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Plantwise Technical Factsheet

darnel (Lolium temulentum)

Host plants / species affected
Allium cepa (onion)
Brassica
Brassica napus var. napus (rape)
Brassica oleracea (cabbages, cauliflowers)
Brassica oleracea var. botrytis (cauliflower)
Brassica oleracea var. capitata (cabbage)
Brassica rapa subsp. oleifera (turnip rape)
Cicer arietinum (chickpea)
Citrullus lanatus (watermelon)
Cucurbita maxima (giant pumpkin)
Cuminum cyminum (cumin)
Daucus carota (carrot)
Eruca vesicaria (purple-vein rocket)
Helianthus annuus (sunflower)
Hordeum vulgare (barley)
Lens culinaris subsp. culinaris (lentil)
Linum usitatissimum (flax)
Macrotyloma uniflorum (horsegram)
Medicago sativa (lucerne)
Phaseolus (beans)
Pisum sativum (pea)
Raphanus sativus (radish)
Secale cereale (rye)
Solanum lycopersicum (tomato)
Solanum tuberosum (potato)
Spinacia oleracea (spinach)
Trifolium alexandrinum (Berseem clover)
Trifolium resupinatum (Shaftal clover)
Triticum aestivum (wheat)
Vicia faba (faba bean)
Description
L. temulentum is an annual plant with a fibrous root system. Culms tufted, solitary, ascending, erect, 60-90 cm tall, glabrous and smooth, or rough at the top.

Leaves are lanceolated, simple with a shiny surface, leaf blades narrowly linear, not contracted at the base, acute at apex, with smooth or scabrid margins, somewhat rough above, glabrous and smooth beneath, 10-30 cm long, 3-10 mm wide, young leaves with involute margins, ligule 1-2 mm long.

Inflorescence is a terminal spike, rigidly erect, 12-30 cm long with 6-30 spikelets, dorsally placed in shallow excavations along a non-articulate rachis with a zigzag shape. Spikelets 12-30 mm in length, usually with 4-10 flowers. Outer glume of the lateral spikelets usually 2.5 cm in length, as long as or longer than the entire spikelets, 7-9-nerved, thinly coriaceous with narrow membranous margins. Flowering glumes are shorter and broader, oblong, usually obtuse with an awn as long as or longer than the glume itself. Some specimens may have awnless glumes or in rare instances the whole spikelet is without awns (Bentham, 1967). The lemmas are up to 8 mm long, obtuse with awns 6-12 mm long. Palea two-keeled. Seeds elliptic-oblong in shape, grooved.
Prevention and control
Cultural Control

Ferrari et al. (1984) considered that long rotations, considerable soil disturbance and high fertilizer applications reduced infestations of this weed (Ferrari et al., 1984). Preventive measures, such as sowing clean seed and preventing seed formation are important.

Handweeding twice at 30 and 60 days after sowing in wheat (Angiras and Modgal, 1981) and at 40 and 70 days after sowing in gobhi sarson (Brassica campestris var. sarson) was found effective to control grassy weeds including L. temulentum (Angiras and Rana, 1990). Small scale farmers use this practice as they can then use the weed for fodder purposes. However, handweeding can be difficult in the vegetative stages as cereals and the weed closely resemble each other. Bidirectional sowing at a row to row spacing of 15 cm has also been found effective to reduce populations of this weed (Angiras and Vinod Sharma, 1996). A stale seed bed in wheat can reduce L. temulentum populations (Deep Kumar, 1998).

Burning resulted in a a reduction of viable seeds of L. temulentum by 99.7 and 97.7% when practised in December and January, respectively (Pearce and Holmes, 1976).

Chemical Control

Due to the variable regulations around (de-)registration of pesticides, we are for the moment not including any specific chemical control recommendations. For further information, we recommend you visit the following resources:

Biological Control

Because of the importance of L. temulentum and related species as forage grasses, there has been no serious consideration of biological control methods.
Impact
L. temulentum is a serious weed of winter crops, especially wheat (Bor, 1960; Angiras and Modgal, 1981), winter vegetable crops (Gad and El Mahde, 1972), flax (Angiras et al., 1991; Cseresnyes et al., 1987) and sunflower (Sarno et al., 1986). According to Holm et al. (1991), it is a weed of 14 crops in 38 countries.

The seeds of L. temulentum have poisonous effects on man and animals when consumed in conjunction with wheat and other cereals (Forsyth, 1979; Ambasta, 1994). They are remarkably similar in size and weight to the grains of wheat and other small grain crops, which makes their separation difficult. When milled with wheat, it causes the flour to become grey and bitter. Toxic effects on livestock have been reported in Argentina (Ratera, 1983). The poisonous compounds are considered to be two alkaloids, temulin and loline, which are present in the seed (Bor, 1960; Smith and Bernhard, 1988), and perloline in the stem (Dannhardt and Steindl, 1985). One theory is that L. temulentum seed is only poisonous when infected by the fungus Endocladium temulentum (Bor, 1960) as it produces the narcotic alkaloid temulin (Ambasta, 1994), but Steyn (1934) reported that no toxic effects were found when large quantities of fungus-infected grains of this weed were fed to animals. Similarly, bread in South Africa often contains infected grains of L. temulentum and such bread is eaten without any ill-effects.

The competitive potential of L. temulentum has rarely been measured, but it is generaly regarded as a competitive weed. Hollies (1982) revealed that grassy weeds, such as L. temulentum, caused yield losses of up to 17% in wheat and barley, whereas net profits were reduced by 25%. Wheat infested with L. temulentum can have an impaired response to N fertilization (Farnworth and Said, 1983). Laboratory studies by Bansal and Singh (1986) revealed that root extracts of L. temulentum were more inhibitory than shoot and flower extracts on the germination and growth of rice, indicating allelopathic effects.

L. temulentum can be a host to a wide range of organisms (see Natural Enemies) and is often implicated as an important alternative host of crop diseases, such as yellow rust (Puccinia striiformis) of wheat (Zhukova and Kupriyanova, 1981), yellow spike disease in wheat caused by Rathayibacter tritici (Vacke, 1975), Oat blue dwarf virus in the Czech Republic (Vacke, 1998), crown rust (Puccinia coronata), stem rust (P. graminis), brown rust (P. recondita), and karnal bunt of wheat (Tilletia indica) (Rattan and Aujla, 1989). It has also been recorded as a host for parasitic nematodes (Meloidogyne) (Ibrahim et al., 1988) and the wainscot moth (Oria musculosa) on barley in Iran (Haidari, 1975).
Related treatment support
 
External factsheets
BioNET-EAFRINET Invasive Plant Factsheets, BioNET-EAFRINET, 2011, English language
University of Illinois Extension Factsheets, University of Illinois, English language
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