Slender speedwell is a prostrate and low growing creeping perennial weed with attractive blue/ silvery blue / mauve/ violet colour flowers in the spring.
The stems and undersides of the alternating leaves are hairy. The leaves begin as oval shaped, but mature more roundish with rounded teeth on the edges.
As a perennial, it has the capacity to persist and spread by rooting at the nodes; roots are shallow and fibrous.
Speedwell flowers from April -June. The flower has four petals, the bottom one being narrower than the three upper petals. Flowers are found on stems that originate at the junction of the main branch and the leaf stem. Leaves are opposite, broad and notched, and often kidney shaped.
Speedwell rarely reproduces by seed, but is more adept at vegetative reproduction, forming new rooting structures from the nodes of the stems.
Most common in lawns as a weed, or in other grassy habitats and able to survive in most soil conditions. The slender speedwell is a member of the snapdragon family. Slender Speedwell is a persistent weed and, once it becomes established in the turf, can be difficult to eradicate.
This weed is easily spread by mowing; fragments of the plant can be transported to different parts of the lawn/turf areas and, under the right conditions, is able to re-establish itself vegetatively.
Individual weeds can be carefully lifted with a fork or pulled out by hand. Ensure all portions of root and stem are lifted to prevent re-growth. Remove existing plants; rake vigorously to raise runners, mow closely and remove all stems to prevent re-rooting. Mow regularly to prevent flower and seed heads forming. Remove all clippings after mowing to prevent spread of seed - just in case. A dressing of lawn sand, applied in the spring, will help to keep the weed under control as the iron in the lawn sand will scorch the leaves. Feed and top-dress to encourage vigorous growth of the turf grasses.
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 and September.
These herbicides are usually applied as a liquid using watering cans, knapsack sprayers and vehicle mounted sprayers.
Effective timing is just one aspect of getting your weed control right. Selecting the right product is also crucial. If you choose the wrong product, and you get ineffective control as the weeds aren't listed as susceptible on the product label, you haven't solved your problem.
Herbicides only work as well as they are applied. Take care when applying them - and set up your sprayer specifically to do the job. Herbicides and fungicides work very differently and are applied to different parts of the sward.
The key is getting the water volume correct to achieve good coverage on the weeds, with a spray droplet size that will achieve this. Coarse droplets will bounce off or roll off a well waxed leaf. Medium and fine droplets are stickier and give better coverage, but need to be used when the wind is low to avoid drift. Water volumes of 150 to 250 litres per hectare are ideal for sportsturf, as all you are hitting is a prostrate open target sitting on top of the grass.
Depending on what suits your operations, early autumn is the ideal time to treat persistent and perennial weeds. This timing takes advantage of their biology - at this time of year, they are sending their nutrients down to their deep roots for next year. Taking advantage of this nutrient flow, you can get far deeper penetration into the plant with a herbicide, giving a higher level of control. The results may not be immediately appreciable, but the following spring there is a significant difference.
After you have treated your weeds, you can predict that they will leave gaps where they once were. Plan to take advantage of this by overseeding and feeding with a good rooting promoter shortly after the weeds have begun to die off properly. This will block out any opportunist germinators, and create a gap-free sward that will block out a high proportion of weeds that are waiting for their place in the sun.
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 programme. Before using any herbicide, carefully review the label for conditions of use, including rates, methods of application and precautions. Never use a herbicide in any manner contrary to its label and be sure that the herbicide will not injure the turfgrass species
One current selective herbicide for the control of Speedwell is Longbow Selective Herbicide 5L Mapp No.14316. Active Ingredients: 70g/l 2,4-D, 70g/l MCPA, 42g/l mecoprop-P and 20g/l dicamba.
Longbow is a translocated selective herbicide which targets a wide range of turf weeds. Longbow's special formulation allows uptake through both the leaves and the roots, providing exceptional weed control. Longbow's powerful combination of 4 active ingredients ensures you are on target.
Author: Laurence Gale MSc, Pitchcare Editor