Au­tumn re­vamp

A long hot sum­mer leaves most lawns look­ing worse for wear. It’s time for some ren­o­va­tion that will soon have lawns look­ing loved again.

Go Gardening - - Editorial / Contents -

Brown bare patches are not only an eye­sore. If we’re not quick to rem­edy them, they’re an in­vi­ta­tion for weeds. Pet urine, lack of wa­ter and com­paction from heavy use are all con­tribut­ing fac­tors, but dead patches in the lawn can also be caused by dis­eases and in­sect pests. In late sum­mer and au­tumn com­mon lawn in­sect pests reach the peak of their de­struc­tive ac­tiv­ity. It’s a good time to lift one of the dead patches and see what’s un­der­neath. Safe and easy-to-use lawn in­sect con­trol is avail­able at your gar­den cen­tre.


Grass grubs can be found just be­neath the sur­face. About 25 mm long, pale cream coloured with a brown head and six legs, they’ll stop mov­ing and curl into a “C” shape when dis­turbed.

The com­mon grass grub is the laval stage of the New Zealand bronze beetle, Coste­ly­tra zealandica, our most ubiq­ui­tous lawn pest. In spring the adult bee­tles hatch from un­der­ground pu­pae, feed­ing on grass, trees and shrubs while they lay eggs in the lawn. When the grubs hatch from the eggs they start feast­ing on lawn roots, pass­ing through three ‘in­stars’ as they shed their skin be­tween growth spurts. In late sum­mer brown patches start show­ing up in the lawn as the fully grown grubs are at their most de­struc­tive stage, their third and fi­nal in­star. An­other mem­ber of the beetle fam­ily that causes sim­i­lar dam­age to lawns is the black beetle from Africa, but this one needs a warm cli­mate and is found only in the North Is­land.


When a po­rina moth lays her eggs in your lawn, the re­sult­ing lar­vae is a cater­pil­lar. The dam­age is eas­ily mis­taken for grass grub, but this time it is not the roots that are eaten, but the leaves. Po­rina moths com­prise sev­eral dif­fer­ent species of na­tive NZ moths. The cater­pil­lars grow up to 7cm long as they chomp their way through lawns. They hide in the soil, emerg­ing at night to graze. Look closely and you may find the en­trances to their tun­nels on the soil sur­face. Smaller cater­pil­lars that in­vade lawns are known as sod web­worms. Sod web­worms also feed at night. Like po­rina cater­pil­lars, their feed­ing re­sults in bare patches, and sub­se­quent weeds.


Black crick­ets are an­other North Is­land prob­lem, oc­cur­ring as lawn pests in North­land, Auck­land, Waikato, Bay of Plenty, Hawkes Bay, Taranaki and Manawatu. They pre­vail in hot dry sum­mers, shel­ter­ing in soil cracks. Un­like bee­tles and moths, they don’t have a pupa stage. Once hatched from the egg, the nymphs look like minia­ture adults ex­cept for their lack of wings. Nymphs and adults de­vour grass leaves and ger­mi­nat­ing seeds. They’re es­pe­cially fond of rye grass.


Com­mon lawn dis­eases in­clude brown patch, dol­lar spot, fusar­ium, rust and red thread. It is a good idea to choose a lawn seed blend that is re­sis­tant to fun­gus dis­eases. To pre­vent dis­ease on new lawns, top brands of lawn seed have a fungi­cide coat­ing. Dis­ease is usu­ally as­so­ci­ated with wet hu­mid weather and can be worse when there is a build up of thatch (old grass clip­pings and other or­ganic mat­ter). Use a scar­i­fier rake to re­move thatch (or hire an ex­pert with a ma­chine for a big lawn). Spray with an ap­pro­pri­ate fungi­cide at the first sign of dis­ease to pre­vent ma­jor out­breaks.

TIP Be in to win a fan­tas­tic au­tumn lawn kit from Bur­net’s. In­cludes: Bos­ton Green lawn seed, EzyS­tart Lawn Starter Fer­tiliser, EzySpread Gran­u­lated Gyp­sum soil con­di­tioner and Ezyfert Slow Re­lease Lawn Food. En­try de­tails on page 30.

ABOVE: Ground­cov­ers like Pra­tia and Leptinella make ex­cel­lent lawn sub­sti­tutes for ar­eas that are tricky to mow.

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