Get ready for the spring pest invasion!

*The sun is beginning to warm your back, buds are swelling, new shoots are soft, there’s a glow of good in your world… it’s spring. Insects like spring for exactly the same reasons.

The triggers: increasing length of day, more and better food… both good reasons for insects to hatch from an egg, emerge from a pupal case and resume their cycle of life… that spoils yours.

Before you expect it, the odd insect becomes a plague and the next you know, thrips are all through the blossoms, aphids are encrusting the buds and shoots, Monoleptas and other flower-eating beetles are emerging from surrounding grassland, to form a swarm intent on denuding the new macadamia and avocado flower buds and, where first you saw an odd butterfly jerking its way through the orchard, now you notice a thousand caterpillar chew marks on the edge of leaves.

Your yield potential is threatened; the war against pests recommences.

Inspections

Such as: say, Mondays, Wednesdays and Fridays, spend time walking through your crop looking for pests. Take someone with you to walk about 2–3 paces ahead of you on the other side of the row. If there are fruit spotting bugs, other bugs or leafhoppers, the point person scares them around to your side… where you can see them.

You are also looking at the tips and buds for aphids; once the flowers open you are looking for the narrow specks of thrips and for beetles among the flower clusters. Olive growers’ main threat is the olive lace bug, always on the underside of the leaves.

Having read previous articles in this series of ‘Know Your Pest’, you may remember what habits the main pests of your crop instinctively follow. You know the white louse scale overwinters on the bark, the weevil and scarab curl grubs are in the mulch. If you are using monitors such as for fruit fly, checking those monitors will be part of your defensive ritual.

Frequent inspections mean you can respond before your yield potential suffers.

Spray applications

Much of insect and mite control is based on application of an insecticide. The equipment can be spray from a wand, a boom, an air blaster or even a drone. The wand is of course harder work – aiming high to allow droplets to settle as well as aiming up under leaves for pests happy to drink upside down. The air blasters disturb the leaves and disperse a range of droplet sizes to contact pests not hiding inside plant tissue. Drones give better coverage than I thought would be the case; spray sensitive papers down in the lower levels of macadamia trees were well speckled.

You can do your own bio-assay test and get visible results in a few minutes. Find pests on a tree or three at the end of a row, apply to those trees, turn at the end of the row and go back on the other side… and stop.  Then look at your handiwork. First you look at what is wet and not wet, then you watch for the reaction of the insects. I am biased but a natural pyrethrum spray delivers dead and dying insects within a couple of minutes.

Even larger caterpillars begin twitching and may ‘bail out’ – descending or ‘abseiling’ downwards on a thin filament of silk. Other insecticides may not be as fast but can still give you a good indication. You can always collect a few in your cap to check for mortality a bit later. And just because you can, and because it might pay off big-time, find another patch of insects and apply this time at a lower rate – provided it is on the label. If the lower rate still gives you very close to 100% hit and kill rate… you just saved a lot of insecticidal money!

Or, if you weren’t happy with the first run, tweak the application rate up or re-aim the nozzles and test again. This change may cost you more money per tree, but you get it back in increased yield and time saved by doing a proper job in the first place.

The insecticides

Pesticides are of many chemical types. Looking back at through 12 months of Tree Crop, you will find Corteva offering Delegate, 250 g/kg spinetoram, a water dispersible granule which is a systemic insecticide, entering the plant tissue to control various caterpillar pests in apples, citrus, grapes, almonds, pome and stone fruit and western flower thrips in pome and stone fruit. Short withholding periods apply. Corteva also released Entrust which is spinosad 240 g/L for use against various Lepidoptera and thrips on a wide range of crops and the withholding period varies between 14 days to one day.

FMC advertised Altacor-Hort, 350 g/L chlorantraniliprole, for control of Lepidoptera in almonds, pome and stone fruits as well as grapes, killing the hatching larvae as they emerge from the eggs. Their Exirel, 100 g/L cyantraniprole is used to control Lepidoptera, Fuller’s rose weevil and Kelly’s citrus thrips in citrus.

Bayer offer Movento and Vayego – systemic insecticides for use on almonds, pome, and stone fruits for control of Carpophilus beetles, various weevils, various moths and Mediterranean fruit fly… with short withholding periods.

Barmac advertised their diazinon, a versatile residual insecticide that has been around for 50+ years. Label claims include a wide range of pests and crops including on pastures and inter-row areas. It kills by contact, with lethal residues lasting a week or so.

Pestech Australia offers PyBo Natural Pyrethrum (100+ years in use) as a contact-only insecticide registered for use against caterpillars, aphids, ants, earwigs, leafhoppers, thrips, whiteflies and other flying insects on all crops. It kills within minutes. The withholding period is just one day.

So you have a range of products: start by using the systemics to kill emerging larvae inside plant tissue where they cannot be reached by residual or contact sprays. Residual sprays stay where they are put but they won’t kill insects that arrive, stand and feed on the new, young growth, but they are also great for use under trees or on pastures to kill insects which would otherwise emerge to attack your trees. And then there is the pyrethrum contact spray to kill whatever insect it hits but degrades within hours in UV light so your product can be on a plate or in a hand ready to eat, tomorrow.

I know, I know… no one these days really wants to use insecticides, but judicious use can help you have healthy trees and produce unblemished product – and lots of it.

The price of superb fruit and nuts is paid for by dead pests!

*Ion Staunton is an entomologist and owner of Pestech Australia, manufacturer of PyBo Natural Pyrethrum Insecticidal Concentrate. ion@pestech.com.au

 

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