common forget-me-not, blue mouse-ear, scorpion grass
Myosotis arvensis (L.) Hill, (Myosotis scorpioides)
Field forget-me-not is a native winter or summer annual, biennial or perennial found on open well-drained land including cultivated ground, gardens and roadsides. Field forget-me-not is common throughout the UK and is recorded up to 1,600 ft. In early surveys it was found chiefly on sand and loam soils and was considered an indicator of loam. It is rarely found on chalk soils. In Europe it shows a preference for soils with low pH.
Field forget-me-not occurs as a weed of arable land, particularly winter cereals. In a study of seedbanks of some arable soils in the English midlands in 1972-3, field forget-me-not seed was recorded in 59% of fields sampled in Oxfordshire and 50% of those in Warwickshire. It is also a common arable weed in France, Denmark and the Netherlands.
Field forget-me-not may carry virus diseases that can infect important crop plants.
Field forget-me-not flowers from April to July and sometimes again from August to September. The flowers are usually self-pollinated and seed is set from May onwards. There are around 700 seeds per plant but a large plant may produce 1,500 to 3,000 seeds. Seed numbers are lower when field forget-me-not is growing in an arable crop.
Seeds shed in summer do not germinate until the autumn. Light promotes seed germination. Dry storage of seed also increases germination levels. The main periods of seedling emergence are March-April and August-November. The emerged seedlings represent around 1% of the soil seedbank. Most seeds germinate in the surface 5 to 20 mm layer of soil.
Some seeds germinate in the autumn after shedding but others remain dormant for 2-3 years or longer. Seeds recovered from excavations and dated at 30 years old are reported to have germinated. Field forget-me-not seeds broadcast onto the soil surface, ploughed to 20 cm and followed over a succession of winter or spring wheat crops had a mean annual decline rate of 40%. The estimated time to 95% decline was 5-8 years. In a similar study in autumn-sown crops the annual decline was 44% and the time to 99% loss was 6.1 years.
Seeds that remain in the spiky calyx may be carried on clothing and animal fur. Field forget-me-not seed has occurred as an impurity in cereal, grass and clover seed, often in home saved seed. Seeds can survive ingestion by cattle and horses.
Control is by surface cultivations in spring and the inclusion of root crops in the rotation. Field forget-me-not plants may regrow after decapitation.
A 1-year fallow reduced seed numbers in soil by 60%. Seed numbers increased considerably when winter wheat was grown for the same period. Fallowing every 5th year over a 15 year period reduced seed numbers by 75%.
Updated October 2007.