Weed of the Week: Common selfheal (Prunella vulgaris L )
By Laurence Gale
What is a weed? By definition a weed is a plant that is growing in the wrong place. Weeds take valuable space, water, sunlight and nutrients that may otherwise be accessible to important crops, in our case turf grasses. Weeds not only compete for these resources they can disfigure and cause problems to playing surfaces.
Weeds are very good competitors and take advantage of any opportunities to colonise turf situations, particularly when the sward is under stress and weak, leaving bare soil areas for weeds to populate. Weeds have many mechanisms and characteristics that enable them to do this, having thick waxy cuticle leaves that can be resistant to some chemicals, fast reproduction methods, the ability to reseed in 6 week cycles and deep tap roots enabling the weed to survive in compacted dry ground conditions.
Weeds have one of three life cycles: annual; biennial or perennial.
- Annual weeds: Live for a single season. These weeds germinate from seed in the spring or summer, flower and then die.
- Biennial weeds: Live for two seasons. During the first growing season, these weeds remain in a vegetative stage and, in the following year, produce flowers, set seed and die.
- Perennial weeds: Live for multiple seasons and flower more than once. Perennial structures (rhizomes, stolons, crowns, entire plants or roots) survive from year to year.
Some weeds may be harmful to the environment or noxious to your regional ecology. For example Japanese Knot weed (Fallopia Japonica) is fast becoming a major weed problem on road side verges and urban landscape areas, a very difficult weed to eradicate. It is very important to recognise weeds and seek effective controls methods to eradicate them from our facilities.
Weeds can also be used as an indicator of soil conditions. For example, knotweed and plantains both indicate soil compaction because they can maintain adequate root respiration at lower oxygen diffusion levels than other plants. Different weeds tolerate different soil conditions, some are alkaline loving and others acid loving. Getting to understand and recognise the physiology of these plants will help you become better turfgrass managers.
This week's weed is: Prunella vulgaris L (Common selfheal)
Prunnela vulgaris L
|Form / Appearance||
Common selfheal is a widely distributed short creeping perennial herbaceous plant that favours dry to moist soil conditions. Self heal is a member of the mint family.
The stems are square and the leaves are opposite. The stems branch freely and are usually about 300mm tall but, when repeatedly mowed, the plants become densely matted, depressed and small leaved.
|Roots||The plant can regenerate itself from rhizomes, short runners that root freely at the nodes.|
|Flowers||Selfheal produces purple flowers from June to November. The flower's colour can vary from light to dark purple.|
|Leaves||Lower leaves are oval or oblong, not hairy, and pale green in colour. However, in closely mowed turf situations, the leaves will have a stunted dark purple appearance.|
|Reproductive method||Selfheal can reproduce itself by seeds and root development from the plant's nodes.|
|Habitat||Self heal grows in meadows, in hedgerows and in ditches, and is very tolerant of poor soils. It will even persist in grass paths subject to frequent walking.|
The word "Prunella" is from the Latin for "purple", "vulgaris" means "common". On close inspection the plant reveals tiny, purple/lavender flowers in the arching swirls characteristic of the Mint family.
It has been used medicinally to cure many ailments, for the treatment of boils, colic, sore throats.
|Cultural Control||Selfheal can be mechanically or physically removed. Care should be taken to ensure that all roots are thoroughly removed. Close mowing prevents seed head formation, whilst maintaining a dense sward will deter or prevent selfheal from establishing.|
Apply selective broadleaf herbicides when plant growth is active. There are a number of products available for controlling broad leaf weeds in established turf.
These chemicals are best used when the weeds are actively growing, usually between April-October.
These herbicides are usually applied as a liquid using watering cans, knapsack sprayers and vehicle mounted sprayers.
Ensure you follow manufacturer's directions, health & safety and product data sheets, and comply with COSHH regulations, when using these chemicals.
Herbicides are an effective tool where high quality turf is desired. However, they must be applied with care and accuracy and in the context of a good overall turf management program. Before using any herbicide, carefully review the label for conditions of use including rates, methods of application, and precautions. Never use an herbicide in any manner contrary to its label and be sure that the herbicide will not injure the turfgrass species