Showing posts with label Pests. Show all posts
Showing posts with label Pests. Show all posts

Friday, August 02, 2013

Peyote plants maimed by birds

As mentioned in the post "Growing peyote (and other cacti) on the balcony" I'm experimenting with growing peyote cacti in window flower boxes on my balcony.

Peyote cactus maimed by bird
Peyote cactus maimed by a bird

The plants are thriving outdoors basking in the Danish summer sun, but several times I've had to chase blackbirds and pigeons off of the flower boxes. Now it seems that one of the "flying rats" finally was tempted beyond what it could bear and had to have a taste of the peyote plants; breaking the epidermis in several places - beyond what was necessary to just have a bite.

Bird damaged peyote in flower box
Bird damaged peyote in flower box

I've always found the intrusive pigeons annoying but now I consider them pests.

Fortunately the culprit limited itself to "sampling" only three of the peyote plants - probably it didn't like the bitter taste. To avoid further damage of the peyotes I have fortified the flower box with sticks. Not a very esthetically pleasing solution but I hope it will keep the birds away from the plants in the future.

Fortified flower box with peyote and Acharagma
Fortified flower box with peyote and Acharagma

Monday, July 29, 2013

Mummified aphids - an aphid parasitoid at play

Acyrthosiphon pisum (pea aphid)
Acyrthosiphon pisum (pea aphid) - courtesy of Wikipedia

Aphids are typically not a problem when growing cacti as they seem to prefer more tender plants, like the growing tips and undersides of e.g. Capsicum plants (a.k.a. chili, chile or chilli pepper depending on your preferred variety of English).

Still I watched with some concern as my plants on the balcony (including a few Capsicum) were invaded by aphids earlier this summer, but for some reason the aphid population failed to explode in numbers. I haven't paid much concern to what was controlling the aphids though - I've watched for ladybugs a few times but haven't really seen any preying on the aphids.

Mummified aphid
The "mummified" remains of an aphid

Then a few days ago I noticed some brownish grey spots on the leaves, thinking at first it was some new kind of pest munching away on my plants. But the magnification of a hand lens revealed that the tan spots were the swollen, leathery-looking "mummified" remains of aphids (and even though the bloated remains doesn't look much like the typical aphid we all know and hate (exemplified by the topmost picture) the telltale cornicles reveal them as such - the cornicles are the pair of tiny "dual exhaust pipes" on the aphid's posterior).

Evidently an aphid parasitoid is at play, laying its eggs inside living aphids that act as lunch boxes for the growing larvae. Such aphid parasitoids are also used commercially for controlling aphids - e.g. Aphidius matricariae are released in many greenhouses.

Larva growing inside immobilized aphid
Larva growing inside immobilized aphid

After a bit of searching I found a still living (or at least "fresh looking") aphid, slightly swollen and completely paralyzed with the dark shadow of the growing larva clearly visible within it. Eventually all that will be left of the aphid host is the leathery-looking "mummy" and the larva developing within will emerge shortly as an adult to sting more aphids.

It's brutal but I side with the aphid parasitoid :-)

Tuesday, April 21, 2009

The power of grafting – 5th anniversary

Five years ago today, I grafted a tiny Lophophora williamsii (SB 854; Starr Co, Tx) seedling onto a robust Trichocereus pachanoi stock. The Lophophora scion has since grown considerably – the main head is approximately 8 cm (~3.2'') wide; the total width including the offshoots now exceeds 14 cm (~5.5'').

Lophophora williamsii grafted onto Trichocereus pachanoi stock
Lophophora williamsii grafted onto Trichocereus pachanoi stock

This growing season the plant hasn't flowered yet but one of the “pups” (new offshoot stems) will do so within days as is evident from the next picture.

Flower bud and red spider mites
Flower bud and red spider mites

Unfortunately not only the plants are returning to life after their winter hibernation – the dreaded red spider mites are also fully active again (you should be able to spot at least four mites in the photo above) so the fight is on once more.

Ripe Lophophora williamsii fruit
Ripe Lophophora williamsii fruit

Even though most of last year's fruits have long since ripened (and been harvested) the odd fruit is still showing. A plant this size gives hundreds of seeds each year making it a virtual seed “factory”.

Lophophora williamsii - rib count increasing?
Lophophora williamsii - rib count increasing?

The plant seems set on increasing its rib count beyond 8 – if I'm lucky it will not be content with growing just a few more ribs but go straight for the next number in the Fibonacci sequence, 13. The more ribs the merrier as it means more areoles and consequently more flowers and seeds.

The main head of the grafted Lophophora williamsii has grown 14 pups (15 if you also count a pup's pup – I guess you could call that a grandpup ;-) and has reached a size where it needs to be repotted soon.

For comparison you can check the posts on the same graft as one, two, three, and four years old.

Thursday, February 09, 2006

Strombocactus Carnage or: How I Opened the Bag and Let in Death by Sciarid Fly

Until lately my Strombocactus disciformis ssp. esperanzae seedlings were thriving and slowly growing in the safe and secluded environment of a plastic bag. Recently I checked the plants and found dried husks and seedlings without roots.

Strombocactus disciformis remains
Strombocactus disciformis remains

When I opened the bag a couple of sciarid flies soared out. The soil was sterilized before use so I expect the flies must have entered one of the times I aired the bag.

Sciarid fly (fungus gnat)
Sciarid fly (fungus gnat)

Sciarid flies as such are not dangerous to the plant but their larvae will feed on root hairs, enter the roots or even attack the crown or stem of the plant. In the future I’ll take heed when airing my seedling bags and avoid organic material in the soil (the larvae of most species are scavengers, primarily feeding on decaying organic matter).

Today only one seedling is still alive and it is not doing well – the few seedlings surviving the attack also had to cope with the abrupt introduction to the harsh environment outside the bag (the soil had to dry out completely to kill off any remaining larvae).

Tuesday, December 27, 2005

Munching on Lophophora williamsii - II

My cold house grown Lophs have been maimed by some critter eating big, hearty lumps out of them. There are no traces of snails so I expect the culprit to be a grasshopper or bush-cricket trapped in the house.

Maimed Lophophora williamsii (SB 854; Starr Co, Texas)
Maimed Lophophora williamsii (SB 854; Starr Co, Texas)

Lophophora diffusa (JR; Higuerillas, Queretaro) remains
Lophophora diffusa (JR; Higuerillas, Queretaro) remains

The plants above were sown May 1, 2004 and have grown in the cold house since. Some of this year’s Lophophora seedlings were also taken out by the “unwanted guest”.

I’ve wrapped the pots in horticultural fleece and hope this will keep the culprit out in the future.

Monday, August 15, 2005

Munching on Lophophora williamsii

Until lately my coldhouse grown Lophophora williamsii (SB 854; Starr Co, Tx; sowed May 1, 2004) were dazzling in their immaculate appearance – until some critter decided to munch on them.

Munched on Lophophora
Munched on Lophophora

The main shoot of my Cylindropuntia tunicata was maimed too. A search of the cacti revealed a great green bush-cricket (Tettigonia viridissima) hiding among the plants. I took the mug shot below before releasing the suspected culprit outdoors.

Captured great green bush-cricket
Captured great green bush-cricket

The harm is not too great and I expect the plants to fully recuperate from the damage.

Friday, February 18, 2005

Return of the red bastards

I recently lost all of last years Lophophora fricii seedlings (and a lot of the L. diffusa and L. williamsii seedlings as well) because of too prudent a watering scheme – or so I presumed.

To my dismay the withering of the surviving seedlings continued, even after generous waterings. After a closer inspection of the seedlings, using a x10 magnifying lens, the reason became clear: a bunch of red spider mites were feasting on the plants.

The plants were promptly sprayed with insect soap and the treatment will be repeated in a week. It probably won’t kill off all of the spider mites, so the battle is now on. Last year I fought the spider mites using soap, predator mites, cinnamon and garlic brews, and by raising the humidity levels and increasing the air circulation – apparently some survived.

I wonder if I would have been able to save my L. fricii plants if the mites had been discovered sooner.

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