Pipfruit

growing in the home garden

History

Pipfruit is the name given to the fruiting trees that include apple, European pear, Asian pear, quince, and medlar.

Apples and pears were amongst the first fruit trees brought into New Zealand by colonising Europeans in the early 1840s. They were found to grow well here and became a popular addition to home gardens. Within 20 years the first commercial orchards had sprung up, catering to the rapidly growing local market. Exporting New Zealand-grown pipfruit to markets in other countries began in 1910, and has steadily increased to become an important industry. Today, apple and pear exports earn New Zealand approximately $4.5b.

Both apples and pears remain popular choices for home garden plantings, but the apple is probably the more common. This is probably because apples are so popular and are relatively easy to grow. Apples are available for eating from the tree over a longer period and can be stored for longer than pears. Apples have in fact been grown in home gardens for centuries although the fruit have changed considerably in both appearance and flavour over time as new varieties (cultivars) have been selected.

Growing systems and the selection of apple
and pear varieties

The apples of today are thought to have descended from crosses between European and Asian Malus species that grew as wild seedlings in the Caucasus region (between the Black and Caspian Seas). Apples of various kinds have been distributed and grown from seed throughout Europe where they have been selected for their fresh-eating or cooking qualities, as well as cider-making. Over time, selections have been made for sweeter eating varieties with longer storage life and firm flesh. The varieties grown commercially today are no longer raised from seed but grafted or budded on to rootstocks. These ensure that even-sized trees with known genetic heritage are produced. The use of specific rootstocks has not only made commercial production possible but provided the home gardener with a choice of rootstocks that produce trees of known vigour. These range from the more vigorous Merton 793 to Malling-Merton 106 and the most dwarfing, Malling 9.

Today, the more tried and true varieties are more commonly available in garden centres, but before choosing it is advisable to talk to your neighbours and garden centre about which varieties grow well in your area. Different varieties can be chosen to obtain a succession of fruit throughout late summer and autumn. Nowadays it is possible to buy apples with different varieties grafted on to an individual tree. When grown on fully dwarfing rootstocks, two to three trees can occupy the same space as a non-dwarf tree. Such trees are well suited to modern smaller gardens.

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Suggested varieties for the home garden

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Site selection

Modern apples have a relatively wide climatic tolerance so they grow well whether they are close to the sea or inland. However, some varieties perform better in certain districts than others so check which varieties do well in your area before choosing. For instance, Granny Smith requires a long growing season and is less suitable for the southern South Island. The choice of apple for planting will depend on a number of factors including its expected use (fresh eating or cooking), the availability of light and space, access to irrigation water and rainfall. One of the most critical considerations is rainfall as high rainfall increases the risk of diseases such as black spot. Poorly drained soils and heavily shaded sites should be avoided.

Fruit set and fruit size of apples and pears are both improved if the flowers are crossed with pollen from another variety. Therefore, it pays to plant more than one variety unless there are other varieties in the vicinity.

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Tree management

Pruning promotes the new growth that is required for the production of new fruiting wood, and allows air movement and light to penetrate the tree canopy. Pears, once established, generally require less pruning than do apples to maintain fruiting, but can grow to very large trees unless grafted on to a modern dwarfing rootstock. The hand removal of apple fruitlets (referred to as thinning) to one or two fruits per cluster is strongly advised after flowering (during November). In addition to producing larger fruit, thinning also enhances fruit quality because a single fruit is less likely to be attacked by insects and suffer diseases.

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Fruit storage

The fruit of some pipfruit varieties are best eaten straight from the tree, while others, particularly late season varieties (e.g. Sturmer, Granny Smith), can also be stored for eating during winter. Store only the best fruit that are free from blemishes and skin punctures, as these keep the longest. For pipfruit to store well, fruit should be stored loosely in well-ventilated crates or boxes, and kept in a cool, dry, dark location. If sorted once or twice during the winter to remove any rotting fruit, fruit can be kept until late November or December, providing a 12-month supply. Pears do not store well once picked, and are consequently best left on the tree until required.

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Integrated Garden Management (IGM)

The underlying approach employed here is to take the scientific approaches used in commercial food production and apply these to the home garden situation. In general, the problems facing the home gardener and commercial producer are the same. However, problems faced by home gardeners tend to be less severe than commercial producers. Such problems are less both in reality (associated with the relatively small productive area) and perception (due to the gardener's greater tolerance of yield and quality). Nonetheless, most of the problems faced by home gardeners benefit from the application of the approaches developed for commercial production by the research and development sector.

The `integration' in IGM refers to the integration of biological and non-biological approaches. It takes a systems or holistic view of the entire garden operation, recognising that all components of the system (pest and disease management, plant nutrition, crop husbandry, cultivation and crop understorey management, site and cultivar selection, etc.) are interrelated, and that changes to one component of the system affect other components.

This is particularly important for insect pest management, where it is known that insecticides applied to control one insect can also reduce numbers of beneficial insects.

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Pest and disease management

The biggest challenges facing growers of apples and pears in the New Zealand home garden lie in dealing with pest and diseases. Scientific studies allow us to understand the life cycles of these various pests in relation to the crop, and this knowledge allows us to identify the most appropriate methods to reduce the impact of these pests and diseases.

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Pest management:

Codling moth ( Cydia pomonella )

Codling moth is usually the most serious problem faced by home garden apple and pear growers. The larvae (caterpillar) of codling moth directly attack fruit, usually by tunnelling into the side of the fruit, where they feed on the fruit flesh and pips, before exiting, often through the calyx. The entry hole is often surrounded by a red halo of fruit skin and is characterised by the presence of frass (faecal pallets).

If left unchecked, 50% or more of the fruit crop is usually affected, although the level of damage varies widely with location and variety. Such high levels of damage reflect the general inability of natural controls (predators, parasites, etc.) to maintain this insect below acceptable levels. This is despite millions of dollars being spent globally in an effort to enhance such biological controls against what is globally an important economic pest. Cultural methods that aim to reduce numbers of overwintering caterpillars and pupae can be used. While these may be, at best, only partially successful in reducing fruit damage, they offer the home gardener the only "low tech" option. Such methods include the removal of vegetation from the orchard understorey during the winter, through cultivation or mulching. However, while some codling do over-winter in the vegetation under trees, most over-winter under loose bark on the trees' lower trunk and limbs. Using a wire brush to remove this loose bark during winter can reduce numbers of over-wintering codling moth caterpillars and pupae. However, the success of such an approach is dependent on how close the nearest unmanaged codling moth-infested tree is because during spring, female moths may simply fly over the fence from another infested tree and lay eggs on your well-managed tree!

Codling moth traps, baited with sex pheromone lures, can be purchased from garden centres. When these are hung in trees, catches of male moths can indicate the best time to apply an insecticide. Moth catches generally increase and then decrease during the season. This reflects a generation of codling moth. When catches of moths total 10 or more in a trap, this indicates the beginning of a generation, and the best time to apply an insecticide. In many parts of New Zealand this occurs during early November (North Island) to early December (South Island). With this timing, a single insecticide application can be sufficient to reduce codling moth to acceptable levels. Another application six weeks later can be made if a further reduction in fruit damage is desired. One or two well-timed insecticide applications offer the home gardener the most effective method of producing codling-free fruit. If the insecticide is chosen wisely, it need not pose a significant risk to the garden ecology, the gardener, or the consumer of the fruit.

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Leafroller caterpillars

These small moths are very common throughout New Zealand. There are several species of leafroller, but the lightbrown apple moth ( Epiphyas postvittana ) is the most common. The caterpillars feed on a wide range of garden plants, tying together leaves with white silken threads to form feeding shelters (or `rolled' leaves). Their pest status on apples and pears is due to surface feeding damage on fruit. As this damage is largely cosmetic, it is best for home gardeners to simply accept this damage. The alternative is monthly applications of insecticides throughout the growing season. However, this represents a level of spraying not considered desirable by most home gardeners. Leafroller can be controlled with fewer insecticides when timed to coincide with each generation of caterpillars, but this varies throughout New Zealand, making recommendations difficult within the context of this publication. Leafroller pheromone traps are available in some (very few) garden centres, and these can be used to identify the beginning of each generation, as described for codling moth.

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Scale insects

These are small sap-sucking insects that are covered with a hard shell, similar to the limpets found in marine environments. Nationally, there are several species that attack pipfruit, which range in size from 1 to 4 mm. Scale insects become a problem mainly due to the sugary `honey dew' they excrete, which in turn provides a food source for the black sooty mould fungus. At some locations they can reach very high numbers, while at other locations they never become problematic. The reason is thought to be the presence or absence of a range of very small parasitic wasps that attack the scale insects.

Control of scale is relatively easily achieved by spraying with mineral oil (at the 2% rate) in the early spring, just as the buds begin to break and the first green tips are visible. Repeat the following spring. On badly infested trees, the addition of an insecticide may be necessary. In high rainfall areas the removal of lichen and moss from the tree may also be necessary prior to spraying - proprietary products are available from garden centres for this purpose.

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Sprays

The growing of fruit of sufficient quality and quantity to satisfy the home gardener can frequently be achieved without the use of sprays. Fruit quality can be considerably enhanced through pruning and hand thinning (as described above). If sprays are to be applied, attention should be given to achieving a thorough coverage of the entire tree, concentrating on the underside of leaves. A spreader/sticker should be added to all sprays, and the correct mixing rates used. If in doubt, garden centres can be contacted for advice.

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Disease management:

Blackspot ( Venturia inaequalis )

The blackspot fungus causes dark lesions on leaves and fruit of apples and pears. When severe, it leads to premature leaf-fall and a lowering of photosynthesis, which in turn can affect fruit size and abundance. Worse, however, is the impact of the fungus on the fruit, which can cause misshapen fruit, and premature drop due to splitting and cracking.

The blackspot life cycle has been well studied on pipfruit, and it is known that the `weak link' that can be exploited to reduce the incidence of this disease is its over-wintering phase. Home gardeners should remove all leaf material from the understorey below the trees, once leaf-fall is complete. This removes the over-wintering asco-spores of the fungus because it is these that release spores early spring and re-infect the foliage. If removing apple leaf litter is not possible, then mulching over leaves will have the same effect, as total leaf breakdown will destroy the ascospores. Adding nitrogen under trees after leaf fall also aids leaf decomposition.

It is difficult to control blackspot using fungicides. Chemical control relies on maintaining a cover of protectant spray deposit on leaves from bud-movement through to late November, as it is during this period when ascospores are released. As newly opened leaves are the most susceptible to blackspot, and the tree is actively growing during this early period, spraying is necessary on a very regular basis; every two weeks and again after significant rainfall.

Studies have also demonstrated that blackspot prefers warm and wet conditions, so pipfruit gardens in locations like Auckland will suffer more from this disease than those in drier climates. Choosing a site for your pipfruit trees that dries out quickly after rainfall or watering can help reduce blackspot problems. Some pipfruit varieties are more susceptible to blackspot infection than others, and a badly infected variety may allow other less susceptible varieties to become worse. Replacement of a highly susceptible variety should be considered where blackspot is severe.

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Powdery mildew ( Podosphaera leucotricha )

This fungus disease affects apples only, and prefers conditions that are hot and dry. It over-winters in infected tissue on shoot tips. During the summer, infected shoot tips are coated with a white powdery substance, new growth aborts, and badly infected shoots shrivel and die. While this disease does not affect fruit directly, severe infestations can reduce new growth to such an extent that few fruit are produced the following summer. However, for the home gardener, this disease is generally less important than blackspot and, as for blackspot, some varieties are more susceptible than others. Management should focus on removal of infected shoots during winter and spring, with any infected prunings thoroughly disposed of. Fungicides can also be used to reduce powdery mildew, although this is not usually necessary in home gardens. However, applying 4 sprays of triforine, or lime sulfur, or sulfur, 7-10 days apart, and applying the first spray at about 10% flowering should reduce powdery mildew to acceptable levels for the entire season.

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Other pest and disease problems

• There are a number of summer rots that can affect the fruit (mainly apples) during summer. Should any of these become severe, spraying with a general fungicide should be tried, such as triforine, cupric hydroxide, or lime sulfur.
• Woolly aphid can sometimes reach high numbers on apple trees. Generally only older trees are affected, or those subject to environmental stresses, e.g. excessively shaded. The use of insecticides applied against codling moth or leafroller can also cause outbreaks of woolly aphid due to their impact on beneficial insects that would otherwise control this pest.
• Leaf curling caused by the apple leaf curling midge is often considered a nuisance by home gardeners. Commercial apple growers are not able to effectively control it despite having a greater range of available pesticides than the home gardener. Attempting to control apple leaf curling midge with insecticides is likely to lead to other problems due to the disruptive impact of the insecticides on beneficial insects.
• Pear leaf blister mite causes reddish blisters on pear foliage and fruitlets. When severe, this problem can be fixed by spraying with lime sulfur (13 ml/L) during spring (late green-tip stage, but prior to flowering). Repeat the following spring.

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Plant nutrition

Like all crops, pipfruit require adequate water and nutrients to fruit well. However, unlike other fruits (e.g. citrus) the fertiliser requirements of pipfruit are not great, and care should be taken not to over-fertilise. In particular, excessive nitrogen will promote excessively vigorous growth, resulting in problems associated with pruning, and pest and disease susceptibility. Maintaining a weed-free growing area around establishing trees is important and can be achieved by mulching, applying herbicide, or hoeing.

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Recipes

Everybody loves apple pie. Line a 20-23 cm pie dish with flaky pastry. Place ½ cup sugar and 2 tablespoons flour in a bowl.Coarsely shred or slice 4-6 unpeeled or peeled apples, and toss in sugar and flour. Pour 25 g melted butter over the apple, add 6 cloves (optional), and further toss. Place mix into pastry lined pie dish. Cover with more pastry and bake at 220°C until golden brown and apple is tender (lower heat to 180°C if pastry browns before apple is cooked). Serve warm, with ice-cream, cream, or yoghurt.

If you think simplicity is sophisticated, then try these whole baked apples . Using an apple corer, remove stem, calyx and core from 6-8 large, clean apples. Place on greased tray, and stuff core cavity with chopped dates (or any dried fruit). Drizzle with strong bush honey (or treacle/golden syrup). Bake at 180°C until fruit is tender (test with skewer). Serve warm, with ice-cream, cream, or yoghurt, and sprinkle with finely chopped nuts.

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Nutritional benefits of apples

We have all heard the saying that, "An apple a day keeps the doctor away." Scientists are now proving this to be correct. Not only are apples low in calories and high in fibre, but nutritionists and scientists are finding that apples can prevent health problems, or at least reduce health risks that our bodies face every day. Their preventative and curative properties are capturing the spotlight in studies around the world.

There are so many reasons to eat an apple a day:

• Convienience – Apples are the perfect, portable snack. They are great tasting, energy-boosting, and free of fat.
• Good and hearty – Research confirms that the antioxidants and phytonutrients found in apples help fight the damaging effects of LDL (bad) cholesterol, and are good for your heart. A Finnish study published in 1996 showed that people who eat a diet rich in flavonoids have a lower incidence of heart disease. Other studies indicate that flavonoids may help prevent strokes.
• Aids digestion and weight loss – Just one apple provides as much dietary fibre as a serving of bran cereal. (That's about one-fifth of the recommended daily intake of fibre.) In addition to aiding digestion, dietary fibre promotes weight loss. A medium apple contains about five grams of fibre, more than most cereals. Also, apples contain almost zero fat and cholesterol, so they are a delicious snack and dessert food that's good for you.
• Lung function – An apple a day strengthens lung function and can also lower the incidence of various lung disorders, including cancer. A recent study of Welsh men indicated that people who ate at least five apples per week experience better lung function. Researchers at the University of Nottingham reported that those who ate five apples per week also had a lower risk of respiratory disease. In the Netherlands at the University of Groningen, apples were singled out as a fruit that could cut smokers' risk of COPD (chronic obstructive pulmonary disease) in half. Scientists believe antioxidants found in apples may ward off disease by countering oxygen's damaging effects on the body.
• Builds strong bones – Apples contain the essential trace element, boron, which has been shown to strengthen bones – a good defence against osteoporosis. It is a good idea to eat apples with their skin. Almost half of the vitamin C content is just underneath the skin. Eating the skin also increases insoluble fibre content. Most of an apple's fragrance cells are also concentrated in the skin. As skin cells ripen they develop more aroma and flavour.
• Cancer prevention and general health benefits – A number of components in apples, most notably fibre and phytonutrients, have been found in studies to lower blood cholesterol and improve bowel function, and may be associated with a reduced risk of ischemic heart disease, stroke, prostate cancer, type II diabetes and asthma. Preliminary research from Finland in 2002 indicates diets with the highest intake of apple phytonutrients were associated with a 46% reduction in the incidence of lung cancer. Findings indicate that two apples a day or 12 ounces of 100% apple juice reduce the damaging effects of the `bad' LDL cholesterol. Increasing numbers of studies are linking apple consumption with reduced cancer risk. A 2001 Mayo Clinic study indicated that quercetin, a flavonoid abundant in apples, helps prevent the growth of prostate cancer cells. A Cornell University study indicated phytochemicals in the skin of an apple inhibited the reproduction of colon cancer cells by 43%. The National Cancer Institute has reported that foods containing flavonoids like those found in apples may reduce the risk of lung cancer by as much as 50%.

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References for health benefits:

Carcinogenesis (March, 2001)
Nature (June, 2000)
Journal of the National Cancer Institute (January, 2000)

Useful terms in understanding apple fruit health benefits:

• Phytochemicals: chemical compounds found in plants, fruits, and vegetables that can act as antioxidants.
• Antioxidants: chemicals that reduce or prevent oxidation, preventing cell and tissue damage from free radicals in the body.
• Phenolic compound: a type of phytochemical.
• Flavonoids: a class of antioxidant. Apples are packed with flavonoids.
• Quercetin: a type of flavonoid found in apples.
• Pectin: a soluble fibre present in most fruits and vegetables.
• Tannins: substance found in apple juice that helps prevent urinary tract infections and may reduce heart disease. Research also suggests tannins may help prevent gum disease.

Source: USFDA 1996

Further sources of information:

Hamilton, R.G. 1969: The home orchard. Dept Ag., Wellington, Govt Printer.
Williams, D. 1985: Home fruit growing in New Zealand. Govt Printer, Wellington.
Ballinger, R.; Ballinger, J. 1981: Fruit gardening in New Zealand. Christchurch, Caxton Press.

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