Pests and Diseases Of Alstroemeria

Luckily alstroemeria tend to have few pests and diseases. One of the best ways to control them is with crop management. A good well watered healthy plant is much less likely to be attacked by pests. Keeping weeds around can encourage pests but they can be used to attract the pests away from alstroemeria (see Whitefly). Some of the ones we encounter and how we deal with them are listed below


Aphid

Slugs and snails

Whitefly

Thrips

 

 

 

Aphids

There are several species but the most common ones seen are usually green but can also be black or pink!

Generally aphids will leave alstroemeria alone if other more palatable plants are near

If levels are fairly low it is best to tolerate them and allow natural predators to keep them under control.

Garden birds love to eat them as do ladybird and lacewings. We get all three as regular visitors in our green houses

Very soon after we see a new patch of aphids we almost always see the signs of aphidus, this is a tiny wasp that lays its eggs in the aphid and causes the aphid to become a mummified food store for its young.

We also see aphids attached by vetticilium fungus. This fungus will attack may insect pests, almost like a fatal athletes foot for insects.

Aphidus, ladybirds and lacewings can all be bought as biological control.

Ladybird larva are as good as, if not better at eating aphids than the adults but they look nothing like the adults. So if you see any of the following leave them alone, smile and encourage them.

Lady Bird stages

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Slugs And Snails

These can sometimes be a problem with new shoots, but again if other plants are about they will generally leave alone. Physical barriers can work well. In our greenhouses we use a mulch of wood shavings. This is over the top of the irrigation pipe, so it stays dry and the slug and snails keep away. I wouldn't recommend wood shavings for mulch in the garden as the first gust of wind will blow it all away but bark or holly leaves can be effective.

Biological control using soil based nematode can also be introduced but the results can be erratic.

If all else fails judicious use of slug pellets are effective

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Whitefly

Alstroemeria are not a favourite food plant for white fly. We occasionally get few in the greenhouses but they are never a problem.

When the nursery next to us use to grow tomatoes commercially we use to get an influx of white fly at the end of the growing season. This was quickly controlled with the tiny parasitic wasp encarsia formosa which use to come soon after.

This wasp is only active at quite high temperatures so is at its most effective in the greenhouse.

Another good control is to plant some nicotiana (tobacco plants) nearby. Whitefly loves these and will flock to them. Simply pull up and burn these when they are covered with whitefly.

One gardener recommenced using a vacuum cleaner. I asked him no further questions but backed away slowly!

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Thrips

We get problems with thrips only at the end of the summer and early autumn. This happens just after the fields of wheat are harvested near the nursery. The thrips leave the wheat in droves searching for other plants to feed on. They usually only stay on the alstroemeria for a few days then disappear.

 

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Lacewing eating an aphid

Aphidus wasp laying egg in aphid

 

 

 

 

Slug

Whitefly

Thrip

Additional information