Blackberries ‘Natchez’ and ‘Ouachita’

Two thornless Arkansas cultivars combining large firm fruit, erect growth and reliable yields

The breeding programme of the University of Arkansas at Clarksville is one of the most influential blackberry breeding centres in the world. It produced the cultivars that first brought together three traits which had previously been hard to combine in a single plant: complete thornlessness, an erect habit, and fruit firm enough to survive picking, transport and several days in the refrigerator.

‘Natchez’ (original designation Ark. 2241) and ‘Ouachita’ (Ark. 1905) are two of them. They are not really competitors but rather a complementary pair in the garden: ‘Natchez’ opens the season with large, long fruit, while ‘Ouachita’ follows a week later with slightly sweeter berries and growth that manages without any trellis.

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Origin and breeding

Both cultivars were created by hand pollination at Clarksville, Arkansas, and both belong to the group of predominantly eastern North American blackberries derived from Rubus allegheniensis (possibly with introgression of R. argutus). Their thornlessness genes come from the British cultivar ‘Merton Thornless’, which in turn derives them from R. ulmifolius.

Plant, growth and pollination

Both cultivars are vigorous and establish quickly after planting – in the case of ‘Ouachita’ even faster than most other thornless cultivars. The difference between them lies in cane stiffness.

The canes of ‘Ouachita’ – both primocanes and floricanes – grow erect and are self-supporting, so the plant needs no trellis. ‘Natchez’ has an erect to semi-erect habit and, although it can be grown freestanding, a wire trellis is recommended: under a heavy crop or in a windy site the canes tend to lodge.

In both cultivars the flowers are white, perfect and highly fertile. ‘Natchez’ blooms on average 2 to 4 days earlier than ‘Ouachita’, which in turn blooms 0 to 2 days earlier than ‘Navaho’. Both are self-fertile, so no second cultivar is needed as a pollinator to obtain a crop.

The fruit

The berries of ‘Natchez’ are large, long and cylindrical, averaging 8–9 g. ‘Ouachita’ produces round-oblong to conical fruit averaging 6.0 g, which is 1.0 to 1.5 g more than its seed parent ‘Navaho’. Importantly, both cultivars maintain fruit size very well throughout the picking season, so the last berries are not markedly smaller than the first.

The colour in both cases is a bright, glossy black. At full ripeness the fruit is very firm: ‘Natchez’ is comparable to ‘Ouachita’, ‘Apache’ and ‘Navaho’, while ‘Ouachita’ itself is rated firmer than ‘Shawnee’ and ‘Choctaw’ and almost as firm as ‘Navaho’.

Flavour in both is good, sweet and mildly subacid with a pronounced blackberry aroma. Soluble solids average 9.5% in ‘Natchez’ and 9.9% in ‘Ouachita’, with ‘Ouachita’ reaching up to 12% in favourable seasons. Average dry seed weight is 4.2 mg in ‘Natchez’ and 4.5 mg in ‘Ouachita’.

Value scales: berry weight and sugar content

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Berry weight is plotted against a 0–10 g scale and soluble solids against a 0–12% scale, the latter corresponding to the maximum recorded in ‘Ouachita’. All figures are averages from trial plantings in Arkansas.

Ripening and yield

‘Natchez’ is an early cultivar. It begins ripening seven days before ‘Ouachita’; in Arkansas the average date of first harvest is 3 June and picking lasts 35–40 days, roughly until 11 July. ‘Ouachita’ is a mid-season cultivar: it starts seven days ahead of ‘Navaho’, on average on 12 June in central Arkansas, with a picking period of about 35 days, roughly until 17 July. In Central European conditions the dates shift according to site and the course of spring, but the interval between the two cultivars remains.

Yields are high and consistent in both, ranging from 2.3 to 3.2 kg per plant. For ‘Ouachita’ this is significantly more than its seed parent ‘Navaho’ and comparable to the highly productive ‘Apache’.

Postharvest storage of fresh fruit is excellent in ‘Ouachita’, comparable to ‘Navaho’ and better than in ‘Shawnee’ and ‘Choctaw’. ‘Natchez’ matches ‘Navaho’, ‘Apache’ and ‘Ouachita’ in this respect.

Cultivars at a glance

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Disease resistance and hardiness

Plant health is among the strongest points of both cultivars. In trial plantings they appeared immune to orange rust (Gymnoconia nitens) and to double blossom, also known as rosette (Cercosporella rubi). Against anthracnose (Elsinoe veneta) they show moderate resistance or tolerance – in high-pressure seasons protection cannot be dispensed with entirely.

Cold hardiness is the weaker side. ‘Natchez’ is hardy to −14 °C and ‘Ouachita’ to −17 °C. What matters is the temperature the floricanes are exposed to during winter – frost damage to buds only becomes visible as a reduced crop the following summer.

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The scale runs from −20 °C to −8 °C. The green end marks greater cold hardiness, the orange end lower hardiness.

Propagation

Both cultivars propagate very well from root cuttings – they produce adventitious shoots from the roots far more readily than ‘Navaho’, the seed parent of ‘Ouachita’. ‘Ouachita’ additionally roots well from softwood cuttings.

A willingness to sucker cuts both ways: it makes propagation easy, but it also means the planting will gradually spread beyond its allotted space unless unwanted shoots are removed regularly.

Which one to choose

If you have room for both, you gain a continuous harvest from the very start of the season into midsummer – from plants that carry no thorns, need no pollinator, and yield fruit that holds its shape in the fridge for days.