Straw: Species and varieties

There is a lot of confusion within the thatching industry regarding the types of cereals that are used for thatching in the UK. Press articles often incorrectly describe long straw and combed wheat reed as separate ‘species.’ In fact, only two main species of wheat have been grown in Britain over the past 1,500 years – ‘bread’ wheat (Triticum aestivum) and ‘rivet’ wheat (Triticum turgidum). More primitive species such as spelt (Triticum spelta) and emmer (Triticum dicoccum) have not been widely grown since the Saxon period (c. 600 AD), although spelt has resurfaced in recent years as a health food.

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After the primary wheat species were domesticated, climatic factors, geographical isolation and human selection over many generations led to the evolution of genetically diverse ‘populations’ with distinctive characteristics. Because wheat is essentially self-pollinating, these differences were perpetuated from generation to generation. Their genetic diversity gave these populations the physiological ability to adapt to different growing conditions and to climate change. This ensured that most of the plants within a field were able to survive frost, drought, high rainfall, infertile soils, diseases and other ecological stresses and produce at least some seed every year. It also ensured that plants within one field varied in height, ripening time, yield and other agronomic characteristic. Scientists now call these populations ‘land races’, and throughout the UK, traditional growing, harvesting and seed cleaning practices led to the development of stable, locally-adapted land races that produced at least famine rations of grain every season no matter how bad the season. Farmers in the UK grew land races until the later 1800s, when they stopped saving their own seed and adopted commercial varieties developed by scientific plant breeding programmes. And until the early 1800s it was also common practice for farmers to grow mixtures of species – bread wheat, rivet wheat and rye – all in one field.

Wheat evolved in areas with very poor soils, and pre-modern varieties are still very efficient at absorbing the slightest traces of nutrients from the soil. In rich soils older varieties will grow very tall, but their stems will also be thin walled and the plants will fall over (lodge) in wet and windy weather. Dwarfing genes have been introduced into modern wheats to prevent them growing tall even in high nitrogen conditions – but their straw is now too short to be used for thatching. Straw grown from plants that have had to slowly draw the nitrogen they require from complex organic sources will be stronger and more durable.

Before the late 18th century, fields were not heavily dunged in order to reduce the risk of lodging, and were fallowed, tilled and hoed regularly to kill weeds. By the later 18th century, cereals were also rotated with legumes in order to maintain a low, but steady, supply of nitrogen. Older varieties also formed symbiotic relationships with root fungi called ‘myccorhiza’, which massively extend the effective root system of the plant and help the crop deal with environmental stresses such as drought and disease attack.

 


The origin of UK thatching varieties

In the UK, wheat varieties ‘breed true’ year after year, and only on rare occasions will a pure variety produce a ‘sport’ that is a little different from the parent. Before 1900, sports were more common (because crops were more genetically diverse) and useful sports were prized and multiplied to produce new varieties. Today sports are rarely noticed and will not change the character of the crop – modern varieties will not ‘degenerate’ over time. In the later 19th century, plant breeders began to select the highest yielding lines from within land race mixtures and discarded the rest, so that product of thousands of years of crop evolution was lost within a generation. These ‘improved’ pure line varieties performed well in ideal conditions, but were less hardy and adaptable than the land races from which they were selected, and could no longer adapt to local growing conditions or climate change.

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Old English wheats were high yielding because of the long UK growing season, but their flour lacked the strong gluten commercial bakeries required to make a ‘lighter, whiter loaf’. And the high gluten wheats grown in warmer countries did not yield as well as English varieties when grown in the UK. English wheats were therefore hybridised with foreign baking varieties, producing the first high-yielding English baking variety (Victor) in 1908. Victor is the product of a cross between an old English wheat called ‘Squarehead’ and a Spanish spring variety called Talavera, and was still being grown as a thatching straw in the 1970s. A cross between Squareheads Master (first grown in the 1860s) and a Polish spring wheat Ghirka produced Little Joss (1910), which performed well on lighter soils and is still occasionally grown for thatching in East Anglia.

The grain and thatching straw sectors diverged with the release of Bersée (1935) and Holdfast (1936). These wheats were too short for use as thatch, but were high yielding, well-suited for mechanical harvesting and became very popular with grain producers. Bersée has been a parent of almost all of the wheats grown in Britain since World War II. One of its descendants, Capelle Desprez (1953), covered 80% of UK wheat fields in the mid-1960s. Capelle was popular with some straw growers into the early 1980s, but reached a suitable height for thatching only when grown with nitrogen fertiliser. Capelle was crossed with Holdfast to produce Maris Widgeon (1964), the most widely grown thatching wheat of the past 30 years. A series of increasingly short stemmed, fertiliser-dependent, varieties was released in the 1960-70s: Elite Lepeuple (1960), Chalk (1962), Maris Widgeon (1964), Maris Dove (1971), Maris Huntsman (1972), Maris Freeman (1974) and Aquila (1976). Maris Widgeon is still grown on a (rapidly diminishing) scale for both LS and CWR thatch. All of these modern varieties will produce a suitable thatching straw only when grown in very rich soils or with artificial fertiliser.

Many straw growers abandoned their old stocks of Squareheads Master, Little Joss and Victor in favour of Capelle and Maris Widgeon in the belief that they could produce both thatching straw and milling wheat from the same crop. Unfortunately, the massive quantities of chemical fertiliser needed to maximise grain yield and quality weakened the straw and led to ‘premature decay’ on many roofs. The damaging effect of nitrogen on straw quality was well-recognised by the mid-1980s, and dedicated straw producers have largely returned to growing older varieties in low input conditions.

 


Modern thatching varieties

The most popular thatching varieties have always been winter forms of ‘common bread wheat’ (Triticum aestivum). Winter varieties are usually sown before early December as they need to ‘vernalise’ (i.e. be exposed to intense cold) for a month or more in order to produce straw and set seed. Many older UK varieties have performed very well in screening trials, but older varieties are not available to growers because of DEFRA restrictions (see below).

NB: Stems heights listed below reflect crops grown on fair quality land in low input conditions.

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  • Maris Widgeon
    Released in 1963 by the Plant Breeding Institute (PBI) in Cambridge; long outclassed as a baking wheat, but kept on the National List (NL) for thatchers and organic growers; straw c. 90 cm, thin walled but moderately resistant to lodging; still popular with many growers and thatchers for long straw and comb wheat reed thatch.
  • Maris Huntsman
    Added to NIAB Recommended List in 1972, and for many years the most widely grown winter wheat in the UK; straw c. 80 cm, thin walled and resistant to lodging; occasionally grown for thatch and by organic grain producers.
  • Squareheads Master
    Several forms of Squareheads Master have been grown in the UK for c. 150 years; original Squareheads Master was probably selected from a Dutch version of the old land race variety Squarehead, and is very similar to ‘Red Standard’; most stocks are derived from an improved line (Squareheads Master 13/4) introduced in 1940; straw c. 110-120 cm, strong, thick walled, reddish-brown in colour; suitable for a wide range of soil types and winter hardy, but will lodge in rich soils; regaining popularity for both combed wheat reed and long straw.
  • N59
    Released in 1959, and now grown primarily for combed wheat reed in the west country; straw c. 105-115 cm, stem walls medium thick, resistant to lodging and light coloured; will lodge in rich soils; most of the present crop is derived from stock maintained by one grower in Devon since 1960.
  • Aquila
    Modern, semi-dwarf wheat widely used for combed wheat reed and long straw in the early 1980s; straw very short (70 cm), thick walled, highly tapered, but resistant to lodging; not recommended for either combed wheat reed or long straw thatch.

Uncommon wheat varieties

  • Little Joss
    Early hybrid released by the PBI in 1910; straw c. 110-120 cm, fine, thin-walled, and prone to lodging; best sown in September on light soils, but can be sown up to early February on heavier soils; occasionally grown for LS in East Anglia.
  • Elite Lepeuple
    French variety released in UK in 1960; straw c. 80-90 cm and thin walled; no longer in cultivation; not recommended for combed wheat red or long straw thatch.
  • Chalk
    Released in 1962; straw c. 90-100 cm, thin walled and waxy; widely grown for CWR in W. Country 1970-1985.
  • Victor
    Early hybrid released by the PBI in 1908; straw c. 110-120 cm, pale coloured with thin walls; resistant to many diseases and suitable for cultivation in wet areas.

‘Experimental’ species and varieties

  • Rampton Rivet (Triticum turgidum)
    Released by the PBI in 1939 for cultivation on heavy soils; straw very tall (120-140 cm), coarse, thick walled and resistant to lodging; must be planted early (September/early October) and thickly due to its lower tillering ability; ripens 2-3 weeks later than most winter wheats; produces top quality long straw and combed wheat reed.
  • Spelt wheat (Triticum spelta)
    An ancient species of wheat that was grown in the UK from the Bronze Age until the early Saxon period; spelt products have become popular in the health food sector in recent decades, and modern ‘pure line’ spelt varieties have been crossed with modern bread wheat varieties to produce higher yielding, high-gluten varieties with shorter stems; older varieties are c. 100-130 cm, with waxy, thick walled straw; recently released hybrid varieties are short and not suitable for use as thatch; older spelts must be grown in low nitrogen conditions, and are suitable for both CWR and LS thatching; ‘spikelets’ of spelt grain are easily threshed from the straw and make an ideal animal feed, but the husks enclosing the grain must then be removed before the grain is milled for human consumption; sowing the grain in spikelet form improves germination and establishment.
  • Emmer wheat (Triticum dicoccum)
    A staple wheat of the ancient Near East and prehistoric Britain from the Neolithic until the early Saxon period; straw 100-140 cm depending on variety: a recently introduced Spanish variety produces very tall, coarse and thick walled straw, and can be planted in the autumn or the spring; must be grown in low input conditions to prevent lodging; suitable for both CWR and LS thatch; grain is husked as with spelt wheat, but grain-bearing spikelets are easily threshed from straw.
  • Rye (Secale cereale)
    Used primarily for CWR and ridging in the past, and was grown both as a pure crop or in ‘maslin’ mixtures with wheat; most varieties are tall, c. 100-140 cm, waxy, flexible and thin walled, and rye straw is not as durable as wheat straw; very hardy and disease resistant, and can be grown in poor soil and very low input conditions; no longer widely grown in UK, and large quantities are now imported from Poland primarily for CWR thatching.
  • Triticale (Triticum x Secale)
    Over the past 10 years, many straw growers have abandoned wheat in favour of Triticale, an artificial hybrid cross of an Italian pasta wheat (Triticum durum) x rye (Secale cereale). Triticale was developed in the laboratory and did not grow in British fields in the past. One of the first commercial varieties (Lasko) was released in Hungary in 1968 as a feed grain. Varieties suitable for UK growing conditions (eg. Purdy, Olympus) were released in the mid-1980s. Thatchers began to experiment with Triticale straw in the late 1990s, and it has now been widely used for the last decade.
    Triticale has become popular with thatchers primarily because it has become popular with straw producers – it is easier to grow than wheat, performs consistently well in poor soils and low input systems, and is disease resistant which allows it to be grown in the same field year after year (with inputs). It also ripens 7-10 days earlier than wheat, which can be an advantage for someone who grows both wheat and Triticale. Combed wheat reed thatchers like Triticale straw because it is usually long (100-120 cm), brightly coloured, waxy, flexible and strongly tapered. Unfortunately, Triticale inherited the softer straw of its rye parent, and many thatchers who used it in the 1990s have reported premature failures and returned to using wheat straw. No scientific evidence is available comparing the straw quality of different Triticale varieties, or Triticale with wheat. As with wheat, the older varieties (eg. Purdy, Lasko) that produce the best quality thatching straw are no longer legally available and have been replaced by higher yielding varieties with shorter straw. Triticale has not been used long enough for its relative durability to be established – but well produced Triticale will probably outlive poorly produced wheat straw.
  • Mixtures
    Many straw producers grow mixtures of varieties, a common practice before 1900. In diversity there is strength – a mix of suitable thatching varieties will be better adapted to variable growing conditions, make more complete use of soil nutrients, be more resistant to disease, be reliably tall, and will ripen more slowly making it easier to cut the entire crop at an optimal time. The genetic diversity within a mixture will hep ensure that a reasonable crop of straw will be harvested no matter how bad the growing season. A mixed crop must be cut before the earliest variety within the mixture has ripened, and the harvest must be stooked in the field long enough for the later ripening varieties to dry out thoroughly before the straw is stacked indoors. All mixtures dominated by Squareheads Master or N59 produce good quality straw. On rich soils, adding Maris Widgeon to the mixture can help prevent the crop from lodging. Rivet wheat should not be mixed with other thatching varieties because it ripens much later and would have to be cut very green.
  • Spring wheat
    The best combed wheat reed and long straw are grown from autumn sown crops. Unlike winter wheats, true spring varieties do not need to be exposed to frost and cold in order to produce straw and seed. The first spring wheats were introduced to the UK in the early 1800s, including April, the parent of April Bearded, a selection that was widely cultivated until 1940. Older spring wheats produce tall (100-130 cm), weak-stemmed, straw susceptible to lodging if grown in fertile soil or in the autumn. However, long straw thatch from a good quality spring variety planted in early March will perform better than poor quality straw from a winter crop. Unfortunately, there are few true spring wheats available that are tall enough to be used as thatch.

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