What's eating my plants?

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Do you sometimes go out in the morning to find pieces of your plants have disappeared overnight? Identifying the culprit can be difficult, but this is a bit like one of those television detective shows where you have to weigh up all the evidence before you can nail the guilty party.

First, clear the names of any suspects that couldn’t possibly have caused the damage. For a start, you know it’s not a sap sucker – they siphon juices out of the plant – so that eliminates aphids, mealybugs and mites.

Next, look at how much plant material has been removed. If big chunks have disappeared, then clearly a large animal has been at work. Possums will be your number one suspect. Listen at night for possum thumps on the roof or for the screeching and gurgling sounds of their nocturnal antics. Commercial possum deterrents can work well if you’re persistent about application. Otherwise try applying home-made remedies like fish sauce or moth flakes, or festoon plants with balls of dog hair or Dynamic Lifter knotted into stocking toes. While these methods work with some possums, there are no guarantees. Often it’s a matter of learning to live with the possums’ nocturnal snacking.

Rats can also eat plant parts, particularly starch-filled sections such as bulbs, swollen stems or ripe fruit. Rats are definitely garden undesirables that can be controlled with a rat bait (called a rodenticide). Choose one that’s most suited to your needs, and make sure you follow instructions carefully. Ratsak is a multiple feed product, which means a rat must eat the bait over a number of days in order to ingest a lethal amount. Ratsak 1Shot is faster acting and more moisture resistant but, like traditional Ratsak pellets, should be kept in as dry a spot as possible. Here’s a tip when baiting outdoors: place bait inside a T-shaped piece of plastic plumbing pipe where it will be protected from the rain and from inquisitive dogs and cats.

Birds are rippers and tearers. They use their beaks to tug at pieces of plants and they’ll rip through the bark searching for fat, juicy borers. If birds are causing lots of plant damage, try some of the bird repellents, or resort to physical barriers such as netting.

Check for caterpillars. By this time of year caterpillar activity is starting to slow down, but it’s amazing how much plant material they can still chomp their way through. Cabbage grubs, lily caterpillars, lawn armyworm, super-sized hawk moths and codling moth caterpillars are chewers to look out for at this time of year. Yates Dipel, a naturally-occurring bacteria which is harmless to humans, is a non-toxic control for caterpillars of the moth and butterfly family. A relatively new solution for problem caterpillars is Yates Success which, having been synthesised from a natural soil extract, also has respectable green credentials. Success will also take care of hard-to-kill pear and cherry slug, a shiny grub that’s a member of the sawfly family.

Other chewers are grasshoppers, weevils, earwigs and beetles. Baythroid, a low toxic synthetic pyrethroid, will control many of these pests.

Snails (pictured) and slugs are voracious chewers that leave slime trails as evidence of their activity. Sprinkle Baysol or Blitzem pellets to protect seedlings from their attack. Place pellets inside a container (e.g. a piece of plastic tubing) to ensure they’re out of reach of domestic pets.


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