Get rid of grubs with­out harm­ing bees

The Tribune (NZ) - - GARDENING - WALLY RICHARDS

As day­light hours in­crease and plants start to grow, prob­lems can be­come ap­par­ent in lawns.

Dur­ing au­tumn, grass grubs were chow­ing down on grass­roots prior to pu­pat­ing.

It means when the grass tries to come away, the roots are in­suf­fi­cient to sus­tain growth and it dies.

It’s too late to do any­thing about this now. The time to treat the lawn for grass grubs is in the au­tumn. when the rain has moist­ened up the soil and the grubs are feed­ing near the sur­face. so they are eas­ier to ac­cess and kill. In spring, the dam­age has been done and the grubs have gone.

How­ever, in a few weeks or a month the cy­cle will start over. In­vad­ing grass grub bee­tles will mate and feed on gar­den plants be­fore lay­ing eggs deep in the soil of the lawn, hatch­ing out as white grass­root chew­ing grubs.

Killing lots of the bee­tles when they ar­rive will greatly re­duce the dam­age to gar­dens and lawns over the next 12 months.

As soon as holes start ap­pear­ing in the fo­liage of roses, cit­rus or other plants with no no­tice­able cul­prits, it’s likely they are caused by feed­ing bee­tles. A torch in the early evening will re­veal the crit­ters hav­ing a munch up.

To counter this, make up a spray of Wallys Su­per Neem Tree Oil at 5mls per litre of wa­ter, add 1ml of Key Pyrethrum and 1ml of Rain­gard to each litre, and un­less it is rain­ing, nightly spray the feed­ing bee­tles.

The pyrethrum will knock them down quickly and the Neem Oil will stop them feed­ing.

An­other tac­tic is to use a light trap. Di­rectly un­der a win­dow, onethird fill a wall­pa­per trough with wa­ter and add a lit­tle kerosene.

At dusk, turn on a bright light be­hind the pane for about 2 - 3 hours. At­tracted by this light, the bee­tles will hit the win­dow and fall into the trough. The kerosene pre­vents their es­cape for easy dis­posal next day.

The worst af­fected lawn ar­eas are usu­ally where there are night lights or street lights. These at­tract the bee­tles to the area, and they lay their eggs nearby.

For a re­ally great lawn, ap­ply Wallys Neem Tree pow­der (avail­able in 3kg bags) to a test area af­ter the grass has been cut, and lightly wa­ter to set­tle the pow­der into the soil. A lawn roller can be used to press in the pow­der, which also treats grass­root ne­ma­todes.

If, af­ter a few weeks there is an im­prove­ment in this test area, treat the rest of the lawn for ne­ma­todes.

An­other prod­uct is 3 in 1 for lawns which is a com­bi­na­tion of eu­ca­lyp­tus and tea tree oils along with a nat­u­ral food and a wet­ting agent. The 1 litre con­cen­trate is wa­tered down at 1: 25 and ap­plied to 50 sqm of lawn which is then fur­ther wa­tered to take it deeper into the soil. It’s safe to use and it takes out all the lawn pests.

Best ap­plied af­ter mow­ing the lawn and be­cause its washed into the soil and is not sys­temic it will do its job with­out harm to pol­li­nat­ing bees

Po­rina cater­pil­lars are an­other lawn pest that feeds at the base of grass stems caus­ing bare patches. Po­rina will also chew through the stems of young gar­den seedlings.

To con­trol these, mow the lawn and make up Wallys Su­per Neem Tree Oil at 5mls per litre with 1ml of Rain­gard, and ei­ther spray or use a Lawn­boy.

When the grubs emerge from their tun­nels at night, the Neem will stop them eat­ing and they’ll starve to death over a week or so.

Badly af­fected ar­eas need a treat­ment about every 3 months.

Prior to any treat­ment, cut a square in the lawn with a spade, lift the turf and see if there are any grass grubs in that square and how many.

If there are 2 or 3 grubs it is hardly worth­while treat­ing as they will not do too much dam­age where on the other hand if there are a num­ber of the grubs then its worth­while treat­ing.

It also pays to lift some turf in dif­fer­ent ar­eas as you may have a big in­fes­ta­tion in one part of the lawn and hardy any in other parts which means why waste your money treat­ing the whole lawn.

The likely parts that will have the worst num­ber of grubs is where there is night lights or street lights nearby as the bee­tles are at­tracted to the lights at night then lay their eggs nearby.

Also ar­eas where there is a his­tory of a prob­lem will also be a good place to check as the bee­tles will re­turn to where they emerged from if not at­tracted away at night by lights.

What treat­ment to use? You want to use a treat­ment which is go­ing to be safe for chil­dren and pets to still use the lawn with­out harm­ing them. Also you do not want to use a treat­ment that will harm bees or bum­ble bees weeks or months later if there are any weeds or clovers in the lawn that are go­ing to flower later.

Chem­i­cals in the fam­ily of Neon­i­coti­noids are ex­tremely harm­ful to honey bees and bum­ble bees these in­clude chem­i­cals from the fam­ily such as im­i­da­clo­prid (found in the brand name Con­fi­dor also).

Prob­lems ring me at 357 0606 Email wal­lyjr@gar­de­news.co.nz Web­site gar­de­news.co.nz

PHOTO: FAIR­FAX NZ

Grass grub bee­tles will soon be chew­ing holes in gar­den fo­liage. They then lay eggs in the soil, and the lar­vae set about de­stroy­ing patches of lawn.

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