Spergula arvensis L.
Corn spurrey is a troublesome annual weed occurring on light sandy soils deficient in lime. It is recorded up to 1,500 ft in Britain. Corn spurrey is found mainly on soils with a pH between 5.0 and 6.0. It occurs primarily on arable land, disturbed grassland and waste places. Corn spurrey grows as a summer annual and has been so plentiful as to cause crop failure. It is common in cereals particularly spring barley. There is evidence that it was a weed of flax during the Iron Age.
Plants vary in seed and flower characters and in hairiness. Seeds differ in the presence or absence of papillae on the seedcoat. The form with papillate seeds is sometimes described as var. vulgaris and the non-papillate as var. vulgaris. Crop morphology can affect the growth habit of corn spurrey plants.
Corn spurrey can become infected with the cucumber mosaic virus which is aphid transmitted. Around 2% of the seeds produced by infected plants may carry the virus.
Corn spurrey is eaten avidly by many animals, particularly sheep, and has been included in seed mixtures. It is rich in sodium and magnesium and has a relatively high fibrosity index similar to that of ryegrass.
Corn spurrey flowers from June to September. The flowers are mainly self-pollinated but there is some insect pollination. Corn spurrey produces seeds in summer and early autumn or until killed by the first frosts. Seed collected 5, 10 and 15 days after flowering gave 4, 8 and 12% germination respectively. There are 25 seeds per capsule. The average seed number per plant is 1,300 but a large plant may produce 22,000 seeds. Plants can develop ripe seeds within 8 to 10 weeks of emerging and 2 generations may occur in a year.
Although seeds differ in the presence or absence of papillae on the seedcoat, individual plants bear only one type of seed. Hybrids with variable amounts of papillae sometimes occur although the species is predominantly self-fertilising. In the UK the non-papillate form has a northern and westerly distribution, the papillate form being found further south and east. The non-papillate seeds germinate more readily at lower temperatures while at higher temperatures the reverse is true. There is a marked reduction in the germination of non-papillate seeds in drier conditions and this may account for the differences in UK distribution.
Laboratory studies suggest that dormancy is broken by rising temperatures in spring and does not depend on exposure to cold winter temperatures. Light, nitrate and desiccation following imbibition, all stimulate seed germination. In the field, seedling emergence occurs from February to October with most emerging from March to July. In a sandy loam soil, field seedlings emerge from the top 30 mm of soil with the majority coming from the top 10 mm.
Seeds can remain viable in soil for at least 5 years. Seed numbers decline faster in cultivated soil. Seed recovered from excavations and dated at 30 years old is reported to have germinated. In dry storage seed longevity is over 15 years.
Corn spurrey seed has been a contaminant of grass, clover and cereal seeds. Short distance seed dispersal is possible in mud on the tyres of farm vehicles. The seeds have been found in cattle, horse, deer and pig droppings. Seedlings have been raised from the excreta of various birds.
Control is by thorough liming or chalking. Frequent surface cultivations should be undertaken whenever possible. To allow more time for spring cultivations, late, quick-growing crops can be sown. Badly infested crops may be grazed with sheep. Corn spurrey does not tolerate trampling.
In grassland and set-aside, cutting time can influence the amount of seed returned to the soil. However, plants defoliated when in active growth can produce new shoots from the base. Corn spurrey is palatable to grazing animals and poultry. The seeds have been found in the crops of pigeons and sparrows.
Small seedlings are susceptible to flame weeding.
Few insects and pathogens are known to attack corn spurrey but exposure to an arbuscular-mycorrhizal fungal inoculum has been shown to reduce the biomass of the weed.
Updated November 2007.