Lawn grubs are a common problem in South East Queensland during the period from November to May, more so to couch lawns rather than ‘Sir Walter’ lawns, they are easily treatable if required, early detection and prevention is the simplest way.
There are two main types of lawn grubs to look out for:
The armyworm is like a caterpillar, usually brown to dull grey, with black stripes on their body, size from 10mm to 30mm long, they are mostly active at night, feeding on the leaf blades of your lawn. They can devastate an entire lawn in 2 – 3 nights
These sod webworms are commonly confused with cut worm, however both are treated the same and look very similar. They are transparent, but you can see the green materials they are eating so they can appear greenish. They are smaller than the army worm in size, about 10mm – 25mm, they are also active at night. The adult moth will lay eggs in flight; hatching should take place in 5-7 days time.
Patches of brown or thinning turf – may suggest there is grubs present, however you need to use one of the methods below to be sure. A visual inspection of the leaf blade can be an effective method, you will actually see holes or part of the leaf missing like chew marks, in bad infestations there will be very little or no leaf at all to see. Use a hose to flood an area, they will come crawling out to the leaf tips, do this in a healthy part of the lawn near infected patches as they prefer the greenest areas. Try pouring a bucket of soapy water over your lawn & look for them. Check under the eaves of your house for furry brown patches these are moth eggs waiting to hatch. Try parting the leaf blades and look for an accumulation of fresh small green pellets of excrement, these are their droppings. If there are orange / black wasps “The Ike Newman Wasp” (Leptobatopsis Indica) flying over your lawn, this will usually indicate that there are grubs present, as the wasp is looking for a host to lay its eggs.
Spray, spread or hose your lawn with an insecticide, there are various types- Must follow label instructions.
We suggest acelepryn or grubguard (available from our Lawn Shop)
If your lawn was damaged by grubs you can fertilize) the patches lightly to aid the recovery.
Tips on Spraying:
Always spray in the evenings, the chemical you are using will breakdown in sunlight within 2 hours of application, which will be before the lawn grubs have a chance to come in contact with the chemical.
Don’t spray if rain is likely within 2 hours
Read the label on the bottle and always follow label rates
Best way to manage lawn grubs.
Over fertilized lawns are prone to frequent attacks so fertilize your lawn correctly.
Avoid fertilizing during summer months (Jan-Feb)
Keep the eaves around the home free from moth’s eggs, remove with a broom or mop.
Remember insecticides can kill lawn grubs and all other natural predators, the lawn grub will recover first, this may cause you to spray until nature (winter or extended cold weather) takes over again, there for only spray if necessary.Outdoor lights & street lights with lush lawns within close proximity will attract the moths, hence lawn grubs, and therefore will be a likely starting point.
White Curl Grub
Scarab beetle larvae, also known as white curl grub are a serious lawn pest. In subtropical areas, lawn damage in commonly seen from November through to January. The most common causal agent is the African black beetle. The African black beetle larvae grow to 20-25 mm in length before pupating in the soil. They have an orange-brown head capsule. Oval-shaped, shiny black adults, 12-15 mm long, emerge during February feeding on stems just below ground level. They are less active through winter and mate in spring.
White curl grubs (scarab beetle larvae - juvenile stage of lawn beetle) have a characteristic ‘C’ shape and three pairs of legs. They live underground, protected by soil. These develop into larger larvae and are voracious feeders on roots and underground stems. The adults also feed on turf but cause much less damage. A problem infestation is generally looked upon to be 25 or more white curl grubs per square metre. If few larvae are present, healthy turf is likely to outgrow the minor damage it will sustain. Under heat and drought stress, the problem may be exacerbated by reduced rates of regrowth and smaller numbers of larvae can cause major damage.
Try pouring a bucket of soapy water over your lawn to move them to the surface
Moisten a hessian bag or piece of carpet and place it on the lawn overnight to detect them the next morning
Use Garden Lighting to attract and to detect adult beetles.
Chemical control measure are most effective on newly hatched larvae
Prior to treatment, water the lawn well to bring the larvae closer to the surface.
Infiltration of chemical will also be improved by mowing and raking of out of thatch
Spray, spread or hose your lawn with an insecticide, there are various types available – Must follow label instructions.
Fungal diseases usually occur in the lawn when conditions are damp and the strength of the grass is low. The appearance of fungus is probably the most common symptom of "run-down" turf arising from such causes as over compaction of soil, nutrient and pH imbalance, inadequate drainage, poor soil aeration, dense shade, over close mowing and a shallow depth of topsoil. The eradication of fungal diseases can only be achieved effectively when the cause can be correctly identified and conditions rectified. The removal of the cause results in a slow disappearance of the fungus and prevention of its return. Attention to general maintenance such as the improvement of drainage, the application of fertiliser to improve the turf quality and aeration will have obvious benefits.
The most common types are:
Either toadstools or an outline of a cloud shape and the outline is darker green than the rest of the lawn.
It appears as small freckles across the lawn about the size of a 50 cent piece
Originated found in Bentgrass (USA) where it formed spots the size of silver dollars, consequently the name "dollar spot” .
Infected areas 10 cm or larger may run together, causing great patches of dollar spot over the turf area. Irregular patches to 3 metres wide
Dollar spot fungi can be spread by mowers, feet, hoses, travelling sprinklers and other maintenance equipment. May be active from late spring to late autumn.
Most problems develop when temperatures are tolerably warm and change rapidly, as with warm days and cool nights.
Heavy layers of a thatch can encourage Dollar spot because water, air and nutrients cannot penetrate to the underlying soil and grass roots. This results in shallow and poorly developed roots that are highly susceptible to drought stress.
Affected leaves will show yellow-green blotches or bands that generally can go undetected. These lesions gradually bleach to a white or straw colour.
On finer-textured turf grasses, individual lesions on the leaves often bridge the width of the grass blade, producing a constricted area resembling an hourglass. On coarser grasses, the spots caused by dollar spot may not span the blade.
The tip of the leaf blade may show the characteristic lesion, or the lesion may be in the middle of the blade, leaving the leaf tip green.
When the turf grass is wet from early morning dew, a fine, white cobweb-like mycelial growth (strands of fungus) may be visible on the diseased leaves. As the grass dries out the mycelium disappears. Be sure not to confuse this with spider webs.
Spray the lawn area with Mancozeb,plus twice more at 6 day intervals if you notice Dollar spot. Please follow directions.
Cut the lawn at least once every 6 day.
Lawn under stress is more susceptible to infection.
Water during daylight hours preferable in the morning
Keeping your equipment clean will help prevent the fungi from spreading,
If watering very late in the day, choose time for grass blades to dry after watering before nightfall arrives
Early morning watering (before sunrise) helps remove dew from the leaf surface
Never water the lawn in the late afternoon or at night as this enhances the growth disease.
Proper lawn management, such as aeration, proper watering and fertilization, will reduce dollar spot problems.
Use fungicides only in situations with recurrent dollar spot problems.
Ensure nitrogen levels are sufficient to sustain a moderate rate of shoot
Interested in learning more?
Call 07 4124 4207 or let us know how we can help.
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