the band of fertiliser, thus covering it and forming a ridge approximately 2ft. wide. This ridge is then levelled slightly by running a light inverted harrow along it.

Sowing the Seed Pumpkin seeds are pushed into the soil point end down to Jin. below the surface; a little deeper may be desirable in very light soils. Planting the seed point end down tends to prevent excess moisture gaining entry and causing the seed to rot. Moreover, the shell of the seed remains longer on the first two leaves and so helps protect them from adverse weather. Seeds are set in pairs 3in. apart at intervals of 2ft. along the row and seedlings are later ' thinned to one every 2ft., the weaker being removed. Side Dressings It is important to ensure that plants are kept growing vigorously and that they do not receive a check in development. Adequate moisture and good manuring play an important part in promoting rapid growth. Before the runners are too far advanced in growth, it is usual to

apply a side dressing, which may consist of equal parts by weight of dried blood, sulphate of ammonia, and superphosphate. This mixture should be sown along each side of the pumpkin rows about 18 to 24in. out from the plants at the rate of from scwt. to lOcwt. to the acre and worked lightly into the soil. Cultivation To check weed growth and to aerate the soil cultivation around the plants and between the rows should be done from the early stages of growth. It is doubtful if any advantages accrue from more frequent cultivation than is necessary to . keep down weed growth. Provided the soil is easily worked, the removal of weeds by sweeps that cut just under the surface is preferable to using implements that stir the soil to a greater depth. Runners that have extended more rapidly than others should be stopped by removing the terminal shoot, though this is not generally practised by commercial growers. This temporarily checks the growth of the vine and induces side shoots on which the flowers form. Harvesting, Curing, and Storing With the exception of. those of the Warren variety, which are harvested ' when they reach an edible stage, pumpkins for long storage should not be harvested until almost mature. This condition is usually reached when the vines have partly died down. Maturity can be recognised by pressure of the thumb nail on the pumpkin skin. If the pumpkin is fairly mature, the skin will resist ordinary pressure of the thumb nail. The crop should not be left on the vines too long after the foliage has died down, as is done by some growers, because if heavy rain is experienced, the moisture taken up by the roots of the plant finds its way to the fruit. This excess moisture in the pumpkin may influence its keeping qualities. Special care should be taken with pumpkins required for long storage to avoid bleeding and bruising of the fruit during harvest. When sufficiently mature, pumpkins should be harvested by severing the vine approximately 4in. each side of the pumpkin stem. They should be placed stem end uppermost and left in the field for about a week to toughen the skin. Before removing the crop from the field the stems should be cut back to within an inch of the base (a pair of secateurs is ideal for this purpose). If the stems are not suitably trimmed, they may damage other pumpkins or get broken off when being handled. Only the best-keeping varieties such as Triamble and Crown are suitable for long storage. They should be well matured and carefully handled during harvesting and storing. Cuts and bruises in the rind provide access for decay organisms that may cause a great deal of loss from . rots in a short time. Good results have been obtained by curing pumpkins in a glasshouse or in a sunny situation at a temperature of 80 to 85 degrees F. for 10 days.

It is an advantage to spray or dip pumpkins in Bordeaux mixture 3: 4: 50 (31b. of bluestone and 41b. of hydrated lime in 50 gallons of water) to destroy any spores of fungus which may cause decay. One pound of 50 per cent. D.D.T. wettable powder added to each 100 gallons of the Bordeaux mixture will protect the fruit from possible damage by insects such as slaters and stem borers. Pumpkins keep best if stored in a dry place where the temperature remains at about 50 to 60 degrees F. The surface of the pumpkin must be kept dry during storage. Temperatures above 60 degrees F. tend to keep the respiration rate too high and shrinkage may result which will impair the quality. Any dry, airy place where a favourable temperature can be maintained is suitable for the storage of pumpkins and they will , keep better if not piled on top of each other. The best method is to provide shelves where they can be placed on their edges in single layers. Storing them in this manner greatly reduces the chances of loss from decay and makes it easy to turn them regularly for inspection and to remove any which show signs of decay. It is evident from losses experienced by growers that better methods of storing pumpkins should be considered, as the prices realised late in the season more than repay the expense and work involved. A suitable storage shed which will store in single layers 20 to 25 tons of pumpkins is described. To secure the benefits of lower temperatures the building should be erected on the south of a tall hedge or under tall trees which will eliminate direct sunlight. Storage Shed The shed illustrated in this. article is 24ft. square and 10ft. 6in. high. It contains 3 tiers of racks with 4 racks

in each tier. The racks are 6ft. wide and 24ft. long and are spaced 20in. apart, the first one beginning Ift. from ground level. To keep out the cold southerly wind the south wall is fully boarded, but to facilitate aeration the other three sides are open. The alleyways provided between the racks are wide enough to permit the passage of a barrow for bringing in the pumpkins. Doors are provided in the boarded end to enable through working. The shelves are a convenient width and height to allow the operator to work in comfort from each side. The roof is provided with an overhang to keep out rain. This style of shed, besides being useful for the storing of pumpkins, is also ideal for drying onion crops before storing or for drying podded or other vegetable seeds. The timber used may be Pinus radiata (insignis) provided it is treated with creosote, which, besides preserving the wood, is very effective in keeping away insect pests and is also claimed to be offensive to rats and mice.

Roofing iron, 24 sheets 9ft. long, 24 sheets 6ft. long. Roof ridging iron, 4 lengths 7ft. 6in. long. Door hinges, 2 pairs. Door fasteners, 2 tower bolts. Creosote, 14 gallons.

Details of Construction Concrete blocks are spaced at equal distances and not less than 6in. above ground level. Bottom plates are of 4in. x 3in. timber halved at the corners and placed on top of concrete blocks with a strip of damp-course 9in. x 6in. between timber and concrete. Studs are of 4in. x 3in., spaced at 4ft. 9in. centres. The top plate is of 4in. x 2in. The rafters are of 4in. x 2in.. spaced 4ft. 9 3/sin. apart at a pitch of about Ift. in 6ft. and securely nailed and tied with 6in. x lin. ties. Purlins are of 3in. x 2in. spaced to suit the iron roof. Shelves, • which are 20in. apart, are of 9in. x lin. boards, spaced ljin. apart with 4in. x lin. facings, having an upstand of 3in., nailed on to outside edges. End bearers are checked into the studs on the weatherboarded end of the shed and extra noggings or dwangs of 4in. x 2in. are set in to carry weatherboards as shown in the diagram of the shed in cross-section. Diseases and Pests Pumpkin crops are not generally affected greatly by attacks from insect pests and diseases, though some growers may experience trouble. The following are common diseases and insect pests and the control measures. Powdery mildew (Erysiphe cichoracearum) is fairly common on pumpkins, but seldom causes heavy losses. It appears first as small, greyish spots ■on the leaves, which later become covered with white powder. In severe .attacks the whole plant assumes a white, mealy appearance, and eventually withers prematurely. Treatment: Copper sprays such as Bordeaux mixture 3 : 4 : 50 should be applied at 10-day intervals until the disease is controlled.

Downy , mildew (Peronoplasmopara cubensis) also attacks pumpkins. It appears as angular, yellowish spots on the leaves, on the lower surface of which a scanty white downy growth develops. This downy growth often cannot be seen with the naked eye. Individual spots are rarely more than Jin. in ■ diameter, but may later coalesce and result in the death of the whole leaf. Treatment: Powdery mildew can be checked by both copper and sulphur fungicides; use Bordeaux mixture 3:4 : 50 or lime sulphur 1 : 150 plus 31b. of colloidal sulphur. Grey mould (Botrytis cinerea) attacks the flowers, and the rot then spreads to the young fruits, This disease is most prevalent in humid weather and where the foliage is dense. If it is prevalent, some of the leaves should be removed to allow sun and air to reach the fruits, and any rotting flowers or fruits ' should be removed immediately. Apart from this there is no practical control. Mycospaerella citrullina: This fungus mainly affects pumpkins in storage. In the field it appears first on the stems and leaves of plants; the fruit becomes infected from this source. It appears on the leaves and stems as light brown spots with minute black fruiting bodies. The fruit rot begins . as water-soaked or greyish areas on the rind; these gradually become dark brown to black. Only a small portion of the rind may be affected or in severe cases a large portion of the pumpkin may be covered. The \ flesh remains firm, but is usually attacked by secondary soft-rotting organisms. Large numbers of small, black fruiting bodies are present on the affected areas. Where the disease is troublesome the crop should be sprayed, particularly when the fruits are nearing maturity, with Bordeaux mixture 3 : 4 : 50. Root rot or canker (Bacterium carotovorum) is sometimes troublesome, especially in areas where pumpkins have been grown for a number of years. It causes a soft brown rot at the base of the stem just above or below soil level and usually results in the death of the plant.

There is no practical control. Crop rotation should reduce the trouble to a minimum. Cucumber mosaic: This virus disease does not affect pumpkin crops in Auckland to the same extent as in other parts of New Zealand, where it sometimes causes serious losses. Symptoms consist of stunting of the plant and mosaic mottling of the foliage and sometimes a mottling and distortion of the fruits occur. Seed should be saved from disease-free plants. Healthy plants should not be touched after handling diseased ones, as the disease may thus be spread. The hands should be thoroughly washed after handling diseased plants. Rogue and destroy affected plants. Aphides: The young leaves of pumpkins sometimes curl from the attacks of dense colonies of softbodied plant lice or aphides. These can be controlled by spraying the plants with 1 part of nicotine sulphate in 600 parts of water. To increase, the effectiveness of the nicotine sulphate soft soap should be added at the rate of 31b. per 100 gallons of spray. The soft soap should first be dissolved in 3 or 4 gallons of warm water and the nicotine sulphate added to the concentrate, which should stand for 15 minutes before the required quantity of water is added. Springtails (collembola) are minute, wingless, yellow, brown, or black globular insects about the size of a pin-head. When disturbed they spring rapidly into the air. The insects sometimes cause considerable damage to young . pumpkin plants by chewing tiny holes in the leaves. Treatment: Spray the plants with 50 per cent. D.D.T. wettable powder at a strength of lib. in 100 gallons of water. To make the spray stick to the foliage it is an advantage if 4oz. of casein powder is added. Acknowledgment Acknowledgment is made to' the Plant Diseases Division of the Department of Scientific and Industrial Research for assistance in the preparation of the section dealing with diseases and their control. All photographs in this article are by' Sparrow Industrial Pictures Ltd.

Dimensions (in.) Total Concrete blocks 18 x 8 x 6 36 Super. Timber: ft. Bottom plate . . 4x3 170 Studs . . 4x3 318 Shelf bearers . . 4x3 360 Top plate . . . . 4x2 32 Rafters . . 4x2 112 End bearers to shelves shelves . . 4x2 48 Purlins . . 3x2 162 Shelf face battens .. 4x1 . . 4x1 192 192 Shelf battens . . 9x1 1512 Cover boards and barge and barge boards . . 6x1 56 Ridge boards and ties .. 6x1 . . 6x1 40 40 Facing boards . . 6x1 28 Doors (tongued and n d grooved and V-jointed) 4 x 1 V-jointed) 4 x 1 62 62 Hoggings . . 4x2 10

MATERIALS REQUIRED