Growing Hazel and Walnut Trees

Growing Hazel and Walnut Trees

The commonest types of nut grown are the hazel and walnut. The two variants of the common hazel, Corylus avellana, are the cobnut with short husks and the filbert with long husks. Both are suitable for planting on poor, stony soils unsuitable for fruit trees, where they make medium growth and crop heavily. On rich soils growth is lush but unproductive.

Both tolerate sunny and shaded sites and wide extremes of soil acidity and alkalinity, but detest wet clays. Sandy barns are ideal for them. As the blossom is frost resistant, the bushes may be planted in low-lying, frosty situations. Cobnuts and filberts are grown as open-centerd bushes raised from suckers detached in the autumn or from layers from whippy growths positioned near ground level. Seedlings are too variable in fruiting to be worthwhile.

A light dressing of farmyard manure may be dug into the soil prior to planting between mid-October and mid-March at 3-5m (10-15ft) apart. Tread the soil firmly round the roots, and stake and tie the bushes if the site is exposed. Mulch liberally in April with decayed garden compost, shoddy, leafmould, or peat, and feed with 50g (2oz) per sq m (sq yd) of sulphate of ammonia. Repeat this mulching and feeding annually, and each autumn dress with 28g (1oz) per sq m (sq yd) of sulphate of potash and 170g (6oz) per sq m (sq yd) of basic slag. Omit feeding with fertilizers on rich soils; sow grass around the bushes and mow it regularly if growth is excessive.

For convenience in picking the bushes can be restricted to a height of 2m (6ft). Pull off all suckers. Cut out all inward-growing, dead and weak shoots in February and shorten the leading shoots of young bushes by half. To promote a succession of young fruiting shoots shorten all lateral shoots in February at blossom time to the first male (catkin), or female (small, round, red) flower.

Over-vigorous lateral shoots can be weakened by brutting them in July or August. This consists in partially breaking each in half, leaving the broken pieces hanging. This precludes secondary growth which would appear if the shoots were cut.

Harvest the nuts on a dry day at the end of September or in early October when the husks are yellowing. Allow them to dry thoroughly before storing them with salt in glass or earthenware jars or tins with air-tight lids.

It is best to interplant varieties to get full crops. The two most popular ones are cobnut, ‘Cosford’—a good bearer of very sweet, thin-shelled nuts which ripen early, an upright grower and an excellent pollinator—and the filbert, ‘Lambert’s Filbert’, otherwise known as ‘Kentish Cob’—a compact bush bearing heavy crops of large nuts with excellent flavor and readily pollinated by ‘Cosford’.

If winter moth caterpillars are seen eating the leaves in spring apply an insecticide spray. The nut gall mite feeds on the terminal buds of the fruiting shoots, causing them to swell and preventing normal development. Where this pest is noticed, spray with 3 percent lime sulphur in late March or early April. The chief pest is the nut weevil which lays eggs singly in the nuts during May ; the grubs burrow through the nuts. Brown rot fungus then gains entry causing a severe nut drop. Control this weevil by spraying with derris towards the end of May.

The walnut, Juglans regta, is a long-lived, imposing and very ornamental tree which makes itself at home in any soil conditions except extreme dryness or wetness. If it has a preference, it is for alkaline soils. As the one-year-old shoots are very susceptible to winter killing, a frost-free site is necessary. An open, sunny position is ideal. Walnuts are sometimes grown in bush form but more usually as a full standard. Allow for an ultimate branch spread of 10m (30ft) diameter. Young trees are propagated by double-tongue grafting under glass in March, or patch-budding in June or July, on seedling rootstocks in both cases. Nurserymen in the British Isles frequently import trees from the Continent where the climate allows grafting to be more certain of success.

The trees should be planted between November and January in well-dug soil, fortified with a general fertilizer. Adding rich organic manure is undesirable as this promotes lush growth susceptible to frost. Ensure firm compaction of the soil round the roots and stake and tie securely. Mulch the soil after it has warmed up in April or May. Subsequently, give an annual dressing of bonemeal at 50g (2oz) per sq m (sq yd).

Young trees require a modicum of pruning in their early years so that they may develop a shapely head. Prune them in July to minimize bleeding of sap, never between November and May. Afterwards, merely remove dead or awkwardly-positioned branches prior to leaf-fall. If wounds do bleed, cauterizing the cut surfaces with a hot iron should stop this.

Walnuts are self-pollinated so they can be planted singly. The French walnut, ‘Franquette’, is one of the most reliable varieties to grow as its leaves appear late and so avoid damage from May frosts.

Walnuts for pickling should be gathered when their shells are soft enough to be pierced with a needle. It is advisable to wear rubber gloves to avoid getting long-lasting stains on the hands. For storing, gather the walnuts when they start to fall naturally and the husks open easily. Dehusk the nuts, lay them out in a single layer and allow to dry thoroughly before storing them with salt.

The grubs of the wood leopard moth and goat moth sometimes tunnel up the trunk or along a bough, causing structural weakness and inducing invasion of wood-rotting fungi. The grubs may be killed by poking a piece of wire along the tunnel where this is short enough. Otherwise, insert a few crystals of paradichlorbenzene and seal the hole with plasticine or putty.

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